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// Copyright 2018, OpenCensus 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 ocgrpc
import (
"go.opencensus.io/trace"
"golang.org/x/net/context"
"google.golang.org/grpc/stats"
)
// ServerHandler implements gRPC stats.Handler recording OpenCensus stats and
// traces. Use with gRPC servers.
//
// When installed (see Example), tracing metadata is read from inbound RPCs
// by default. If no tracing metadata is present, or if the tracing metadata is
// present but the SpanContext isn't sampled, then a new trace may be started
// (as determined by Sampler).
type ServerHandler struct {
// IsPublicEndpoint may be set to true to always start a new trace around
// each RPC. Any SpanContext in the RPC metadata will be added as a linked
// span instead of making it the parent of the span created around the
// server RPC.
//
// Be aware that if you leave this false (the default) on a public-facing
// server, callers will be able to send tracing metadata in gRPC headers
// and trigger traces in your backend.
IsPublicEndpoint bool
// StartOptions to use for to spans started around RPCs handled by this server.
//
// These will apply even if there is tracing metadata already
// present on the inbound RPC but the SpanContext is not sampled. This
// ensures that each service has some opportunity to be traced. If you would
// like to not add any additional traces for this gRPC service, set:
//
// StartOptions.Sampler = trace.ProbabilitySampler(0.0)
//
// StartOptions.SpanKind will always be set to trace.SpanKindServer
// for spans started by this handler.
StartOptions trace.StartOptions
}
var _ stats.Handler = (*ServerHandler)(nil)
// HandleConn exists to satisfy gRPC stats.Handler.
func (s *ServerHandler) HandleConn(ctx context.Context, cs stats.ConnStats) {
// no-op
}
// TagConn exists to satisfy gRPC stats.Handler.
func (s *ServerHandler) TagConn(ctx context.Context, cti *stats.ConnTagInfo) context.Context {
// no-op
return ctx
}
// HandleRPC implements per-RPC tracing and stats instrumentation.
func (s *ServerHandler) HandleRPC(ctx context.Context, rs stats.RPCStats) {
traceHandleRPC(ctx, rs)
statsHandleRPC(ctx, rs)
}
// TagRPC implements per-RPC context management.
func (s *ServerHandler) TagRPC(ctx context.Context, rti *stats.RPCTagInfo) context.Context {
ctx = s.traceTagRPC(ctx, rti)
ctx = s.statsTagRPC(ctx, rti)
return ctx
}
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