62 lines
2 KiB
Go
62 lines
2 KiB
Go
// Copyright 2018, OpenCensus Authors
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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 ochttp
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import (
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"context"
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"net/http"
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"go.opencensus.io/tag"
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)
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// SetRoute sets the http_server_route tag to the given value.
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// It's useful when an HTTP framework does not support the http.Handler interface
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// and using WithRouteTag is not an option, but provides a way to hook into the request flow.
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func SetRoute(ctx context.Context, route string) {
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if a, ok := ctx.Value(addedTagsKey{}).(*addedTags); ok {
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a.t = append(a.t, tag.Upsert(KeyServerRoute, route))
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}
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}
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// WithRouteTag returns an http.Handler that records stats with the
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// http_server_route tag set to the given value.
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func WithRouteTag(handler http.Handler, route string) http.Handler {
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return taggedHandlerFunc(func(w http.ResponseWriter, r *http.Request) []tag.Mutator {
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addRoute := []tag.Mutator{tag.Upsert(KeyServerRoute, route)}
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ctx, _ := tag.New(r.Context(), addRoute...)
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r = r.WithContext(ctx)
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handler.ServeHTTP(w, r)
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return addRoute
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})
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}
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// taggedHandlerFunc is a http.Handler that returns tags describing the
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// processing of the request. These tags will be recorded along with the
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// measures in this package at the end of the request.
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type taggedHandlerFunc func(w http.ResponseWriter, r *http.Request) []tag.Mutator
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func (h taggedHandlerFunc) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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tags := h(w, r)
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if a, ok := r.Context().Value(addedTagsKey{}).(*addedTags); ok {
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a.t = append(a.t, tags...)
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}
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}
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type addedTagsKey struct{}
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type addedTags struct {
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t []tag.Mutator
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}
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