# Package org.apache.cassandra.utils.concurrent

- Interface Summary
  Interface | Description
  --- | ---
  WaitQueue.Signal | A Signal is a one-time-use mechanism for a thread to wait for notification that some condition state has transitioned that it may be interested in (and hence should check if it is).

- Class Summary
  Class | Description
  --- | ---
  Locks |
  OpOrder | A class for providing synchronization between producers and consumers that do not communicate directly with each other, but where the consumers need to process their work in contiguous batches.
  OpOrder.Group | Represents a group of identically ordered operations, i.e.
  SimpleCondition |
  WaitQueue | A relatively easy to use utility for general purpose thread signalling.
  WaitQueue.AbstractSignal | An abstract signal implementation

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