code: void lowerActiveGetCount( H2ONode h2o ) {
      assert _key.home();    // Only the HOME node for a key tracks replicas
      assert h2o != H2O.SELF;// Do not track self as a replica
      while( true ) {        // Repeat, in case racing GETs are bumping the counter
        int old = _rwlock.get(); // Read the lock-word
        assert old > 0;      // Since lowering, must be at least 1
        assert old != -1;    // Not write-locked, because we are an active reader
        assert _replicas.contains(h2o._unique_idx); // Self-bit is set
        if( RW_CAS(old,old-1,"rlock-") ) {
          if( old-1 == 0 )   // GET count fell to zero?
            synchronized( this ) { notifyAll(); } // Notify any pending blocked PUTs
          return;            // Repeat until count is lowered
        }
      }
    }
docs: Atomically lower active GET count