diff options
Diffstat (limited to 'vendor/golang.org/x/net/context/context.go')
| -rw-r--r-- | vendor/golang.org/x/net/context/context.go | 112 |
1 files changed, 100 insertions, 12 deletions
diff --git a/vendor/golang.org/x/net/context/context.go b/vendor/golang.org/x/net/context/context.go index cf66309c4..db1c95fab 100644 --- a/vendor/golang.org/x/net/context/context.go +++ b/vendor/golang.org/x/net/context/context.go @@ -3,29 +3,31 @@ // 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 +// cancellation signals, and other request-scoped values across API boundaries // and between processes. // As of Go 1.7 this package is available in the standard library under the -// name context. https://golang.org/pkg/context. +// name [context], and migrating to it can be done automatically with [go fix]. // -// 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. +// Incoming requests to a server should create a [Context], and outgoing +// calls to servers should accept a Context. The chain of function +// calls between them must propagate the Context, optionally replacing +// it with a derived Context created using [WithCancel], [WithDeadline], +// [WithTimeout], 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 +// explicitly to each function that needs it. This is discussed further in +// https://go.dev/blog/context-and-structs. 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 +// 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 @@ -34,9 +36,30 @@ // 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 +// See https://go.dev/blog/context for example code for a server that uses // Contexts. -package context // import "golang.org/x/net/context" +// +// [go fix]: https://go.dev/cmd/go#hdr-Update_packages_to_use_new_APIs +package context + +import ( + "context" // standard library's context, as of Go 1.7 + "time" +) + +// A Context carries a deadline, a cancellation signal, and other values across +// API boundaries. +// +// Context's methods may be called by multiple goroutines simultaneously. +type Context = context.Context + +// Canceled is the error returned by [Context.Err] when the context is canceled +// for some reason other than its deadline passing. +var Canceled = context.Canceled + +// DeadlineExceeded is the error returned by [Context.Err] when the context is canceled +// due to its deadline passing. +var DeadlineExceeded = context.DeadlineExceeded // 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, @@ -49,8 +72,73 @@ func Background() Context { // 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. +// parameter). func TODO() Context { return todo } + +var ( + background = context.Background() + todo = context.TODO() +) + +// A CancelFunc tells an operation to abandon its work. +// A CancelFunc does not wait for the work to stop. +// A CancelFunc may be called by multiple goroutines simultaneously. +// After the first call, subsequent calls to a CancelFunc do nothing. +type CancelFunc = context.CancelFunc + +// WithCancel returns a derived context that points to the parent context +// but has 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) { + return context.WithCancel(parent) +} + +// WithDeadline returns a derived context that points to the parent context +// but has 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.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, d time.Time) (Context, CancelFunc) { + return context.WithDeadline(parent, d) +} + +// 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 context.WithTimeout(parent, timeout) +} + +// WithValue returns a derived context that points to the parent Context. +// In the derived context, 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. +// +// The provided key must be comparable and should not be of type +// string or any other built-in type to avoid collisions between +// packages using context. Users of WithValue should define their own +// types for keys. To avoid allocating when assigning to an +// interface{}, context keys often have concrete type +// struct{}. Alternatively, exported context key variables' static +// type should be a pointer or interface. +func WithValue(parent Context, key, val interface{}) Context { + return context.WithValue(parent, key, val) +} |