topical media & game development
lib-of-vs-libs-Poco-include-Poco-Semaphore.h / h
//
// Semaphore.h
//
//
//
// 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"
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
(C) Æliens
04/09/2009
You may not copy or print any of this material without explicit permission of the author or the publisher.
In case of other copyright issues, contact the author.
