server_stats_handler.go

Documentation: go.opencensus.io/plugin/ocgrpc

     1  // Copyright 2017, OpenCensus Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  //
    15  
    16  package ocgrpc
    17  
    18  import (
    19  	"time"
    20  
    21  	"context"
    22  
    23  	"go.opencensus.io/tag"
    24  	"google.golang.org/grpc/grpclog"
    25  	"google.golang.org/grpc/stats"
    26  )
    27  
    28  // statsTagRPC gets the metadata from gRPC context, extracts the encoded tags from
    29  // it and creates a new tag.Map and puts them into the returned context.
    30  func (h *ServerHandler) statsTagRPC(ctx context.Context, info *stats.RPCTagInfo) context.Context {
    31  	startTime := time.Now()
    32  	if info == nil {
    33  		if grpclog.V(2) {
    34  			grpclog.Infof("opencensus: TagRPC called with nil info.")
    35  		}
    36  		return ctx
    37  	}
    38  	d := &rpcData{
    39  		startTime: startTime,
    40  		method:    info.FullMethodName,
    41  	}
    42  	propagated := h.extractPropagatedTags(ctx)
    43  	ctx = tag.NewContext(ctx, propagated)
    44  	ctx, _ = tag.New(ctx, tag.Upsert(KeyServerMethod, methodName(info.FullMethodName)))
    45  	return context.WithValue(ctx, rpcDataKey, d)
    46  }
    47  
    48  // extractPropagatedTags creates a new tag map containing the tags extracted from the
    49  // gRPC metadata.
    50  func (h *ServerHandler) extractPropagatedTags(ctx context.Context) *tag.Map {
    51  	buf := stats.Tags(ctx)
    52  	if buf == nil {
    53  		return nil
    54  	}
    55  	propagated, err := tag.Decode(buf)
    56  	if err != nil {
    57  		if grpclog.V(2) {
    58  			grpclog.Warningf("opencensus: Failed to decode tags from gRPC metadata failed to decode: %v", err)
    59  		}
    60  		return nil
    61  	}
    62  	return propagated
    63  }
    64
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