/*
 *  gstvaapivideopool.c - Video object pool abstraction
 *
 *  Copyright (C) 2010-2011 Splitted-Desktop Systems
 *  Copyright (C) 2012 Intel Corporation
 *
 *  This library 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 2.1
 *  of the License, or (at your option) any later version.
 *
 *  This library 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 library; if not, write to the Free
 *  Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *  Boston, MA 02110-1301 USA
 */

/**
 * SECTION:gstvaapivideopool
 * @short_description: Video object pool abstraction
 */

#include "sysdeps.h"
#include "gstvaapivideopool.h"
#include "gstvaapivideopool_priv.h"
#include "gstvaapiobject.h"

#define DEBUG 1
#include "gstvaapidebug.h"

/* Ensure those symbols are actually defined in the resulting libraries */
#undef gst_vaapi_video_pool_ref
#undef gst_vaapi_video_pool_unref
#undef gst_vaapi_video_pool_replace

#define GST_VAAPI_VIDEO_POOL_GET_CLASS(obj) \
    gst_vaapi_video_pool_get_class(GST_VAAPI_VIDEO_POOL(obj))

static inline const GstVaapiVideoPoolClass *
gst_vaapi_video_pool_get_class(GstVaapiVideoPool *pool)
{
    return GST_VAAPI_VIDEO_POOL_CLASS(GST_VAAPI_MINI_OBJECT_GET_CLASS(pool));
}

static inline gpointer
gst_vaapi_video_pool_alloc_object(GstVaapiVideoPool *pool)
{
    return GST_VAAPI_VIDEO_POOL_GET_CLASS(pool)->alloc_object(pool);
}

void
gst_vaapi_video_pool_init(GstVaapiVideoPool *pool, GstVaapiDisplay *display,
    GstVaapiVideoPoolObjectType object_type)
{
    pool->object_type   = object_type;
    pool->display       = gst_vaapi_display_ref(display);
    pool->used_objects  = NULL;
    pool->used_count    = 0;
    pool->capacity      = 0;

    g_queue_init(&pool->free_objects);
    g_mutex_init(&pool->mutex);
}

void
gst_vaapi_video_pool_finalize(GstVaapiVideoPool *pool)
{
    g_list_free_full(pool->used_objects, gst_vaapi_object_unref);
    g_queue_foreach(&pool->free_objects, (GFunc)gst_vaapi_object_unref, NULL);
    g_queue_clear(&pool->free_objects);
    gst_vaapi_display_replace(&pool->display, NULL);
    g_mutex_clear(&pool->mutex);
}

/**
 * gst_vaapi_video_pool_ref:
 * @pool: a #GstVaapiVideoPool
 *
 * Atomically increases the reference count of the given @pool by one.
 *
 * Returns: The same @pool argument
 */
GstVaapiVideoPool *
gst_vaapi_video_pool_ref(GstVaapiVideoPool *pool)
{
    return gst_vaapi_video_pool_ref_internal(pool);
}

/**
 * gst_vaapi_video_pool_unref:
 * @pool: a #GstVaapiVideoPool
 *
 * Atomically decreases the reference count of the @pool by one. If
 * the reference count reaches zero, the pool will be free'd.
 */
void
gst_vaapi_video_pool_unref(GstVaapiVideoPool *pool)
{
    gst_vaapi_video_pool_unref_internal(pool);
}

/**
 * gst_vaapi_video_pool_replace:
 * @old_pool_ptr: a pointer to a #GstVaapiVideoPool
 * @new_pool: a #GstVaapiVideoPool
 *
 * Atomically replaces the pool pool held in @old_pool_ptr with
 * @new_pool. This means that @old_pool_ptr shall reference a valid
 * pool. However, @new_pool can be NULL.
 */
void
gst_vaapi_video_pool_replace(GstVaapiVideoPool **old_pool_ptr,
    GstVaapiVideoPool *new_pool)
{
    gst_vaapi_video_pool_replace_internal(old_pool_ptr, new_pool);
}

/**
 * gst_vaapi_video_pool_get_display:
 * @pool: a #GstVaapiVideoPool
 *
 * Retrieves the #GstVaapiDisplay the @pool is bound to. The @pool
 * owns the returned object and it shall not be unref'ed.
 *
 * Return value: the #GstVaapiDisplay the @pool is bound to
 */
GstVaapiDisplay *
gst_vaapi_video_pool_get_display(GstVaapiVideoPool *pool)
{
    g_return_val_if_fail(pool != NULL, NULL);

    return pool->display;
}

/**
 * gst_vaapi_video_pool_get_object_type:
 * @pool: a #GstVaapiVideoPool
 *
 * Retrieves the type of objects the video @pool supports.
 *
 * Return value: the #GstVaapiVideoPoolObjectType of the underlying pool
 *   objects
 */
GstVaapiVideoPoolObjectType
gst_vaapi_video_pool_get_object_type(GstVaapiVideoPool *pool)
{
    g_return_val_if_fail(pool != NULL, (GstVaapiVideoPoolObjectType)0);

    return pool->object_type;
}

/**
 * gst_vaapi_video_pool_get_object:
 * @pool: a #GstVaapiVideoPool
 *
 * Retrieves a new object from the @pool, or allocates a new one if
 * none was found. The @pool holds a reference on the returned object
 * and thus shall be released through gst_vaapi_video_pool_put_object()
 * when it's no longer needed.
 *
 * Return value: a possibly newly allocated object, or %NULL on error
 */
static gpointer
gst_vaapi_video_pool_get_object_unlocked(GstVaapiVideoPool *pool)
{
    gpointer object;

    if (pool->capacity && pool->used_count >= pool->capacity)
        return NULL;

    object = g_queue_pop_head(&pool->free_objects);
    if (!object) {
        object = gst_vaapi_video_pool_alloc_object(pool);
        if (!object)
            return NULL;
    }

    ++pool->used_count;
    pool->used_objects = g_list_prepend(pool->used_objects, object);
    return gst_vaapi_object_ref(object);
}

gpointer
gst_vaapi_video_pool_get_object(GstVaapiVideoPool *pool)
{
    gpointer object;

    g_return_val_if_fail(pool != NULL, NULL);

    g_mutex_lock(&pool->mutex);
    object = gst_vaapi_video_pool_get_object_unlocked(pool);
    g_mutex_unlock(&pool->mutex);
    return object;
}

/**
 * gst_vaapi_video_pool_put_object:
 * @pool: a #GstVaapiVideoPool
 * @object: the object to add back to the pool
 *
 * Pushes the @object back into the pool. The @object shall be
 * obtained from the @pool through gst_vaapi_video_pool_get_object().
 * Calling this function with an arbitrary object yields undefined
 * behaviour.
 */
static void
gst_vaapi_video_pool_put_object_unlocked(GstVaapiVideoPool *pool,
    gpointer object)
{
    GList *elem;

    elem = g_list_find(pool->used_objects, object);
    if (!elem)
        return;

    gst_vaapi_object_unref(object);
    --pool->used_count;
    pool->used_objects = g_list_delete_link(pool->used_objects, elem);
    g_queue_push_tail(&pool->free_objects, object);
}

void
gst_vaapi_video_pool_put_object(GstVaapiVideoPool *pool, gpointer object)
{
    g_return_if_fail(pool != NULL);
    g_return_if_fail(object != NULL);

    g_mutex_lock(&pool->mutex);
    gst_vaapi_video_pool_put_object_unlocked(pool, object);
    g_mutex_unlock(&pool->mutex);
}

/**
 * gst_vaapi_video_pool_add_object:
 * @pool: a #GstVaapiVideoPool
 * @object: the object to add to the pool
 *
 * Adds the @object to the pool. The pool then holds a reference on
 * the @object. This operation does not change the capacity of the
 * pool.
 *
 * Return value: %TRUE on success.
 */
static inline gboolean
gst_vaapi_video_pool_add_object_unlocked(GstVaapiVideoPool *pool,
    gpointer object)
{
    g_queue_push_tail(&pool->free_objects, gst_vaapi_object_ref(object));
    return TRUE;
}

gboolean
gst_vaapi_video_pool_add_object(GstVaapiVideoPool *pool, gpointer object)
{
    gboolean success;

    g_return_val_if_fail(pool != NULL, FALSE);
    g_return_val_if_fail(object != NULL, FALSE);

    g_mutex_lock(&pool->mutex);
    success = gst_vaapi_video_pool_add_object_unlocked(pool, object);
    g_mutex_unlock(&pool->mutex);
    return success;
}

/**
 * gst_vaapi_video_pool_add_objects:
 * @pool: a #GstVaapiVideoPool
 * @objects: a #GPtrArray of objects
 *
 * Adds the @objects to the pool. The pool then holds a reference on
 * the @objects. This operation does not change the capacity of the
 * pool and is just a wrapper around gst_vaapi_video_pool_add_object().
 *
 * Return value: %TRUE on success.
 */
static gboolean
gst_vaapi_video_pool_add_objects_unlocked(GstVaapiVideoPool *pool,
    GPtrArray *objects)
{
    guint i;

    for (i = 0; i < objects->len; i++) {
        gpointer const object = g_ptr_array_index(objects, i);
        if (!gst_vaapi_video_pool_add_object_unlocked(pool, object))
            return FALSE;
    }
    return TRUE;
}

gboolean
gst_vaapi_video_pool_add_objects(GstVaapiVideoPool *pool, GPtrArray *objects)
{
    gboolean success;

    g_return_val_if_fail(pool != NULL, FALSE);

    g_mutex_lock(&pool->mutex);
    success = gst_vaapi_video_pool_add_objects_unlocked(pool, objects);
    g_mutex_unlock(&pool->mutex);
    return success;
}

/**
 * gst_vaapi_video_pool_get_size:
 * @pool: a #GstVaapiVideoPool
 *
 * Returns the number of free objects available in the pool.
 *
 * Return value: number of free objects in the pool
 */
guint
gst_vaapi_video_pool_get_size(GstVaapiVideoPool *pool)
{
    guint size;

    g_return_val_if_fail(pool != NULL, 0);

    g_mutex_lock(&pool->mutex);
    size = g_queue_get_length(&pool->free_objects);
    g_mutex_unlock(&pool->mutex);
    return size;
}

/**
 * gst_vaapi_video_pool_reserve:
 * @pool: a #GstVaapiVideoPool
 * @n: the number of objects to pre-allocate
 *
 * Pre-allocates up to @n objects in the pool. If @n is less than or
 * equal to the number of free and used objects in the pool, this call
 * has no effect. Otherwise, it is a request for allocation of
 * additional objects.
 *
 * Return value: %TRUE on success
 */
static gboolean
gst_vaapi_video_pool_reserve_unlocked(GstVaapiVideoPool *pool, guint n)
{
    guint i, num_allocated;

    num_allocated = gst_vaapi_video_pool_get_size(pool) + pool->used_count;
    if (n < num_allocated)
        return TRUE;

    if ((n -= num_allocated) > pool->capacity)
        n = pool->capacity;

    for (i = num_allocated; i < n; i++) {
        gpointer const object = gst_vaapi_video_pool_alloc_object(pool);
        if (!object)
            return FALSE;
        g_queue_push_tail(&pool->free_objects, object);
    }
    return TRUE;
}

gboolean
gst_vaapi_video_pool_reserve(GstVaapiVideoPool *pool, guint n)
{
    gboolean success;

    g_return_val_if_fail(pool != NULL, 0);

    g_mutex_lock(&pool->mutex);
    success = gst_vaapi_video_pool_reserve_unlocked(pool, n);
    g_mutex_unlock(&pool->mutex);
    return success;
}

/**
 * gst_vaapi_video_pool_get_capacity:
 * @pool: a #GstVaapiVideoPool
 *
 * Returns the maximum number of objects in the pool. i.e. the maximum
 * number of objects that can be returned by gst_vaapi_video_pool_get_object().
 *
 * Return value: the capacity of the pool
 */
guint
gst_vaapi_video_pool_get_capacity(GstVaapiVideoPool *pool)
{
    guint capacity;

    g_return_val_if_fail(pool != NULL, 0);

    g_mutex_lock(&pool->mutex);
    capacity = pool->capacity;
    g_mutex_unlock(&pool->mutex);

    return capacity;
}

/**
 * gst_vaapi_video_pool_set_capacity:
 * @pool: a #GstVaapiVideoPool
 * @capacity: the maximal capacity of the pool
 *
 * Sets the maximum number of objects that can be allocated in the pool.
 */
void
gst_vaapi_video_pool_set_capacity(GstVaapiVideoPool *pool, guint capacity)
{
    g_return_if_fail(pool != NULL);

    g_mutex_lock(&pool->mutex);
    pool->capacity = capacity;
    g_mutex_unlock(&pool->mutex);
}