forked from TrueCloudLab/restic
108 lines
4.1 KiB
Go
108 lines
4.1 KiB
Go
// Copyright 2017 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package trace
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import (
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"encoding/hex"
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"fmt"
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"cloud.google.com/go/internal/tracecontext"
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"golang.org/x/net/context"
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"google.golang.org/grpc"
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"google.golang.org/grpc/metadata"
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)
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const grpcMetadataKey = "grpc-trace-bin"
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// GRPCClientInterceptor returns a grpc.UnaryClientInterceptor that traces all outgoing requests from a gRPC client.
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// The calling context should already have a *trace.Span; a child span will be
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// created for the outgoing gRPC call. If the calling context doesn't have a span,
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// the call will not be traced. If the client is nil, then the interceptor just
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// passes through the request.
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//
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// The functionality in gRPC that this feature relies on is currently experimental.
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func (c *Client) GRPCClientInterceptor() grpc.UnaryClientInterceptor {
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if c == nil {
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return func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
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return invoker(ctx, method, req, reply, cc, opts...)
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}
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}
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return grpc.UnaryClientInterceptor(c.grpcUnaryInterceptor)
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}
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func (c *Client) grpcUnaryInterceptor(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
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// TODO: also intercept streams.
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span := FromContext(ctx).NewChild(method)
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if span == nil {
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span = c.NewSpan(method)
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}
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defer span.Finish()
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traceContext := make([]byte, tracecontext.Len)
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// traceID is a hex-encoded 128-bit value.
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// TODO(jbd): Decode trace IDs upon arrival and
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// represent trace IDs with 16 bytes internally.
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tid, err := hex.DecodeString(span.trace.traceID)
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if err != nil {
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return invoker(ctx, method, req, reply, cc, opts...)
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}
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tracecontext.Encode(traceContext, tid, span.span.SpanId, byte(span.trace.globalOptions))
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md, ok := metadata.FromOutgoingContext(ctx)
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if !ok {
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md = metadata.Pairs(grpcMetadataKey, string(traceContext))
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} else {
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md = md.Copy() // metadata is immutable, copy.
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md[grpcMetadataKey] = []string{string(traceContext)}
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}
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ctx = metadata.NewOutgoingContext(ctx, md)
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err = invoker(ctx, method, req, reply, cc, opts...)
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if err != nil {
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// TODO: standardize gRPC label names?
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span.SetLabel("error", err.Error())
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}
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return err
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}
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// GRPCServerInterceptor returns a grpc.UnaryServerInterceptor that enables the tracing of the incoming
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// gRPC calls. Incoming call's context can be used to extract the span on servers that enabled this option:
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//
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// span := trace.FromContext(ctx)
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//
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// If the client is nil, then the interceptor just invokes the handler.
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//
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// The functionality in gRPC that this feature relies on is currently experimental.
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func (c *Client) GRPCServerInterceptor() grpc.UnaryServerInterceptor {
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if c == nil {
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return func(ctx context.Context, req interface{}, _ *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
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return handler(ctx, req)
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}
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}
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return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (resp interface{}, err error) {
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md, _ := metadata.FromIncomingContext(ctx)
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var traceHeader string
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if header, ok := md[grpcMetadataKey]; ok {
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traceID, spanID, opts, ok := tracecontext.Decode([]byte(header[0]))
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if ok {
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// TODO(jbd): Generate a span directly from string(traceID), spanID and opts.
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traceHeader = fmt.Sprintf("%x/%d;o=%d", traceID, spanID, opts)
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}
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}
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span := c.SpanFromHeader(info.FullMethod, traceHeader)
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defer span.Finish()
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ctx = NewContext(ctx, span)
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return handler(ctx, req)
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}
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}
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