github.com/m3db/m3@v1.5.0/src/x/context/cancel.go (about)

     1  // Copyright (c) 2018 Uber Technologies, Inc.
     2  //
     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
     4  // of this software and associated documentation files (the "Software"), to deal
     5  // in the Software without restriction, including without limitation the rights
     6  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     7  // copies of the Software, and to permit persons to whom the Software is
     8  // furnished to do so, subject to the following conditions:
     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    18  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    19  // THE SOFTWARE.
    20  
    21  package context
    22  
    23  import "sync/atomic"
    24  
    25  type cancellable struct {
    26  	cancelled int32
    27  }
    28  
    29  // NewCancellable creates a new cancellable object
    30  func NewCancellable() Cancellable {
    31  	return &cancellable{}
    32  }
    33  
    34  func (c *cancellable) IsCancelled() bool { return atomic.LoadInt32(&c.cancelled) == 1 }
    35  func (c *cancellable) Cancel()           { atomic.StoreInt32(&c.cancelled, 1) }
    36  func (c *cancellable) Reset()            { atomic.StoreInt32(&c.cancelled, 0) }
    37  
    38  // NoOpCancellable is a no-op cancellable
    39  var noOpCancellable Cancellable = cancellableNoOp{}
    40  
    41  type cancellableNoOp struct{}
    42  
    43  // NewNoOpCanncellable returns a no-op cancellable
    44  func NewNoOpCanncellable() Cancellable      { return noOpCancellable }
    45  func (c cancellableNoOp) IsCancelled() bool { return false }
    46  func (c cancellableNoOp) Cancel()           {}
    47  func (c cancellableNoOp) Reset()            {}