_content/blog/context/interface.go

//go:build OMIT
// +build OMIT

package context

import "time"

// A Context carries a deadline, cancellation signal, and request-scoped values
// across API boundaries. Its methods are safe for simultaneous use by multiple
// goroutines.
type Context interface {
	// Done returns a channel that is closed when this Context is canceled
	// or times out.
	Done() <-chan struct{}

	// Err indicates why this context was canceled, after the Done channel
	// is closed.
	Err() error

	// Deadline returns the time when this Context will be canceled, if any.
	Deadline() (deadline time.Time, ok bool)

	// Value returns the value associated with key or nil if none.
	Value(key interface{}) interface{}
}

// WithCancel returns a copy of parent whose Done channel is closed as soon as
// parent.Done is closed or cancel is called.
func WithCancel(parent Context) (ctx Context, cancel CancelFunc)

// A CancelFunc cancels a Context.
type CancelFunc func()

// WithTimeout returns a copy of parent whose Done channel is closed as soon as
// parent.Done is closed, cancel is called, or timeout elapses. The new
// Context's Deadline is the sooner of now+timeout and the parent's deadline, if
// any. If the timer is still running, the cancel function releases its
// resources.
func WithTimeout(parent Context, timeout time.Duration) (Context, CancelFunc)

// WithValue returns a copy of parent whose Value method returns val for key.
func WithValue(parent Context, key interface{}, val interface{}) Context

// Background returns an empty Context. It is never canceled, has no deadline,
// and has no values. Background is typically used in main, init, and tests,
// and as the top-level Context for incoming requests.
func Background() Context