// // Semaphore.h // // $Id: //poco/svn/Foundation/include/Poco/Semaphore.h#2 $ // // Library: Foundation // Package: Threading // Module: Semaphore // // Definition of the Semaphore class. // // Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH. // and Contributors. // // Permission is hereby granted, free of charge, to any person or organization // obtaining a copy of the software and accompanying documentation covered by // this license (the "Software") to use, reproduce, display, distribute, // execute, and transmit the Software, and to prepare derivative works of the // Software, and to permit third-parties to whom the Software is furnished to // do so, all subject to the following: // // The copyright notices in the Software and this entire statement, including // the above license grant, this restriction and the following disclaimer, // must be included in all copies of the Software, in whole or in part, and // all derivative works of the Software, unless such copies or derivative // works are solely in the form of machine-executable object code generated by // a source language processor. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, // FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT // SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE // FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE, // ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER // DEALINGS IN THE SOFTWARE. // #ifndef Foundation_Semaphore_INCLUDED #define Foundation_Semaphore_INCLUDED #include "Poco/Foundation.h" #include "Poco/Exception.h" #if defined(POCO_OS_FAMILY_WINDOWS) #include "Poco/Semaphore_WIN32.h" #elif defined(POCO_VXWORKS) #include "Poco/Semaphore_VX.h" #else #include "Poco/Semaphore_POSIX.h" #endif namespace Poco { class Foundation_API Semaphore: private SemaphoreImpl /// A Semaphore is a synchronization object with the following /// characteristics: /// A semaphore has a value that is constrained to be a non-negative /// integer and two atomic operations. The allowable operations are V /// (here called set()) and P (here called wait()). A V (set()) operation /// increases the value of the semaphore by one. /// A P (wait()) operation decreases the value of the semaphore by one, /// provided that can be done without violating the constraint that the /// value be non-negative. A P (wait()) operation that is initiated when /// the value of the semaphore is 0 suspends the calling thread. /// The calling thread may continue when the value becomes positive again. { public: Semaphore(int n); Semaphore(int n, int max); /// Creates the semaphore. The current value /// of the semaphore is given in n. The /// maximum value of the semaphore is given /// in max. /// If only n is given, it must be greater than /// zero. /// If both n and max are given, max must be /// greater than zero, n must be greater than /// or equal to zero and less than or equal /// to max. ~Semaphore(); /// Destroys the semaphore. void set(); /// Increments the semaphore's value by one and /// thus signals the semaphore. Another thread /// waiting for the semaphore will be able /// to continue. void wait(); /// Waits for the semaphore to become signalled. /// To become signalled, a semaphore's value must /// be greater than zero. /// Decrements the semaphore's value by one. void wait(long milliseconds); /// Waits for the semaphore to become signalled. /// To become signalled, a semaphore's value must /// be greater than zero. /// Throws a TimeoutException if the semaphore /// does not become signalled within the specified /// time interval. /// Decrements the semaphore's value by one /// if successful. bool tryWait(long milliseconds); /// Waits for the semaphore to become signalled. /// To become signalled, a semaphore's value must /// be greater than zero. /// Returns true if the semaphore /// became signalled within the specified /// time interval, false otherwise. /// Decrements the semaphore's value by one /// if successful. private: Semaphore(); Semaphore(const Semaphore&); Semaphore& operator = (const Semaphore&); }; // // inlines // inline void Semaphore::set() { setImpl(); } inline void Semaphore::wait() { waitImpl(); } inline void Semaphore::wait(long milliseconds) { if (!waitImpl(milliseconds)) throw TimeoutException(); } inline bool Semaphore::tryWait(long milliseconds) { return waitImpl(milliseconds); } } // namespace Poco #endif // Foundation_Semaphore_INCLUDED