public void ReturnBuffer(byte[] buffer)
{
if (buffer == null)
throw new ArgumentNullException("buffer");
// The purpose of the buffer pool is to try to reduce the
// amount of garbage generated, so it doesn't matter if
// the buffer gets tossed out. Since we don't want to
// take the perf hit of taking a lock, we only return
// the buffer if we can grab the control cookie.
Object cookie = null;
try
{
// If a ThreadAbortException gets thrown after the exchange,
// but before the result is assigned to cookie, then the
// control cookie is lost forever. However, the buffer pool
// will still function normally and return everybody a new
// buffer each time (that isn't very likely to happen,
// so we don't really care).
cookie = Interlocked.Exchange(ref _controlCookie, null);
if (cookie != null)
{
if (_current == -1)
{
_bufferPool[0] = buffer;
_current = 0;
_last = 0;
}
else
{
int newLast = (_last + 1) % _max;
if (newLast != _current)
{
// the pool isn't full so store this buffer
_last = newLast;
_bufferPool[_last] = buffer;
}
}
_controlCookie = cookie;
}
}
catch (ThreadAbortException)
{
if (cookie != null)
{
// This should be rare, so just reset
// everything to the initial state.
_current = -1;
_last = -1;
// restore cookie
_controlCookie = cookie;
}
throw;
}
} // ReturnBuffer
