vendor: remove context
This commit is contained in:
parent
7ecce5f503
commit
73e9bd59d4
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@ -1,156 +0,0 @@
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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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// Package context defines the Context type, which carries deadlines,
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// cancelation signals, and other request-scoped values across API boundaries
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// and between processes.
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//
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// Incoming requests to a server should create a Context, and outgoing calls to
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// servers should accept a Context. The chain of function calls between must
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// propagate the Context, optionally replacing it with a modified copy created
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// using WithDeadline, WithTimeout, WithCancel, or WithValue.
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//
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// Programs that use Contexts should follow these rules to keep interfaces
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// consistent across packages and enable static analysis tools to check context
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// propagation:
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//
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// Do not store Contexts inside a struct type; instead, pass a Context
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// explicitly to each function that needs it. The Context should be the first
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// parameter, typically named ctx:
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//
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// func DoSomething(ctx context.Context, arg Arg) error {
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// // ... use ctx ...
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// }
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//
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// Do not pass a nil Context, even if a function permits it. Pass context.TODO
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// if you are unsure about which Context to use.
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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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//
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// The same Context may be passed to functions running in different goroutines;
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// Contexts are safe for simultaneous use by multiple goroutines.
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//
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// See http://blog.golang.org/context for example code for a server that uses
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// Contexts.
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package context // import "golang.org/x/net/context"
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import "time"
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// A Context carries a deadline, a cancelation signal, and other values across
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// API boundaries.
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//
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// Context's methods may be called by multiple goroutines simultaneously.
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type Context interface {
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// Deadline returns the time when work done on behalf of this context
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// should be canceled. Deadline returns ok==false when no deadline is
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// set. Successive calls to Deadline return the same results.
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Deadline() (deadline time.Time, ok bool)
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// Done returns a channel that's closed when work done on behalf of this
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// context should be canceled. Done may return nil if this context can
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// never be canceled. Successive calls to Done return the same value.
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//
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// WithCancel arranges for Done to be closed when cancel is called;
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// WithDeadline arranges for Done to be closed when the deadline
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// expires; WithTimeout arranges for Done to be closed when the timeout
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// elapses.
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//
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// Done is provided for use in select statements:
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//
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// // Stream generates values with DoSomething and sends them to out
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// // until DoSomething returns an error or ctx.Done is closed.
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// func Stream(ctx context.Context, out chan<- Value) error {
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// for {
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// v, err := DoSomething(ctx)
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// if err != nil {
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// return err
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// }
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// select {
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// case <-ctx.Done():
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// return ctx.Err()
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// case out <- v:
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// }
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// }
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// }
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//
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// See http://blog.golang.org/pipelines for more examples of how to use
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// a Done channel for cancelation.
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Done() <-chan struct{}
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// Err returns a non-nil error value after Done is closed. Err returns
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// Canceled if the context was canceled or DeadlineExceeded if the
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// context's deadline passed. No other values for Err are defined.
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// After Done is closed, successive calls to Err return the same value.
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Err() error
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// Value returns the value associated with this context for key, or nil
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// if no value is associated with key. Successive calls to Value with
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// the same key returns the same result.
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//
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// Use context values only for request-scoped data that transits
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// processes and API boundaries, not for passing optional parameters to
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// functions.
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//
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// A key identifies a specific value in a Context. Functions that wish
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// to store values in Context typically allocate a key in a global
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// variable then use that key as the argument to context.WithValue and
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// Context.Value. A key can be any type that supports equality;
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// packages should define keys as an unexported type to avoid
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// collisions.
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//
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// Packages that define a Context key should provide type-safe accessors
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// for the values stores using that key:
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//
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// // Package user defines a User type that's stored in Contexts.
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// package user
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//
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// import "golang.org/x/net/context"
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//
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// // User is the type of value stored in the Contexts.
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// type User struct {...}
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//
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// // key is an unexported type for keys defined in this package.
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// // This prevents collisions with keys defined in other packages.
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// type key int
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//
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// // userKey is the key for user.User values in Contexts. It is
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// // unexported; clients use user.NewContext and user.FromContext
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// // instead of using this key directly.
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// var userKey key = 0
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//
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// // NewContext returns a new Context that carries value u.
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// func NewContext(ctx context.Context, u *User) context.Context {
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// return context.WithValue(ctx, userKey, u)
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// }
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//
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// // FromContext returns the User value stored in ctx, if any.
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// func FromContext(ctx context.Context) (*User, bool) {
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// u, ok := ctx.Value(userKey).(*User)
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// return u, ok
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// }
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Value(key interface{}) interface{}
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}
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// Background returns a non-nil, empty Context. It is never canceled, has no
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// values, and has no deadline. It is typically used by the main function,
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// initialization, and tests, and as the top-level Context for incoming
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// requests.
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func Background() Context {
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return background
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}
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// TODO returns a non-nil, empty Context. Code should use context.TODO when
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// it's unclear which Context to use or it is not yet available (because the
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// surrounding function has not yet been extended to accept a Context
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// parameter). TODO is recognized by static analysis tools that determine
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// whether Contexts are propagated correctly in a program.
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func TODO() Context {
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return todo
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}
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// A CancelFunc tells an operation to abandon its work.
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// A CancelFunc does not wait for the work to stop.
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// After the first call, subsequent calls to a CancelFunc do nothing.
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type CancelFunc func()
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@ -1,583 +0,0 @@
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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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"fmt"
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"math/rand"
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"runtime"
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"strings"
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"sync"
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"testing"
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"time"
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)
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// otherContext is a Context that's not one of the types defined in context.go.
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// This lets us test code paths that differ based on the underlying type of the
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// Context.
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type otherContext struct {
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Context
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}
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func TestBackground(t *testing.T) {
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c := Background()
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if c == nil {
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t.Fatalf("Background returned nil")
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}
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select {
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case x := <-c.Done():
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t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
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default:
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}
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if got, want := fmt.Sprint(c), "context.Background"; got != want {
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t.Errorf("Background().String() = %q want %q", got, want)
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}
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}
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func TestTODO(t *testing.T) {
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c := TODO()
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if c == nil {
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t.Fatalf("TODO returned nil")
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}
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select {
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case x := <-c.Done():
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t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
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default:
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}
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if got, want := fmt.Sprint(c), "context.TODO"; got != want {
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t.Errorf("TODO().String() = %q want %q", got, want)
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}
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}
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func TestWithCancel(t *testing.T) {
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c1, cancel := WithCancel(Background())
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if got, want := fmt.Sprint(c1), "context.Background.WithCancel"; got != want {
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t.Errorf("c1.String() = %q want %q", got, want)
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}
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o := otherContext{c1}
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c2, _ := WithCancel(o)
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contexts := []Context{c1, o, c2}
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for i, c := range contexts {
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if d := c.Done(); d == nil {
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t.Errorf("c[%d].Done() == %v want non-nil", i, d)
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}
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if e := c.Err(); e != nil {
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t.Errorf("c[%d].Err() == %v want nil", i, e)
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}
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select {
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case x := <-c.Done():
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t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
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default:
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}
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}
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cancel()
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time.Sleep(100 * time.Millisecond) // let cancelation propagate
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for i, c := range contexts {
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select {
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case <-c.Done():
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default:
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t.Errorf("<-c[%d].Done() blocked, but shouldn't have", i)
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}
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if e := c.Err(); e != Canceled {
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t.Errorf("c[%d].Err() == %v want %v", i, e, Canceled)
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}
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}
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}
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func TestParentFinishesChild(t *testing.T) {
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// Context tree:
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// parent -> cancelChild
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// parent -> valueChild -> timerChild
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parent, cancel := WithCancel(Background())
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cancelChild, stop := WithCancel(parent)
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defer stop()
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valueChild := WithValue(parent, "key", "value")
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timerChild, stop := WithTimeout(valueChild, 10000*time.Hour)
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defer stop()
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select {
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case x := <-parent.Done():
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t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
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case x := <-cancelChild.Done():
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t.Errorf("<-cancelChild.Done() == %v want nothing (it should block)", x)
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case x := <-timerChild.Done():
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t.Errorf("<-timerChild.Done() == %v want nothing (it should block)", x)
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case x := <-valueChild.Done():
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t.Errorf("<-valueChild.Done() == %v want nothing (it should block)", x)
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default:
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}
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// The parent's children should contain the two cancelable children.
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pc := parent.(*cancelCtx)
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cc := cancelChild.(*cancelCtx)
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tc := timerChild.(*timerCtx)
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pc.mu.Lock()
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if len(pc.children) != 2 || !pc.children[cc] || !pc.children[tc] {
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t.Errorf("bad linkage: pc.children = %v, want %v and %v",
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pc.children, cc, tc)
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}
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pc.mu.Unlock()
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if p, ok := parentCancelCtx(cc.Context); !ok || p != pc {
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t.Errorf("bad linkage: parentCancelCtx(cancelChild.Context) = %v, %v want %v, true", p, ok, pc)
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}
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if p, ok := parentCancelCtx(tc.Context); !ok || p != pc {
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t.Errorf("bad linkage: parentCancelCtx(timerChild.Context) = %v, %v want %v, true", p, ok, pc)
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}
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cancel()
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pc.mu.Lock()
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if len(pc.children) != 0 {
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t.Errorf("pc.cancel didn't clear pc.children = %v", pc.children)
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}
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pc.mu.Unlock()
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// parent and children should all be finished.
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check := func(ctx Context, name string) {
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select {
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case <-ctx.Done():
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default:
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t.Errorf("<-%s.Done() blocked, but shouldn't have", name)
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}
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if e := ctx.Err(); e != Canceled {
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t.Errorf("%s.Err() == %v want %v", name, e, Canceled)
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}
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}
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check(parent, "parent")
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check(cancelChild, "cancelChild")
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check(valueChild, "valueChild")
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check(timerChild, "timerChild")
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// WithCancel should return a canceled context on a canceled parent.
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precanceledChild := WithValue(parent, "key", "value")
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select {
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case <-precanceledChild.Done():
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default:
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t.Errorf("<-precanceledChild.Done() blocked, but shouldn't have")
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}
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if e := precanceledChild.Err(); e != Canceled {
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t.Errorf("precanceledChild.Err() == %v want %v", e, Canceled)
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}
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}
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func TestChildFinishesFirst(t *testing.T) {
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cancelable, stop := WithCancel(Background())
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defer stop()
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for _, parent := range []Context{Background(), cancelable} {
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child, cancel := WithCancel(parent)
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select {
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case x := <-parent.Done():
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t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
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case x := <-child.Done():
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t.Errorf("<-child.Done() == %v want nothing (it should block)", x)
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default:
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}
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cc := child.(*cancelCtx)
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pc, pcok := parent.(*cancelCtx) // pcok == false when parent == Background()
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if p, ok := parentCancelCtx(cc.Context); ok != pcok || (ok && pc != p) {
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t.Errorf("bad linkage: parentCancelCtx(cc.Context) = %v, %v want %v, %v", p, ok, pc, pcok)
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}
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if pcok {
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pc.mu.Lock()
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if len(pc.children) != 1 || !pc.children[cc] {
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t.Errorf("bad linkage: pc.children = %v, cc = %v", pc.children, cc)
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}
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pc.mu.Unlock()
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}
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cancel()
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if pcok {
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pc.mu.Lock()
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if len(pc.children) != 0 {
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t.Errorf("child's cancel didn't remove self from pc.children = %v", pc.children)
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}
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pc.mu.Unlock()
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}
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// child should be finished.
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select {
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case <-child.Done():
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default:
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t.Errorf("<-child.Done() blocked, but shouldn't have")
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}
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if e := child.Err(); e != Canceled {
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t.Errorf("child.Err() == %v want %v", e, Canceled)
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}
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// parent should not be finished.
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select {
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case x := <-parent.Done():
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t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
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default:
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}
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if e := parent.Err(); e != nil {
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t.Errorf("parent.Err() == %v want nil", e)
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}
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}
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}
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func testDeadline(c Context, wait time.Duration, t *testing.T) {
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select {
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case <-time.After(wait):
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t.Fatalf("context should have timed out")
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case <-c.Done():
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}
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if e := c.Err(); e != DeadlineExceeded {
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t.Errorf("c.Err() == %v want %v", e, DeadlineExceeded)
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}
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}
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func TestDeadline(t *testing.T) {
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t.Parallel()
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const timeUnit = 500 * time.Millisecond
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c, _ := WithDeadline(Background(), time.Now().Add(1*timeUnit))
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if got, prefix := fmt.Sprint(c), "context.Background.WithDeadline("; !strings.HasPrefix(got, prefix) {
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t.Errorf("c.String() = %q want prefix %q", got, prefix)
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}
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testDeadline(c, 2*timeUnit, t)
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c, _ = WithDeadline(Background(), time.Now().Add(1*timeUnit))
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o := otherContext{c}
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testDeadline(o, 2*timeUnit, t)
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c, _ = WithDeadline(Background(), time.Now().Add(1*timeUnit))
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o = otherContext{c}
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c, _ = WithDeadline(o, time.Now().Add(3*timeUnit))
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testDeadline(c, 2*timeUnit, t)
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}
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func TestTimeout(t *testing.T) {
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t.Parallel()
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const timeUnit = 500 * time.Millisecond
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c, _ := WithTimeout(Background(), 1*timeUnit)
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if got, prefix := fmt.Sprint(c), "context.Background.WithDeadline("; !strings.HasPrefix(got, prefix) {
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t.Errorf("c.String() = %q want prefix %q", got, prefix)
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}
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testDeadline(c, 2*timeUnit, t)
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c, _ = WithTimeout(Background(), 1*timeUnit)
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o := otherContext{c}
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testDeadline(o, 2*timeUnit, t)
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c, _ = WithTimeout(Background(), 1*timeUnit)
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o = otherContext{c}
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c, _ = WithTimeout(o, 3*timeUnit)
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testDeadline(c, 2*timeUnit, t)
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}
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func TestCanceledTimeout(t *testing.T) {
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t.Parallel()
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const timeUnit = 500 * time.Millisecond
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c, _ := WithTimeout(Background(), 2*timeUnit)
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o := otherContext{c}
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c, cancel := WithTimeout(o, 4*timeUnit)
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cancel()
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time.Sleep(1 * timeUnit) // let cancelation propagate
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select {
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case <-c.Done():
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default:
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t.Errorf("<-c.Done() blocked, but shouldn't have")
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}
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if e := c.Err(); e != Canceled {
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t.Errorf("c.Err() == %v want %v", e, Canceled)
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}
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}
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type key1 int
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type key2 int
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var k1 = key1(1)
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var k2 = key2(1) // same int as k1, different type
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var k3 = key2(3) // same type as k2, different int
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func TestValues(t *testing.T) {
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check := func(c Context, nm, v1, v2, v3 string) {
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if v, ok := c.Value(k1).(string); ok == (len(v1) == 0) || v != v1 {
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t.Errorf(`%s.Value(k1).(string) = %q, %t want %q, %t`, nm, v, ok, v1, len(v1) != 0)
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}
|
||||
if v, ok := c.Value(k2).(string); ok == (len(v2) == 0) || v != v2 {
|
||||
t.Errorf(`%s.Value(k2).(string) = %q, %t want %q, %t`, nm, v, ok, v2, len(v2) != 0)
|
||||
}
|
||||
if v, ok := c.Value(k3).(string); ok == (len(v3) == 0) || v != v3 {
|
||||
t.Errorf(`%s.Value(k3).(string) = %q, %t want %q, %t`, nm, v, ok, v3, len(v3) != 0)
|
||||
}
|
||||
}
|
||||
|
||||
c0 := Background()
|
||||
check(c0, "c0", "", "", "")
|
||||
|
||||
c1 := WithValue(Background(), k1, "c1k1")
|
||||
check(c1, "c1", "c1k1", "", "")
|
||||
|
||||
if got, want := fmt.Sprint(c1), `context.Background.WithValue(1, "c1k1")`; got != want {
|
||||
t.Errorf("c.String() = %q want %q", got, want)
|
||||
}
|
||||
|
||||
c2 := WithValue(c1, k2, "c2k2")
|
||||
check(c2, "c2", "c1k1", "c2k2", "")
|
||||
|
||||
c3 := WithValue(c2, k3, "c3k3")
|
||||
check(c3, "c2", "c1k1", "c2k2", "c3k3")
|
||||
|
||||
c4 := WithValue(c3, k1, nil)
|
||||
check(c4, "c4", "", "c2k2", "c3k3")
|
||||
|
||||
o0 := otherContext{Background()}
|
||||
check(o0, "o0", "", "", "")
|
||||
|
||||
o1 := otherContext{WithValue(Background(), k1, "c1k1")}
|
||||
check(o1, "o1", "c1k1", "", "")
|
||||
|
||||
o2 := WithValue(o1, k2, "o2k2")
|
||||
check(o2, "o2", "c1k1", "o2k2", "")
|
||||
|
||||
o3 := otherContext{c4}
|
||||
check(o3, "o3", "", "c2k2", "c3k3")
|
||||
|
||||
o4 := WithValue(o3, k3, nil)
|
||||
check(o4, "o4", "", "c2k2", "")
|
||||
}
|
||||
|
||||
func TestAllocs(t *testing.T) {
|
||||
bg := Background()
|
||||
for _, test := range []struct {
|
||||
desc string
|
||||
f func()
|
||||
limit float64
|
||||
gccgoLimit float64
|
||||
}{
|
||||
{
|
||||
desc: "Background()",
|
||||
f: func() { Background() },
|
||||
limit: 0,
|
||||
gccgoLimit: 0,
|
||||
},
|
||||
{
|
||||
desc: fmt.Sprintf("WithValue(bg, %v, nil)", k1),
|
||||
f: func() {
|
||||
c := WithValue(bg, k1, nil)
|
||||
c.Value(k1)
|
||||
},
|
||||
limit: 3,
|
||||
gccgoLimit: 3,
|
||||
},
|
||||
{
|
||||
desc: "WithTimeout(bg, 15*time.Millisecond)",
|
||||
f: func() {
|
||||
c, _ := WithTimeout(bg, 15*time.Millisecond)
|
||||
<-c.Done()
|
||||
},
|
||||
limit: 8,
|
||||
gccgoLimit: 16,
|
||||
},
|
||||
{
|
||||
desc: "WithCancel(bg)",
|
||||
f: func() {
|
||||
c, cancel := WithCancel(bg)
|
||||
cancel()
|
||||
<-c.Done()
|
||||
},
|
||||
limit: 5,
|
||||
gccgoLimit: 8,
|
||||
},
|
||||
{
|
||||
desc: "WithTimeout(bg, 100*time.Millisecond)",
|
||||
f: func() {
|
||||
c, cancel := WithTimeout(bg, 100*time.Millisecond)
|
||||
cancel()
|
||||
<-c.Done()
|
||||
},
|
||||
limit: 8,
|
||||
gccgoLimit: 25,
|
||||
},
|
||||
} {
|
||||
limit := test.limit
|
||||
if runtime.Compiler == "gccgo" {
|
||||
// gccgo does not yet do escape analysis.
|
||||
// TODO(iant): Remove this when gccgo does do escape analysis.
|
||||
limit = test.gccgoLimit
|
||||
}
|
||||
if n := testing.AllocsPerRun(100, test.f); n > limit {
|
||||
t.Errorf("%s allocs = %f want %d", test.desc, n, int(limit))
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
func TestSimultaneousCancels(t *testing.T) {
|
||||
root, cancel := WithCancel(Background())
|
||||
m := map[Context]CancelFunc{root: cancel}
|
||||
q := []Context{root}
|
||||
// Create a tree of contexts.
|
||||
for len(q) != 0 && len(m) < 100 {
|
||||
parent := q[0]
|
||||
q = q[1:]
|
||||
for i := 0; i < 4; i++ {
|
||||
ctx, cancel := WithCancel(parent)
|
||||
m[ctx] = cancel
|
||||
q = append(q, ctx)
|
||||
}
|
||||
}
|
||||
// Start all the cancels in a random order.
|
||||
var wg sync.WaitGroup
|
||||
wg.Add(len(m))
|
||||
for _, cancel := range m {
|
||||
go func(cancel CancelFunc) {
|
||||
cancel()
|
||||
wg.Done()
|
||||
}(cancel)
|
||||
}
|
||||
// Wait on all the contexts in a random order.
|
||||
for ctx := range m {
|
||||
select {
|
||||
case <-ctx.Done():
|
||||
case <-time.After(1 * time.Second):
|
||||
buf := make([]byte, 10<<10)
|
||||
n := runtime.Stack(buf, true)
|
||||
t.Fatalf("timed out waiting for <-ctx.Done(); stacks:\n%s", buf[:n])
|
||||
}
|
||||
}
|
||||
// Wait for all the cancel functions to return.
|
||||
done := make(chan struct{})
|
||||
go func() {
|
||||
wg.Wait()
|
||||
close(done)
|
||||
}()
|
||||
select {
|
||||
case <-done:
|
||||
case <-time.After(1 * time.Second):
|
||||
buf := make([]byte, 10<<10)
|
||||
n := runtime.Stack(buf, true)
|
||||
t.Fatalf("timed out waiting for cancel functions; stacks:\n%s", buf[:n])
|
||||
}
|
||||
}
|
||||
|
||||
func TestInterlockedCancels(t *testing.T) {
|
||||
parent, cancelParent := WithCancel(Background())
|
||||
child, cancelChild := WithCancel(parent)
|
||||
go func() {
|
||||
parent.Done()
|
||||
cancelChild()
|
||||
}()
|
||||
cancelParent()
|
||||
select {
|
||||
case <-child.Done():
|
||||
case <-time.After(1 * time.Second):
|
||||
buf := make([]byte, 10<<10)
|
||||
n := runtime.Stack(buf, true)
|
||||
t.Fatalf("timed out waiting for child.Done(); stacks:\n%s", buf[:n])
|
||||
}
|
||||
}
|
||||
|
||||
func TestLayersCancel(t *testing.T) {
|
||||
testLayers(t, time.Now().UnixNano(), false)
|
||||
}
|
||||
|
||||
func TestLayersTimeout(t *testing.T) {
|
||||
testLayers(t, time.Now().UnixNano(), true)
|
||||
}
|
||||
|
||||
func testLayers(t *testing.T, seed int64, testTimeout bool) {
|
||||
rand.Seed(seed)
|
||||
errorf := func(format string, a ...interface{}) {
|
||||
t.Errorf(fmt.Sprintf("seed=%d: %s", seed, format), a...)
|
||||
}
|
||||
const (
|
||||
timeout = 200 * time.Millisecond
|
||||
minLayers = 30
|
||||
)
|
||||
type value int
|
||||
var (
|
||||
vals []*value
|
||||
cancels []CancelFunc
|
||||
numTimers int
|
||||
ctx = Background()
|
||||
)
|
||||
for i := 0; i < minLayers || numTimers == 0 || len(cancels) == 0 || len(vals) == 0; i++ {
|
||||
switch rand.Intn(3) {
|
||||
case 0:
|
||||
v := new(value)
|
||||
ctx = WithValue(ctx, v, v)
|
||||
vals = append(vals, v)
|
||||
case 1:
|
||||
var cancel CancelFunc
|
||||
ctx, cancel = WithCancel(ctx)
|
||||
cancels = append(cancels, cancel)
|
||||
case 2:
|
||||
var cancel CancelFunc
|
||||
ctx, cancel = WithTimeout(ctx, timeout)
|
||||
cancels = append(cancels, cancel)
|
||||
numTimers++
|
||||
}
|
||||
}
|
||||
checkValues := func(when string) {
|
||||
for _, key := range vals {
|
||||
if val := ctx.Value(key).(*value); key != val {
|
||||
errorf("%s: ctx.Value(%p) = %p want %p", when, key, val, key)
|
||||
}
|
||||
}
|
||||
}
|
||||
select {
|
||||
case <-ctx.Done():
|
||||
errorf("ctx should not be canceled yet")
|
||||
default:
|
||||
}
|
||||
if s, prefix := fmt.Sprint(ctx), "context.Background."; !strings.HasPrefix(s, prefix) {
|
||||
t.Errorf("ctx.String() = %q want prefix %q", s, prefix)
|
||||
}
|
||||
t.Log(ctx)
|
||||
checkValues("before cancel")
|
||||
if testTimeout {
|
||||
select {
|
||||
case <-ctx.Done():
|
||||
case <-time.After(timeout + 100*time.Millisecond):
|
||||
errorf("ctx should have timed out")
|
||||
}
|
||||
checkValues("after timeout")
|
||||
} else {
|
||||
cancel := cancels[rand.Intn(len(cancels))]
|
||||
cancel()
|
||||
select {
|
||||
case <-ctx.Done():
|
||||
default:
|
||||
errorf("ctx should be canceled")
|
||||
}
|
||||
checkValues("after cancel")
|
||||
}
|
||||
}
|
||||
|
||||
func TestCancelRemoves(t *testing.T) {
|
||||
checkChildren := func(when string, ctx Context, want int) {
|
||||
if got := len(ctx.(*cancelCtx).children); got != want {
|
||||
t.Errorf("%s: context has %d children, want %d", when, got, want)
|
||||
}
|
||||
}
|
||||
|
||||
ctx, _ := WithCancel(Background())
|
||||
checkChildren("after creation", ctx, 0)
|
||||
_, cancel := WithCancel(ctx)
|
||||
checkChildren("with WithCancel child ", ctx, 1)
|
||||
cancel()
|
||||
checkChildren("after cancelling WithCancel child", ctx, 0)
|
||||
|
||||
ctx, _ = WithCancel(Background())
|
||||
checkChildren("after creation", ctx, 0)
|
||||
_, cancel = WithTimeout(ctx, 60*time.Minute)
|
||||
checkChildren("with WithTimeout child ", ctx, 1)
|
||||
cancel()
|
||||
checkChildren("after cancelling WithTimeout child", ctx, 0)
|
||||
}
|
||||
|
|
@ -1,74 +0,0 @@
|
|||
// Copyright 2016 The Go Authors. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
// +build go1.7
|
||||
|
||||
// Package ctxhttp provides helper functions for performing context-aware HTTP requests.
|
||||
package ctxhttp // import "golang.org/x/net/context/ctxhttp"
|
||||
|
||||
import (
|
||||
"io"
|
||||
"net/http"
|
||||
"net/url"
|
||||
"strings"
|
||||
|
||||
"golang.org/x/net/context"
|
||||
)
|
||||
|
||||
// Do sends an HTTP request with the provided http.Client and returns
|
||||
// an HTTP response.
|
||||
//
|
||||
// If the client is nil, http.DefaultClient is used.
|
||||
//
|
||||
// The provided ctx must be non-nil. If it is canceled or times out,
|
||||
// ctx.Err() will be returned.
|
||||
func Do(ctx context.Context, client *http.Client, req *http.Request) (*http.Response, error) {
|
||||
if client == nil {
|
||||
client = http.DefaultClient
|
||||
}
|
||||
resp, err := client.Do(req.WithContext(ctx))
|
||||
// If we got an error, and the context has been canceled,
|
||||
// the context's error is probably more useful.
|
||||
if err != nil {
|
||||
select {
|
||||
case <-ctx.Done():
|
||||
err = ctx.Err()
|
||||
default:
|
||||
}
|
||||
}
|
||||
return resp, err
|
||||
}
|
||||
|
||||
// Get issues a GET request via the Do function.
|
||||
func Get(ctx context.Context, client *http.Client, url string) (*http.Response, error) {
|
||||
req, err := http.NewRequest("GET", url, nil)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
return Do(ctx, client, req)
|
||||
}
|
||||
|
||||
// Head issues a HEAD request via the Do function.
|
||||
func Head(ctx context.Context, client *http.Client, url string) (*http.Response, error) {
|
||||
req, err := http.NewRequest("HEAD", url, nil)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
return Do(ctx, client, req)
|
||||
}
|
||||
|
||||
// Post issues a POST request via the Do function.
|
||||
func Post(ctx context.Context, client *http.Client, url string, bodyType string, body io.Reader) (*http.Response, error) {
|
||||
req, err := http.NewRequest("POST", url, body)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
req.Header.Set("Content-Type", bodyType)
|
||||
return Do(ctx, client, req)
|
||||
}
|
||||
|
||||
// PostForm issues a POST request via the Do function.
|
||||
func PostForm(ctx context.Context, client *http.Client, url string, data url.Values) (*http.Response, error) {
|
||||
return Post(ctx, client, url, "application/x-www-form-urlencoded", strings.NewReader(data.Encode()))
|
||||
}
|
||||
|
|
@ -1,147 +0,0 @@
|
|||
// Copyright 2015 The Go Authors. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
// +build !go1.7
|
||||
|
||||
package ctxhttp // import "golang.org/x/net/context/ctxhttp"
|
||||
|
||||
import (
|
||||
"io"
|
||||
"net/http"
|
||||
"net/url"
|
||||
"strings"
|
||||
|
||||
"golang.org/x/net/context"
|
||||
)
|
||||
|
||||
func nop() {}
|
||||
|
||||
var (
|
||||
testHookContextDoneBeforeHeaders = nop
|
||||
testHookDoReturned = nop
|
||||
testHookDidBodyClose = nop
|
||||
)
|
||||
|
||||
// Do sends an HTTP request with the provided http.Client and returns an HTTP response.
|
||||
// If the client is nil, http.DefaultClient is used.
|
||||
// If the context is canceled or times out, ctx.Err() will be returned.
|
||||
func Do(ctx context.Context, client *http.Client, req *http.Request) (*http.Response, error) {
|
||||
if client == nil {
|
||||
client = http.DefaultClient
|
||||
}
|
||||
|
||||
// TODO(djd): Respect any existing value of req.Cancel.
|
||||
cancel := make(chan struct{})
|
||||
req.Cancel = cancel
|
||||
|
||||
type responseAndError struct {
|
||||
resp *http.Response
|
||||
err error
|
||||
}
|
||||
result := make(chan responseAndError, 1)
|
||||
|
||||
// Make local copies of test hooks closed over by goroutines below.
|
||||
// Prevents data races in tests.
|
||||
testHookDoReturned := testHookDoReturned
|
||||
testHookDidBodyClose := testHookDidBodyClose
|
||||
|
||||
go func() {
|
||||
resp, err := client.Do(req)
|
||||
testHookDoReturned()
|
||||
result <- responseAndError{resp, err}
|
||||
}()
|
||||
|
||||
var resp *http.Response
|
||||
|
||||
select {
|
||||
case <-ctx.Done():
|
||||
testHookContextDoneBeforeHeaders()
|
||||
close(cancel)
|
||||
// Clean up after the goroutine calling client.Do:
|
||||
go func() {
|
||||
if r := <-result; r.resp != nil {
|
||||
testHookDidBodyClose()
|
||||
r.resp.Body.Close()
|
||||
}
|
||||
}()
|
||||
return nil, ctx.Err()
|
||||
case r := <-result:
|
||||
var err error
|
||||
resp, err = r.resp, r.err
|
||||
if err != nil {
|
||||
return resp, err
|
||||
}
|
||||
}
|
||||
|
||||
c := make(chan struct{})
|
||||
go func() {
|
||||
select {
|
||||
case <-ctx.Done():
|
||||
close(cancel)
|
||||
case <-c:
|
||||
// The response's Body is closed.
|
||||
}
|
||||
}()
|
||||
resp.Body = ¬ifyingReader{resp.Body, c}
|
||||
|
||||
return resp, nil
|
||||
}
|
||||
|
||||
// Get issues a GET request via the Do function.
|
||||
func Get(ctx context.Context, client *http.Client, url string) (*http.Response, error) {
|
||||
req, err := http.NewRequest("GET", url, nil)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
return Do(ctx, client, req)
|
||||
}
|
||||
|
||||
// Head issues a HEAD request via the Do function.
|
||||
func Head(ctx context.Context, client *http.Client, url string) (*http.Response, error) {
|
||||
req, err := http.NewRequest("HEAD", url, nil)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
return Do(ctx, client, req)
|
||||
}
|
||||
|
||||
// Post issues a POST request via the Do function.
|
||||
func Post(ctx context.Context, client *http.Client, url string, bodyType string, body io.Reader) (*http.Response, error) {
|
||||
req, err := http.NewRequest("POST", url, body)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
req.Header.Set("Content-Type", bodyType)
|
||||
return Do(ctx, client, req)
|
||||
}
|
||||
|
||||
// PostForm issues a POST request via the Do function.
|
||||
func PostForm(ctx context.Context, client *http.Client, url string, data url.Values) (*http.Response, error) {
|
||||
return Post(ctx, client, url, "application/x-www-form-urlencoded", strings.NewReader(data.Encode()))
|
||||
}
|
||||
|
||||
// notifyingReader is an io.ReadCloser that closes the notify channel after
|
||||
// Close is called or a Read fails on the underlying ReadCloser.
|
||||
type notifyingReader struct {
|
||||
io.ReadCloser
|
||||
notify chan<- struct{}
|
||||
}
|
||||
|
||||
func (r *notifyingReader) Read(p []byte) (int, error) {
|
||||
n, err := r.ReadCloser.Read(p)
|
||||
if err != nil && r.notify != nil {
|
||||
close(r.notify)
|
||||
r.notify = nil
|
||||
}
|
||||
return n, err
|
||||
}
|
||||
|
||||
func (r *notifyingReader) Close() error {
|
||||
err := r.ReadCloser.Close()
|
||||
if r.notify != nil {
|
||||
close(r.notify)
|
||||
r.notify = nil
|
||||
}
|
||||
return err
|
||||
}
|
||||
|
|
@ -1,79 +0,0 @@
|
|||
// Copyright 2015 The Go Authors. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
// +build !plan9,!go1.7
|
||||
|
||||
package ctxhttp
|
||||
|
||||
import (
|
||||
"net"
|
||||
"net/http"
|
||||
"net/http/httptest"
|
||||
"sync"
|
||||
"testing"
|
||||
"time"
|
||||
|
||||
"golang.org/x/net/context"
|
||||
)
|
||||
|
||||
// golang.org/issue/14065
|
||||
func TestClosesResponseBodyOnCancel(t *testing.T) {
|
||||
defer func() { testHookContextDoneBeforeHeaders = nop }()
|
||||
defer func() { testHookDoReturned = nop }()
|
||||
defer func() { testHookDidBodyClose = nop }()
|
||||
|
||||
ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
|
||||
defer ts.Close()
|
||||
|
||||
ctx, cancel := context.WithCancel(context.Background())
|
||||
|
||||
// closed when Do enters select case <-ctx.Done()
|
||||
enteredDonePath := make(chan struct{})
|
||||
|
||||
testHookContextDoneBeforeHeaders = func() {
|
||||
close(enteredDonePath)
|
||||
}
|
||||
|
||||
testHookDoReturned = func() {
|
||||
// We now have the result (the Flush'd headers) at least,
|
||||
// so we can cancel the request.
|
||||
cancel()
|
||||
|
||||
// But block the client.Do goroutine from sending
|
||||
// until Do enters into the <-ctx.Done() path, since
|
||||
// otherwise if both channels are readable, select
|
||||
// picks a random one.
|
||||
<-enteredDonePath
|
||||
}
|
||||
|
||||
sawBodyClose := make(chan struct{})
|
||||
testHookDidBodyClose = func() { close(sawBodyClose) }
|
||||
|
||||
tr := &http.Transport{}
|
||||
defer tr.CloseIdleConnections()
|
||||
c := &http.Client{Transport: tr}
|
||||
req, _ := http.NewRequest("GET", ts.URL, nil)
|
||||
_, doErr := Do(ctx, c, req)
|
||||
|
||||
select {
|
||||
case <-sawBodyClose:
|
||||
case <-time.After(5 * time.Second):
|
||||
t.Fatal("timeout waiting for body to close")
|
||||
}
|
||||
|
||||
if doErr != ctx.Err() {
|
||||
t.Errorf("Do error = %v; want %v", doErr, ctx.Err())
|
||||
}
|
||||
}
|
||||
|
||||
type noteCloseConn struct {
|
||||
net.Conn
|
||||
onceClose sync.Once
|
||||
closefn func()
|
||||
}
|
||||
|
||||
func (c *noteCloseConn) Close() error {
|
||||
c.onceClose.Do(c.closefn)
|
||||
return c.Conn.Close()
|
||||
}
|
||||
|
|
@ -1,72 +0,0 @@
|
|||
// Copyright 2016 The Go Authors. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
// +build go1.7
|
||||
|
||||
package context
|
||||
|
||||
import (
|
||||
"context" // standard library's context, as of Go 1.7
|
||||
"time"
|
||||
)
|
||||
|
||||
var (
|
||||
todo = context.TODO()
|
||||
background = context.Background()
|
||||
)
|
||||
|
||||
// Canceled is the error returned by Context.Err when the context is canceled.
|
||||
var Canceled = context.Canceled
|
||||
|
||||
// DeadlineExceeded is the error returned by Context.Err when the context's
|
||||
// deadline passes.
|
||||
var DeadlineExceeded = context.DeadlineExceeded
|
||||
|
||||
// WithCancel returns a copy of parent with a new Done channel. The returned
|
||||
// context's Done channel is closed when the returned cancel function is called
|
||||
// or when the parent context's Done channel is closed, whichever happens first.
|
||||
//
|
||||
// Canceling this context releases resources associated with it, so code should
|
||||
// call cancel as soon as the operations running in this Context complete.
|
||||
func WithCancel(parent Context) (ctx Context, cancel CancelFunc) {
|
||||
ctx, f := context.WithCancel(parent)
|
||||
return ctx, CancelFunc(f)
|
||||
}
|
||||
|
||||
// WithDeadline returns a copy of the parent context with the deadline adjusted
|
||||
// to be no later than d. If the parent's deadline is already earlier than d,
|
||||
// WithDeadline(parent, d) is semantically equivalent to parent. The returned
|
||||
// context's Done channel is closed when the deadline expires, when the returned
|
||||
// cancel function is called, or when the parent context's Done channel is
|
||||
// closed, whichever happens first.
|
||||
//
|
||||
// Canceling this context releases resources associated with it, so code should
|
||||
// call cancel as soon as the operations running in this Context complete.
|
||||
func WithDeadline(parent Context, deadline time.Time) (Context, CancelFunc) {
|
||||
ctx, f := context.WithDeadline(parent, deadline)
|
||||
return ctx, CancelFunc(f)
|
||||
}
|
||||
|
||||
// WithTimeout returns WithDeadline(parent, time.Now().Add(timeout)).
|
||||
//
|
||||
// Canceling this context releases resources associated with it, so code should
|
||||
// call cancel as soon as the operations running in this Context complete:
|
||||
//
|
||||
// func slowOperationWithTimeout(ctx context.Context) (Result, error) {
|
||||
// ctx, cancel := context.WithTimeout(ctx, 100*time.Millisecond)
|
||||
// defer cancel() // releases resources if slowOperation completes before timeout elapses
|
||||
// return slowOperation(ctx)
|
||||
// }
|
||||
func WithTimeout(parent Context, timeout time.Duration) (Context, CancelFunc) {
|
||||
return WithDeadline(parent, time.Now().Add(timeout))
|
||||
}
|
||||
|
||||
// WithValue returns a copy of parent in which the value associated with key is
|
||||
// val.
|
||||
//
|
||||
// Use context Values only for request-scoped data that transits processes and
|
||||
// APIs, not for passing optional parameters to functions.
|
||||
func WithValue(parent Context, key interface{}, val interface{}) Context {
|
||||
return context.WithValue(parent, key, val)
|
||||
}
|
||||
|
|
@ -1,300 +0,0 @@
|
|||
// Copyright 2014 The Go Authors. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
// +build !go1.7
|
||||
|
||||
package context
|
||||
|
||||
import (
|
||||
"errors"
|
||||
"fmt"
|
||||
"sync"
|
||||
"time"
|
||||
)
|
||||
|
||||
// An emptyCtx is never canceled, has no values, and has no deadline. It is not
|
||||
// struct{}, since vars of this type must have distinct addresses.
|
||||
type emptyCtx int
|
||||
|
||||
func (*emptyCtx) Deadline() (deadline time.Time, ok bool) {
|
||||
return
|
||||
}
|
||||
|
||||
func (*emptyCtx) Done() <-chan struct{} {
|
||||
return nil
|
||||
}
|
||||
|
||||
func (*emptyCtx) Err() error {
|
||||
return nil
|
||||
}
|
||||
|
||||
func (*emptyCtx) Value(key interface{}) interface{} {
|
||||
return nil
|
||||
}
|
||||
|
||||
func (e *emptyCtx) String() string {
|
||||
switch e {
|
||||
case background:
|
||||
return "context.Background"
|
||||
case todo:
|
||||
return "context.TODO"
|
||||
}
|
||||
return "unknown empty Context"
|
||||
}
|
||||
|
||||
var (
|
||||
background = new(emptyCtx)
|
||||
todo = new(emptyCtx)
|
||||
)
|
||||
|
||||
// Canceled is the error returned by Context.Err when the context is canceled.
|
||||
var Canceled = errors.New("context canceled")
|
||||
|
||||
// DeadlineExceeded is the error returned by Context.Err when the context's
|
||||
// deadline passes.
|
||||
var DeadlineExceeded = errors.New("context deadline exceeded")
|
||||
|
||||
// WithCancel returns a copy of parent with a new Done channel. The returned
|
||||
// context's Done channel is closed when the returned cancel function is called
|
||||
// or when the parent context's Done channel is closed, whichever happens first.
|
||||
//
|
||||
// Canceling this context releases resources associated with it, so code should
|
||||
// call cancel as soon as the operations running in this Context complete.
|
||||
func WithCancel(parent Context) (ctx Context, cancel CancelFunc) {
|
||||
c := newCancelCtx(parent)
|
||||
propagateCancel(parent, c)
|
||||
return c, func() { c.cancel(true, Canceled) }
|
||||
}
|
||||
|
||||
// newCancelCtx returns an initialized cancelCtx.
|
||||
func newCancelCtx(parent Context) *cancelCtx {
|
||||
return &cancelCtx{
|
||||
Context: parent,
|
||||
done: make(chan struct{}),
|
||||
}
|
||||
}
|
||||
|
||||
// propagateCancel arranges for child to be canceled when parent is.
|
||||
func propagateCancel(parent Context, child canceler) {
|
||||
if parent.Done() == nil {
|
||||
return // parent is never canceled
|
||||
}
|
||||
if p, ok := parentCancelCtx(parent); ok {
|
||||
p.mu.Lock()
|
||||
if p.err != nil {
|
||||
// parent has already been canceled
|
||||
child.cancel(false, p.err)
|
||||
} else {
|
||||
if p.children == nil {
|
||||
p.children = make(map[canceler]bool)
|
||||
}
|
||||
p.children[child] = true
|
||||
}
|
||||
p.mu.Unlock()
|
||||
} else {
|
||||
go func() {
|
||||
select {
|
||||
case <-parent.Done():
|
||||
child.cancel(false, parent.Err())
|
||||
case <-child.Done():
|
||||
}
|
||||
}()
|
||||
}
|
||||
}
|
||||
|
||||
// parentCancelCtx follows a chain of parent references until it finds a
|
||||
// *cancelCtx. This function understands how each of the concrete types in this
|
||||
// package represents its parent.
|
||||
func parentCancelCtx(parent Context) (*cancelCtx, bool) {
|
||||
for {
|
||||
switch c := parent.(type) {
|
||||
case *cancelCtx:
|
||||
return c, true
|
||||
case *timerCtx:
|
||||
return c.cancelCtx, true
|
||||
case *valueCtx:
|
||||
parent = c.Context
|
||||
default:
|
||||
return nil, false
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// removeChild removes a context from its parent.
|
||||
func removeChild(parent Context, child canceler) {
|
||||
p, ok := parentCancelCtx(parent)
|
||||
if !ok {
|
||||
return
|
||||
}
|
||||
p.mu.Lock()
|
||||
if p.children != nil {
|
||||
delete(p.children, child)
|
||||
}
|
||||
p.mu.Unlock()
|
||||
}
|
||||
|
||||
// A canceler is a context type that can be canceled directly. The
|
||||
// implementations are *cancelCtx and *timerCtx.
|
||||
type canceler interface {
|
||||
cancel(removeFromParent bool, err error)
|
||||
Done() <-chan struct{}
|
||||
}
|
||||
|
||||
// A cancelCtx can be canceled. When canceled, it also cancels any children
|
||||
// that implement canceler.
|
||||
type cancelCtx struct {
|
||||
Context
|
||||
|
||||
done chan struct{} // closed by the first cancel call.
|
||||
|
||||
mu sync.Mutex
|
||||
children map[canceler]bool // set to nil by the first cancel call
|
||||
err error // set to non-nil by the first cancel call
|
||||
}
|
||||
|
||||
func (c *cancelCtx) Done() <-chan struct{} {
|
||||
return c.done
|
||||
}
|
||||
|
||||
func (c *cancelCtx) Err() error {
|
||||
c.mu.Lock()
|
||||
defer c.mu.Unlock()
|
||||
return c.err
|
||||
}
|
||||
|
||||
func (c *cancelCtx) String() string {
|
||||
return fmt.Sprintf("%v.WithCancel", c.Context)
|
||||
}
|
||||
|
||||
// cancel closes c.done, cancels each of c's children, and, if
|
||||
// removeFromParent is true, removes c from its parent's children.
|
||||
func (c *cancelCtx) cancel(removeFromParent bool, err error) {
|
||||
if err == nil {
|
||||
panic("context: internal error: missing cancel error")
|
||||
}
|
||||
c.mu.Lock()
|
||||
if c.err != nil {
|
||||
c.mu.Unlock()
|
||||
return // already canceled
|
||||
}
|
||||
c.err = err
|
||||
close(c.done)
|
||||
for child := range c.children {
|
||||
// NOTE: acquiring the child's lock while holding parent's lock.
|
||||
child.cancel(false, err)
|
||||
}
|
||||
c.children = nil
|
||||
c.mu.Unlock()
|
||||
|
||||
if removeFromParent {
|
||||
removeChild(c.Context, c)
|
||||
}
|
||||
}
|
||||
|
||||
// WithDeadline returns a copy of the parent context with the deadline adjusted
|
||||
// to be no later than d. If the parent's deadline is already earlier than d,
|
||||
// WithDeadline(parent, d) is semantically equivalent to parent. The returned
|
||||
// context's Done channel is closed when the deadline expires, when the returned
|
||||
// cancel function is called, or when the parent context's Done channel is
|
||||
// closed, whichever happens first.
|
||||
//
|
||||
// Canceling this context releases resources associated with it, so code should
|
||||
// call cancel as soon as the operations running in this Context complete.
|
||||
func WithDeadline(parent Context, deadline time.Time) (Context, CancelFunc) {
|
||||
if cur, ok := parent.Deadline(); ok && cur.Before(deadline) {
|
||||
// The current deadline is already sooner than the new one.
|
||||
return WithCancel(parent)
|
||||
}
|
||||
c := &timerCtx{
|
||||
cancelCtx: newCancelCtx(parent),
|
||||
deadline: deadline,
|
||||
}
|
||||
propagateCancel(parent, c)
|
||||
d := deadline.Sub(time.Now())
|
||||
if d <= 0 {
|
||||
c.cancel(true, DeadlineExceeded) // deadline has already passed
|
||||
return c, func() { c.cancel(true, Canceled) }
|
||||
}
|
||||
c.mu.Lock()
|
||||
defer c.mu.Unlock()
|
||||
if c.err == nil {
|
||||
c.timer = time.AfterFunc(d, func() {
|
||||
c.cancel(true, DeadlineExceeded)
|
||||
})
|
||||
}
|
||||
return c, func() { c.cancel(true, Canceled) }
|
||||
}
|
||||
|
||||
// A timerCtx carries a timer and a deadline. It embeds a cancelCtx to
|
||||
// implement Done and Err. It implements cancel by stopping its timer then
|
||||
// delegating to cancelCtx.cancel.
|
||||
type timerCtx struct {
|
||||
*cancelCtx
|
||||
timer *time.Timer // Under cancelCtx.mu.
|
||||
|
||||
deadline time.Time
|
||||
}
|
||||
|
||||
func (c *timerCtx) Deadline() (deadline time.Time, ok bool) {
|
||||
return c.deadline, true
|
||||
}
|
||||
|
||||
func (c *timerCtx) String() string {
|
||||
return fmt.Sprintf("%v.WithDeadline(%s [%s])", c.cancelCtx.Context, c.deadline, c.deadline.Sub(time.Now()))
|
||||
}
|
||||
|
||||
func (c *timerCtx) cancel(removeFromParent bool, err error) {
|
||||
c.cancelCtx.cancel(false, err)
|
||||
if removeFromParent {
|
||||
// Remove this timerCtx from its parent cancelCtx's children.
|
||||
removeChild(c.cancelCtx.Context, c)
|
||||
}
|
||||
c.mu.Lock()
|
||||
if c.timer != nil {
|
||||
c.timer.Stop()
|
||||
c.timer = nil
|
||||
}
|
||||
c.mu.Unlock()
|
||||
}
|
||||
|
||||
// WithTimeout returns WithDeadline(parent, time.Now().Add(timeout)).
|
||||
//
|
||||
// Canceling this context releases resources associated with it, so code should
|
||||
// call cancel as soon as the operations running in this Context complete:
|
||||
//
|
||||
// func slowOperationWithTimeout(ctx context.Context) (Result, error) {
|
||||
// ctx, cancel := context.WithTimeout(ctx, 100*time.Millisecond)
|
||||
// defer cancel() // releases resources if slowOperation completes before timeout elapses
|
||||
// return slowOperation(ctx)
|
||||
// }
|
||||
func WithTimeout(parent Context, timeout time.Duration) (Context, CancelFunc) {
|
||||
return WithDeadline(parent, time.Now().Add(timeout))
|
||||
}
|
||||
|
||||
// WithValue returns a copy of parent in which the value associated with key is
|
||||
// val.
|
||||
//
|
||||
// Use context Values only for request-scoped data that transits processes and
|
||||
// APIs, not for passing optional parameters to functions.
|
||||
func WithValue(parent Context, key interface{}, val interface{}) Context {
|
||||
return &valueCtx{parent, key, val}
|
||||
}
|
||||
|
||||
// A valueCtx carries a key-value pair. It implements Value for that key and
|
||||
// delegates all other calls to the embedded Context.
|
||||
type valueCtx struct {
|
||||
Context
|
||||
key, val interface{}
|
||||
}
|
||||
|
||||
func (c *valueCtx) String() string {
|
||||
return fmt.Sprintf("%v.WithValue(%#v, %#v)", c.Context, c.key, c.val)
|
||||
}
|
||||
|
||||
func (c *valueCtx) Value(key interface{}) interface{} {
|
||||
if c.key == key {
|
||||
return c.val
|
||||
}
|
||||
return c.Context.Value(key)
|
||||
}
|
||||
Loading…
Reference in New Issue