moby/internal/compatcontext/cancel.go
Paweł Gronowski f6e44bc0e8
internal: Add compatcontext.WithoutCancel
Copy the implementation of `context.WithoutCancel` introduced in Go 1.21
to be able to use it when building with older versions.
This will use the stdlib directly when building with Go 1.21+.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
2023-09-27 11:46:30 +02:00

89 lines
2.9 KiB
Go

//go:build !go1.21
// Copyright (c) 2009 The Go Authors. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// - Redistributions of source code must retain the above copyright
//
// notice, this list of conditions and the following disclaimer.
// - Redistributions in binary form must reproduce the above
//
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// - Neither the name of Google Inc. nor the names of its
//
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Source: https://cs.opensource.google/go/go/+/refs/tags/go1.21.1:src/context/context.go
// The only modifications to the original source were:
// - replacing the usage of internal reflectlite with reflect
// - replacing the usage of private value function with Value method call
package compatcontext // import "github.com/docker/docker/internal/compatcontext"
import (
"context"
"reflect"
"time"
)
// WithoutCancel returns a copy of parent that is not canceled when parent is canceled.
// The returned context returns no Deadline or Err, and its Done channel is nil.
// Calling [Cause] on the returned context returns nil.
func WithoutCancel(parent context.Context) context.Context {
if parent == nil {
panic("cannot create context from nil parent")
}
return withoutCancelCtx{parent}
}
type withoutCancelCtx struct {
c context.Context
}
func (withoutCancelCtx) Deadline() (deadline time.Time, ok bool) {
return
}
func (withoutCancelCtx) Done() <-chan struct{} {
return nil
}
func (withoutCancelCtx) Err() error {
return nil
}
func (c withoutCancelCtx) Value(key any) any {
return c.c.Value(key)
}
func (c withoutCancelCtx) String() string {
return contextName(c.c) + ".WithoutCancel"
}
type stringer interface {
String() string
}
func contextName(c context.Context) string {
if s, ok := c.(stringer); ok {
return s.String()
}
return reflect.TypeOf(c).String()
}