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tripperware.go
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tripperware.go
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// Copyright 2017 Mark Nevill. All Rights Reserved.
// See LICENSE for licensing terms.
package http_metrics
import (
"net/http"
"net/http/httptrace"
"time"
"github.com/Solution/go-httpwares"
)
// Tripperware returns a new client-side ware that exports request metrics.
// If the tags tripperware is used, this should be placed after tags to pick up metadata.
func Tripperware(reporter Reporter) httpwares.Tripperware {
return func(next http.RoundTripper) http.RoundTripper {
if reporter == nil {
return next
}
return httpwares.RoundTripperFunc(func(req *http.Request) (*http.Response, error) {
tracker := reporter.Track(req)
start := time.Now()
tracker.RequestStarted()
// If present, wrap body to track number of bytes written
reqSize := 0
if req.Body != nil {
req.Body = wrapBody(req.Body, func(size int) {
reqSize = size
})
}
// Use httptrace to get notified when writing request completed
trace := httptrace.ContextClientTrace(req.Context())
if trace == nil {
trace = &httptrace.ClientTrace{}
}
prevWroteRequest := trace.WroteRequest
trace.WroteRequest = func(info httptrace.WroteRequestInfo) {
tracker.RequestRead(time.Since(start), reqSize)
if prevWroteRequest != nil {
prevWroteRequest(info)
}
}
req = req.WithContext(httptrace.WithClientTrace(req.Context(), trace))
resp, err := next.RoundTrip(req)
dur := time.Since(start)
if err != nil {
tracker.ResponseStarted(dur, 599, nil)
tracker.ResponseDone(dur, 599, 0)
return resp, err
}
tracker.ResponseStarted(dur, resp.StatusCode, resp.Header)
resp.Body = wrapBody(resp.Body, func(size int) {
tracker.ResponseDone(time.Since(start), resp.StatusCode, size)
})
return resp, err
})
}
}