Source file src/github.com/aws/smithy-go/sync/error.go

Documentation: github.com/aws/smithy-go/sync

     1  package sync
     2  
     3  import "sync"
     4  
     5  // OnceErr wraps the behavior of recording an error
     6  // once and signal on a channel when this has occurred.
     7  // Signaling is done by closing of the channel.
     8  //
     9  // Type is safe for concurrent usage.
    10  type OnceErr struct {
    11  	mu  sync.RWMutex
    12  	err error
    13  	ch  chan struct{}
    14  }
    15  
    16  // NewOnceErr return a new OnceErr
    17  func NewOnceErr() *OnceErr {
    18  	return &OnceErr{
    19  		ch: make(chan struct{}, 1),
    20  	}
    21  }
    22  
    23  // Err acquires a read-lock and returns an
    24  // error if one has been set.
    25  func (e *OnceErr) Err() error {
    26  	e.mu.RLock()
    27  	err := e.err
    28  	e.mu.RUnlock()
    29  
    30  	return err
    31  }
    32  
    33  // SetError acquires a write-lock and will set
    34  // the underlying error value if one has not been set.
    35  func (e *OnceErr) SetError(err error) {
    36  	if err == nil {
    37  		return
    38  	}
    39  
    40  	e.mu.Lock()
    41  	if e.err == nil {
    42  		e.err = err
    43  		close(e.ch)
    44  	}
    45  	e.mu.Unlock()
    46  }
    47  
    48  // ErrorSet returns a channel that will be used to signal
    49  // that an error has been set. This channel will be closed
    50  // when the error value has been set for OnceErr.
    51  func (e *OnceErr) ErrorSet() <-chan struct{} {
    52  	return e.ch
    53  }
    54  

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