rpc_util: Fix RecvBufferPool deactivation issues (#6766)

experimental/shared_buffer_pool_test.go

@@ -26,12 +26,12 @@ import (
 	"time"
 
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/encoding/gzip"
 	"google.golang.org/grpc/experimental"
 	"google.golang.org/grpc/internal/grpctest"
 	"google.golang.org/grpc/internal/stubserver"
 
 	testgrpc "google.golang.org/grpc/interop/grpc_testing"
-	testpb "google.golang.org/grpc/interop/grpc_testing"
 )
 
 type s struct {
@@ -44,17 +44,35 @@ func Test(t *testing.T) {
 
 const defaultTestTimeout = 10 * time.Second
 
-func (s) TestRecvBufferPool(t *testing.T) {
+func (s) TestRecvBufferPoolStream(t *testing.T) {
+	tcs := []struct {
+		name     string
+		callOpts []grpc.CallOption
+	}{
+		{
+			name: "default",
+		},
+		{
+			name: "useCompressor",
+			callOpts: []grpc.CallOption{
+				grpc.UseCompressor(gzip.Name),
+			},
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			const reqCount = 10
+
 			ss := &stubserver.StubServer{
 				FullDuplexCallF: func(stream testgrpc.TestService_FullDuplexCallServer) error {
-			for i := 0; i < 10; i++ {
+					for i := 0; i < reqCount; i++ {
 						preparedMsg := &grpc.PreparedMsg{}
-				err := preparedMsg.Encode(stream, &testpb.StreamingOutputCallResponse{
-					Payload: &testpb.Payload{
+						if err := preparedMsg.Encode(stream, &testgrpc.StreamingOutputCallResponse{
+							Payload: &testgrpc.Payload{
 								Body: []byte{'0' + uint8(i)},
 							},
-				})
-				if err != nil {
+						}); err != nil {
 							return err
 						}
 						stream.SendMsg(preparedMsg)
@@ -62,8 +80,10 @@ func (s) TestRecvBufferPool(t *testing.T) {
 					return nil
 				},
 			}
-	sopts := []grpc.ServerOption{experimental.RecvBufferPool(grpc.NewSharedBufferPool())}
-	dopts := []grpc.DialOption{experimental.WithRecvBufferPool(grpc.NewSharedBufferPool())}
+
+			pool := &checkBufferPool{}
+			sopts := []grpc.ServerOption{experimental.RecvBufferPool(pool)}
+			dopts := []grpc.DialOption{experimental.WithRecvBufferPool(pool)}
 			if err := ss.Start(sopts, dopts...); err != nil {
 				t.Fatalf("Error starting endpoint server: %v", err)
 			}
@@ -72,9 +92,9 @@ func (s) TestRecvBufferPool(t *testing.T) {
 			ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
 			defer cancel()
 
-	stream, err := ss.Client.FullDuplexCall(ctx)
+			stream, err := ss.Client.FullDuplexCall(ctx, tc.callOpts...)
 			if err != nil {
-		t.Fatalf("ss.Client.FullDuplexCall failed: %f", err)
+				t.Fatalf("ss.Client.FullDuplexCall failed: %v", err)
 			}
 
 			var ngot int
@@ -94,9 +114,91 @@ func (s) TestRecvBufferPool(t *testing.T) {
 				buf.Write(reply.GetPayload().GetBody())
 			}
 			if want := 10; ngot != want {
-		t.Errorf("Got %d replies, want %d", ngot, want)
+				t.Fatalf("Got %d replies, want %d", ngot, want)
 			}
 			if got, want := buf.String(), "0,1,2,3,4,5,6,7,8,9"; got != want {
-		t.Errorf("Got replies %q; want %q", got, want)
+				t.Fatalf("Got replies %q; want %q", got, want)
+			}
+
+			if len(pool.puts) != reqCount {
+				t.Fatalf("Expected 10 buffers to be returned to the pool, got %d", len(pool.puts))
+			}
+		})
 	}
 }
+
+func (s) TestRecvBufferPoolUnary(t *testing.T) {
+	tcs := []struct {
+		name     string
+		callOpts []grpc.CallOption
+	}{
+		{
+			name: "default",
+		},
+		{
+			name: "useCompressor",
+			callOpts: []grpc.CallOption{
+				grpc.UseCompressor(gzip.Name),
+			},
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			const largeSize = 1024
+
+			ss := &stubserver.StubServer{
+				UnaryCallF: func(ctx context.Context, in *testgrpc.SimpleRequest) (*testgrpc.SimpleResponse, error) {
+					return &testgrpc.SimpleResponse{
+						Payload: &testgrpc.Payload{
+							Body: make([]byte, largeSize),
+						},
+					}, nil
+				},
+			}
+
+			pool := &checkBufferPool{}
+			sopts := []grpc.ServerOption{experimental.RecvBufferPool(pool)}
+			dopts := []grpc.DialOption{experimental.WithRecvBufferPool(pool)}
+			if err := ss.Start(sopts, dopts...); err != nil {
+				t.Fatalf("Error starting endpoint server: %v", err)
+			}
+			defer ss.Stop()
+
+			ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+			defer cancel()
+
+			const reqCount = 10
+			for i := 0; i < reqCount; i++ {
+				if _, err := ss.Client.UnaryCall(
+					ctx,
+					&testgrpc.SimpleRequest{
+						Payload: &testgrpc.Payload{
+							Body: make([]byte, largeSize),
+						},
+					},
+					tc.callOpts...,
+				); err != nil {
+					t.Fatalf("ss.Client.UnaryCall failed: %v", err)
+				}
+			}
+
+			const bufferCount = reqCount * 2 // req + resp
+			if len(pool.puts) != bufferCount {
+				t.Fatalf("Expected %d buffers to be returned to the pool, got %d", bufferCount, len(pool.puts))
+			}
+		})
+	}
+}
+
+type checkBufferPool struct {
+	puts [][]byte
+}
+
+func (p *checkBufferPool) Get(size int) []byte {
+	return make([]byte, size)
+}
+
+func (p *checkBufferPool) Put(bs *[]byte) {
+	p.puts = append(p.puts, *bs)
+}

rpc_util.go

@@ -744,17 +744,19 @@ type payloadInfo struct {
 	uncompressedBytes []byte
 }
 
-func recvAndDecompress(p *parser, s *transport.Stream, dc Decompressor, maxReceiveMessageSize int, payInfo *payloadInfo, compressor encoding.Compressor) ([]byte, error) {
-	pf, buf, err := p.recvMsg(maxReceiveMessageSize)
+// recvAndDecompress reads a message from the stream, decompressing it if necessary.
+//
+// Cancelling the returned cancel function releases the buffer back to the pool. So the caller should cancel as soon as
+// the buffer is no longer needed.
+func recvAndDecompress(p *parser, s *transport.Stream, dc Decompressor, maxReceiveMessageSize int, payInfo *payloadInfo, compressor encoding.Compressor,
+) (uncompressedBuf []byte, cancel func(), err error) {
+	pf, compressedBuf, err := p.recvMsg(maxReceiveMessageSize)
 	if err != nil {
-		return nil, err
-	}
-	if payInfo != nil {
-		payInfo.compressedLength = len(buf)
+		return nil, nil, err
 	}
 
 	if st := checkRecvPayload(pf, s.RecvCompress(), compressor != nil || dc != nil); st != nil {
-		return nil, st.Err()
+		return nil, nil, st.Err()
 	}
 
 	var size int
@@ -762,21 +764,35 @@ func recvAndDecompress(p *parser, s *transport.Stream, dc Decompressor, maxRecei
 		// To match legacy behavior, if the decompressor is set by WithDecompressor or RPCDecompressor,
 		// use this decompressor as the default.
 		if dc != nil {
-			buf, err = dc.Do(bytes.NewReader(buf))
-			size = len(buf)
+			uncompressedBuf, err = dc.Do(bytes.NewReader(compressedBuf))
+			size = len(uncompressedBuf)
 		} else {
-			buf, size, err = decompress(compressor, buf, maxReceiveMessageSize)
+			uncompressedBuf, size, err = decompress(compressor, compressedBuf, maxReceiveMessageSize)
 		}
 		if err != nil {
-			return nil, status.Errorf(codes.Internal, "grpc: failed to decompress the received message: %v", err)
+			return nil, nil, status.Errorf(codes.Internal, "grpc: failed to decompress the received message: %v", err)
 		}
 		if size > maxReceiveMessageSize {
 			// TODO: Revisit the error code. Currently keep it consistent with java
 			// implementation.
-			return nil, status.Errorf(codes.ResourceExhausted, "grpc: received message after decompression larger than max (%d vs. %d)", size, maxReceiveMessageSize)
+			return nil, nil, status.Errorf(codes.ResourceExhausted, "grpc: received message after decompression larger than max (%d vs. %d)", size, maxReceiveMessageSize)
+		}
+	} else {
+		uncompressedBuf = compressedBuf
+	}
+
+	if payInfo != nil {
+		payInfo.compressedLength = len(compressedBuf)
+		payInfo.uncompressedBytes = uncompressedBuf
+
+		cancel = func() {}
+	} else {
+		cancel = func() {
+			p.recvBufferPool.Put(&compressedBuf)
 		}
 	}
-	return buf, nil
+
+	return uncompressedBuf, cancel, nil
 }
 
 // Using compressor, decompress d, returning data and size.
@@ -796,6 +812,9 @@ func decompress(compressor encoding.Compressor, d []byte, maxReceiveMessageSize
 			// size is used as an estimate to size the buffer, but we
 			// will read more data if available.
 			// +MinRead so ReadFrom will not reallocate if size is correct.
+			//
+			// TODO: If we ensure that the buffer size is the same as the DecompressedSize,
+			// we can also utilize the recv buffer pool here.
 			buf := bytes.NewBuffer(make([]byte, 0, size+bytes.MinRead))
 			bytesRead, err := buf.ReadFrom(io.LimitReader(dcReader, int64(maxReceiveMessageSize)+1))
 			return buf.Bytes(), int(bytesRead), err
@@ -811,18 +830,15 @@ func decompress(compressor encoding.Compressor, d []byte, maxReceiveMessageSize
 // dc takes precedence over compressor.
 // TODO(dfawley): wrap the old compressor/decompressor using the new API?
 func recv(p *parser, c baseCodec, s *transport.Stream, dc Decompressor, m any, maxReceiveMessageSize int, payInfo *payloadInfo, compressor encoding.Compressor) error {
-	buf, err := recvAndDecompress(p, s, dc, maxReceiveMessageSize, payInfo, compressor)
+	buf, cancel, err := recvAndDecompress(p, s, dc, maxReceiveMessageSize, payInfo, compressor)
 	if err != nil {
 		return err
 	}
+	defer cancel()
+
 	if err := c.Unmarshal(buf, m); err != nil {
 		return status.Errorf(codes.Internal, "grpc: failed to unmarshal the received message: %v", err)
 	}
-	if payInfo != nil {
-		payInfo.uncompressedBytes = buf
-	} else {
-		p.recvBufferPool.Put(&buf)
-	}
 	return nil
 }
 

server.go

@@ -1340,7 +1340,8 @@ func (s *Server) processUnaryRPC(ctx context.Context, t transport.ServerTranspor
 	if len(shs) != 0 || len(binlogs) != 0 {
 		payInfo = &payloadInfo{}
 	}
-	d, err := recvAndDecompress(&parser{r: stream, recvBufferPool: s.opts.recvBufferPool}, stream, dc, s.opts.maxReceiveMessageSize, payInfo, decomp)
+
+	d, cancel, err := recvAndDecompress(&parser{r: stream, recvBufferPool: s.opts.recvBufferPool}, stream, dc, s.opts.maxReceiveMessageSize, payInfo, decomp)
 	if err != nil {
 		if e := t.WriteStatus(stream, status.Convert(err)); e != nil {
 			channelz.Warningf(logger, s.channelzID, "grpc: Server.processUnaryRPC failed to write status: %v", e)
@@ -1351,6 +1352,8 @@ func (s *Server) processUnaryRPC(ctx context.Context, t transport.ServerTranspor
 		t.IncrMsgRecv()
 	}
 	df := func(v any) error {
+		defer cancel()
+
 		if err := s.getCodec(stream.ContentSubtype()).Unmarshal(d, v); err != nil {
 			return status.Errorf(codes.Internal, "grpc: error unmarshalling request: %v", err)
 		}