vendor: add buildkit

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

vendor/github.com/moby/buildkit/session/grpc.go

@@ -0,0 +1,81 @@
+package session
+
+import (
+	"context"
+	"net"
+	"sync/atomic"
+	"time"
+
+	"github.com/grpc-ecosystem/grpc-opentracing/go/otgrpc"
+	opentracing "github.com/opentracing/opentracing-go"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+	"golang.org/x/net/http2"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/health/grpc_health_v1"
+)
+
+func serve(ctx context.Context, grpcServer *grpc.Server, conn net.Conn) {
+	go func() {
+		<-ctx.Done()
+		conn.Close()
+	}()
+	logrus.Debugf("serving grpc connection")
+	(&http2.Server{}).ServeConn(conn, &http2.ServeConnOpts{Handler: grpcServer})
+}
+
+func grpcClientConn(ctx context.Context, conn net.Conn) (context.Context, *grpc.ClientConn, error) {
+	var dialCount int64
+	dialer := grpc.WithDialer(func(addr string, d time.Duration) (net.Conn, error) {
+		if c := atomic.AddInt64(&dialCount, 1); c > 1 {
+			return nil, errors.Errorf("only one connection allowed")
+		}
+		return conn, nil
+	})
+
+	dialOpts := []grpc.DialOption{
+		dialer,
+		grpc.WithInsecure(),
+	}
+
+	if span := opentracing.SpanFromContext(ctx); span != nil {
+		tracer := span.Tracer()
+		dialOpts = append(dialOpts,
+			grpc.WithUnaryInterceptor(otgrpc.OpenTracingClientInterceptor(tracer, traceFilter())),
+			grpc.WithStreamInterceptor(otgrpc.OpenTracingStreamClientInterceptor(tracer, traceFilter())),
+		)
+	}
+
+	cc, err := grpc.DialContext(ctx, "", dialOpts...)
+	if err != nil {
+		return nil, nil, errors.Wrap(err, "failed to create grpc client")
+	}
+
+	ctx, cancel := context.WithCancel(ctx)
+	go monitorHealth(ctx, cc, cancel)
+
+	return ctx, cc, nil
+}
+
+func monitorHealth(ctx context.Context, cc *grpc.ClientConn, cancelConn func()) {
+	defer cancelConn()
+	defer cc.Close()
+
+	ticker := time.NewTicker(1 * time.Second)
+	defer ticker.Stop()
+	healthClient := grpc_health_v1.NewHealthClient(cc)
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-ticker.C:
+			ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
+			_, err := healthClient.Check(ctx, &grpc_health_v1.HealthCheckRequest{})
+			cancel()
+			if err != nil {
+				return
+			}
+		}
+	}
+}