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opentelemetry-go/plugin/othttp/wrap.go
Krzesimir Nowak cf7a4d909c
Refactor propagators (#467)
* Remove binary propagators

They are in process of being dropped from the specification and we
haven't be using them anywhere in the project. Can reintroduce them
later.

* Rename Supplier to HTTPSupplier

The supplier is used only in HTTP propagators currently. It's not
clear if it will be useful for binary propagators if they get to be
specified at some point.

* Rework propagation interfaces

The biggest change here is that HTTP extractors return a new context
with whatever information the propagator is able to retrieve from the
supplier. Such interface does not hardcode any extractor's
functionality (like it was before by explicitly returning a span
context and correlation context) and makes it easy to chain multiple
propagators.

Injection part hasn't changed.

* Add Propagators interface

This interface (and its default implementation) is likely going to be
the propagation API used the most. Single injectors, extractors or
propagators are likely going to be used just as parameters to the
Option functions that configure the Propagators implementation.

* Drop noop propagator

It's rather pointless - just create an empty Propagators instance.

* Fix wrong name in docs

Co-authored-by: Joshua MacDonald <jmacd@users.noreply.github.com>
2020-02-13 23:16:04 -08:00

98 lines
2.4 KiB
Go

// Copyright 2019, OpenTelemetry 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 othttp
import (
"context"
"io"
"net/http"
"go.opentelemetry.io/otel/api/propagation"
)
var _ io.ReadCloser = &bodyWrapper{}
// bodyWrapper wraps a http.Request.Body (an io.ReadCloser) to track the number
// of bytes read and the last error
type bodyWrapper struct {
io.ReadCloser
record func(n int64) // must not be nil
read int64
err error
}
func (w *bodyWrapper) Read(b []byte) (int, error) {
n, err := w.ReadCloser.Read(b)
n1 := int64(n)
w.read += n1
w.err = err
w.record(n1)
return n, err
}
func (w *bodyWrapper) Close() error {
return w.ReadCloser.Close()
}
var _ http.ResponseWriter = &respWriterWrapper{}
// respWriterWrapper wraps a http.ResponseWriter in order to track the number of
// bytes written, the last error, and to catch the returned statusCode
// TODO: The wrapped http.ResponseWriter doesn't implement any of the optional
// types (http.Hijacker, http.Pusher, http.CloseNotifier, http.Flusher, etc)
// that may be useful when using it in real life situations.
type respWriterWrapper struct {
http.ResponseWriter
record func(n int64) // must not be nil
// used to inject the header
ctx context.Context
props propagation.Propagators
written int64
statusCode int
err error
wroteHeader bool
}
func (w *respWriterWrapper) Header() http.Header {
return w.ResponseWriter.Header()
}
func (w *respWriterWrapper) Write(p []byte) (int, error) {
if !w.wroteHeader {
w.WriteHeader(http.StatusOK)
w.wroteHeader = true
}
n, err := w.ResponseWriter.Write(p)
n1 := int64(n)
w.record(n1)
w.written += n1
w.err = err
return n, err
}
func (w *respWriterWrapper) WriteHeader(statusCode int) {
if w.wroteHeader {
return
}
w.wroteHeader = true
w.statusCode = statusCode
propagation.InjectHTTP(w.ctx, w.props, w.Header())
w.ResponseWriter.WriteHeader(statusCode)
}