126 lines
3.0 KiB
Go
126 lines
3.0 KiB
Go
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// 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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"io"
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"net/http"
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"strconv"
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"sync"
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"time"
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"go.opencensus.io/stats"
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"go.opencensus.io/tag"
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)
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// statsTransport is an http.RoundTripper that collects stats for the outgoing requests.
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type statsTransport struct {
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base http.RoundTripper
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}
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// RoundTrip implements http.RoundTripper, delegating to Base and recording stats for the request.
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func (t statsTransport) RoundTrip(req *http.Request) (*http.Response, error) {
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ctx, _ := tag.New(req.Context(),
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tag.Upsert(Host, req.URL.Host),
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tag.Upsert(Path, req.URL.Path),
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tag.Upsert(Method, req.Method))
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req = req.WithContext(ctx)
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track := &tracker{
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start: time.Now(),
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ctx: ctx,
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}
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if req.Body == nil {
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// TODO: Handle cases where ContentLength is not set.
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track.reqSize = -1
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} else if req.ContentLength > 0 {
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track.reqSize = req.ContentLength
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}
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stats.Record(ctx, ClientRequestCount.M(1))
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// Perform request.
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resp, err := t.base.RoundTrip(req)
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if err != nil {
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track.statusCode = http.StatusInternalServerError
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track.end()
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} else {
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track.statusCode = resp.StatusCode
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if resp.Body == nil {
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track.end()
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} else {
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track.body = resp.Body
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resp.Body = track
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}
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}
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return resp, err
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}
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// CancelRequest cancels an in-flight request by closing its connection.
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func (t statsTransport) CancelRequest(req *http.Request) {
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type canceler interface {
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CancelRequest(*http.Request)
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}
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if cr, ok := t.base.(canceler); ok {
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cr.CancelRequest(req)
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}
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}
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type tracker struct {
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ctx context.Context
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respSize int64
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reqSize int64
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start time.Time
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body io.ReadCloser
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statusCode int
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endOnce sync.Once
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}
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var _ io.ReadCloser = (*tracker)(nil)
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func (t *tracker) end() {
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t.endOnce.Do(func() {
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m := []stats.Measurement{
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ClientLatency.M(float64(time.Since(t.start)) / float64(time.Millisecond)),
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ClientResponseBytes.M(t.respSize),
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}
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if t.reqSize >= 0 {
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m = append(m, ClientRequestBytes.M(t.reqSize))
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}
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ctx, _ := tag.New(t.ctx, tag.Upsert(StatusCode, strconv.Itoa(t.statusCode)))
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stats.Record(ctx, m...)
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})
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}
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func (t *tracker) Read(b []byte) (int, error) {
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n, err := t.body.Read(b)
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switch err {
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case nil:
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t.respSize += int64(n)
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return n, nil
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case io.EOF:
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t.end()
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}
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return n, err
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}
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func (t *tracker) Close() error {
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// Invoking endSpan on Close will help catch the cases
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// in which a read returned a non-nil error, we set the
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// span status but didn't end the span.
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t.end()
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return t.body.Close()
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}
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