/*! \file pisemaphore.h
 * \ingroup Semaphore
 * \~\brief
 * \~english Basic semaphore
 * \~russian Простой семафор
 */
/*
    PIP - Platform Independent Primitives
	PISemaphore, PISemaphoreLocker
	Ivan Pelipenko peri4ko@yandex.ru

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef PISEMAPHORE_H
#define PISEMAPHORE_H

#include "piconditionvar.h"


class PIP_EXPORT PISemaphore {
public:
	NO_COPY_CLASS(PISemaphore)

	//! \~english Constructs semaphore with \"initial\" available resources.
	//! \~russian Создает семафор с \"initial\" начальными свободными ресурсами.
	PISemaphore(int initial = 0);

	//! \~english Destroy semaphore.
	//! \~russian Деструктор семафора.
	~PISemaphore();


	//! \~english Acquire \"cnt\" resources. If no available resources, than blocks until they freed.
	//! \~russian Захватывает \"cnt\" ресурсов. Если свободных ресурсов недостаточно, то блокирует до их появления.
	void acquire(int cnt = 1);

	//! \~english Try to acquire \"cnt\" resources. Returns if operation was successfull.
	//! \~russian Пробует захватывает \"cnt\" ресурсов. Возвращает успех захвата.
	bool tryAcquire(int cnt = 1);

	//! \~english Try to acquire \"cnt\" resources for \"timeout\". Returns if operation was successfull (timeout has not expired).
	//! \~russian Пробует захватывает \"cnt\" ресурсов в течении \"timeout\". Возвращает успех захвата (не истек ли тайм-аут).
	bool tryAcquire(int cnt, PISystemTime timeout);

	//! \~english Release \"cnt\" resources.
	//! \~russian Освобождает \"cnt\" ресурсов.
	void release(int cnt = 1);

	//! \~english Returns available resources count.
	//! \~russian Возвращает количество свободных ресурсов.
	int available() const;

private:
	int count = 0;
	mutable PIMutex mutex;
	PIConditionVariable var;
};


class PIP_EXPORT PISemaphoreLocker {
public:
	NO_COPY_CLASS(PISemaphoreLocker);

	//! \~english Constructs and acquire \"cnt\" resources on semaphore "s" if "condition" is \c true.
	//! \~russian Создается и захватывает \"cnt\" ресурсов у семафора "s" если "condition" \c true.
	PISemaphoreLocker(PISemaphore & s, int cnt = 1, bool condition = true): sem(s), count(cnt), cond(condition) {
		if (cond) sem.acquire(count);
	}

	//! \~english Release "cnt" resources on semaphore if "condition" was \c true.
	//! \~russian Освобождает "cnt" ресурсов у семафора если "condition" был \c true.
	~PISemaphoreLocker() {
		if (cond) sem.release(count);
	}

private:
	PISemaphore & sem;
	int count = 1;
	bool cond = true;
};


#endif