mirror of https://github.com/ethereum/go-ethereum
This adds compatibility with Go 1.7, where context has moved into the standard library.pull/2819/head
Felix Lange
8 years ago
parent
74be4a62c5
commit
39b4ef4b02
@ -1,19 +0,0 @@ |
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build go1.5
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package ctxhttp |
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import "net/http" |
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func canceler(client *http.Client, req *http.Request) func() { |
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// TODO(djd): Respect any existing value of req.Cancel.
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ch := make(chan struct{}) |
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req.Cancel = ch |
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return func() { |
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close(ch) |
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} |
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} |
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@ -1,23 +0,0 @@ |
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build !go1.5
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package ctxhttp |
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import "net/http" |
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type requestCanceler interface { |
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CancelRequest(*http.Request) |
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} |
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func canceler(client *http.Client, req *http.Request) func() { |
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rc, ok := client.Transport.(requestCanceler) |
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if !ok { |
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return func() {} |
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} |
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return func() { |
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rc.CancelRequest(req) |
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} |
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} |
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@ -1,140 +0,0 @@ |
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package ctxhttp provides helper functions for performing context-aware HTTP requests.
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package ctxhttp |
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import ( |
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"io" |
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"net/http" |
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"net/url" |
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"strings" |
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"golang.org/x/net/context" |
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) |
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func nop() {} |
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var ( |
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testHookContextDoneBeforeHeaders = nop |
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testHookDoReturned = nop |
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testHookDidBodyClose = nop |
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) |
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// Do sends an HTTP request with the provided http.Client and returns an HTTP response.
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// If the client is nil, http.DefaultClient is used.
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// If the context is canceled or times out, ctx.Err() will be returned.
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func Do(ctx context.Context, client *http.Client, req *http.Request) (*http.Response, error) { |
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if client == nil { |
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client = http.DefaultClient |
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} |
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// Request cancelation changed in Go 1.5, see cancelreq.go and cancelreq_go14.go.
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cancel := canceler(client, req) |
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type responseAndError struct { |
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resp *http.Response |
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err error |
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} |
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result := make(chan responseAndError, 1) |
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go func() { |
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resp, err := client.Do(req) |
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testHookDoReturned() |
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result <- responseAndError{resp, err} |
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}() |
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var resp *http.Response |
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select { |
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case <-ctx.Done(): |
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testHookContextDoneBeforeHeaders() |
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cancel() |
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// Clean up after the goroutine calling client.Do:
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go func() { |
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if r := <-result; r.resp != nil { |
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testHookDidBodyClose() |
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r.resp.Body.Close() |
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} |
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}() |
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return nil, ctx.Err() |
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case r := <-result: |
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var err error |
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resp, err = r.resp, r.err |
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if err != nil { |
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return resp, err |
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} |
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} |
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c := make(chan struct{}) |
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go func() { |
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select { |
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case <-ctx.Done(): |
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cancel() |
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case <-c: |
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// The response's Body is closed.
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} |
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}() |
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resp.Body = ¬ifyingReader{resp.Body, c} |
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return resp, nil |
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} |
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// Get issues a GET request via the Do function.
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func Get(ctx context.Context, client *http.Client, url string) (*http.Response, error) { |
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req, err := http.NewRequest("GET", url, nil) |
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if err != nil { |
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return nil, err |
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} |
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return Do(ctx, client, req) |
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} |
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// Head issues a HEAD request via the Do function.
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func Head(ctx context.Context, client *http.Client, url string) (*http.Response, error) { |
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req, err := http.NewRequest("HEAD", url, nil) |
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if err != nil { |
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return nil, err |
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} |
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return Do(ctx, client, req) |
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} |
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// Post issues a POST request via the Do function.
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func Post(ctx context.Context, client *http.Client, url string, bodyType string, body io.Reader) (*http.Response, error) { |
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req, err := http.NewRequest("POST", url, body) |
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if err != nil { |
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return nil, err |
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} |
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req.Header.Set("Content-Type", bodyType) |
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return Do(ctx, client, req) |
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} |
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// PostForm issues a POST request via the Do function.
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func PostForm(ctx context.Context, client *http.Client, url string, data url.Values) (*http.Response, error) { |
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return Post(ctx, client, url, "application/x-www-form-urlencoded", strings.NewReader(data.Encode())) |
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} |
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// notifyingReader is an io.ReadCloser that closes the notify channel after
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// Close is called or a Read fails on the underlying ReadCloser.
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type notifyingReader struct { |
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io.ReadCloser |
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notify chan<- struct{} |
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} |
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func (r *notifyingReader) Read(p []byte) (int, error) { |
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n, err := r.ReadCloser.Read(p) |
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if err != nil && r.notify != nil { |
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close(r.notify) |
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r.notify = nil |
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} |
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return n, err |
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} |
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func (r *notifyingReader) Close() error { |
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err := r.ReadCloser.Close() |
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if r.notify != nil { |
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close(r.notify) |
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r.notify = nil |
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} |
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return err |
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} |
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@ -0,0 +1,72 @@ |
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// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build go1.7
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package context |
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import ( |
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"context" // standard library's context, as of Go 1.7
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"time" |
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) |
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var ( |
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todo = context.TODO() |
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background = context.Background() |
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) |
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// Canceled is the error returned by Context.Err when the context is canceled.
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var Canceled = context.Canceled |
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// DeadlineExceeded is the error returned by Context.Err when the context's
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// deadline passes.
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var DeadlineExceeded = context.DeadlineExceeded |
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// WithCancel returns a copy of parent with a new Done channel. The returned
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// context's Done channel is closed when the returned cancel function is called
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// or when the parent context's Done channel is closed, whichever happens first.
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//
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// Canceling this context releases resources associated with it, so code should
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// call cancel as soon as the operations running in this Context complete.
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func WithCancel(parent Context) (ctx Context, cancel CancelFunc) { |
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ctx, f := context.WithCancel(parent) |
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return ctx, CancelFunc(f) |
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} |
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// WithDeadline returns a copy of the parent context with the deadline adjusted
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// to be no later than d. If the parent's deadline is already earlier than d,
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// WithDeadline(parent, d) is semantically equivalent to parent. The returned
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// context's Done channel is closed when the deadline expires, when the returned
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// cancel function is called, or when the parent context's Done channel is
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// closed, whichever happens first.
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//
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// Canceling this context releases resources associated with it, so code should
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// call cancel as soon as the operations running in this Context complete.
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func WithDeadline(parent Context, deadline time.Time) (Context, CancelFunc) { |
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ctx, f := context.WithDeadline(parent, deadline) |
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return ctx, CancelFunc(f) |
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} |
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// WithTimeout returns WithDeadline(parent, time.Now().Add(timeout)).
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//
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// Canceling this context releases resources associated with it, so code should
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// call cancel as soon as the operations running in this Context complete:
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//
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// func slowOperationWithTimeout(ctx context.Context) (Result, error) {
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// ctx, cancel := context.WithTimeout(ctx, 100*time.Millisecond)
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// defer cancel() // releases resources if slowOperation completes before timeout elapses
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// return slowOperation(ctx)
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// }
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func WithTimeout(parent Context, timeout time.Duration) (Context, CancelFunc) { |
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return WithDeadline(parent, time.Now().Add(timeout)) |
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} |
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// WithValue returns a copy of parent in which the value associated with key is
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// val.
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//
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// Use context Values only for request-scoped data that transits processes and
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// APIs, not for passing optional parameters to functions.
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func WithValue(parent Context, key interface{}, val interface{}) Context { |
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return context.WithValue(parent, key, val) |
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} |
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@ -0,0 +1,300 @@ |
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// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build !go1.7
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package context |
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import ( |
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"errors" |
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"fmt" |
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"sync" |
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"time" |
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) |
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// An emptyCtx is never canceled, has no values, and has no deadline. It is not
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// struct{}, since vars of this type must have distinct addresses.
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type emptyCtx int |
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func (*emptyCtx) Deadline() (deadline time.Time, ok bool) { |
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return |
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} |
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func (*emptyCtx) Done() <-chan struct{} { |
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return nil |
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} |
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func (*emptyCtx) Err() error { |
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return nil |
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} |
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func (*emptyCtx) Value(key interface{}) interface{} { |
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return nil |
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} |
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func (e *emptyCtx) String() string { |
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switch e { |
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case background: |
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return "context.Background" |
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case todo: |
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return "context.TODO" |
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} |
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return "unknown empty Context" |
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} |
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var ( |
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background = new(emptyCtx) |
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todo = new(emptyCtx) |
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) |
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// Canceled is the error returned by Context.Err when the context is canceled.
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var Canceled = errors.New("context canceled") |
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// DeadlineExceeded is the error returned by Context.Err when the context's
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// deadline passes.
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var DeadlineExceeded = errors.New("context deadline exceeded") |
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// WithCancel returns a copy of parent with a new Done channel. The returned
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// context's Done channel is closed when the returned cancel function is called
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// or when the parent context's Done channel is closed, whichever happens first.
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//
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// Canceling this context releases resources associated with it, so code should
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// call cancel as soon as the operations running in this Context complete.
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func WithCancel(parent Context) (ctx Context, cancel CancelFunc) { |
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c := newCancelCtx(parent) |
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propagateCancel(parent, c) |
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return c, func() { c.cancel(true, Canceled) } |
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} |
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// newCancelCtx returns an initialized cancelCtx.
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func newCancelCtx(parent Context) *cancelCtx { |
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return &cancelCtx{ |
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Context: parent, |
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done: make(chan struct{}), |
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} |
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} |
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// propagateCancel arranges for child to be canceled when parent is.
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func propagateCancel(parent Context, child canceler) { |
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if parent.Done() == nil { |
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return // parent is never canceled
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} |
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if p, ok := parentCancelCtx(parent); ok { |
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p.mu.Lock() |
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if p.err != nil { |
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// parent has already been canceled
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child.cancel(false, p.err) |
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} else { |
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if p.children == nil { |
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p.children = make(map[canceler]bool) |
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} |
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p.children[child] = true |
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} |
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p.mu.Unlock() |
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} else { |
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go func() { |
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select { |
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case <-parent.Done(): |
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child.cancel(false, parent.Err()) |
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case <-child.Done(): |
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} |
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}() |
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} |
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} |
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// parentCancelCtx follows a chain of parent references until it finds a
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// *cancelCtx. This function understands how each of the concrete types in this
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// package represents its parent.
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func parentCancelCtx(parent Context) (*cancelCtx, bool) { |
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for { |
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switch c := parent.(type) { |
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case *cancelCtx: |
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return c, true |
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case *timerCtx: |
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return c.cancelCtx, true |
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case *valueCtx: |
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parent = c.Context |
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default: |
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return nil, false |
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} |
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} |
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} |
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// removeChild removes a context from its parent.
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func removeChild(parent Context, child canceler) { |
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p, ok := parentCancelCtx(parent) |
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if !ok { |
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return |
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} |
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p.mu.Lock() |
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if p.children != nil { |
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delete(p.children, child) |
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} |
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p.mu.Unlock() |
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} |
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// A canceler is a context type that can be canceled directly. The
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// implementations are *cancelCtx and *timerCtx.
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type canceler interface { |
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cancel(removeFromParent bool, err error) |
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Done() <-chan struct{} |
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} |
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// A cancelCtx can be canceled. When canceled, it also cancels any children
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// that implement canceler.
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type cancelCtx struct { |
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Context |
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done chan struct{} // closed by the first cancel call.
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mu sync.Mutex |
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children map[canceler]bool // set to nil by the first cancel call
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err error // set to non-nil by the first cancel call
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} |
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func (c *cancelCtx) Done() <-chan struct{} { |
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return c.done |
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} |
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func (c *cancelCtx) Err() error { |
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c.mu.Lock() |
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defer c.mu.Unlock() |
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return c.err |
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} |
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func (c *cancelCtx) String() string { |
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return fmt.Sprintf("%v.WithCancel", c.Context) |
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} |
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// cancel closes c.done, cancels each of c's children, and, if
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// removeFromParent is true, removes c from its parent's children.
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func (c *cancelCtx) cancel(removeFromParent bool, err error) { |
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if err == nil { |
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panic("context: internal error: missing cancel error") |
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} |
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c.mu.Lock() |
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if c.err != nil { |
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c.mu.Unlock() |
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return // already canceled
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} |
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c.err = err |
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close(c.done) |
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for child := range c.children { |
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// NOTE: acquiring the child's lock while holding parent's lock.
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child.cancel(false, err) |
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} |
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c.children = nil |
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c.mu.Unlock() |
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if removeFromParent { |
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removeChild(c.Context, c) |
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} |
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} |
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// WithDeadline returns a copy of the parent context with the deadline adjusted
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// to be no later than d. If the parent's deadline is already earlier than d,
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// WithDeadline(parent, d) is semantically equivalent to parent. The returned
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// context's Done channel is closed when the deadline expires, when the returned
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// cancel function is called, or when the parent context's Done channel is
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// closed, whichever happens first.
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//
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// Canceling this context releases resources associated with it, so code should
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// call cancel as soon as the operations running in this Context complete.
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func WithDeadline(parent Context, deadline time.Time) (Context, CancelFunc) { |
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if cur, ok := parent.Deadline(); ok && cur.Before(deadline) { |
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// The current deadline is already sooner than the new one.
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return WithCancel(parent) |
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} |
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c := &timerCtx{ |
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cancelCtx: newCancelCtx(parent), |
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deadline: deadline, |
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} |
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propagateCancel(parent, c) |
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d := deadline.Sub(time.Now()) |
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if d <= 0 { |
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c.cancel(true, DeadlineExceeded) // deadline has already passed
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return c, func() { c.cancel(true, Canceled) } |
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} |
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c.mu.Lock() |
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defer c.mu.Unlock() |
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if c.err == nil { |
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c.timer = time.AfterFunc(d, func() { |
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c.cancel(true, DeadlineExceeded) |
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}) |
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} |
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return c, func() { c.cancel(true, Canceled) } |
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} |
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// A timerCtx carries a timer and a deadline. It embeds a cancelCtx to
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// implement Done and Err. It implements cancel by stopping its timer then
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// delegating to cancelCtx.cancel.
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type timerCtx struct { |
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*cancelCtx |
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timer *time.Timer // Under cancelCtx.mu.
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deadline time.Time |
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} |
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func (c *timerCtx) Deadline() (deadline time.Time, ok bool) { |
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return c.deadline, true |
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} |
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func (c *timerCtx) String() string { |
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return fmt.Sprintf("%v.WithDeadline(%s [%s])", c.cancelCtx.Context, c.deadline, c.deadline.Sub(time.Now())) |
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} |
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func (c *timerCtx) cancel(removeFromParent bool, err error) { |
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c.cancelCtx.cancel(false, err) |
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if removeFromParent { |
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// Remove this timerCtx from its parent cancelCtx's children.
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removeChild(c.cancelCtx.Context, c) |
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} |
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c.mu.Lock() |
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if c.timer != nil { |
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c.timer.Stop() |
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c.timer = nil |
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} |
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c.mu.Unlock() |
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} |
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|
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// WithTimeout returns WithDeadline(parent, time.Now().Add(timeout)).
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//
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// Canceling this context releases resources associated with it, so code should
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// call cancel as soon as the operations running in this Context complete:
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//
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// func slowOperationWithTimeout(ctx context.Context) (Result, error) {
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// ctx, cancel := context.WithTimeout(ctx, 100*time.Millisecond)
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// defer cancel() // releases resources if slowOperation completes before timeout elapses
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// return slowOperation(ctx)
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// }
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func WithTimeout(parent Context, timeout time.Duration) (Context, CancelFunc) { |
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return WithDeadline(parent, time.Now().Add(timeout)) |
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} |
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|
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// WithValue returns a copy of parent in which the value associated with key is
|
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// val.
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//
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// Use context Values only for request-scoped data that transits processes and
|
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// APIs, not for passing optional parameters to functions.
|
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func WithValue(parent Context, key interface{}, val interface{}) Context { |
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return &valueCtx{parent, key, val} |
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} |
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|
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// A valueCtx carries a key-value pair. It implements Value for that key and
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// delegates all other calls to the embedded Context.
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type valueCtx struct { |
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Context |
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key, val interface{} |
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} |
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func (c *valueCtx) String() string { |
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return fmt.Sprintf("%v.WithValue(%#v, %#v)", c.Context, c.key, c.val) |
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} |
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func (c *valueCtx) Value(key interface{}) interface{} { |
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if c.key == key { |
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return c.val |
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} |
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return c.Context.Value(key) |
||||
} |
||||
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Reference in new issue