/*
* Copyright Onix Solutions Limited [OnixS]. All rights reserved.
*
* This software owned by Onix Solutions Limited [OnixS] and is protected by copyright law
* and international copyright treaties.
*
* Access to and use of the software is governed by the terms of the applicable OnixS Software
* Services Agreement (the Agreement) and Customer end user license agreements granting
* a non-assignable, non-transferable and non-exclusive license to use the software
* for it's own data processing purposes under the terms defined in the Agreement.
*
* Except as otherwise granted within the terms of the Agreement, copying or reproduction of any part
* of this source code or associated reference material to any other location for further reproduction
* or redistribution, and any amendments to this copyright notice, are expressly prohibited.
*
* Any reproduction or redistribution for sale or hiring of the Software not in accordance with
* the terms of the Agreement is a violation of copyright law.
*/

#pragma once

#include <OnixS/FIXEngine/ABI.h>

namespace OnixS {
namespace Threading {
/// The limits number of threads that can access the shared resource simultaneously.
class ONIXS_FIXENGINE_API Semaphore
{
public:
    /// Initializes the instance with the given value of
    /// the "count". The @param count indicates the initial "count"
    /// for the semaphore. The state of the semaphore is signaled
    /// when its count is greater than zero and
    /// non-signaled when it is zero.
    Semaphore(unsigned int count = 1);

    /// Destructs the object.
    ~Semaphore();

    /// Decrements the semaphore "counter" by one.
    /// If the semaphore "counter" is already zero,
    /// blocks the thread until the semaphore "count"
    /// becomes greater than zero.
    void acquire();

    /// Tries to acquire the semaphore object. If
    /// its "counter" is already zero, returns
    /// @c false. In all cases, it doesn't block
    /// the thread and quites immediately.
    bool tryAcquire();

    /// Increments the semaphore "counter" by one.
    /// If there are other threads waiting for
    /// the object, it blocks one the them.
    void release();

private:
    // Implementation details.
    void * impl_;

    // Copying & assignment is prohibited.

    Semaphore(const Semaphore &);
    Semaphore & operator = (const Semaphore &);
};
}
}