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Diffstat (limited to 'kube2msb/src/vendor/golang.org/x/net/context/context.go')
| -rw-r--r-- | kube2msb/src/vendor/golang.org/x/net/context/context.go | 447 |
1 files changed, 0 insertions, 447 deletions
diff --git a/kube2msb/src/vendor/golang.org/x/net/context/context.go b/kube2msb/src/vendor/golang.org/x/net/context/context.go deleted file mode 100644 index 11bd8d3..0000000 --- a/kube2msb/src/vendor/golang.org/x/net/context/context.go +++ /dev/null @@ -1,447 +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. - -// Package context defines the Context type, which carries deadlines, -// cancelation signals, and other request-scoped values across API boundaries -// and between processes. -// -// Incoming requests to a server should create a Context, and outgoing calls to -// servers should accept a Context. The chain of function calls between must -// propagate the Context, optionally replacing it with a modified copy created -// using WithDeadline, WithTimeout, WithCancel, or WithValue. -// -// Programs that use Contexts should follow these rules to keep interfaces -// consistent across packages and enable static analysis tools to check context -// propagation: -// -// Do not store Contexts inside a struct type; instead, pass a Context -// explicitly to each function that needs it. The Context should be the first -// parameter, typically named ctx: -// -// func DoSomething(ctx context.Context, arg Arg) error { -// // ... use ctx ... -// } -// -// Do not pass a nil Context, even if a function permits it. Pass context.TODO -// if you are unsure about which Context to use. -// -// Use context Values only for request-scoped data that transits processes and -// APIs, not for passing optional parameters to functions. -// -// The same Context may be passed to functions running in different goroutines; -// Contexts are safe for simultaneous use by multiple goroutines. -// -// See http://blog.golang.org/context for example code for a server that uses -// Contexts. -package context - -import ( - "errors" - "fmt" - "sync" - "time" -) - -// A Context carries a deadline, a cancelation signal, and other values across -// API boundaries. -// -// Context's methods may be called by multiple goroutines simultaneously. -type Context interface { - // Deadline returns the time when work done on behalf of this context - // should be canceled. Deadline returns ok==false when no deadline is - // set. Successive calls to Deadline return the same results. - Deadline() (deadline time.Time, ok bool) - - // Done returns a channel that's closed when work done on behalf of this - // context should be canceled. Done may return nil if this context can - // never be canceled. Successive calls to Done return the same value. - // - // WithCancel arranges for Done to be closed when cancel is called; - // WithDeadline arranges for Done to be closed when the deadline - // expires; WithTimeout arranges for Done to be closed when the timeout - // elapses. - // - // Done is provided for use in select statements: - // - // // Stream generates values with DoSomething and sends them to out - // // until DoSomething returns an error or ctx.Done is closed. - // func Stream(ctx context.Context, out <-chan Value) error { - // for { - // v, err := DoSomething(ctx) - // if err != nil { - // return err - // } - // select { - // case <-ctx.Done(): - // return ctx.Err() - // case out <- v: - // } - // } - // } - // - // See http://blog.golang.org/pipelines for more examples of how to use - // a Done channel for cancelation. - Done() <-chan struct{} - - // Err returns a non-nil error value after Done is closed. Err returns - // Canceled if the context was canceled or DeadlineExceeded if the - // context's deadline passed. No other values for Err are defined. - // After Done is closed, successive calls to Err return the same value. - Err() error - - // Value returns the value associated with this context for key, or nil - // if no value is associated with key. Successive calls to Value with - // the same key returns the same result. - // - // Use context values only for request-scoped data that transits - // processes and API boundaries, not for passing optional parameters to - // functions. - // - // A key identifies a specific value in a Context. Functions that wish - // to store values in Context typically allocate a key in a global - // variable then use that key as the argument to context.WithValue and - // Context.Value. A key can be any type that supports equality; - // packages should define keys as an unexported type to avoid - // collisions. - // - // Packages that define a Context key should provide type-safe accessors - // for the values stores using that key: - // - // // Package user defines a User type that's stored in Contexts. - // package user - // - // import "golang.org/x/net/context" - // - // // User is the type of value stored in the Contexts. - // type User struct {...} - // - // // key is an unexported type for keys defined in this package. - // // This prevents collisions with keys defined in other packages. - // type key int - // - // // userKey is the key for user.User values in Contexts. It is - // // unexported; clients use user.NewContext and user.FromContext - // // instead of using this key directly. - // var userKey key = 0 - // - // // NewContext returns a new Context that carries value u. - // func NewContext(ctx context.Context, u *User) context.Context { - // return context.WithValue(ctx, userKey, u) - // } - // - // // FromContext returns the User value stored in ctx, if any. - // func FromContext(ctx context.Context) (*User, bool) { - // u, ok := ctx.Value(userKey).(*User) - // return u, ok - // } - 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 -// requests. -func Background() Context { - return background -} - -// TODO returns a non-nil, empty Context. Code should use context.TODO when -// it's unclear which Context to use or it is not yet available (because the -// surrounding function has not yet been extended to accept a Context -// parameter). TODO is recognized by static analysis tools that determine -// whether Contexts are propagated correctly in a program. -func TODO() Context { - return todo -} - -// A CancelFunc tells an operation to abandon its work. -// 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) -} |