git » go-net » commit afc22ee

diff --git a/context/context.go b/context/context.go
index 19235cf..7350678 100644
--- a/context/context.go
+++ b/context/context.go
@@ -36,12 +36,7 @@
 // Contexts.
 package context // import "golang.org/x/net/context"
 
-import (
-	"errors"
-	"fmt"
-	"sync"
-	"time"
-)
+import "time"
 
 // A Context carries a deadline, a cancelation signal, and other values across
 // API boundaries.
@@ -138,48 +133,6 @@ type Context interface {
 	Value(key interface{}) interface{}
 }
 
-// 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")
-
-// 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)
-)
-
 // Background returns a non-nil, empty Context. It is never canceled, has no
 // values, and has no deadline.  It is typically used by the main function,
 // initialization, and tests, and as the top-level Context for incoming
@@ -201,247 +154,3 @@ func TODO() Context {
 // A CancelFunc does not wait for the work to stop.
 // After the first call, subsequent calls to a CancelFunc do nothing.
 type CancelFunc func()
-
-// 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)
-}
diff --git a/context/context_test.go b/context/context_test.go
index 05345fc..fa73096 100644
--- a/context/context_test.go
+++ b/context/context_test.go
@@ -2,6 +2,8 @@
 // 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 (
diff --git a/context/go17.go b/context/go17.go
new file mode 100644
index 0000000..f8cda19
--- /dev/null
+++ b/context/go17.go
@@ -0,0 +1,72 @@
+// 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)
+}
diff --git a/context/pre_go17.go b/context/pre_go17.go
new file mode 100644
index 0000000..5a30aca
--- /dev/null
+++ b/context/pre_go17.go
@@ -0,0 +1,300 @@
+// 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)
+}