/* GStreamer
* Copyright (C) 2009 Edward Hervey <bilboed@bilboed.com>
* Copyright (C) 2015 Tim-Philipp Müller <tim@centricular.com>
*
* gstqueuearray.c:
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
/**
* SECTION:gstqueuearray
* @title: GstQueueArray
* @short_description: Array based queue object
*
* #GstQueueArray is an object that provides standard queue functionality
* based on an array instead of linked lists. This reduces the overhead
* caused by memory management by a large factor.
*/
#include <string.h>
#include <gst/gst.h>
#include "gstqueuearray.h"
struct _GstQueueArray
{
/* < private > */
guint8 *array;
guint size;
guint head;
guint tail;
guint length;
guint elt_size;
gboolean struct_array;
};
/**
* gst_queue_array_new_for_struct: (skip)
* @struct_size: Size of each element (e.g. structure) in the array
* @initial_size: Initial size of the new queue
*
* Allocates a new #GstQueueArray object for elements (e.g. structures)
* of size @struct_size, with an initial queue size of @initial_size.
*
* Returns: a new #GstQueueArray object
*
* Since: 1.6
*/
GstQueueArray *
gst_queue_array_new_for_struct (gsize struct_size, guint initial_size)
{
GstQueueArray *array;
g_return_val_if_fail (struct_size > 0, NULL);
array = g_slice_new (GstQueueArray);
array->elt_size = struct_size;
array->size = initial_size;
array->array = g_malloc0 (struct_size * initial_size);
array->head = 0;
array->tail = 0;
array->length = 0;
array->struct_array = TRUE;
return array;
}
/**
* gst_queue_array_new: (skip)
* @initial_size: Initial size of the new queue
*
* Allocates a new #GstQueueArray object with an initial
* queue size of @initial_size.
*
* Returns: a new #GstQueueArray object
*
* Since: 1.2
*/
GstQueueArray *
gst_queue_array_new (guint initial_size)
{
GstQueueArray *array;
array = gst_queue_array_new_for_struct (sizeof (gpointer), initial_size);
array->struct_array = FALSE;
return array;
}
/**
* gst_queue_array_free: (skip)
* @array: a #GstQueueArray object
*
* Frees queue @array and all memory associated to it.
*
* Since: 1.2
*/
void
gst_queue_array_free (GstQueueArray * array)
{
g_return_if_fail (array != NULL);
g_free (array->array);
g_slice_free (GstQueueArray, array);
}
/**
* gst_queue_array_pop_head_struct: (skip)
* @array: a #GstQueueArray object
*
* Returns the head of the queue @array and removes it from the queue.
*
* Returns: pointer to element or struct, or NULL if @array was empty. The
* data pointed to by the returned pointer stays valid only as long as
* the queue array is not modified further!
*
* Since: 1.6
*/
gpointer
gst_queue_array_pop_head_struct (GstQueueArray * array)
{
gpointer p_struct;
g_return_val_if_fail (array != NULL, NULL);
/* empty array */
if (G_UNLIKELY (array->length == 0))
return NULL;
p_struct = array->array + (array->elt_size * array->head);
array->head++;
array->head %= array->size;
array->length--;
return p_struct;
}
/**
* gst_queue_array_pop_head: (skip)
* @array: a #GstQueueArray object
*
* Returns and head of the queue @array and removes
* it from the queue.
*
* Returns: The head of the queue
*
* Since: 1.2
*/
gpointer
gst_queue_array_pop_head (GstQueueArray * array)
{
gpointer ret;
g_return_val_if_fail (array != NULL, NULL);
/* empty array */
if (G_UNLIKELY (array->length == 0))
return NULL;
ret = *(gpointer *) (array->array + (sizeof (gpointer) * array->head));
array->head++;
array->head %= array->size;
array->length--;
return ret;
}
/**
* gst_queue_array_peek_head_struct: (skip)
* @array: a #GstQueueArray object
*
* Returns the head of the queue @array without removing it from the queue.
*
* Returns: pointer to element or struct, or NULL if @array was empty. The
* data pointed to by the returned pointer stays valid only as long as
* the queue array is not modified further!
*
* Since: 1.6
*/
gpointer
gst_queue_array_peek_head_struct (GstQueueArray * array)
{
g_return_val_if_fail (array != NULL, NULL);
/* empty array */
if (G_UNLIKELY (array->length == 0))
return NULL;
return array->array + (array->elt_size * array->head);
}
/**
* gst_queue_array_peek_head: (skip)
* @array: a #GstQueueArray object
*
* Returns the head of the queue @array and does not
* remove it from the queue.
*
* Returns: The head of the queue
*
* Since: 1.2
*/
gpointer
gst_queue_array_peek_head (GstQueueArray * array)
{
g_return_val_if_fail (array != NULL, NULL);
/* empty array */
if (G_UNLIKELY (array->length == 0))
return NULL;
return *(gpointer *) (array->array + (sizeof (gpointer) * array->head));
}
static void
gst_queue_array_do_expand (GstQueueArray * array)
{
guint elt_size = array->elt_size;
/* newsize is 50% bigger */
guint oldsize = array->size;
guint newsize = MAX ((3 * oldsize) / 2, oldsize + 1);
/* copy over data */
if (array->tail != 0) {
guint8 *array2 = g_malloc0 (elt_size * newsize);
guint t1 = array->head;
guint t2 = oldsize - array->head;
/* [0-----TAIL][HEAD------SIZE]
*
* We want to end up with
* [HEAD------------------TAIL][----FREEDATA------NEWSIZE]
*
* 1) move [HEAD-----SIZE] part to beginning of new array
* 2) move [0-------TAIL] part new array, after previous part
*/
memcpy (array2, array->array + (elt_size * array->head), t2 * elt_size);
memcpy (array2 + t2 * elt_size, array->array, t1 * elt_size);
g_free (array->array);
array->array = array2;
array->head = 0;
} else {
/* Fast path, we just need to grow the array */
array->array = g_realloc (array->array, elt_size * newsize);
memset (array->array + elt_size * oldsize, 0,
elt_size * (newsize - oldsize));
}
array->tail = oldsize;
array->size = newsize;
}
/**
* gst_queue_array_push_element_tail: (skip)
* @array: a #GstQueueArray object
* @p_struct: address of element or structure to push to the tail of the queue
*
* Pushes the element at address @p_struct to the tail of the queue @array
* (Copies the contents of a structure of the struct_size specified when
* creating the queue into the array).
*
* Since: 1.6
*/
void
gst_queue_array_push_tail_struct (GstQueueArray * array, gpointer p_struct)
{
guint elt_size;
g_return_if_fail (p_struct != NULL);
g_return_if_fail (array != NULL);
elt_size = array->elt_size;
/* Check if we need to make room */
if (G_UNLIKELY (array->length == array->size))
gst_queue_array_do_expand (array);
memcpy (array->array + elt_size * array->tail, p_struct, elt_size);
array->tail++;
array->tail %= array->size;
array->length++;
}
/**
* gst_queue_array_push_tail: (skip)
* @array: a #GstQueueArray object
* @data: object to push
*
* Pushes @data to the tail of the queue @array.
*
* Since: 1.2
*/
void
gst_queue_array_push_tail (GstQueueArray * array, gpointer data)
{
g_return_if_fail (array != NULL);
/* Check if we need to make room */
if (G_UNLIKELY (array->length == array->size))
gst_queue_array_do_expand (array);
*(gpointer *) (array->array + sizeof (gpointer) * array->tail) = data;
array->tail++;
array->tail %= array->size;
array->length++;
}
/**
* gst_queue_array_peek_tail: (skip)
* @array: a #GstQueueArray object
*
* Returns the tail of the queue @array, but does not remove it from the queue.
*
* Returns: The tail of the queue
*
* Since: 1.14
*/
gpointer
gst_queue_array_peek_tail (GstQueueArray * array)
{
guint len, idx;
g_return_val_if_fail (array != NULL, NULL);
len = array->length;
/* empty array */
if (len == 0)
return NULL;
idx = (array->head + (len - 1)) % array->size;
return *(gpointer *) (array->array + (sizeof (gpointer) * idx));
}
/**
* gst_queue_array_peek_tail_struct: (skip)
* @array: a #GstQueueArray object
*
* Returns the tail of the queue @array, but does not remove it from the queue.
*
* Returns: The tail of the queue
*
* Since: 1.14
*/
gpointer
gst_queue_array_peek_tail_struct (GstQueueArray * array)
{
guint len, idx;
g_return_val_if_fail (array != NULL, NULL);
len = array->length;
/* empty array */
if (len == 0)
return NULL;
idx = (array->head + (len - 1)) % array->size;
return array->array + (array->elt_size * idx);
}
/**
* gst_queue_array_pop_tail: (skip)
* @array: a #GstQueueArray object
*
* Returns the tail of the queue @array and removes
* it from the queue.
*
* Returns: The tail of the queue
*
* Since: 1.14
*/
gpointer
gst_queue_array_pop_tail (GstQueueArray * array)
{
gpointer ret;
guint len, idx;
g_return_val_if_fail (array != NULL, NULL);
len = array->length;
/* empty array */
if (len == 0)
return NULL;
idx = (array->head + (len - 1)) % array->size;
ret = *(gpointer *) (array->array + (sizeof (gpointer) * idx));
array->tail = idx;
array->length--;
return ret;
}
/**
* gst_queue_array_pop_tail_struct: (skip)
* @array: a #GstQueueArray object
*
* Returns the tail of the queue @array and removes
* it from the queue.
*
* Returns: The tail of the queue
*
* Since: 1.14
*/
gpointer
gst_queue_array_pop_tail_struct (GstQueueArray * array)
{
gpointer ret;
guint len, idx;
g_return_val_if_fail (array != NULL, NULL);
len = array->length;
/* empty array */
if (len == 0)
return NULL;
idx = (array->head + (len - 1)) % array->size;
ret = array->array + (array->elt_size * idx);
array->tail = idx;
array->length--;
return ret;
}
/**
* gst_queue_array_is_empty: (skip)
* @array: a #GstQueueArray object
*
* Checks if the queue @array is empty.
*
* Returns: %TRUE if the queue @array is empty
*
* Since: 1.2
*/
gboolean
gst_queue_array_is_empty (GstQueueArray * array)
{
g_return_val_if_fail (array != NULL, FALSE);
return (array->length == 0);
}
/**
* gst_queue_array_drop_struct: (skip)
* @array: a #GstQueueArray object
* @idx: index to drop
* @p_struct: address into which to store the data of the dropped structure, or NULL
*
* Drops the queue element at position @idx from queue @array and copies the
* data of the element or structure that was removed into @p_struct if
* @p_struct is set (not NULL).
*
* Returns: TRUE on success, or FALSE on error
*
* Since: 1.6
*/
gboolean
gst_queue_array_drop_struct (GstQueueArray * array, guint idx,
gpointer p_struct)
{
int first_item_index, last_item_index;
guint elt_size;
g_return_val_if_fail (array != NULL, FALSE);
g_return_val_if_fail (array->length > 0, FALSE);
g_return_val_if_fail (idx < array->size, FALSE);
elt_size = array->elt_size;
first_item_index = array->head;
/* tail points to the first free spot */
last_item_index = (array->tail - 1 + array->size) % array->size;
if (p_struct != NULL)
memcpy (p_struct, array->array + elt_size * idx, elt_size);
/* simple case idx == first item */
if (idx == first_item_index) {
/* move the head plus one */
array->head++;
array->head %= array->size;
array->length--;
return TRUE;
}
/* simple case idx == last item */
if (idx == last_item_index) {
/* move tail minus one, potentially wrapping */
array->tail = (array->tail - 1 + array->size) % array->size;
array->length--;
return TRUE;
}
/* non-wrapped case */
if (first_item_index < last_item_index) {
g_assert (first_item_index < idx && idx < last_item_index);
/* move everything beyond idx one step towards zero in array */
memmove (array->array + elt_size * idx,
array->array + elt_size * (idx + 1),
(last_item_index - idx) * elt_size);
/* tail might wrap, ie if tail == 0 (and last_item_index == size) */
array->tail = (array->tail - 1 + array->size) % array->size;
array->length--;
return TRUE;
}
/* only wrapped cases left */
g_assert (first_item_index > last_item_index);
if (idx < last_item_index) {
/* idx is before last_item_index, move data towards zero */
memmove (array->array + elt_size * idx,
array->array + elt_size * (idx + 1),
(last_item_index - idx) * elt_size);
/* tail should not wrap in this case! */
g_assert (array->tail > 0);
array->tail--;
array->length--;
return TRUE;
}
if (idx > first_item_index) {
/* idx is after first_item_index, move data to higher indices */
memmove (array->array + elt_size * (first_item_index + 1),
array->array + elt_size * first_item_index,
(idx - first_item_index) * elt_size);
array->head++;
/* head should not wrap in this case! */
g_assert (array->head < array->size);
array->length--;
return TRUE;
}
g_return_val_if_reached (FALSE);
}
/**
* gst_queue_array_drop_element: (skip)
* @array: a #GstQueueArray object
* @idx: index to drop
*
* Drops the queue element at position @idx from queue @array.
*
* Returns: the dropped element
*
* Since: 1.2
*/
gpointer
gst_queue_array_drop_element (GstQueueArray * array, guint idx)
{
gpointer ptr;
if (!gst_queue_array_drop_struct (array, idx, &ptr))
return NULL;
return ptr;
}
/**
* gst_queue_array_find: (skip)
* @array: a #GstQueueArray object
* @func: (allow-none): comparison function, or %NULL to find @data by value
* @data: data for comparison function
*
* Finds an element in the queue @array, either by comparing every element
* with @func or by looking up @data if no compare function @func is provided,
* and returning the index of the found element.
*
* Note that the index is not 0-based, but an internal index number with a
* random offset. The index can be used in connection with
* gst_queue_array_drop_element(). FIXME: return index 0-based and make
* gst_queue_array_drop_element() take a 0-based index.
*
* Returns: Index of the found element or -1 if nothing was found.
*
* Since: 1.2
*/
guint
gst_queue_array_find (GstQueueArray * array, GCompareFunc func, gpointer data)
{
gpointer p_element;
guint elt_size;
guint i;
/* For struct arrays we need to implement this differently so that
* the user gets a pointer to the element data not the dereferenced
* pointer itself */
g_return_val_if_fail (array != NULL, -1);
g_return_val_if_fail (array->struct_array == FALSE, -1);
elt_size = array->elt_size;
if (func != NULL) {
/* Scan from head to tail */
for (i = 0; i < array->length; i++) {
p_element = array->array + ((i + array->head) % array->size) * elt_size;
if (func (*(gpointer *) p_element, data) == 0)
return (i + array->head) % array->size;
}
} else {
for (i = 0; i < array->length; i++) {
p_element = array->array + ((i + array->head) % array->size) * elt_size;
if (*(gpointer *) p_element == data)
return (i + array->head) % array->size;
}
}
return -1;
}
/**
* gst_queue_array_get_length: (skip)
* @array: a #GstQueueArray object
*
* Returns the length of the queue @array
*
* Returns: the length of the queue @array.
*
* Since: 1.2
*/
guint
gst_queue_array_get_length (GstQueueArray * array)
{
g_return_val_if_fail (array != NULL, 0);
return array->length;
}