Scott Baker | 1fe7273 | 2019-10-21 10:58:51 -0700 | [diff] [blame] | 1 | // Copyright 2014 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | // Package context defines the Context type, which carries deadlines, |
| 6 | // cancelation signals, and other request-scoped values across API boundaries |
| 7 | // and between processes. |
| 8 | // As of Go 1.7 this package is available in the standard library under the |
| 9 | // name context. https://golang.org/pkg/context. |
| 10 | // |
| 11 | // Incoming requests to a server should create a Context, and outgoing calls to |
| 12 | // servers should accept a Context. The chain of function calls between must |
| 13 | // propagate the Context, optionally replacing it with a modified copy created |
| 14 | // using WithDeadline, WithTimeout, WithCancel, or WithValue. |
| 15 | // |
| 16 | // Programs that use Contexts should follow these rules to keep interfaces |
| 17 | // consistent across packages and enable static analysis tools to check context |
| 18 | // propagation: |
| 19 | // |
| 20 | // Do not store Contexts inside a struct type; instead, pass a Context |
| 21 | // explicitly to each function that needs it. The Context should be the first |
| 22 | // parameter, typically named ctx: |
| 23 | // |
| 24 | // func DoSomething(ctx context.Context, arg Arg) error { |
| 25 | // // ... use ctx ... |
| 26 | // } |
| 27 | // |
| 28 | // Do not pass a nil Context, even if a function permits it. Pass context.TODO |
| 29 | // if you are unsure about which Context to use. |
| 30 | // |
| 31 | // Use context Values only for request-scoped data that transits processes and |
| 32 | // APIs, not for passing optional parameters to functions. |
| 33 | // |
| 34 | // The same Context may be passed to functions running in different goroutines; |
| 35 | // Contexts are safe for simultaneous use by multiple goroutines. |
| 36 | // |
| 37 | // See http://blog.golang.org/context for example code for a server that uses |
| 38 | // Contexts. |
| 39 | package context // import "golang.org/x/net/context" |
| 40 | |
| 41 | // Background returns a non-nil, empty Context. It is never canceled, has no |
| 42 | // values, and has no deadline. It is typically used by the main function, |
| 43 | // initialization, and tests, and as the top-level Context for incoming |
| 44 | // requests. |
| 45 | func Background() Context { |
| 46 | return background |
| 47 | } |
| 48 | |
| 49 | // TODO returns a non-nil, empty Context. Code should use context.TODO when |
| 50 | // it's unclear which Context to use or it is not yet available (because the |
| 51 | // surrounding function has not yet been extended to accept a Context |
| 52 | // parameter). TODO is recognized by static analysis tools that determine |
| 53 | // whether Contexts are propagated correctly in a program. |
| 54 | func TODO() Context { |
| 55 | return todo |
| 56 | } |