/usr/share/cruisecontrol-bin-2.6.1/projects/qpid-trunk/cpp/src/qpid/sys/Semaphore.h

00001 #ifndef _sys_Semaphore_h
00002 #define _sys_Semaphore_h
00003 
00004 /*
00005  *
00006  * Copyright (c) 2006 The Apache Software Foundation
00007  *
00008  * Licensed under the Apache License, Version 2.0 (the "License");
00009  * you may not use this file except in compliance with the License.
00010  * You may obtain a copy of the License at
00011  *
00012  *    http://www.apache.org/licenses/LICENSE-2.0
00013  *
00014  * Unless required by applicable law or agreed to in writing, software
00015  * distributed under the License is distributed on an "AS IS" BASIS,
00016  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00017  * See the License for the specific language governing permissions and
00018  * limitations under the License.
00019  *
00020  */
00021 
00022 #include "Monitor.h"
00023 
00024 namespace qpid {
00025 namespace sys {
00026 
00027 class Semaphore
00028 {
00029 public:
00030     Semaphore(uint c = 1) : count(c) {}
00031 
00032     void lock() { acquire(); }
00033     void unlock() { release(); }
00034     bool trylock() { return tryAcquire(); }
00035 
00036     bool tryAcquire() 
00037     {
00038         Monitor::ScopedLock l(monitor);
00039         if (count) {
00040             count--;
00041             return true;
00042         } else {
00043             return false;
00044         }
00045     }
00046 
00047     void acquire() 
00048     {
00049         Monitor::ScopedLock l(monitor);
00050         while (count == 0) monitor.wait();
00051         count--;
00052     }
00053 
00054     void release()
00055     {
00056         Monitor::ScopedLock l(monitor);
00057         if (!count++) monitor.notifyAll();
00058     }
00059 
00060 private:
00061     Monitor monitor;
00062     uint count;
00063 };
00064 
00065 }}
00066 
00067 #endif  

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