1 private void awaitAvailable(long timeout) throws InterruptedException, TimeoutException, ResourcePoolException
 2     {
 3         assert Thread.holdsLock( this );
 4 
 5         if (force_kill_acquires)
 6             throw new ResourcePoolException("A ResourcePool cannot acquire a new resource -- the factory or source appears to be down.");
 7 
 8         Thread t = Thread.currentThread();
 9         try
10         {
11             acquireWaiters.add( t );
12 
13             int avail;
14             long start = ( timeout > 0 ? System.currentTimeMillis() : -1);
15             if (Debug.DEBUG && Debug.TRACE == Debug.TRACE_MAX)
16             {
17                 if ( logger.isLoggable( MLevel.FINE ) )
18                     logger.fine("awaitAvailable(): " + 
19                                     (exampleResource != null ? 
20                                                     exampleResource : 
21                                     "[unknown]") );
22                 trace();
23             }
24             while ((avail = unused.size()) == 0) 
25             {
26                 // the if case below can only occur when 1) a user attempts a
27                 // checkout which would provoke an acquire; 2) this
28                 // increments the pending acquires, so we go to the
29                 // wait below without provoking postAcquireMore(); 3)
30                 // the resources are acquired; 4) external management
31                 // of the pool (via for instance unpoolResource() 
32                 // depletes the newly acquired resources before we
33                 // regain this‘ monitor; 5) we fall into wait() with
34                 // no acquires being scheduled, and perhaps a managed.size()
35                 // of zero, leading to deadlock. This could only occur in
36                 // fairly pathological situations where the pool is being
37                 // externally forced to a very low (even zero) size, but 
38                 // since I‘ve seen it, I‘ve fixed it.
39                 if (pending_acquires == 0 && managed.size() < max)
40                     _recheckResizePool();
41 
42                 this.wait(timeout);
43                 if (timeout > 0 && System.currentTimeMillis() - start > timeout)
44                     throw new TimeoutException("A client timed out while waiting to acquire a resource from " + this + " -- timeout at awaitAvailable()");
45                 if (force_kill_acquires)
46                     throw new CannotAcquireResourceException("A ResourcePool could not acquire a resource from its primary factory or source.");
47                 ensureNotBroken();
48             }
49         }
50         finally
51         {
52             acquireWaiters.remove( t );
53             if (acquireWaiters.size() == 0)
54                 this.notifyAll();
55         }
56     }