FreeRDP/winpr/libwinpr/utils/collections/MessageQueue.c

/**
 * WinPR: Windows Portable Runtime
 * Message Queue
 *
 * Copyright 2012 Marc-Andre Moreau <marcandre.moreau@gmail.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <winpr/crt.h>

#include <winpr/collections.h>

/**
 * Message Queue inspired from Windows:
 * http://msdn.microsoft.com/en-us/library/ms632590/
 */

/**
 * Properties
 */

/**
 * Gets an event which is set when the queue is non-empty
 */

HANDLE MessageQueue_Event(wMessageQueue* queue)
{
	return queue->event;
}

/**
 * Methods
 */

void MessageQueue_Clear(wMessageQueue* queue)
{
	int index;

	WaitForSingleObject(queue->mutex, INFINITE);

	for (index = queue->head; index != queue->tail; index = (index + 1) % queue->capacity)
	{
		queue->array[index] = NULL;
	}

	queue->size = 0;
	queue->head = queue->tail = 0;

	ReleaseMutex(queue->mutex);
}

void MessageQueue_Dispatch(wMessageQueue* queue, wMessage* message)
{
	WaitForSingleObject(queue->mutex, INFINITE);

	if (queue->size == queue->capacity)
	{
		int old_capacity;
		int new_capacity;

		old_capacity = queue->capacity;
		new_capacity = queue->capacity * 2;

		queue->capacity = new_capacity;
		queue->array = (wMessage**) realloc(queue->array, sizeof(wMessage*) * queue->capacity);
		ZeroMemory(&(queue->array[old_capacity]), old_capacity * sizeof(wMessage*));

		if (queue->tail < (old_capacity - 1))
		{
			CopyMemory(&(queue->array[old_capacity]), queue->array, queue->tail * sizeof(wMessage*));
			queue->tail += old_capacity;
		}
	}

	queue->array[queue->tail] = message;
	queue->tail = (queue->tail + 1) % queue->capacity;
	queue->size++;

	SetEvent(queue->event);

	ReleaseMutex(queue->mutex);
}

void MessageQueue_Post(wMessageQueue* queue, void* context, UINT32 type, void* wParam, void* lParam)
{
	wMessage* message;

	message = (wMessage*) malloc(sizeof(wMessage));

	if (message)
	{
		message->context = context;
		message->type = type;
		message->wParam = wParam;
		message->lParam = lParam;

		MessageQueue_Dispatch(queue, message);
	}
}

wMessage* MessageQueue_Get(wMessageQueue* queue)
{
	wMessage* message = NULL;

	WaitForSingleObject(queue->mutex, INFINITE);

	if (queue->size > 0)
	{
		message = queue->array[queue->head];
		queue->array[queue->head] = NULL;
		queue->head = (queue->head + 1) % queue->capacity;
		queue->size--;
	}

	if (queue->size < 1)
		ResetEvent(queue->event);

	ReleaseMutex(queue->mutex);

	return message;
}

wMessage* MessageQueue_Peek(wMessageQueue* queue)
{
	wMessage* message = NULL;

	WaitForSingleObject(queue->mutex, INFINITE);

	if (queue->size > 0)
		message = queue->array[queue->head];

	ReleaseMutex(queue->mutex);

	return message;
}

/**
 * Construction, Destruction
 */

wMessageQueue* MessageQueue_New()
{
	wMessageQueue* queue = NULL;

	queue = (wMessageQueue*) malloc(sizeof(wMessageQueue));

	if (queue)
	{
		queue->head = 0;
		queue->tail = 0;
		queue->size = 0;

		queue->capacity = 32;
		queue->array = (wMessage**) malloc(sizeof(wMessage*) * queue->capacity);

		queue->mutex = CreateMutex(NULL, FALSE, NULL);
		queue->event = CreateEvent(NULL, TRUE, FALSE, NULL);
	}

	return queue;
}

void MessageQueue_Free(wMessageQueue* queue)
{
	MessageQueue_Clear(queue);

	CloseHandle(queue->event);
	CloseHandle(queue->mutex);

	free(queue->array);
	free(queue);
}