Polls this queue to see if a reference object is available.

  Polls this queue to see if a reference object is available. If one is
available without further delay then it is removed from the queue and
returned. Otherwise this method immediately returns null.
Returns: A reference object, if one was immediately available, otherwise null

  Removes the next reference object in this queue, blocking until one becomes available.

  Removes the next reference object in this queue, blocking until one
becomes available.
Returns: A reference object, blocking until one becomes available
Throws:
- InterruptedException - If the wait is interrupted

  Removes the next reference object in this queue, blocking until either one becomes available or the given timeout period expires.

  Removes the next reference object in this queue, blocking until either one becomes available or the given timeout period expires.

This method does not offer real-time guarantees: It schedules the timeout as if by invoking the Object.wait(long) method.
Returns: A reference object, if one was available within the specified timeout period, otherwise null
Parameters:
- timeout - If positive, block for up to timeout milliseconds while waiting for a reference to be added to this queue. If zero, block indefinitely.
Throws:
- IllegalArgumentException - If the value of the timeout argument is negative
- InterruptedException - If the timeout wait is interrupted