golang.org/x/net@v0.25.1-0.20240516223405-c87a5b62e243/context/context.go (about)

     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  }