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138 lines
3.3 KiB
C++
138 lines
3.3 KiB
C++
//
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// Semaphore.h
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//
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// Library: Foundation
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// Package: Threading
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// Module: Semaphore
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//
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// Definition of the Semaphore class.
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//
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// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// SPDX-License-Identifier: BSL-1.0
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//
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#ifndef Foundation_Semaphore_INCLUDED
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#define Foundation_Semaphore_INCLUDED
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#include "Poco/Foundation.h"
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#include "Poco/Exception.h"
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#if defined(POCO_OS_FAMILY_WINDOWS)
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#include "Poco/Semaphore_WIN32.h"
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#elif defined(POCO_VXWORKS)
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#include "Poco/Semaphore_VX.h"
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#else
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#include "Poco/Semaphore_POSIX.h"
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#endif
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namespace Poco {
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class Foundation_API Semaphore: private SemaphoreImpl
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/// A Semaphore is a synchronization object with the following
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/// characteristics:
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/// A semaphore has a value that is constrained to be a non-negative
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/// integer and two atomic operations. The allowable operations are V
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/// (here called set()) and P (here called wait()). A V (set()) operation
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/// increases the value of the semaphore by one.
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/// A P (wait()) operation decreases the value of the semaphore by one,
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/// provided that can be done without violating the constraint that the
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/// value be non-negative. A P (wait()) operation that is initiated when
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/// the value of the semaphore is 0 suspends the calling thread.
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/// The calling thread may continue when the value becomes positive again.
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{
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public:
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Semaphore(int n);
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Semaphore(int n, int max);
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/// Creates the semaphore. The current value
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/// of the semaphore is given in n. The
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/// maximum value of the semaphore is given
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/// in max.
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/// If only n is given, it must be greater than
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/// zero.
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/// If both n and max are given, max must be
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/// greater than zero, n must be greater than
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/// or equal to zero and less than or equal
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/// to max.
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~Semaphore();
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/// Destroys the semaphore.
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void set();
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/// Increments the semaphore's value by one and
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/// thus signals the semaphore. Another thread
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/// waiting for the semaphore will be able
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/// to continue.
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void wait();
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/// Waits for the semaphore to become signalled.
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/// To become signalled, a semaphore's value must
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/// be greater than zero.
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/// Decrements the semaphore's value by one.
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void wait(long milliseconds);
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/// Waits for the semaphore to become signalled.
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/// To become signalled, a semaphore's value must
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/// be greater than zero.
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/// Throws a TimeoutException if the semaphore
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/// does not become signalled within the specified
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/// time interval.
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/// Decrements the semaphore's value by one
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/// if successful.
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bool tryWait(long milliseconds);
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/// Waits for the semaphore to become signalled.
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/// To become signalled, a semaphore's value must
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/// be greater than zero.
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/// Returns true if the semaphore
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/// became signalled within the specified
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/// time interval, false otherwise.
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/// Decrements the semaphore's value by one
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/// if successful.
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private:
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Semaphore();
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Semaphore(const Semaphore&);
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Semaphore& operator = (const Semaphore&);
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};
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//
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// inlines
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//
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inline void Semaphore::set()
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{
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setImpl();
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}
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inline void Semaphore::wait()
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{
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waitImpl();
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}
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inline void Semaphore::wait(long milliseconds)
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{
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if (!waitImpl(milliseconds))
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throw TimeoutException();
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}
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inline bool Semaphore::tryWait(long milliseconds)
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{
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return waitImpl(milliseconds);
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}
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} // namespace Poco
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#endif // Foundation_Semaphore_INCLUDED
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