102 lines
4.0 KiB
C++
102 lines
4.0 KiB
C++
/*! \file pisemaphore.h
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* \ingroup Thread
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* \~\brief
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* \~english Counting semaphore for shared resources
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* \~russian Счетный семафор для общих ресурсов
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*/
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/*
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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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#ifndef PISEMAPHORE_H
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#define PISEMAPHORE_H
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#include "piconditionvar.h"
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//! \~\ingroup Thread
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//! \~\brief
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//! \~english Counting semaphore that tracks available resource units.
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//! \~russian Счетный семафор, отслеживающий количество доступных единиц ресурса.
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class PIP_EXPORT PISemaphore {
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public:
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NO_COPY_CLASS(PISemaphore)
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//! \~english Constructs semaphore with \"initial\" available resources.
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//! \~russian Создает семафор с \"initial\" начальными свободными ресурсами.
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PISemaphore(int initial = 0);
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//! \~english Destroy semaphore.
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//! \~russian Деструктор семафора.
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~PISemaphore();
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//! \~english Acquires \a cnt resource units, waiting until enough units become available.
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//! \~russian Захватывает \a cnt единиц ресурса, ожидая появления достаточного количества.
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void acquire(int cnt = 1);
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//! \~english Tries to acquire \a cnt resource units without waiting.
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//! \~russian Пытается захватить \a cnt единиц ресурса без ожидания.
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bool tryAcquire(int cnt = 1);
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//! \~english Tries to acquire \a cnt resource units within \a timeout.
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//! \~russian Пытается захватить \a cnt единиц ресурса в пределах \a timeout.
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bool tryAcquire(int cnt, PISystemTime timeout);
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//! \~english Releases \a cnt resource units and wakes waiting threads.
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//! \~russian Освобождает \a cnt единиц ресурса и пробуждает ожидающие потоки.
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void release(int cnt = 1);
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//! \~english Returns the current number of available resource units.
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//! \~russian Возвращает текущее количество доступных единиц ресурса.
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int available() const;
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private:
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int count = 0;
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mutable PIMutex mutex;
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PIConditionVariable var;
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};
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//! \~\ingroup Thread
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//! \~\brief
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//! \~english Scope guard that acquires semaphore units in constructor and releases them in destructor.
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//! \~russian Защитник области видимости, который захватывает единицы семафора в конструкторе и освобождает их в деструкторе.
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class PIP_EXPORT PISemaphoreLocker {
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public:
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NO_COPY_CLASS(PISemaphoreLocker);
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//! \~english Constructs and acquire \"cnt\" resources on semaphore "s" if "condition" is \c true.
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//! \~russian Создается и захватывает \"cnt\" ресурсов у семафора "s" если "condition" \c true.
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PISemaphoreLocker(PISemaphore & s, int cnt = 1, bool condition = true): sem(s), count(cnt), cond(condition) {
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if (cond) sem.acquire(count);
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}
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//! \~english Release "cnt" resources on semaphore if "condition" was \c true.
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//! \~russian Освобождает "cnt" ресурсов у семафора если "condition" был \c true.
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~PISemaphoreLocker() {
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if (cond) sem.release(count);
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}
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private:
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PISemaphore & sem;
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int count = 1;
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bool cond = true;
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};
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#endif // PISEMAPHORE_H
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