153 lines
4.2 KiB
C++
153 lines
4.2 KiB
C++
/*
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PIP - Platform Independent Primitives
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PISemaphore, PISemaphoreLocker
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Ivan Pelipenko peri4ko@yandex.ru
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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//! \addtogroup Thread
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//! \{
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//! \class PISemaphore pisemaphore.h
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//!
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//! \~\brief
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//! \~english Basic semaphore
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//! \~russian Простой семафор
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//!
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//!
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//! \~\details
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//! \~english \section PISemaphore_sec0 Synopsis
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//! \~russian \section PISemaphore_sec0 Краткий обзор
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//!
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//! \~english
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//! %PISemaphore provides critical code section defence between several threads with resource counting.
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//! Semaphore contains logic counter and functions to change it:
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//! \a release(), \a acquire() and \a tryAcquire().
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//!
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//! For automatic acquire-release use \a PISemaphoreLocker.
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//!
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//! \~russian
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//! %PISemaphore предоставляет межпотоковую защиту критических секций кода с подсчетом ресурсов.
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//! Семафор состоит из логического счетчика и методов для его изменения:
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//! \a release(), \a acquire() and \a tryAcquire().
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//!
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//! Для автоматического захвата-освобождения используйте \a PISemaphoreLocker.
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//!
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//! \~english \section PISemaphore_sec1 Usage
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//! \~russian \section PISemaphore_sec1 Использование
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//!
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//! \~english
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//!
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//! \~russian
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//!
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//! \~\code
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//! \endcode
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//! \}
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//! \addtogroup Thread
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//! \{
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//! \class PISemaphoreLocker pisemaphore.h
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//!
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//! \~\brief
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//! \~english %PISemaphore autolocker
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//! \~russian Автоблокировщик %PISemaphore
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//!
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//!
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//! \~\details
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//!
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//! \~english
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//! When a %PISemaphoreLocker object is created, it attempts to acquire the semaphore resources, if "condition" \c true.
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//! When control leaves the scope in which the %PISemaphoreLocker object was created,
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//! the %PISemaphoreLocker is destructed and the resources are released, if "condition" was \c true.
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//!
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//! If "condition" \c false this class do nothing.
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//!
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//! The %PISemaphoreLocker class is non-copyable.
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//!
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//! \~russian
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//! При создании экземпляра %PISemaphoreLocker захватываются ресурсы семафора, если "condition" \c true.
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//! Когда выполнение покидает область жизни объекта, вызывается его деструктор и ресурсы
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//! освобождаются, если "condition" был \c true.
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//!
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//! Если "condition" \c false, то этот объект ничего не делает.
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//!
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//! Класс %PISemaphoreLocker некопируемый.
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//!
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//! \~\code
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//! // critical section start
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//! {
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//! PISemaphoreLocker locker(mutex, 5);
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//! // ... your code here
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//! }
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//! // critical section end
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//! \endcode
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//! \}
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#include "pisemaphore.h"
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PISemaphore::PISemaphore(int initial) {
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count = initial;
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}
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PISemaphore::~PISemaphore() {
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var.notifyAll();
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}
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void PISemaphore::acquire(int cnt) {
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PIMutexLocker _ml(mutex);
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while (count < cnt) {
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var.wait(mutex);
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}
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count -= cnt;
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}
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bool PISemaphore::tryAcquire(int cnt) {
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PIMutexLocker _ml(mutex);
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if (count < cnt) return false;
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count -= cnt;
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return true;
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}
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bool PISemaphore::tryAcquire(int cnt, PISystemTime timeout) {
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PITimeMeasurer tm;
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PIMutexLocker _ml(mutex);
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while (count < cnt) {
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PISystemTime remain = timeout - tm.elapsed();
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if (remain.isNegative()) return false;
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var.waitFor(mutex, remain);
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}
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count -= cnt;
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return true;
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}
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void PISemaphore::release(int cnt) {
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PIMutexLocker _ml(mutex);
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count += cnt;
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var.notifyAll();
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}
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int PISemaphore::available() const {
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PIMutexLocker _ml(mutex);
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return count;
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}
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