/*
 * Copyright 2004, Ingo Weinhold, ingo_weinhold@gmx.de.
 * All rights reserved. Distributed under the terms of the MIT license.
 */
#ifndef BLOCKING_QUEUE_H
#define BLOCKING_QUEUE_H

#include <AutoLocker.h>
#include <OS.h>

#include "DebugSupport.h"
#include "Locker.h"
#include "Vector.h"

template<typename Element>
class BlockingQueue : public Locker {
public:
                                                                BlockingQueue(const char* name = NULL);
                                                                ~BlockingQueue();

                        status_t                        InitCheck() const;

                        status_t                        Close(bool deleteElements,
                                                                        const Vector<Element*>** elements = NULL);

                        status_t                        Push(Element* element);
                        status_t                        Pop(Element** element,
                                                                        bigtime_t timeout = B_INFINITE_TIMEOUT);
                        status_t                        Peek(Element** element);
                        status_t                        Remove(Element* element);

                        int32                           Size() const;

private:
                        Vector<Element*>        fElements;
                        sem_id                          fElementSemaphore;
};

// constructor
template<typename Element>
BlockingQueue<Element>::BlockingQueue(const char* name)
        : fElements(),
          fElementSemaphore(-1)
{
        fElementSemaphore = create_sem(0, (name ? name : "blocking queue"));
}

// destructor
template<typename Element>
BlockingQueue<Element>::~BlockingQueue()
{
        if (fElementSemaphore >= 0)
                delete_sem(fElementSemaphore);
}

// InitCheck
template<typename Element>
status_t
BlockingQueue<Element>::InitCheck() const
{
        return (fElementSemaphore < 0 ? fElementSemaphore : B_OK);
}

// Close
template<typename Element>
status_t
BlockingQueue<Element>::Close(bool deleteElements,
        const Vector<Element*>** elements)
{
        AutoLocker<Locker> _(this);
        status_t error = delete_sem(fElementSemaphore);
        if (error != B_OK)
                return error;
        fElementSemaphore = -1;
        if (elements)
                *elements = &fElements;
        if (deleteElements) {
                int32 count = fElements.Count();
                for (int32 i = 0; i < count; i++)
                        delete fElements.ElementAt(i);
        }
        return error;
}

// Push
template<typename Element>
status_t
BlockingQueue<Element>::Push(Element* element)
{
        AutoLocker<Locker> _(this);
        if (fElementSemaphore < 0)
                return B_NO_INIT;
        status_t error = fElements.PushBack(element);
        if (error != B_OK)
                return error;
        error = release_sem(fElementSemaphore);
        if (error != B_OK)
                fElements.Erase(fElements.Count() - 1);
        return error;
}

// Pop
template<typename Element>
status_t
BlockingQueue<Element>::Pop(Element** element, bigtime_t timeout)
{
        status_t error = acquire_sem_etc(fElementSemaphore, 1, B_RELATIVE_TIMEOUT,
                timeout);
        if (error != B_OK)
                return error;
        AutoLocker<Locker> _(this);
        if (fElementSemaphore < 0)
                return B_NO_INIT;
        int32 count = fElements.Count();
        if (count == 0)
                return B_ERROR;
        *element = fElements.ElementAt(0);
        fElements.Erase(0);
        return B_OK;
}

// Peek
template<typename Element>
status_t
BlockingQueue<Element>::Peek(Element** element)
{
        AutoLocker<Locker> _(this);
        if (fElementSemaphore < 0)
                return B_NO_INIT;
        int32 count = fElements.Count();
        if (count == 0)
                return B_ENTRY_NOT_FOUND;
        *element = fElements.ElementAt(0);
        return B_OK;
}

// Remove
template<typename Element>
status_t
BlockingQueue<Element>::Remove(Element* element)
{
        status_t error = acquire_sem_etc(fElementSemaphore, 1,
                B_RELATIVE_TIMEOUT, 0);
        if (error != B_OK)
                return error;
        AutoLocker<Locker> _(this);
        if (fElementSemaphore < 0)
                return B_NO_INIT;
        int32 count = fElements.Remove(element);
        if (count == 0) {
                release_sem(fElementSemaphore);
                return B_ENTRY_NOT_FOUND;
        }
        if (count > 1) {
                ERROR("ERROR: BlockingQueue::Remove(): Removed %ld elements!\n",
                        count);
        }
        return error;
}

// Size
template<typename Element>
int32
BlockingQueue<Element>::Size() const
{
        AutoLocker<Locker> _(this);
        return (fElements.Count());
}

#endif  // BLOCKING_QUEUE_H