@Override public final K acquire(){
  K ctx=null;
  Reference<K> ref=null;
  while ((ctx == null) && ((ref=ctxQueue.poll()) != null)) {
    ctx=ref.get();
  }
  if (ctx == null) {
    ctx=newContext();
    ctx.usage=USAGE_CLQ;
  }
  return ctx;
}

@ Override public final K acquire ( ) { K ctx = null ; Reference < K > ref = null ; while ( ( ctx == null ) && ( ( ref = ctxQueue . poll ( ) ) != null ) ) { ctx = ref . get ( ) ; } if ( ctx == null ) { ctx = newContext ( ) ; ctx . usage = USAGE_CLQ ; } return ctx ; }
give a reentrantcontext instance for the current thread
