vendor: update buildkit to opentelemetry support

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/go.opentelemetry.io/otel/sdk/LICENSE

@@ -0,0 +1,201 @@
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vendor/go.opentelemetry.io/otel/sdk/instrumentation/library.go

@@ -0,0 +1,36 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/*
+Package instrumentation provides an instrumentation library structure to be
+passed to both the OpenTelemetry Tracer and Meter components.
+
+This package is currently in a Release Candidate phase. Backwards incompatible changes
+may be introduced prior to v1.0.0, but we believe the current API is ready to stabilize.
+
+For more information see
+[this](https://github.com/open-telemetry/oteps/blob/main/text/0083-component.md).
+*/
+package instrumentation // import "go.opentelemetry.io/otel/sdk/instrumentation"
+
+// Library represents the instrumentation library.
+type Library struct {
+	// Name is the name of the instrumentation library. This should be the
+	// Go package name of that library.
+	Name string
+	// Version is the version of the instrumentation library.
+	Version string
+	// SchemaURL of the telemetry emitted by the library.
+	SchemaURL string
+}

vendor/go.opentelemetry.io/otel/sdk/internal/internal.go

@@ -0,0 +1,37 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package internal // import "go.opentelemetry.io/otel/sdk/internal"
+
+import (
+	"fmt"
+	"time"
+
+	"go.opentelemetry.io/otel"
+)
+
+// UserAgent is the user agent to be added to the outgoing
+// requests from the exporters.
+var UserAgent = fmt.Sprintf("opentelemetry-go/%s", otel.Version())
+
+// MonotonicEndTime returns the end time at present
+// but offset from start, monotonically.
+//
+// The monotonic clock is used in subtractions hence
+// the duration since start added back to start gives
+// end as a monotonic time.
+// See https://golang.org/pkg/time/#hdr-Monotonic_Clocks
+func MonotonicEndTime(start time.Time) time.Time {
+	return start.Add(time.Since(start))
+}

vendor/go.opentelemetry.io/otel/sdk/internal/sanitize.go

@@ -0,0 +1,50 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package internal
+
+import (
+	"strings"
+	"unicode"
+)
+
+const labelKeySizeLimit = 100
+
+// Sanitize returns a string that is trunacated to 100 characters if it's too
+// long, and replaces non-alphanumeric characters to underscores.
+func Sanitize(s string) string {
+	if len(s) == 0 {
+		return s
+	}
+	if len(s) > labelKeySizeLimit {
+		s = s[:labelKeySizeLimit]
+	}
+	s = strings.Map(sanitizeRune, s)
+	if unicode.IsDigit(rune(s[0])) {
+		s = "key_" + s
+	}
+	if s[0] == '_' {
+		s = "key" + s
+	}
+	return s
+}
+
+// converts anything that is not a letter or digit to an underscore
+func sanitizeRune(r rune) rune {
+	if unicode.IsLetter(r) || unicode.IsDigit(r) {
+		return r
+	}
+	// Everything else turns into an underscore
+	return '_'
+}

vendor/go.opentelemetry.io/otel/sdk/resource/auto.go

@@ -0,0 +1,72 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"context"
+	"errors"
+	"fmt"
+)
+
+var (
+	// ErrPartialResource is returned by a detector when complete source
+	// information for a Resource is unavailable or the source information
+	// contains invalid values that are omitted from the returned Resource.
+	ErrPartialResource = errors.New("partial resource")
+)
+
+// Detector detects OpenTelemetry resource information
+type Detector interface {
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+
+	// Detect returns an initialized Resource based on gathered information.
+	// If the source information to construct a Resource contains invalid
+	// values, a Resource is returned with the valid parts of the source
+	// information used for initialization along with an appropriately
+	// wrapped ErrPartialResource error.
+	Detect(ctx context.Context) (*Resource, error)
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+}
+
+// Detect calls all input detectors sequentially and merges each result with the previous one.
+// It returns the merged error too.
+func Detect(ctx context.Context, detectors ...Detector) (*Resource, error) {
+	var autoDetectedRes *Resource
+	var errInfo []string
+	for _, detector := range detectors {
+		if detector == nil {
+			continue
+		}
+		res, err := detector.Detect(ctx)
+		if err != nil {
+			errInfo = append(errInfo, err.Error())
+			if !errors.Is(err, ErrPartialResource) {
+				continue
+			}
+		}
+		autoDetectedRes, err = Merge(autoDetectedRes, res)
+		if err != nil {
+			errInfo = append(errInfo, err.Error())
+		}
+	}
+
+	var aggregatedError error
+	if len(errInfo) > 0 {
+		aggregatedError = fmt.Errorf("detecting resources: %s", errInfo)
+	}
+	return autoDetectedRes, aggregatedError
+}

vendor/go.opentelemetry.io/otel/sdk/resource/builtin.go

@@ -0,0 +1,107 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
+)
+
+type (
+	// telemetrySDK is a Detector that provides information about
+	// the OpenTelemetry SDK used.  This Detector is included as a
+	// builtin. If these resource attributes are not wanted, use
+	// the WithTelemetrySDK(nil) or WithoutBuiltin() options to
+	// explicitly disable them.
+	telemetrySDK struct{}
+
+	// host is a Detector that provides information about the host
+	// being run on. This Detector is included as a builtin. If
+	// these resource attributes are not wanted, use the
+	// WithHost(nil) or WithoutBuiltin() options to explicitly
+	// disable them.
+	host struct{}
+
+	stringDetector struct {
+		schemaURL string
+		K         attribute.Key
+		F         func() (string, error)
+	}
+
+	defaultServiceNameDetector struct{}
+)
+
+var (
+	_ Detector = telemetrySDK{}
+	_ Detector = host{}
+	_ Detector = stringDetector{}
+	_ Detector = defaultServiceNameDetector{}
+)
+
+// Detect returns a *Resource that describes the OpenTelemetry SDK used.
+func (telemetrySDK) Detect(context.Context) (*Resource, error) {
+	return NewWithAttributes(
+		semconv.SchemaURL,
+		semconv.TelemetrySDKNameKey.String("opentelemetry"),
+		semconv.TelemetrySDKLanguageKey.String("go"),
+		semconv.TelemetrySDKVersionKey.String(otel.Version()),
+	), nil
+}
+
+// Detect returns a *Resource that describes the host being run on.
+func (host) Detect(ctx context.Context) (*Resource, error) {
+	return StringDetector(semconv.SchemaURL, semconv.HostNameKey, os.Hostname).Detect(ctx)
+}
+
+// StringDetector returns a Detector that will produce a *Resource
+// containing the string as a value corresponding to k. The resulting Resource
+// will have the specified schemaURL.
+func StringDetector(schemaURL string, k attribute.Key, f func() (string, error)) Detector {
+	return stringDetector{schemaURL: schemaURL, K: k, F: f}
+}
+
+// Detect implements Detector.
+func (sd stringDetector) Detect(ctx context.Context) (*Resource, error) {
+	value, err := sd.F()
+	if err != nil {
+		return nil, fmt.Errorf("%s: %w", string(sd.K), err)
+	}
+	a := sd.K.String(value)
+	if !a.Valid() {
+		return nil, fmt.Errorf("invalid attribute: %q -> %q", a.Key, a.Value.Emit())
+	}
+	return NewWithAttributes(sd.schemaURL, sd.K.String(value)), nil
+}
+
+// Detect implements Detector
+func (defaultServiceNameDetector) Detect(ctx context.Context) (*Resource, error) {
+	return StringDetector(
+		semconv.SchemaURL,
+		semconv.ServiceNameKey,
+		func() (string, error) {
+			executable, err := os.Executable()
+			if err != nil {
+				return "unknown_service:go", nil
+			}
+			return "unknown_service:" + filepath.Base(executable), nil
+		},
+	).Detect(ctx)
+}

vendor/go.opentelemetry.io/otel/sdk/resource/config.go

@@ -0,0 +1,94 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/attribute"
+)
+
+// config contains configuration for Resource creation.
+type config struct {
+	// detectors that will be evaluated.
+	detectors []Detector
+	// SchemaURL to associate with the Resource.
+	schemaURL string
+}
+
+// Option is the interface that applies a configuration option.
+type Option interface {
+	// apply sets the Option value of a config.
+	apply(*config)
+}
+
+// WithAttributes adds attributes to the configured Resource.
+func WithAttributes(attributes ...attribute.KeyValue) Option {
+	return WithDetectors(detectAttributes{attributes})
+}
+
+type detectAttributes struct {
+	attributes []attribute.KeyValue
+}
+
+func (d detectAttributes) Detect(context.Context) (*Resource, error) {
+	return NewSchemaless(d.attributes...), nil
+}
+
+// WithDetectors adds detectors to be evaluated for the configured resource.
+func WithDetectors(detectors ...Detector) Option {
+	return detectorsOption{detectors: detectors}
+}
+
+type detectorsOption struct {
+	detectors []Detector
+}
+
+func (o detectorsOption) apply(cfg *config) {
+	cfg.detectors = append(cfg.detectors, o.detectors...)
+}
+
+// WithBuiltinDetectors adds the built detectors to the configured resource.
+func WithBuiltinDetectors() Option {
+	return WithDetectors(telemetrySDK{},
+		host{},
+		fromEnv{})
+}
+
+// WithFromEnv adds attributes from environment variables to the configured resource.
+func WithFromEnv() Option {
+	return WithDetectors(fromEnv{})
+}
+
+// WithHost adds attributes from the host to the configured resource.
+func WithHost() Option {
+	return WithDetectors(host{})
+}
+
+// WithTelemetrySDK adds TelemetrySDK version info to the configured resource.
+func WithTelemetrySDK() Option {
+	return WithDetectors(telemetrySDK{})
+}
+
+// WithSchemaURL sets the schema URL for the configured resource.
+func WithSchemaURL(schemaURL string) Option {
+	return schemaURLOption(schemaURL)
+}
+
+type schemaURLOption string
+
+func (o schemaURLOption) apply(cfg *config) {
+	cfg.schemaURL = string(o)
+}

vendor/go.opentelemetry.io/otel/sdk/resource/doc.go

@@ -0,0 +1,31 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package resource provides detecting and representing resources.
+//
+// This package is currently in a Release Candidate phase. Backwards incompatible changes
+// may be introduced prior to v1.0.0, but we believe the current API is ready to stabilize.
+//
+// The fundamental struct is a Resource which holds identifying information
+// about the entities for which telemetry is exported.
+//
+// To automatically construct Resources from an environment a Detector
+// interface is defined. Implementations of this interface can be passed to
+// the Detect function to generate a Resource from the merged information.
+//
+// To load a user defined Resource from the environment variable
+// OTEL_RESOURCE_ATTRIBUTES the FromEnv Detector can be used. It will interpret
+// the value as a list of comma delimited key/value pairs
+// (e.g. `<key1>=<value1>,<key2>=<value2>,...`).
+package resource // import "go.opentelemetry.io/otel/sdk/resource"

vendor/go.opentelemetry.io/otel/sdk/resource/env.go

@@ -0,0 +1,96 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"strings"
+
+	"go.opentelemetry.io/otel/attribute"
+	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
+)
+
+const (
+	// resourceAttrKey is the environment variable name OpenTelemetry Resource information will be read from.
+	resourceAttrKey = "OTEL_RESOURCE_ATTRIBUTES"
+
+	// svcNameKey is the environment variable name that Service Name information will be read from.
+	svcNameKey = "OTEL_SERVICE_NAME"
+)
+
+var (
+	// errMissingValue is returned when a resource value is missing.
+	errMissingValue = fmt.Errorf("%w: missing value", ErrPartialResource)
+)
+
+// fromEnv is a Detector that implements the Detector and collects
+// resources from environment.  This Detector is included as a
+// builtin.
+type fromEnv struct{}
+
+// compile time assertion that FromEnv implements Detector interface
+var _ Detector = fromEnv{}
+
+// Detect collects resources from environment
+func (fromEnv) Detect(context.Context) (*Resource, error) {
+	attrs := strings.TrimSpace(os.Getenv(resourceAttrKey))
+	svcName := strings.TrimSpace(os.Getenv(svcNameKey))
+
+	if attrs == "" && svcName == "" {
+		return Empty(), nil
+	}
+
+	var res *Resource
+
+	if svcName != "" {
+		res = NewSchemaless(semconv.ServiceNameKey.String(svcName))
+	}
+
+	r2, err := constructOTResources(attrs)
+
+	// Ensure that the resource with the service name from OTEL_SERVICE_NAME
+	// takes precedence, if it was defined.
+	res, err2 := Merge(r2, res)
+
+	if err == nil {
+		err = err2
+	} else if err2 != nil {
+		err = fmt.Errorf("detecting resources: %s", []string{err.Error(), err2.Error()})
+	}
+
+	return res, err
+}
+
+func constructOTResources(s string) (*Resource, error) {
+	pairs := strings.Split(s, ",")
+	attrs := []attribute.KeyValue{}
+	var invalid []string
+	for _, p := range pairs {
+		field := strings.SplitN(p, "=", 2)
+		if len(field) != 2 {
+			invalid = append(invalid, p)
+			continue
+		}
+		k, v := strings.TrimSpace(field[0]), strings.TrimSpace(field[1])
+		attrs = append(attrs, attribute.String(k, v))
+	}
+	var err error
+	if len(invalid) > 0 {
+		err = fmt.Errorf("%w: %v", errMissingValue, invalid)
+	}
+	return NewSchemaless(attrs...), err
+}

vendor/go.opentelemetry.io/otel/sdk/resource/os.go

@@ -0,0 +1,40 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"context"
+	"strings"
+
+	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
+)
+
+type osTypeDetector struct{}
+
+// Detect returns a *Resource that describes the operating system type the
+// service is running on.
+func (osTypeDetector) Detect(ctx context.Context) (*Resource, error) {
+	osType := runtimeOS()
+
+	return NewWithAttributes(
+		semconv.SchemaURL,
+		semconv.OSTypeKey.String(strings.ToLower(osType)),
+	), nil
+}
+
+// WithOSType adds an attribute with the operating system type to the configured Resource.
+func WithOSType() Option {
+	return WithDetectors(osTypeDetector{})
+}

vendor/go.opentelemetry.io/otel/sdk/resource/process.go

@@ -0,0 +1,238 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/user"
+	"path/filepath"
+	"runtime"
+
+	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
+)
+
+type pidProvider func() int
+type executablePathProvider func() (string, error)
+type commandArgsProvider func() []string
+type ownerProvider func() (*user.User, error)
+type runtimeNameProvider func() string
+type runtimeVersionProvider func() string
+type runtimeOSProvider func() string
+type runtimeArchProvider func() string
+
+var (
+	defaultPidProvider            pidProvider            = os.Getpid
+	defaultExecutablePathProvider executablePathProvider = os.Executable
+	defaultCommandArgsProvider    commandArgsProvider    = func() []string { return os.Args }
+	defaultOwnerProvider          ownerProvider          = user.Current
+	defaultRuntimeNameProvider    runtimeNameProvider    = func() string { return runtime.Compiler }
+	defaultRuntimeVersionProvider runtimeVersionProvider = runtime.Version
+	defaultRuntimeOSProvider      runtimeOSProvider      = func() string { return runtime.GOOS }
+	defaultRuntimeArchProvider    runtimeArchProvider    = func() string { return runtime.GOARCH }
+)
+
+var (
+	pid            = defaultPidProvider
+	executablePath = defaultExecutablePathProvider
+	commandArgs    = defaultCommandArgsProvider
+	owner          = defaultOwnerProvider
+	runtimeName    = defaultRuntimeNameProvider
+	runtimeVersion = defaultRuntimeVersionProvider
+	runtimeOS      = defaultRuntimeOSProvider
+	runtimeArch    = defaultRuntimeArchProvider
+)
+
+func setDefaultOSProviders() {
+	setOSProviders(
+		defaultPidProvider,
+		defaultExecutablePathProvider,
+		defaultCommandArgsProvider,
+	)
+}
+
+func setOSProviders(
+	pidProvider pidProvider,
+	executablePathProvider executablePathProvider,
+	commandArgsProvider commandArgsProvider,
+) {
+	pid = pidProvider
+	executablePath = executablePathProvider
+	commandArgs = commandArgsProvider
+}
+
+func setDefaultRuntimeProviders() {
+	setRuntimeProviders(
+		defaultRuntimeNameProvider,
+		defaultRuntimeVersionProvider,
+		defaultRuntimeOSProvider,
+		defaultRuntimeArchProvider,
+	)
+}
+
+func setRuntimeProviders(
+	runtimeNameProvider runtimeNameProvider,
+	runtimeVersionProvider runtimeVersionProvider,
+	runtimeOSProvider runtimeOSProvider,
+	runtimeArchProvider runtimeArchProvider,
+) {
+	runtimeName = runtimeNameProvider
+	runtimeVersion = runtimeVersionProvider
+	runtimeOS = runtimeOSProvider
+	runtimeArch = runtimeArchProvider
+}
+
+func setDefaultUserProviders() {
+	setUserProviders(defaultOwnerProvider)
+}
+
+func setUserProviders(ownerProvider ownerProvider) {
+	owner = ownerProvider
+}
+
+type processPIDDetector struct{}
+type processExecutableNameDetector struct{}
+type processExecutablePathDetector struct{}
+type processCommandArgsDetector struct{}
+type processOwnerDetector struct{}
+type processRuntimeNameDetector struct{}
+type processRuntimeVersionDetector struct{}
+type processRuntimeDescriptionDetector struct{}
+
+// Detect returns a *Resource that describes the process identifier (PID) of the
+// executing process.
+func (processPIDDetector) Detect(ctx context.Context) (*Resource, error) {
+	return NewWithAttributes(semconv.SchemaURL, semconv.ProcessPIDKey.Int(pid())), nil
+}
+
+// Detect returns a *Resource that describes the name of the process executable.
+func (processExecutableNameDetector) Detect(ctx context.Context) (*Resource, error) {
+	executableName := filepath.Base(commandArgs()[0])
+
+	return NewWithAttributes(semconv.SchemaURL, semconv.ProcessExecutableNameKey.String(executableName)), nil
+}
+
+// Detect returns a *Resource that describes the full path of the process executable.
+func (processExecutablePathDetector) Detect(ctx context.Context) (*Resource, error) {
+	executablePath, err := executablePath()
+	if err != nil {
+		return nil, err
+	}
+
+	return NewWithAttributes(semconv.SchemaURL, semconv.ProcessExecutablePathKey.String(executablePath)), nil
+}
+
+// Detect returns a *Resource that describes all the command arguments as received
+// by the process.
+func (processCommandArgsDetector) Detect(ctx context.Context) (*Resource, error) {
+	return NewWithAttributes(semconv.SchemaURL, semconv.ProcessCommandArgsKey.Array(commandArgs())), nil
+}
+
+// Detect returns a *Resource that describes the username of the user that owns the
+// process.
+func (processOwnerDetector) Detect(ctx context.Context) (*Resource, error) {
+	owner, err := owner()
+	if err != nil {
+		return nil, err
+	}
+
+	return NewWithAttributes(semconv.SchemaURL, semconv.ProcessOwnerKey.String(owner.Username)), nil
+}
+
+// Detect returns a *Resource that describes the name of the compiler used to compile
+// this process image.
+func (processRuntimeNameDetector) Detect(ctx context.Context) (*Resource, error) {
+	return NewWithAttributes(semconv.SchemaURL, semconv.ProcessRuntimeNameKey.String(runtimeName())), nil
+}
+
+// Detect returns a *Resource that describes the version of the runtime of this process.
+func (processRuntimeVersionDetector) Detect(ctx context.Context) (*Resource, error) {
+	return NewWithAttributes(semconv.SchemaURL, semconv.ProcessRuntimeVersionKey.String(runtimeVersion())), nil
+}
+
+// Detect returns a *Resource that describes the runtime of this process.
+func (processRuntimeDescriptionDetector) Detect(ctx context.Context) (*Resource, error) {
+	runtimeDescription := fmt.Sprintf(
+		"go version %s %s/%s", runtimeVersion(), runtimeOS(), runtimeArch())
+
+	return NewWithAttributes(
+		semconv.SchemaURL,
+		semconv.ProcessRuntimeDescriptionKey.String(runtimeDescription),
+	), nil
+}
+
+// WithProcessPID adds an attribute with the process identifier (PID) to the
+// configured Resource.
+func WithProcessPID() Option {
+	return WithDetectors(processPIDDetector{})
+}
+
+// WithProcessExecutableName adds an attribute with the name of the process
+// executable to the configured Resource.
+func WithProcessExecutableName() Option {
+	return WithDetectors(processExecutableNameDetector{})
+}
+
+// WithProcessExecutablePath adds an attribute with the full path to the process
+// executable to the configured Resource.
+func WithProcessExecutablePath() Option {
+	return WithDetectors(processExecutablePathDetector{})
+}
+
+// WithProcessCommandArgs adds an attribute with all the command arguments (including
+// the command/executable itself) as received by the process the configured Resource.
+func WithProcessCommandArgs() Option {
+	return WithDetectors(processCommandArgsDetector{})
+}
+
+// WithProcessOwner adds an attribute with the username of the user that owns the process
+// to the configured Resource.
+func WithProcessOwner() Option {
+	return WithDetectors(processOwnerDetector{})
+}
+
+// WithProcessRuntimeName adds an attribute with the name of the runtime of this
+// process to the configured Resource.
+func WithProcessRuntimeName() Option {
+	return WithDetectors(processRuntimeNameDetector{})
+}
+
+// WithProcessRuntimeVersion adds an attribute with the version of the runtime of
+// this process to the configured Resource.
+func WithProcessRuntimeVersion() Option {
+	return WithDetectors(processRuntimeVersionDetector{})
+}
+
+// WithProcessRuntimeDescription adds an attribute with an additional description
+// about the runtime of the process to the configured Resource.
+func WithProcessRuntimeDescription() Option {
+	return WithDetectors(processRuntimeDescriptionDetector{})
+}
+
+// WithProcess adds all the Process attributes to the configured Resource.
+// See individual WithProcess* functions to configure specific attributes.
+func WithProcess() Option {
+	return WithDetectors(
+		processPIDDetector{},
+		processExecutableNameDetector{},
+		processExecutablePathDetector{},
+		processCommandArgsDetector{},
+		processOwnerDetector{},
+		processRuntimeNameDetector{},
+		processRuntimeVersionDetector{},
+		processRuntimeDescriptionDetector{},
+	)
+}

vendor/go.opentelemetry.io/otel/sdk/resource/resource.go

@@ -0,0 +1,256 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+)
+
+// Resource describes an entity about which identifying information
+// and metadata is exposed.  Resource is an immutable object,
+// equivalent to a map from key to unique value.
+//
+// Resources should be passed and stored as pointers
+// (`*resource.Resource`).  The `nil` value is equivalent to an empty
+// Resource.
+type Resource struct {
+	attrs     attribute.Set
+	schemaURL string
+}
+
+var (
+	emptyResource Resource
+
+	defaultResource = func(r *Resource, err error) *Resource {
+		if err != nil {
+			otel.Handle(err)
+		}
+		return r
+	}(Detect(context.Background(), defaultServiceNameDetector{}, fromEnv{}, telemetrySDK{}))
+)
+
+var (
+	errMergeConflictSchemaURL = errors.New("cannot merge resource due to conflicting Schema URL")
+)
+
+// New returns a Resource combined from the user-provided detectors.
+func New(ctx context.Context, opts ...Option) (*Resource, error) {
+	cfg := config{}
+	for _, opt := range opts {
+		opt.apply(&cfg)
+	}
+
+	resource, err := Detect(ctx, cfg.detectors...)
+
+	var err2 error
+	resource, err2 = Merge(resource, &Resource{schemaURL: cfg.schemaURL})
+	if err == nil {
+		err = err2
+	} else if err2 != nil {
+		err = fmt.Errorf("detecting resources: %s", []string{err.Error(), err2.Error()})
+	}
+
+	return resource, err
+}
+
+// NewWithAttributes creates a resource from attrs and associates the resource with a
+// schema URL. If attrs contains duplicate keys, the last value will be used. If attrs
+// contains any invalid items those items will be dropped. The attrs are assumed to be
+// in a schema identified by schemaURL.
+func NewWithAttributes(schemaURL string, attrs ...attribute.KeyValue) *Resource {
+	resource := NewSchemaless(attrs...)
+	resource.schemaURL = schemaURL
+	return resource
+}
+
+// NewSchemaless creates a resource from attrs. If attrs contains duplicate keys,
+// the last value will be used. If attrs contains any invalid items those items will
+// be dropped. The resource will not be associated with a schema URL. If the schema
+// of the attrs is known use NewWithAttributes instead.
+func NewSchemaless(attrs ...attribute.KeyValue) *Resource {
+	if len(attrs) == 0 {
+		return &emptyResource
+	}
+
+	// Ensure attributes comply with the specification:
+	// https://github.com/open-telemetry/opentelemetry-specification/blob/v1.0.1/specification/common/common.md#attributes
+	s, _ := attribute.NewSetWithFiltered(attrs, func(kv attribute.KeyValue) bool {
+		return kv.Valid()
+	})
+
+	// If attrs only contains invalid entries do not allocate a new resource.
+	if s.Len() == 0 {
+		return &emptyResource
+	}
+
+	return &Resource{attrs: s} //nolint
+}
+
+// String implements the Stringer interface and provides a
+// human-readable form of the resource.
+//
+// Avoid using this representation as the key in a map of resources,
+// use Equivalent() as the key instead.
+func (r *Resource) String() string {
+	if r == nil {
+		return ""
+	}
+	return r.attrs.Encoded(attribute.DefaultEncoder())
+}
+
+// Attributes returns a copy of attributes from the resource in a sorted order.
+// To avoid allocating a new slice, use an iterator.
+func (r *Resource) Attributes() []attribute.KeyValue {
+	if r == nil {
+		r = Empty()
+	}
+	return r.attrs.ToSlice()
+}
+
+func (r *Resource) SchemaURL() string {
+	return r.schemaURL
+}
+
+// Iter returns an interator of the Resource attributes.
+// This is ideal to use if you do not want a copy of the attributes.
+func (r *Resource) Iter() attribute.Iterator {
+	if r == nil {
+		r = Empty()
+	}
+	return r.attrs.Iter()
+}
+
+// Equal returns true when a Resource is equivalent to this Resource.
+func (r *Resource) Equal(eq *Resource) bool {
+	if r == nil {
+		r = Empty()
+	}
+	if eq == nil {
+		eq = Empty()
+	}
+	return r.Equivalent() == eq.Equivalent()
+}
+
+// Merge creates a new resource by combining resource a and b.
+//
+// If there are common keys between resource a and b, then the value
+// from resource b will overwrite the value from resource a, even
+// if resource b's value is empty.
+//
+// The SchemaURL of the resources will be merged according to the spec rules:
+// https://github.com/open-telemetry/opentelemetry-specification/blob/bad49c714a62da5493f2d1d9bafd7ebe8c8ce7eb/specification/resource/sdk.md#merge
+// If the resources have different non-empty schemaURL an empty resource and an error
+// will be returned.
+func Merge(a, b *Resource) (*Resource, error) {
+	if a == nil && b == nil {
+		return Empty(), nil
+	}
+	if a == nil {
+		return b, nil
+	}
+	if b == nil {
+		return a, nil
+	}
+
+	// Merge the schema URL.
+	var schemaURL string
+	if a.schemaURL == "" {
+		schemaURL = b.schemaURL
+	} else if b.schemaURL == "" {
+		schemaURL = a.schemaURL
+	} else if a.schemaURL == b.schemaURL {
+		schemaURL = a.schemaURL
+	} else {
+		return Empty(), errMergeConflictSchemaURL
+	}
+
+	// Note: 'b' attributes will overwrite 'a' with last-value-wins in attribute.Key()
+	// Meaning this is equivalent to: append(a.Attributes(), b.Attributes()...)
+	mi := attribute.NewMergeIterator(b.Set(), a.Set())
+	combine := make([]attribute.KeyValue, 0, a.Len()+b.Len())
+	for mi.Next() {
+		combine = append(combine, mi.Label())
+	}
+	merged := NewWithAttributes(schemaURL, combine...)
+	return merged, nil
+}
+
+// Empty returns an instance of Resource with no attributes.  It is
+// equivalent to a `nil` Resource.
+func Empty() *Resource {
+	return &emptyResource
+}
+
+// Default returns an instance of Resource with a default
+// "service.name" and OpenTelemetrySDK attributes
+func Default() *Resource {
+	return defaultResource
+}
+
+// Environment returns an instance of Resource with attributes
+// extracted from the OTEL_RESOURCE_ATTRIBUTES environment variable.
+func Environment() *Resource {
+	detector := &fromEnv{}
+	resource, err := detector.Detect(context.Background())
+	if err != nil {
+		otel.Handle(err)
+	}
+	return resource
+}
+
+// Equivalent returns an object that can be compared for equality
+// between two resources.  This value is suitable for use as a key in
+// a map.
+func (r *Resource) Equivalent() attribute.Distinct {
+	return r.Set().Equivalent()
+}
+
+// Set returns the equivalent *attribute.Set of this resources attributes.
+func (r *Resource) Set() *attribute.Set {
+	if r == nil {
+		r = Empty()
+	}
+	return &r.attrs
+}
+
+// MarshalJSON encodes the resource attributes as a JSON list of { "Key":
+// "...", "Value": ... } pairs in order sorted by key.
+func (r *Resource) MarshalJSON() ([]byte, error) {
+	if r == nil {
+		r = Empty()
+	}
+	return r.attrs.MarshalJSON()
+}
+
+// Len returns the number of unique key-values in this Resource.
+func (r *Resource) Len() int {
+	if r == nil {
+		return 0
+	}
+	return r.attrs.Len()
+}
+
+// Encoded returns an encoded representation of the resource.
+func (r *Resource) Encoded(enc attribute.Encoder) string {
+	if r == nil {
+		return ""
+	}
+	return r.attrs.Encoded(enc)
+}

vendor/go.opentelemetry.io/otel/sdk/trace/attributesmap.go

@@ -0,0 +1,91 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace // import "go.opentelemetry.io/otel/sdk/trace"
+
+import (
+	"container/list"
+
+	"go.opentelemetry.io/otel/attribute"
+)
+
+// attributesMap is a capped map of attributes, holding the most recent attributes.
+// Eviction is done via a LRU method, the oldest entry is removed to create room for a new entry.
+// Updates are allowed and they refresh the usage of the key.
+//
+// This is based from https://github.com/hashicorp/golang-lru/blob/master/simplelru/lru.go
+// With a subset of the its operations and specific for holding attribute.KeyValue
+type attributesMap struct {
+	attributes   map[attribute.Key]*list.Element
+	evictList    *list.List
+	droppedCount int
+	capacity     int
+}
+
+func newAttributesMap(capacity int) *attributesMap {
+	lm := &attributesMap{
+		attributes: make(map[attribute.Key]*list.Element),
+		evictList:  list.New(),
+		capacity:   capacity,
+	}
+	return lm
+}
+
+func (am *attributesMap) add(kv attribute.KeyValue) {
+	// Check for existing item
+	if ent, ok := am.attributes[kv.Key]; ok {
+		am.evictList.MoveToFront(ent)
+		ent.Value = &kv
+		return
+	}
+
+	// Add new item
+	entry := am.evictList.PushFront(&kv)
+	am.attributes[kv.Key] = entry
+
+	// Verify size not exceeded
+	if am.evictList.Len() > am.capacity {
+		am.removeOldest()
+		am.droppedCount++
+	}
+}
+
+// toKeyValue copies the attributesMap into a slice of attribute.KeyValue and
+// returns it. If the map is empty, a nil is returned.
+// TODO: Is it more efficient to return a pointer to the slice?
+func (am *attributesMap) toKeyValue() []attribute.KeyValue {
+	len := am.evictList.Len()
+	if len == 0 {
+		return nil
+	}
+
+	attributes := make([]attribute.KeyValue, 0, len)
+	for ent := am.evictList.Back(); ent != nil; ent = ent.Prev() {
+		if value, ok := ent.Value.(*attribute.KeyValue); ok {
+			attributes = append(attributes, *value)
+		}
+	}
+
+	return attributes
+}
+
+// removeOldest removes the oldest item from the cache.
+func (am *attributesMap) removeOldest() {
+	ent := am.evictList.Back()
+	if ent != nil {
+		am.evictList.Remove(ent)
+		kv := ent.Value.(*attribute.KeyValue)
+		delete(am.attributes, kv.Key)
+	}
+}

vendor/go.opentelemetry.io/otel/sdk/trace/batch_span_processor.go

@@ -0,0 +1,334 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace // import "go.opentelemetry.io/otel/sdk/trace"
+
+import (
+	"context"
+	"runtime"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"go.opentelemetry.io/otel"
+)
+
+// Defaults for BatchSpanProcessorOptions.
+const (
+	DefaultMaxQueueSize       = 2048
+	DefaultBatchTimeout       = 5000 * time.Millisecond
+	DefaultExportTimeout      = 30000 * time.Millisecond
+	DefaultMaxExportBatchSize = 512
+)
+
+type BatchSpanProcessorOption func(o *BatchSpanProcessorOptions)
+
+type BatchSpanProcessorOptions struct {
+	// MaxQueueSize is the maximum queue size to buffer spans for delayed processing. If the
+	// queue gets full it drops the spans. Use BlockOnQueueFull to change this behavior.
+	// The default value of MaxQueueSize is 2048.
+	MaxQueueSize int
+
+	// BatchTimeout is the maximum duration for constructing a batch. Processor
+	// forcefully sends available spans when timeout is reached.
+	// The default value of BatchTimeout is 5000 msec.
+	BatchTimeout time.Duration
+
+	// ExportTimeout specifies the maximum duration for exporting spans. If the timeout
+	// is reached, the export will be cancelled.
+	// The default value of ExportTimeout is 30000 msec.
+	ExportTimeout time.Duration
+
+	// MaxExportBatchSize is the maximum number of spans to process in a single batch.
+	// If there are more than one batch worth of spans then it processes multiple batches
+	// of spans one batch after the other without any delay.
+	// The default value of MaxExportBatchSize is 512.
+	MaxExportBatchSize int
+
+	// BlockOnQueueFull blocks onEnd() and onStart() method if the queue is full
+	// AND if BlockOnQueueFull is set to true.
+	// Blocking option should be used carefully as it can severely affect the performance of an
+	// application.
+	BlockOnQueueFull bool
+}
+
+// batchSpanProcessor is a SpanProcessor that batches asynchronously-received
+// spans and sends them to a trace.Exporter when complete.
+type batchSpanProcessor struct {
+	e SpanExporter
+	o BatchSpanProcessorOptions
+
+	queue   chan ReadOnlySpan
+	dropped uint32
+
+	batch      []ReadOnlySpan
+	batchMutex sync.Mutex
+	timer      *time.Timer
+	stopWait   sync.WaitGroup
+	stopOnce   sync.Once
+	stopCh     chan struct{}
+}
+
+var _ SpanProcessor = (*batchSpanProcessor)(nil)
+
+// NewBatchSpanProcessor creates a new SpanProcessor that will send completed
+// span batches to the exporter with the supplied options.
+//
+// If the exporter is nil, the span processor will preform no action.
+func NewBatchSpanProcessor(exporter SpanExporter, options ...BatchSpanProcessorOption) SpanProcessor {
+	o := BatchSpanProcessorOptions{
+		BatchTimeout:       DefaultBatchTimeout,
+		ExportTimeout:      DefaultExportTimeout,
+		MaxQueueSize:       DefaultMaxQueueSize,
+		MaxExportBatchSize: DefaultMaxExportBatchSize,
+	}
+	for _, opt := range options {
+		opt(&o)
+	}
+	bsp := &batchSpanProcessor{
+		e:      exporter,
+		o:      o,
+		batch:  make([]ReadOnlySpan, 0, o.MaxExportBatchSize),
+		timer:  time.NewTimer(o.BatchTimeout),
+		queue:  make(chan ReadOnlySpan, o.MaxQueueSize),
+		stopCh: make(chan struct{}),
+	}
+
+	bsp.stopWait.Add(1)
+	go func() {
+		defer bsp.stopWait.Done()
+		bsp.processQueue()
+		bsp.drainQueue()
+	}()
+
+	return bsp
+}
+
+// OnStart method does nothing.
+func (bsp *batchSpanProcessor) OnStart(parent context.Context, s ReadWriteSpan) {}
+
+// OnEnd method enqueues a ReadOnlySpan for later processing.
+func (bsp *batchSpanProcessor) OnEnd(s ReadOnlySpan) {
+	// Do not enqueue spans if we are just going to drop them.
+	if bsp.e == nil {
+		return
+	}
+	bsp.enqueue(s)
+}
+
+// Shutdown flushes the queue and waits until all spans are processed.
+// It only executes once. Subsequent call does nothing.
+func (bsp *batchSpanProcessor) Shutdown(ctx context.Context) error {
+	var err error
+	bsp.stopOnce.Do(func() {
+		wait := make(chan struct{})
+		go func() {
+			close(bsp.stopCh)
+			bsp.stopWait.Wait()
+			if bsp.e != nil {
+				if err := bsp.e.Shutdown(ctx); err != nil {
+					otel.Handle(err)
+				}
+			}
+			close(wait)
+		}()
+		// Wait until the wait group is done or the context is cancelled
+		select {
+		case <-wait:
+		case <-ctx.Done():
+			err = ctx.Err()
+		}
+	})
+	return err
+}
+
+// ForceFlush exports all ended spans that have not yet been exported.
+func (bsp *batchSpanProcessor) ForceFlush(ctx context.Context) error {
+	var err error
+	if bsp.e != nil {
+		wait := make(chan error)
+		go func() {
+			wait <- bsp.exportSpans(ctx)
+			close(wait)
+		}()
+		// Wait until the export is finished or the context is cancelled/timed out
+		select {
+		case err = <-wait:
+		case <-ctx.Done():
+			err = ctx.Err()
+		}
+	}
+	return err
+}
+
+func WithMaxQueueSize(size int) BatchSpanProcessorOption {
+	return func(o *BatchSpanProcessorOptions) {
+		o.MaxQueueSize = size
+	}
+}
+
+func WithMaxExportBatchSize(size int) BatchSpanProcessorOption {
+	return func(o *BatchSpanProcessorOptions) {
+		o.MaxExportBatchSize = size
+	}
+}
+
+func WithBatchTimeout(delay time.Duration) BatchSpanProcessorOption {
+	return func(o *BatchSpanProcessorOptions) {
+		o.BatchTimeout = delay
+	}
+}
+
+func WithExportTimeout(timeout time.Duration) BatchSpanProcessorOption {
+	return func(o *BatchSpanProcessorOptions) {
+		o.ExportTimeout = timeout
+	}
+}
+
+func WithBlocking() BatchSpanProcessorOption {
+	return func(o *BatchSpanProcessorOptions) {
+		o.BlockOnQueueFull = true
+	}
+}
+
+// exportSpans is a subroutine of processing and draining the queue.
+func (bsp *batchSpanProcessor) exportSpans(ctx context.Context) error {
+	bsp.timer.Reset(bsp.o.BatchTimeout)
+
+	bsp.batchMutex.Lock()
+	defer bsp.batchMutex.Unlock()
+
+	if bsp.o.ExportTimeout > 0 {
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ctx, bsp.o.ExportTimeout)
+		defer cancel()
+	}
+
+	if l := len(bsp.batch); l > 0 {
+		err := bsp.e.ExportSpans(ctx, bsp.batch)
+
+		// A new batch is always created after exporting, even if the batch failed to be exported.
+		//
+		// It is up to the exporter to implement any type of retry logic if a batch is failing
+		// to be exported, since it is specific to the protocol and backend being sent to.
+		bsp.batch = bsp.batch[:0]
+
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// processQueue removes spans from the `queue` channel until processor
+// is shut down. It calls the exporter in batches of up to MaxExportBatchSize
+// waiting up to BatchTimeout to form a batch.
+func (bsp *batchSpanProcessor) processQueue() {
+	defer bsp.timer.Stop()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	for {
+		select {
+		case <-bsp.stopCh:
+			return
+		case <-bsp.timer.C:
+			if err := bsp.exportSpans(ctx); err != nil {
+				otel.Handle(err)
+			}
+		case sd := <-bsp.queue:
+			bsp.batchMutex.Lock()
+			bsp.batch = append(bsp.batch, sd)
+			shouldExport := len(bsp.batch) >= bsp.o.MaxExportBatchSize
+			bsp.batchMutex.Unlock()
+			if shouldExport {
+				if !bsp.timer.Stop() {
+					<-bsp.timer.C
+				}
+				if err := bsp.exportSpans(ctx); err != nil {
+					otel.Handle(err)
+				}
+			}
+		}
+	}
+}
+
+// drainQueue awaits the any caller that had added to bsp.stopWait
+// to finish the enqueue, then exports the final batch.
+func (bsp *batchSpanProcessor) drainQueue() {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	for {
+		select {
+		case sd := <-bsp.queue:
+			if sd == nil {
+				if err := bsp.exportSpans(ctx); err != nil {
+					otel.Handle(err)
+				}
+				return
+			}
+
+			bsp.batchMutex.Lock()
+			bsp.batch = append(bsp.batch, sd)
+			shouldExport := len(bsp.batch) == bsp.o.MaxExportBatchSize
+			bsp.batchMutex.Unlock()
+
+			if shouldExport {
+				if err := bsp.exportSpans(ctx); err != nil {
+					otel.Handle(err)
+				}
+			}
+		default:
+			close(bsp.queue)
+		}
+	}
+}
+
+func (bsp *batchSpanProcessor) enqueue(sd ReadOnlySpan) {
+	if !sd.SpanContext().IsSampled() {
+		return
+	}
+
+	// This ensures the bsp.queue<- below does not panic as the
+	// processor shuts down.
+	defer func() {
+		x := recover()
+		switch err := x.(type) {
+		case nil:
+			return
+		case runtime.Error:
+			if err.Error() == "send on closed channel" {
+				return
+			}
+		}
+		panic(x)
+	}()
+
+	select {
+	case <-bsp.stopCh:
+		return
+	default:
+	}
+
+	if bsp.o.BlockOnQueueFull {
+		bsp.queue <- sd
+		return
+	}
+
+	select {
+	case bsp.queue <- sd:
+	default:
+		atomic.AddUint32(&bsp.dropped, 1)
+	}
+}

vendor/go.opentelemetry.io/otel/sdk/trace/config.go

@@ -0,0 +1,68 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace // import "go.opentelemetry.io/otel/sdk/trace"
+
+// SpanLimits represents the limits of a span.
+type SpanLimits struct {
+	// AttributeCountLimit is the maximum allowed span attribute count.
+	AttributeCountLimit int
+
+	// EventCountLimit is the maximum allowed span event count.
+	EventCountLimit int
+
+	// LinkCountLimit is the maximum allowed span link count.
+	LinkCountLimit int
+
+	// AttributePerEventCountLimit is the maximum allowed attribute per span event count.
+	AttributePerEventCountLimit int
+
+	// AttributePerLinkCountLimit is the maximum allowed attribute per span link count.
+	AttributePerLinkCountLimit int
+}
+
+func (sl *SpanLimits) ensureDefault() {
+	if sl.EventCountLimit <= 0 {
+		sl.EventCountLimit = DefaultEventCountLimit
+	}
+	if sl.AttributeCountLimit <= 0 {
+		sl.AttributeCountLimit = DefaultAttributeCountLimit
+	}
+	if sl.LinkCountLimit <= 0 {
+		sl.LinkCountLimit = DefaultLinkCountLimit
+	}
+	if sl.AttributePerEventCountLimit <= 0 {
+		sl.AttributePerEventCountLimit = DefaultAttributePerEventCountLimit
+	}
+	if sl.AttributePerLinkCountLimit <= 0 {
+		sl.AttributePerLinkCountLimit = DefaultAttributePerLinkCountLimit
+	}
+}
+
+const (
+	// DefaultAttributeCountLimit is the default maximum allowed span attribute count.
+	DefaultAttributeCountLimit = 128
+
+	// DefaultEventCountLimit is the default maximum allowed span event count.
+	DefaultEventCountLimit = 128
+
+	// DefaultLinkCountLimit is the default maximum allowed span link count.
+	DefaultLinkCountLimit = 128
+
+	// DefaultAttributePerEventCountLimit is the default maximum allowed attribute per span event count.
+	DefaultAttributePerEventCountLimit = 128
+
+	// DefaultAttributePerLinkCountLimit is the default maximum allowed attribute per span link count.
+	DefaultAttributePerLinkCountLimit = 128
+)

vendor/go.opentelemetry.io/otel/sdk/trace/doc.go

@@ -0,0 +1,24 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/*
+Package trace contains support for OpenTelemetry distributed tracing.
+
+This package is currently in a Release Candidate phase. Backwards incompatible changes
+may be introduced prior to v1.0.0, but we believe the current API is ready to stabilize.
+
+The following assumes a basic familiarity with OpenTelemetry concepts.
+See https://opentelemetry.io.
+*/
+package trace // import "go.opentelemetry.io/otel/sdk/trace"

vendor/go.opentelemetry.io/otel/sdk/trace/event.go

@@ -0,0 +1,37 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace
+
+import (
+	"time"
+
+	"go.opentelemetry.io/otel/attribute"
+)
+
+// Event is a thing that happened during a Span's lifetime.
+type Event struct {
+	// Name is the name of this event
+	Name string
+
+	// Attributes describe the aspects of the event.
+	Attributes []attribute.KeyValue
+
+	// DroppedAttributeCount is the number of attributes that were not
+	// recorded due to configured limits being reached.
+	DroppedAttributeCount int
+
+	// Time at which this event was recorded.
+	Time time.Time
+}

vendor/go.opentelemetry.io/otel/sdk/trace/evictedqueue.go

@@ -0,0 +1,38 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace // import "go.opentelemetry.io/otel/sdk/trace"
+
+type evictedQueue struct {
+	queue        []interface{}
+	capacity     int
+	droppedCount int
+}
+
+func newEvictedQueue(capacity int) *evictedQueue {
+	eq := &evictedQueue{
+		capacity: capacity,
+		queue:    make([]interface{}, 0),
+	}
+
+	return eq
+}
+
+func (eq *evictedQueue) add(value interface{}) {
+	if len(eq.queue) == eq.capacity {
+		eq.queue = eq.queue[1:]
+		eq.droppedCount++
+	}
+	eq.queue = append(eq.queue, value)
+}

vendor/go.opentelemetry.io/otel/sdk/trace/id_generator.go

@@ -0,0 +1,77 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace // import "go.opentelemetry.io/otel/sdk/trace"
+
+import (
+	"context"
+	crand "crypto/rand"
+	"encoding/binary"
+	"math/rand"
+	"sync"
+
+	"go.opentelemetry.io/otel/trace"
+)
+
+// IDGenerator allows custom generators for TraceID and SpanID.
+type IDGenerator interface {
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+
+	// NewIDs returns a new trace and span ID.
+	NewIDs(ctx context.Context) (trace.TraceID, trace.SpanID)
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+
+	// NewSpanID returns a ID for a new span in the trace with traceID.
+	NewSpanID(ctx context.Context, traceID trace.TraceID) trace.SpanID
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+}
+
+type randomIDGenerator struct {
+	sync.Mutex
+	randSource *rand.Rand
+}
+
+var _ IDGenerator = &randomIDGenerator{}
+
+// NewSpanID returns a non-zero span ID from a randomly-chosen sequence.
+func (gen *randomIDGenerator) NewSpanID(ctx context.Context, traceID trace.TraceID) trace.SpanID {
+	gen.Lock()
+	defer gen.Unlock()
+	sid := trace.SpanID{}
+	gen.randSource.Read(sid[:])
+	return sid
+}
+
+// NewIDs returns a non-zero trace ID and a non-zero span ID from a
+// randomly-chosen sequence.
+func (gen *randomIDGenerator) NewIDs(ctx context.Context) (trace.TraceID, trace.SpanID) {
+	gen.Lock()
+	defer gen.Unlock()
+	tid := trace.TraceID{}
+	gen.randSource.Read(tid[:])
+	sid := trace.SpanID{}
+	gen.randSource.Read(sid[:])
+	return tid, sid
+}
+
+func defaultIDGenerator() IDGenerator {
+	gen := &randomIDGenerator{}
+	var rngSeed int64
+	_ = binary.Read(crand.Reader, binary.LittleEndian, &rngSeed)
+	gen.randSource = rand.New(rand.NewSource(rngSeed))
+	return gen
+}

vendor/go.opentelemetry.io/otel/sdk/trace/provider.go

@@ -0,0 +1,345 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace // import "go.opentelemetry.io/otel/sdk/trace"
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"sync/atomic"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/trace"
+
+	"go.opentelemetry.io/otel/sdk/instrumentation"
+	"go.opentelemetry.io/otel/sdk/resource"
+)
+
+const (
+	defaultTracerName = "go.opentelemetry.io/otel/sdk/tracer"
+)
+
+// tracerProviderConfig
+type tracerProviderConfig struct {
+	// processors contains collection of SpanProcessors that are processing pipeline
+	// for spans in the trace signal.
+	// SpanProcessors registered with a TracerProvider and are called at the start
+	// and end of a Span's lifecycle, and are called in the order they are
+	// registered.
+	processors []SpanProcessor
+
+	// sampler is the default sampler used when creating new spans.
+	sampler Sampler
+
+	// idGenerator is used to generate all Span and Trace IDs when needed.
+	idGenerator IDGenerator
+
+	// spanLimits defines the attribute, event, and link limits for spans.
+	spanLimits SpanLimits
+
+	// resource contains attributes representing an entity that produces telemetry.
+	resource *resource.Resource
+}
+
+type TracerProvider struct {
+	mu             sync.Mutex
+	namedTracer    map[instrumentation.Library]*tracer
+	spanProcessors atomic.Value
+	sampler        Sampler
+	idGenerator    IDGenerator
+	spanLimits     SpanLimits
+	resource       *resource.Resource
+}
+
+var _ trace.TracerProvider = &TracerProvider{}
+
+// NewTracerProvider returns a new and configured TracerProvider.
+//
+// By default the returned TracerProvider is configured with:
+//  - a ParentBased(AlwaysSample) Sampler
+//  - a random number IDGenerator
+//  - the resource.Default() Resource
+//  - the default SpanLimits.
+//
+// The passed opts are used to override these default values and configure the
+// returned TracerProvider appropriately.
+func NewTracerProvider(opts ...TracerProviderOption) *TracerProvider {
+	o := &tracerProviderConfig{}
+
+	for _, opt := range opts {
+		opt.apply(o)
+	}
+
+	ensureValidTracerProviderConfig(o)
+
+	tp := &TracerProvider{
+		namedTracer: make(map[instrumentation.Library]*tracer),
+		sampler:     o.sampler,
+		idGenerator: o.idGenerator,
+		spanLimits:  o.spanLimits,
+		resource:    o.resource,
+	}
+
+	for _, sp := range o.processors {
+		tp.RegisterSpanProcessor(sp)
+	}
+
+	return tp
+}
+
+// Tracer returns a Tracer with the given name and options. If a Tracer for
+// the given name and options does not exist it is created, otherwise the
+// existing Tracer is returned.
+//
+// If name is empty, DefaultTracerName is used instead.
+//
+// This method is safe to be called concurrently.
+func (p *TracerProvider) Tracer(name string, opts ...trace.TracerOption) trace.Tracer {
+	c := trace.NewTracerConfig(opts...)
+
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if name == "" {
+		name = defaultTracerName
+	}
+	il := instrumentation.Library{
+		Name:      name,
+		Version:   c.InstrumentationVersion(),
+		SchemaURL: c.SchemaURL(),
+	}
+	t, ok := p.namedTracer[il]
+	if !ok {
+		t = &tracer{
+			provider:               p,
+			instrumentationLibrary: il,
+		}
+		p.namedTracer[il] = t
+	}
+	return t
+}
+
+// RegisterSpanProcessor adds the given SpanProcessor to the list of SpanProcessors
+func (p *TracerProvider) RegisterSpanProcessor(s SpanProcessor) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	new := spanProcessorStates{}
+	if old, ok := p.spanProcessors.Load().(spanProcessorStates); ok {
+		new = append(new, old...)
+	}
+	newSpanSync := &spanProcessorState{
+		sp:    s,
+		state: &sync.Once{},
+	}
+	new = append(new, newSpanSync)
+	p.spanProcessors.Store(new)
+}
+
+// UnregisterSpanProcessor removes the given SpanProcessor from the list of SpanProcessors
+func (p *TracerProvider) UnregisterSpanProcessor(s SpanProcessor) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	spss := spanProcessorStates{}
+	old, ok := p.spanProcessors.Load().(spanProcessorStates)
+	if !ok || len(old) == 0 {
+		return
+	}
+	spss = append(spss, old...)
+
+	// stop the span processor if it is started and remove it from the list
+	var stopOnce *spanProcessorState
+	var idx int
+	for i, sps := range spss {
+		if sps.sp == s {
+			stopOnce = sps
+			idx = i
+		}
+	}
+	if stopOnce != nil {
+		stopOnce.state.Do(func() {
+			if err := s.Shutdown(context.Background()); err != nil {
+				otel.Handle(err)
+			}
+		})
+	}
+	if len(spss) > 1 {
+		copy(spss[idx:], spss[idx+1:])
+	}
+	spss[len(spss)-1] = nil
+	spss = spss[:len(spss)-1]
+
+	p.spanProcessors.Store(spss)
+}
+
+// ForceFlush immediately exports all spans that have not yet been exported for
+// all the registered span processors.
+func (p *TracerProvider) ForceFlush(ctx context.Context) error {
+	spss, ok := p.spanProcessors.Load().(spanProcessorStates)
+	if !ok {
+		return fmt.Errorf("failed to load span processors")
+	}
+	if len(spss) == 0 {
+		return nil
+	}
+
+	for _, sps := range spss {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		default:
+		}
+
+		if err := sps.sp.ForceFlush(ctx); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Shutdown shuts down the span processors in the order they were registered.
+func (p *TracerProvider) Shutdown(ctx context.Context) error {
+	spss, ok := p.spanProcessors.Load().(spanProcessorStates)
+	if !ok {
+		return fmt.Errorf("failed to load span processors")
+	}
+	if len(spss) == 0 {
+		return nil
+	}
+
+	for _, sps := range spss {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		default:
+		}
+
+		var err error
+		sps.state.Do(func() {
+			err = sps.sp.Shutdown(ctx)
+		})
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+type TracerProviderOption interface {
+	apply(*tracerProviderConfig)
+}
+
+type traceProviderOptionFunc func(*tracerProviderConfig)
+
+func (fn traceProviderOptionFunc) apply(cfg *tracerProviderConfig) {
+	fn(cfg)
+}
+
+// WithSyncer registers the exporter with the TracerProvider using a
+// SimpleSpanProcessor.
+//
+// This is not recommended for production use. The synchronous nature of the
+// SimpleSpanProcessor that will wrap the exporter make it good for testing,
+// debugging, or showing examples of other feature, but it will be slow and
+// have a high computation resource usage overhead. The WithBatcher option is
+// recommended for production use instead.
+func WithSyncer(e SpanExporter) TracerProviderOption {
+	return WithSpanProcessor(NewSimpleSpanProcessor(e))
+}
+
+// WithBatcher registers the exporter with the TracerProvider using a
+// BatchSpanProcessor configured with the passed opts.
+func WithBatcher(e SpanExporter, opts ...BatchSpanProcessorOption) TracerProviderOption {
+	return WithSpanProcessor(NewBatchSpanProcessor(e, opts...))
+}
+
+// WithSpanProcessor registers the SpanProcessor with a TracerProvider.
+func WithSpanProcessor(sp SpanProcessor) TracerProviderOption {
+	return traceProviderOptionFunc(func(cfg *tracerProviderConfig) {
+		cfg.processors = append(cfg.processors, sp)
+	})
+}
+
+// WithResource returns a TracerProviderOption that will configure the
+// Resource r as a TracerProvider's Resource. The configured Resource is
+// referenced by all the Tracers the TracerProvider creates. It represents the
+// entity producing telemetry.
+//
+// If this option is not used, the TracerProvider will use the
+// resource.Default() Resource by default.
+func WithResource(r *resource.Resource) TracerProviderOption {
+	return traceProviderOptionFunc(func(cfg *tracerProviderConfig) {
+		var err error
+		cfg.resource, err = resource.Merge(resource.Environment(), r)
+		if err != nil {
+			otel.Handle(err)
+		}
+	})
+}
+
+// WithIDGenerator returns a TracerProviderOption that will configure the
+// IDGenerator g as a TracerProvider's IDGenerator. The configured IDGenerator
+// is used by the Tracers the TracerProvider creates to generate new Span and
+// Trace IDs.
+//
+// If this option is not used, the TracerProvider will use a random number
+// IDGenerator by default.
+func WithIDGenerator(g IDGenerator) TracerProviderOption {
+	return traceProviderOptionFunc(func(cfg *tracerProviderConfig) {
+		if g != nil {
+			cfg.idGenerator = g
+		}
+	})
+}
+
+// WithSampler returns a TracerProviderOption that will configure the Sampler
+// s as a TracerProvider's Sampler. The configured Sampler is used by the
+// Tracers the TracerProvider creates to make their sampling decisions for the
+// Spans they create.
+//
+// If this option is not used, the TracerProvider will use a
+// ParentBased(AlwaysSample) Sampler by default.
+func WithSampler(s Sampler) TracerProviderOption {
+	return traceProviderOptionFunc(func(cfg *tracerProviderConfig) {
+		if s != nil {
+			cfg.sampler = s
+		}
+	})
+}
+
+// WithSpanLimits returns a TracerProviderOption that will configure the
+// SpanLimits sl as a TracerProvider's SpanLimits. The configured SpanLimits
+// are used used by the Tracers the TracerProvider and the Spans they create
+// to limit tracing resources used.
+//
+// If this option is not used, the TracerProvider will use the default
+// SpanLimits.
+func WithSpanLimits(sl SpanLimits) TracerProviderOption {
+	return traceProviderOptionFunc(func(cfg *tracerProviderConfig) {
+		cfg.spanLimits = sl
+	})
+}
+
+// ensureValidTracerProviderConfig ensures that given TracerProviderConfig is valid.
+func ensureValidTracerProviderConfig(cfg *tracerProviderConfig) {
+	if cfg.sampler == nil {
+		cfg.sampler = ParentBased(AlwaysSample())
+	}
+	if cfg.idGenerator == nil {
+		cfg.idGenerator = defaultIDGenerator()
+	}
+	cfg.spanLimits.ensureDefault()
+	if cfg.resource == nil {
+		cfg.resource = resource.Default()
+	}
+}

vendor/go.opentelemetry.io/otel/sdk/trace/sampling.go

@@ -0,0 +1,288 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace // import "go.opentelemetry.io/otel/sdk/trace"
+
+import (
+	"context"
+	"encoding/binary"
+	"fmt"
+
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/trace"
+)
+
+// Sampler decides whether a trace should be sampled and exported.
+type Sampler interface {
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+
+	// ShouldSample returns a SamplingResult based on a decision made from the
+	// passed parameters.
+	ShouldSample(parameters SamplingParameters) SamplingResult
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+
+	// Description returns information describing the Sampler.
+	Description() string
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+}
+
+// SamplingParameters contains the values passed to a Sampler.
+type SamplingParameters struct {
+	ParentContext context.Context
+	TraceID       trace.TraceID
+	Name          string
+	Kind          trace.SpanKind
+	Attributes    []attribute.KeyValue
+	Links         []trace.Link
+}
+
+// SamplingDecision indicates whether a span is dropped, recorded and/or sampled.
+type SamplingDecision uint8
+
+// Valid sampling decisions
+const (
+	// Drop will not record the span and all attributes/events will be dropped
+	Drop SamplingDecision = iota
+
+	// Record indicates the span's `IsRecording() == true`, but `Sampled` flag
+	// *must not* be set
+	RecordOnly
+
+	// RecordAndSample has span's `IsRecording() == true` and `Sampled` flag
+	// *must* be set
+	RecordAndSample
+)
+
+// SamplingResult conveys a SamplingDecision, set of Attributes and a Tracestate.
+type SamplingResult struct {
+	Decision   SamplingDecision
+	Attributes []attribute.KeyValue
+	Tracestate trace.TraceState
+}
+
+type traceIDRatioSampler struct {
+	traceIDUpperBound uint64
+	description       string
+}
+
+func (ts traceIDRatioSampler) ShouldSample(p SamplingParameters) SamplingResult {
+	psc := trace.SpanContextFromContext(p.ParentContext)
+	x := binary.BigEndian.Uint64(p.TraceID[0:8]) >> 1
+	if x < ts.traceIDUpperBound {
+		return SamplingResult{
+			Decision:   RecordAndSample,
+			Tracestate: psc.TraceState(),
+		}
+	}
+	return SamplingResult{
+		Decision:   Drop,
+		Tracestate: psc.TraceState(),
+	}
+}
+
+func (ts traceIDRatioSampler) Description() string {
+	return ts.description
+}
+
+// TraceIDRatioBased samples a given fraction of traces. Fractions >= 1 will
+// always sample. Fractions < 0 are treated as zero. To respect the
+// parent trace's `SampledFlag`, the `TraceIDRatioBased` sampler should be used
+// as a delegate of a `Parent` sampler.
+//nolint:revive // revive complains about stutter of `trace.TraceIDRatioBased`
+func TraceIDRatioBased(fraction float64) Sampler {
+	if fraction >= 1 {
+		return AlwaysSample()
+	}
+
+	if fraction <= 0 {
+		fraction = 0
+	}
+
+	return &traceIDRatioSampler{
+		traceIDUpperBound: uint64(fraction * (1 << 63)),
+		description:       fmt.Sprintf("TraceIDRatioBased{%g}", fraction),
+	}
+}
+
+type alwaysOnSampler struct{}
+
+func (as alwaysOnSampler) ShouldSample(p SamplingParameters) SamplingResult {
+	return SamplingResult{
+		Decision:   RecordAndSample,
+		Tracestate: trace.SpanContextFromContext(p.ParentContext).TraceState(),
+	}
+}
+
+func (as alwaysOnSampler) Description() string {
+	return "AlwaysOnSampler"
+}
+
+// AlwaysSample returns a Sampler that samples every trace.
+// Be careful about using this sampler in a production application with
+// significant traffic: a new trace will be started and exported for every
+// request.
+func AlwaysSample() Sampler {
+	return alwaysOnSampler{}
+}
+
+type alwaysOffSampler struct{}
+
+func (as alwaysOffSampler) ShouldSample(p SamplingParameters) SamplingResult {
+	return SamplingResult{
+		Decision:   Drop,
+		Tracestate: trace.SpanContextFromContext(p.ParentContext).TraceState(),
+	}
+}
+
+func (as alwaysOffSampler) Description() string {
+	return "AlwaysOffSampler"
+}
+
+// NeverSample returns a Sampler that samples no traces.
+func NeverSample() Sampler {
+	return alwaysOffSampler{}
+}
+
+// ParentBased returns a composite sampler which behaves differently,
+// based on the parent of the span. If the span has no parent,
+// the root(Sampler) is used to make sampling decision. If the span has
+// a parent, depending on whether the parent is remote and whether it
+// is sampled, one of the following samplers will apply:
+// - remoteParentSampled(Sampler) (default: AlwaysOn)
+// - remoteParentNotSampled(Sampler) (default: AlwaysOff)
+// - localParentSampled(Sampler) (default: AlwaysOn)
+// - localParentNotSampled(Sampler) (default: AlwaysOff)
+func ParentBased(root Sampler, samplers ...ParentBasedSamplerOption) Sampler {
+	return parentBased{
+		root:   root,
+		config: configureSamplersForParentBased(samplers),
+	}
+}
+
+type parentBased struct {
+	root   Sampler
+	config samplerConfig
+}
+
+func configureSamplersForParentBased(samplers []ParentBasedSamplerOption) samplerConfig {
+	c := samplerConfig{
+		remoteParentSampled:    AlwaysSample(),
+		remoteParentNotSampled: NeverSample(),
+		localParentSampled:     AlwaysSample(),
+		localParentNotSampled:  NeverSample(),
+	}
+
+	for _, so := range samplers {
+		so.apply(&c)
+	}
+
+	return c
+}
+
+// samplerConfig is a group of options for parentBased sampler.
+type samplerConfig struct {
+	remoteParentSampled, remoteParentNotSampled Sampler
+	localParentSampled, localParentNotSampled   Sampler
+}
+
+// ParentBasedSamplerOption configures the sampler for a particular sampling case.
+type ParentBasedSamplerOption interface {
+	apply(*samplerConfig)
+}
+
+// WithRemoteParentSampled sets the sampler for the case of sampled remote parent.
+func WithRemoteParentSampled(s Sampler) ParentBasedSamplerOption {
+	return remoteParentSampledOption{s}
+}
+
+type remoteParentSampledOption struct {
+	s Sampler
+}
+
+func (o remoteParentSampledOption) apply(config *samplerConfig) {
+	config.remoteParentSampled = o.s
+}
+
+// WithRemoteParentNotSampled sets the sampler for the case of remote parent
+// which is not sampled.
+func WithRemoteParentNotSampled(s Sampler) ParentBasedSamplerOption {
+	return remoteParentNotSampledOption{s}
+}
+
+type remoteParentNotSampledOption struct {
+	s Sampler
+}
+
+func (o remoteParentNotSampledOption) apply(config *samplerConfig) {
+	config.remoteParentNotSampled = o.s
+}
+
+// WithLocalParentSampled sets the sampler for the case of sampled local parent.
+func WithLocalParentSampled(s Sampler) ParentBasedSamplerOption {
+	return localParentSampledOption{s}
+}
+
+type localParentSampledOption struct {
+	s Sampler
+}
+
+func (o localParentSampledOption) apply(config *samplerConfig) {
+	config.localParentSampled = o.s
+}
+
+// WithLocalParentNotSampled sets the sampler for the case of local parent
+// which is not sampled.
+func WithLocalParentNotSampled(s Sampler) ParentBasedSamplerOption {
+	return localParentNotSampledOption{s}
+}
+
+type localParentNotSampledOption struct {
+	s Sampler
+}
+
+func (o localParentNotSampledOption) apply(config *samplerConfig) {
+	config.localParentNotSampled = o.s
+}
+
+func (pb parentBased) ShouldSample(p SamplingParameters) SamplingResult {
+	psc := trace.SpanContextFromContext(p.ParentContext)
+	if psc.IsValid() {
+		if psc.IsRemote() {
+			if psc.IsSampled() {
+				return pb.config.remoteParentSampled.ShouldSample(p)
+			}
+			return pb.config.remoteParentNotSampled.ShouldSample(p)
+		}
+
+		if psc.IsSampled() {
+			return pb.config.localParentSampled.ShouldSample(p)
+		}
+		return pb.config.localParentNotSampled.ShouldSample(p)
+	}
+	return pb.root.ShouldSample(p)
+}
+
+func (pb parentBased) Description() string {
+	return fmt.Sprintf("ParentBased{root:%s,remoteParentSampled:%s,"+
+		"remoteParentNotSampled:%s,localParentSampled:%s,localParentNotSampled:%s}",
+		pb.root.Description(),
+		pb.config.remoteParentSampled.Description(),
+		pb.config.remoteParentNotSampled.Description(),
+		pb.config.localParentSampled.Description(),
+		pb.config.localParentNotSampled.Description(),
+	)
+}

vendor/go.opentelemetry.io/otel/sdk/trace/simple_span_processor.go

@@ -0,0 +1,103 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace // import "go.opentelemetry.io/otel/sdk/trace"
+
+import (
+	"context"
+	"sync"
+
+	"go.opentelemetry.io/otel"
+)
+
+// simpleSpanProcessor is a SpanProcessor that synchronously sends all
+// completed Spans to a trace.Exporter immediately.
+type simpleSpanProcessor struct {
+	exporterMu sync.RWMutex
+	exporter   SpanExporter
+	stopOnce   sync.Once
+}
+
+var _ SpanProcessor = (*simpleSpanProcessor)(nil)
+
+// NewSimpleSpanProcessor returns a new SpanProcessor that will synchronously
+// send completed spans to the exporter immediately.
+//
+// This SpanProcessor is not recommended for production use. The synchronous
+// nature of this SpanProcessor make it good for testing, debugging, or
+// showing examples of other feature, but it will be slow and have a high
+// computation resource usage overhead. The BatchSpanProcessor is recommended
+// for production use instead.
+func NewSimpleSpanProcessor(exporter SpanExporter) SpanProcessor {
+	ssp := &simpleSpanProcessor{
+		exporter: exporter,
+	}
+	return ssp
+}
+
+// OnStart does nothing.
+func (ssp *simpleSpanProcessor) OnStart(context.Context, ReadWriteSpan) {}
+
+// OnEnd immediately exports a ReadOnlySpan.
+func (ssp *simpleSpanProcessor) OnEnd(s ReadOnlySpan) {
+	ssp.exporterMu.RLock()
+	defer ssp.exporterMu.RUnlock()
+
+	if ssp.exporter != nil && s.SpanContext().TraceFlags().IsSampled() {
+		if err := ssp.exporter.ExportSpans(context.Background(), []ReadOnlySpan{s}); err != nil {
+			otel.Handle(err)
+		}
+	}
+}
+
+// Shutdown shuts down the exporter this SimpleSpanProcessor exports to.
+func (ssp *simpleSpanProcessor) Shutdown(ctx context.Context) error {
+	var err error
+	ssp.stopOnce.Do(func() {
+		stopFunc := func(exp SpanExporter) (<-chan error, func()) {
+			done := make(chan error)
+			return done, func() { done <- exp.Shutdown(ctx) }
+		}
+
+		// The exporter field of the simpleSpanProcessor needs to be zeroed to
+		// signal it is shut down, meaning all subsequent calls to OnEnd will
+		// be gracefully ignored. This needs to be done synchronously to avoid
+		// any race condition.
+		//
+		// A closure is used to keep reference to the exporter and then the
+		// field is zeroed. This ensures the simpleSpanProcessor is shut down
+		// before the exporter. This order is important as it avoids a
+		// potential deadlock. If the exporter shut down operation generates a
+		// span, that span would need to be exported. Meaning, OnEnd would be
+		// called and try acquiring the lock that is held here.
+		ssp.exporterMu.Lock()
+		done, shutdown := stopFunc(ssp.exporter)
+		ssp.exporter = nil
+		ssp.exporterMu.Unlock()
+
+		go shutdown()
+
+		select {
+		case err = <-done:
+		case <-ctx.Done():
+			err = ctx.Err()
+		}
+	})
+	return err
+}
+
+// ForceFlush does nothing as there is no data to flush.
+func (ssp *simpleSpanProcessor) ForceFlush(context.Context) error {
+	return nil
+}

vendor/go.opentelemetry.io/otel/sdk/trace/snapshot.go

@@ -0,0 +1,138 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace
+
+import (
+	"time"
+
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/sdk/instrumentation"
+	"go.opentelemetry.io/otel/sdk/resource"
+	"go.opentelemetry.io/otel/trace"
+)
+
+// snapshot is an record of a spans state at a particular checkpointed time.
+// It is used as a read-only representation of that state.
+type snapshot struct {
+	name                   string
+	spanContext            trace.SpanContext
+	parent                 trace.SpanContext
+	spanKind               trace.SpanKind
+	startTime              time.Time
+	endTime                time.Time
+	attributes             []attribute.KeyValue
+	events                 []Event
+	links                  []trace.Link
+	status                 Status
+	childSpanCount         int
+	droppedAttributeCount  int
+	droppedEventCount      int
+	droppedLinkCount       int
+	resource               *resource.Resource
+	instrumentationLibrary instrumentation.Library
+}
+
+var _ ReadOnlySpan = snapshot{}
+
+func (s snapshot) private() {}
+
+// Name returns the name of the span.
+func (s snapshot) Name() string {
+	return s.name
+}
+
+// SpanContext returns the unique SpanContext that identifies the span.
+func (s snapshot) SpanContext() trace.SpanContext {
+	return s.spanContext
+}
+
+// Parent returns the unique SpanContext that identifies the parent of the
+// span if one exists. If the span has no parent the returned SpanContext
+// will be invalid.
+func (s snapshot) Parent() trace.SpanContext {
+	return s.parent
+}
+
+// SpanKind returns the role the span plays in a Trace.
+func (s snapshot) SpanKind() trace.SpanKind {
+	return s.spanKind
+}
+
+// StartTime returns the time the span started recording.
+func (s snapshot) StartTime() time.Time {
+	return s.startTime
+}
+
+// EndTime returns the time the span stopped recording. It will be zero if
+// the span has not ended.
+func (s snapshot) EndTime() time.Time {
+	return s.endTime
+}
+
+// Attributes returns the defining attributes of the span.
+func (s snapshot) Attributes() []attribute.KeyValue {
+	return s.attributes
+}
+
+// Links returns all the links the span has to other spans.
+func (s snapshot) Links() []trace.Link {
+	return s.links
+}
+
+// Events returns all the events that occurred within in the spans
+// lifetime.
+func (s snapshot) Events() []Event {
+	return s.events
+}
+
+// Status returns the spans status.
+func (s snapshot) Status() Status {
+	return s.status
+}
+
+// InstrumentationLibrary returns information about the instrumentation
+// library that created the span.
+func (s snapshot) InstrumentationLibrary() instrumentation.Library {
+	return s.instrumentationLibrary
+}
+
+// Resource returns information about the entity that produced the span.
+func (s snapshot) Resource() *resource.Resource {
+	return s.resource
+}
+
+// DroppedAttributes returns the number of attributes dropped by the span
+// due to limits being reached.
+func (s snapshot) DroppedAttributes() int {
+	return s.droppedAttributeCount
+}
+
+// DroppedLinks returns the number of links dropped by the span due to limits
+// being reached.
+func (s snapshot) DroppedLinks() int {
+	return s.droppedLinkCount
+}
+
+// DroppedEvents returns the number of events dropped by the span due to
+// limits being reached.
+func (s snapshot) DroppedEvents() int {
+	return s.droppedEventCount
+}
+
+// ChildSpanCount returns the count of spans that consider the span a
+// direct parent.
+func (s snapshot) ChildSpanCount() int {
+	return s.childSpanCount
+}

vendor/go.opentelemetry.io/otel/sdk/trace/span.go

@@ -0,0 +1,641 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace // import "go.opentelemetry.io/otel/sdk/trace"
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+	"sync"
+	"time"
+
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/codes"
+	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
+	"go.opentelemetry.io/otel/trace"
+
+	"go.opentelemetry.io/otel/sdk/instrumentation"
+	"go.opentelemetry.io/otel/sdk/internal"
+	"go.opentelemetry.io/otel/sdk/resource"
+)
+
+// ReadOnlySpan allows reading information from the data structure underlying a
+// trace.Span. It is used in places where reading information from a span is
+// necessary but changing the span isn't necessary or allowed.
+//
+// Warning: methods may be added to this interface in minor releases.
+type ReadOnlySpan interface {
+	// Name returns the name of the span.
+	Name() string
+	// SpanContext returns the unique SpanContext that identifies the span.
+	SpanContext() trace.SpanContext
+	// Parent returns the unique SpanContext that identifies the parent of the
+	// span if one exists. If the span has no parent the returned SpanContext
+	// will be invalid.
+	Parent() trace.SpanContext
+	// SpanKind returns the role the span plays in a Trace.
+	SpanKind() trace.SpanKind
+	// StartTime returns the time the span started recording.
+	StartTime() time.Time
+	// EndTime returns the time the span stopped recording. It will be zero if
+	// the span has not ended.
+	EndTime() time.Time
+	// Attributes returns the defining attributes of the span.
+	Attributes() []attribute.KeyValue
+	// Links returns all the links the span has to other spans.
+	Links() []trace.Link
+	// Events returns all the events that occurred within in the spans
+	// lifetime.
+	Events() []Event
+	// Status returns the spans status.
+	Status() Status
+	// InstrumentationLibrary returns information about the instrumentation
+	// library that created the span.
+	InstrumentationLibrary() instrumentation.Library
+	// Resource returns information about the entity that produced the span.
+	Resource() *resource.Resource
+	// DroppedAttributes returns the number of attributes dropped by the span
+	// due to limits being reached.
+	DroppedAttributes() int
+	// DroppedLinks returns the number of links dropped by the span due to
+	// limits being reached.
+	DroppedLinks() int
+	// DroppedEvents returns the number of events dropped by the span due to
+	// limits being reached.
+	DroppedEvents() int
+	// ChildSpanCount returns the count of spans that consider the span a
+	// direct parent.
+	ChildSpanCount() int
+
+	// A private method to prevent users implementing the
+	// interface and so future additions to it will not
+	// violate compatibility.
+	private()
+}
+
+// ReadWriteSpan exposes the same methods as trace.Span and in addition allows
+// reading information from the underlying data structure.
+// This interface exposes the union of the methods of trace.Span (which is a
+// "write-only" span) and ReadOnlySpan. New methods for writing or reading span
+// information should be added under trace.Span or ReadOnlySpan, respectively.
+//
+// Warning: methods may be added to this interface in minor releases.
+type ReadWriteSpan interface {
+	trace.Span
+	ReadOnlySpan
+}
+
+// span is an implementation of the OpenTelemetry Span API representing the
+// individual component of a trace.
+type span struct {
+	// mu protects the contents of this span.
+	mu sync.Mutex
+
+	// parent holds the parent span of this span as a trace.SpanContext.
+	parent trace.SpanContext
+
+	// spanKind represents the kind of this span as a trace.SpanKind.
+	spanKind trace.SpanKind
+
+	// name is the name of this span.
+	name string
+
+	// startTime is the time at which this span was started.
+	startTime time.Time
+
+	// endTime is the time at which this span was ended. It contains the zero
+	// value of time.Time until the span is ended.
+	endTime time.Time
+
+	// status is the status of this span.
+	status Status
+
+	// childSpanCount holds the number of child spans created for this span.
+	childSpanCount int
+
+	// resource contains attributes representing an entity that produced this
+	// span.
+	resource *resource.Resource
+
+	// instrumentationLibrary defines the instrumentation library used to
+	// provide instrumentation.
+	instrumentationLibrary instrumentation.Library
+
+	// spanContext holds the SpanContext of this span.
+	spanContext trace.SpanContext
+
+	// attributes are capped at configured limit. When the capacity is reached
+	// an oldest entry is removed to create room for a new entry.
+	attributes *attributesMap
+
+	// events are stored in FIFO queue capped by configured limit.
+	events *evictedQueue
+
+	// links are stored in FIFO queue capped by configured limit.
+	links *evictedQueue
+
+	// executionTracerTaskEnd ends the execution tracer span.
+	executionTracerTaskEnd func()
+
+	// tracer is the SDK tracer that created this span.
+	tracer *tracer
+
+	// spanLimits holds the limits to this span.
+	spanLimits SpanLimits
+}
+
+var _ trace.Span = &span{}
+
+// SpanContext returns the SpanContext of this span.
+func (s *span) SpanContext() trace.SpanContext {
+	if s == nil {
+		return trace.SpanContext{}
+	}
+	return s.spanContext
+}
+
+// IsRecording returns if this span is being recorded. If this span has ended
+// this will return false.
+func (s *span) IsRecording() bool {
+	if s == nil {
+		return false
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	return !s.startTime.IsZero() && s.endTime.IsZero()
+}
+
+// SetStatus sets the status of the Span in the form of a code and a
+// description, overriding previous values set. The description is only
+// included in the set status when the code is for an error. If this span is
+// not being recorded than this method does nothing.
+func (s *span) SetStatus(code codes.Code, description string) {
+	if !s.IsRecording() {
+		return
+	}
+
+	status := Status{Code: code}
+	if code == codes.Error {
+		status.Description = description
+	}
+
+	s.mu.Lock()
+	s.status = status
+	s.mu.Unlock()
+}
+
+// SetAttributes sets attributes of this span.
+//
+// If a key from attributes already exists the value associated with that key
+// will be overwritten with the value contained in attributes.
+//
+// If this span is not being recorded than this method does nothing.
+func (s *span) SetAttributes(attributes ...attribute.KeyValue) {
+	if !s.IsRecording() {
+		return
+	}
+	s.copyToCappedAttributes(attributes...)
+}
+
+// End ends the span. This method does nothing if the span is already ended or
+// is not being recorded.
+//
+// The only SpanOption currently supported is WithTimestamp which will set the
+// end time for a Span's life-cycle.
+//
+// If this method is called while panicking an error event is added to the
+// Span before ending it and the panic is continued.
+func (s *span) End(options ...trace.SpanEndOption) {
+	// Do not start by checking if the span is being recorded which requires
+	// acquiring a lock. Make a minimal check that the span is not nil.
+	if s == nil {
+		return
+	}
+
+	// Store the end time as soon as possible to avoid artificially increasing
+	// the span's duration in case some operation below takes a while.
+	et := internal.MonotonicEndTime(s.startTime)
+
+	// Do relative expensive check now that we have an end time and see if we
+	// need to do any more processing.
+	if !s.IsRecording() {
+		return
+	}
+
+	if recovered := recover(); recovered != nil {
+		// Record but don't stop the panic.
+		defer panic(recovered)
+		s.addEvent(
+			semconv.ExceptionEventName,
+			trace.WithAttributes(
+				semconv.ExceptionTypeKey.String(typeStr(recovered)),
+				semconv.ExceptionMessageKey.String(fmt.Sprint(recovered)),
+			),
+		)
+	}
+
+	if s.executionTracerTaskEnd != nil {
+		s.executionTracerTaskEnd()
+	}
+
+	config := trace.NewSpanEndConfig(options...)
+
+	s.mu.Lock()
+	// Setting endTime to non-zero marks the span as ended and not recording.
+	if config.Timestamp().IsZero() {
+		s.endTime = et
+	} else {
+		s.endTime = config.Timestamp()
+	}
+	s.mu.Unlock()
+
+	sps, ok := s.tracer.provider.spanProcessors.Load().(spanProcessorStates)
+	mustExportOrProcess := ok && len(sps) > 0
+	if mustExportOrProcess {
+		for _, sp := range sps {
+			sp.sp.OnEnd(s.snapshot())
+		}
+	}
+}
+
+// RecordError will record err as a span event for this span. An additional call to
+// SetStatus is required if the Status of the Span should be set to Error, this method
+// does not change the Span status. If this span is not being recorded or err is nil
+// than this method does nothing.
+func (s *span) RecordError(err error, opts ...trace.EventOption) {
+	if s == nil || err == nil || !s.IsRecording() {
+		return
+	}
+
+	opts = append(opts, trace.WithAttributes(
+		semconv.ExceptionTypeKey.String(typeStr(err)),
+		semconv.ExceptionMessageKey.String(err.Error()),
+	))
+	s.addEvent(semconv.ExceptionEventName, opts...)
+}
+
+func typeStr(i interface{}) string {
+	t := reflect.TypeOf(i)
+	if t.PkgPath() == "" && t.Name() == "" {
+		// Likely a builtin type.
+		return t.String()
+	}
+	return fmt.Sprintf("%s.%s", t.PkgPath(), t.Name())
+}
+
+// AddEvent adds an event with the provided name and options. If this span is
+// not being recorded than this method does nothing.
+func (s *span) AddEvent(name string, o ...trace.EventOption) {
+	if !s.IsRecording() {
+		return
+	}
+	s.addEvent(name, o...)
+}
+
+func (s *span) addEvent(name string, o ...trace.EventOption) {
+	c := trace.NewEventConfig(o...)
+
+	// Discard over limited attributes
+	attributes := c.Attributes()
+	var discarded int
+	if len(attributes) > s.spanLimits.AttributePerEventCountLimit {
+		discarded = len(attributes) - s.spanLimits.AttributePerEventCountLimit
+		attributes = attributes[:s.spanLimits.AttributePerEventCountLimit]
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.events.add(Event{
+		Name:                  name,
+		Attributes:            attributes,
+		DroppedAttributeCount: discarded,
+		Time:                  c.Timestamp(),
+	})
+}
+
+// SetName sets the name of this span. If this span is not being recorded than
+// this method does nothing.
+func (s *span) SetName(name string) {
+	if !s.IsRecording() {
+		return
+	}
+
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.name = name
+}
+
+// Name returns the name of this span.
+func (s *span) Name() string {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.name
+}
+
+// Name returns the SpanContext of this span's parent span.
+func (s *span) Parent() trace.SpanContext {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.parent
+}
+
+// SpanKind returns the SpanKind of this span.
+func (s *span) SpanKind() trace.SpanKind {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.spanKind
+}
+
+// StartTime returns the time this span started.
+func (s *span) StartTime() time.Time {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.startTime
+}
+
+// EndTime returns the time this span ended. For spans that have not yet
+// ended, the returned value will be the zero value of time.Time.
+func (s *span) EndTime() time.Time {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.endTime
+}
+
+// Attributes returns the attributes of this span.
+func (s *span) Attributes() []attribute.KeyValue {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.attributes.evictList.Len() == 0 {
+		return []attribute.KeyValue{}
+	}
+	return s.attributes.toKeyValue()
+}
+
+// Links returns the links of this span.
+func (s *span) Links() []trace.Link {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if len(s.links.queue) == 0 {
+		return []trace.Link{}
+	}
+	return s.interfaceArrayToLinksArray()
+}
+
+// Events returns the events of this span.
+func (s *span) Events() []Event {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if len(s.events.queue) == 0 {
+		return []Event{}
+	}
+	return s.interfaceArrayToEventArray()
+}
+
+// Status returns the status of this span.
+func (s *span) Status() Status {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.status
+}
+
+// InstrumentationLibrary returns the instrumentation.Library associated with
+// the Tracer that created this span.
+func (s *span) InstrumentationLibrary() instrumentation.Library {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.instrumentationLibrary
+}
+
+// Resource returns the Resource associated with the Tracer that created this
+// span.
+func (s *span) Resource() *resource.Resource {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.resource
+}
+
+func (s *span) addLink(link trace.Link) {
+	if !s.IsRecording() {
+		return
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	// Discard over limited attributes
+	if len(link.Attributes) > s.spanLimits.AttributePerLinkCountLimit {
+		link.DroppedAttributeCount = len(link.Attributes) - s.spanLimits.AttributePerLinkCountLimit
+		link.Attributes = link.Attributes[:s.spanLimits.AttributePerLinkCountLimit]
+	}
+
+	s.links.add(link)
+}
+
+// DroppedAttributes returns the number of attributes dropped by the span
+// due to limits being reached.
+func (s *span) DroppedAttributes() int {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.attributes.droppedCount
+}
+
+// DroppedLinks returns the number of links dropped by the span due to limits
+// being reached.
+func (s *span) DroppedLinks() int {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.links.droppedCount
+}
+
+// DroppedEvents returns the number of events dropped by the span due to
+// limits being reached.
+func (s *span) DroppedEvents() int {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.events.droppedCount
+}
+
+// ChildSpanCount returns the count of spans that consider the span a
+// direct parent.
+func (s *span) ChildSpanCount() int {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.childSpanCount
+}
+
+// TracerProvider returns a trace.TracerProvider that can be used to generate
+// additional Spans on the same telemetry pipeline as the current Span.
+func (s *span) TracerProvider() trace.TracerProvider {
+	return s.tracer.provider
+}
+
+// snapshot creates a read-only copy of the current state of the span.
+func (s *span) snapshot() ReadOnlySpan {
+	var sd snapshot
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	sd.endTime = s.endTime
+	sd.instrumentationLibrary = s.instrumentationLibrary
+	sd.name = s.name
+	sd.parent = s.parent
+	sd.resource = s.resource
+	sd.spanContext = s.spanContext
+	sd.spanKind = s.spanKind
+	sd.startTime = s.startTime
+	sd.status = s.status
+	sd.childSpanCount = s.childSpanCount
+
+	if s.attributes.evictList.Len() > 0 {
+		sd.attributes = s.attributes.toKeyValue()
+		sd.droppedAttributeCount = s.attributes.droppedCount
+	}
+	if len(s.events.queue) > 0 {
+		sd.events = s.interfaceArrayToEventArray()
+		sd.droppedEventCount = s.events.droppedCount
+	}
+	if len(s.links.queue) > 0 {
+		sd.links = s.interfaceArrayToLinksArray()
+		sd.droppedLinkCount = s.links.droppedCount
+	}
+	return &sd
+}
+
+func (s *span) interfaceArrayToLinksArray() []trace.Link {
+	linkArr := make([]trace.Link, 0)
+	for _, value := range s.links.queue {
+		linkArr = append(linkArr, value.(trace.Link))
+	}
+	return linkArr
+}
+
+func (s *span) interfaceArrayToEventArray() []Event {
+	eventArr := make([]Event, 0)
+	for _, value := range s.events.queue {
+		eventArr = append(eventArr, value.(Event))
+	}
+	return eventArr
+}
+
+func (s *span) copyToCappedAttributes(attributes ...attribute.KeyValue) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	for _, a := range attributes {
+		// Ensure attributes conform to the specification:
+		// https://github.com/open-telemetry/opentelemetry-specification/blob/v1.0.1/specification/common/common.md#attributes
+		if a.Valid() {
+			s.attributes.add(a)
+		}
+	}
+}
+
+func (s *span) addChild() {
+	if !s.IsRecording() {
+		return
+	}
+	s.mu.Lock()
+	s.childSpanCount++
+	s.mu.Unlock()
+}
+
+func (*span) private() {}
+
+func startSpanInternal(ctx context.Context, tr *tracer, name string, o *trace.SpanConfig) *span {
+	span := &span{}
+
+	provider := tr.provider
+
+	// If told explicitly to make this a new root use a zero value SpanContext
+	// as a parent which contains an invalid trace ID and is not remote.
+	var psc trace.SpanContext
+	if !o.NewRoot() {
+		psc = trace.SpanContextFromContext(ctx)
+	}
+
+	// If there is a valid parent trace ID, use it to ensure the continuity of
+	// the trace. Always generate a new span ID so other components can rely
+	// on a unique span ID, even if the Span is non-recording.
+	var tid trace.TraceID
+	var sid trace.SpanID
+	if !psc.TraceID().IsValid() {
+		tid, sid = provider.idGenerator.NewIDs(ctx)
+	} else {
+		tid = psc.TraceID()
+		sid = provider.idGenerator.NewSpanID(ctx, tid)
+	}
+
+	spanLimits := provider.spanLimits
+	span.attributes = newAttributesMap(spanLimits.AttributeCountLimit)
+	span.events = newEvictedQueue(spanLimits.EventCountLimit)
+	span.links = newEvictedQueue(spanLimits.LinkCountLimit)
+	span.spanLimits = spanLimits
+
+	samplingResult := provider.sampler.ShouldSample(SamplingParameters{
+		ParentContext: ctx,
+		TraceID:       tid,
+		Name:          name,
+		Kind:          o.SpanKind(),
+		Attributes:    o.Attributes(),
+		Links:         o.Links(),
+	})
+
+	scc := trace.SpanContextConfig{
+		TraceID:    tid,
+		SpanID:     sid,
+		TraceState: samplingResult.Tracestate,
+	}
+	if isSampled(samplingResult) {
+		scc.TraceFlags = psc.TraceFlags() | trace.FlagsSampled
+	} else {
+		scc.TraceFlags = psc.TraceFlags() &^ trace.FlagsSampled
+	}
+	span.spanContext = trace.NewSpanContext(scc)
+
+	if !isRecording(samplingResult) {
+		return span
+	}
+
+	startTime := o.Timestamp()
+	if startTime.IsZero() {
+		startTime = time.Now()
+	}
+	span.startTime = startTime
+
+	span.spanKind = trace.ValidateSpanKind(o.SpanKind())
+	span.name = name
+	span.parent = psc
+	span.resource = provider.resource
+	span.instrumentationLibrary = tr.instrumentationLibrary
+
+	span.SetAttributes(samplingResult.Attributes...)
+
+	return span
+}
+
+func isRecording(s SamplingResult) bool {
+	return s.Decision == RecordOnly || s.Decision == RecordAndSample
+}
+
+func isSampled(s SamplingResult) bool {
+	return s.Decision == RecordAndSample
+}
+
+// Status is the classified state of a Span.
+type Status struct {
+	// Code is an identifier of a Spans state classification.
+	Code codes.Code
+	// Message is a user hint about why that status was set. It is only
+	// applicable when Code is Error.
+	Description string
+}

vendor/go.opentelemetry.io/otel/sdk/trace/span_exporter.go

@@ -0,0 +1,47 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace // import "go.opentelemetry.io/otel/sdk/trace"
+
+import "context"
+
+// SpanExporter handles the delivery of spans to external receivers. This is
+// the final component in the trace export pipeline.
+type SpanExporter interface {
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+
+	// ExportSpans exports a batch of spans.
+	//
+	// This function is called synchronously, so there is no concurrency
+	// safety requirement. However, due to the synchronous calling pattern,
+	// it is critical that all timeouts and cancellations contained in the
+	// passed context must be honored.
+	//
+	// Any retry logic must be contained in this function. The SDK that
+	// calls this function will not implement any retry logic. All errors
+	// returned by this function are considered unrecoverable and will be
+	// reported to a configured error Handler.
+	ExportSpans(ctx context.Context, spans []ReadOnlySpan) error
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+
+	// Shutdown notifies the exporter of a pending halt to operations. The
+	// exporter is expected to preform any cleanup or synchronization it
+	// requires while honoring all timeouts and cancellations contained in
+	// the passed context.
+	Shutdown(ctx context.Context) error
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+}

vendor/go.opentelemetry.io/otel/sdk/trace/span_processor.go

@@ -0,0 +1,67 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace // import "go.opentelemetry.io/otel/sdk/trace"
+
+import (
+	"context"
+	"sync"
+)
+
+// SpanProcessor is a processing pipeline for spans in the trace signal.
+// SpanProcessors registered with a TracerProvider and are called at the start
+// and end of a Span's lifecycle, and are called in the order they are
+// registered.
+type SpanProcessor interface {
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+
+	// OnStart is called when a span is started. It is called synchronously
+	// and should not block.
+	OnStart(parent context.Context, s ReadWriteSpan)
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+
+	// OnEnd is called when span is finished. It is called synchronously and
+	// hence not block.
+	OnEnd(s ReadOnlySpan)
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+
+	// Shutdown is called when the SDK shuts down. Any cleanup or release of
+	// resources held by the processor should be done in this call.
+	//
+	// Calls to OnStart, OnEnd, or ForceFlush after this has been called
+	// should be ignored.
+	//
+	// All timeouts and cancellations contained in ctx must be honored, this
+	// should not block indefinitely.
+	Shutdown(ctx context.Context) error
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+
+	// ForceFlush exports all ended spans to the configured Exporter that have not yet
+	// been exported.  It should only be called when absolutely necessary, such as when
+	// using a FaaS provider that may suspend the process after an invocation, but before
+	// the Processor can export the completed spans.
+	ForceFlush(ctx context.Context) error
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+}
+
+type spanProcessorState struct {
+	sp    SpanProcessor
+	state *sync.Once
+}
+type spanProcessorStates []*spanProcessorState

vendor/go.opentelemetry.io/otel/sdk/trace/tracer.go

@@ -0,0 +1,75 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace // import "go.opentelemetry.io/otel/sdk/trace"
+
+import (
+	"context"
+	rt "runtime/trace"
+
+	"go.opentelemetry.io/otel/trace"
+
+	"go.opentelemetry.io/otel/sdk/instrumentation"
+)
+
+type tracer struct {
+	provider               *TracerProvider
+	instrumentationLibrary instrumentation.Library
+}
+
+var _ trace.Tracer = &tracer{}
+
+// Start starts a Span and returns it along with a context containing it.
+//
+// The Span is created with the provided name and as a child of any existing
+// span context found in the passed context. The created Span will be
+// configured appropriately by any SpanOption passed. Any Timestamp option
+// passed will be used as the start time of the Span's life-cycle.
+func (tr *tracer) Start(ctx context.Context, name string, options ...trace.SpanStartOption) (context.Context, trace.Span) {
+	config := trace.NewSpanStartConfig(options...)
+
+	// For local spans created by this SDK, track child span count.
+	if p := trace.SpanFromContext(ctx); p != nil {
+		if sdkSpan, ok := p.(*span); ok {
+			sdkSpan.addChild()
+		}
+	}
+
+	span := startSpanInternal(ctx, tr, name, config)
+	for _, l := range config.Links() {
+		span.addLink(l)
+	}
+	span.SetAttributes(config.Attributes()...)
+
+	span.tracer = tr
+
+	if span.IsRecording() {
+		sps, _ := tr.provider.spanProcessors.Load().(spanProcessorStates)
+		for _, sp := range sps {
+			sp.sp.OnStart(ctx, span)
+		}
+	}
+
+	ctx, span.executionTracerTaskEnd = func(ctx context.Context) (context.Context, func()) {
+		if !rt.IsEnabled() {
+			// Avoid additional overhead if
+			// runtime/trace is not enabled.
+			return ctx, func() {}
+		}
+		nctx, task := rt.NewTask(ctx, name)
+		return nctx, task.End
+	}(ctx)
+
+	return trace.ContextWithSpan(ctx, span), span
+}