Commit f6dc8eba authored by Wim Taymans's avatar Wim Taymans

memory: cleanups and improve docs

Make the fallback copy use the same memory allocator as the original object.
Improve some docs.
Require an alloc function when registering an allocator.
Remove gst_memory_allocator_get_default() and merge the feature in
gst_memory_allocator_find()
Fix locks on the hashtable.
Remove defined but not-implemented gst_memory_span() method.
parent 9886c712
......@@ -27,7 +27,13 @@
* GstMemory is a lightweight refcounted object that wraps a region of memory.
* They are typically used to manage the data of a #GstBuffer.
*
* Memory is created by allocators.
* Memory is usually created by allocators with a gst_memory_allocator_alloc()
* method call. When NULL is used as the allocator, the default allocator will
* be used.
*
* New allocators can be registered with gst_memory_allocator_register().
* Allocators are identified by name and can be retrieved with
* gst_memory_allocator_find().
*
* New memory can be created with gst_memory_new_wrapped() that wraps the memory
* allocated elsewhere.
......@@ -49,7 +55,7 @@
* Memory can be efficiently merged when gst_memory_is_span() returns TRUE and
* with the function gst_memory_span().
*
* Last reviewed on 2011-03-30 (0.11.0)
* Last reviewed on 2011-06-08 (0.11.0)
*/
#include "config.h"
......@@ -283,15 +289,19 @@ _default_mem_is_span (GstMemoryDefault * mem1, GstMemoryDefault * mem2,
static GstMemory *
_fallback_copy (GstMemory * mem, gsize offset, gsize size)
{
GstMemoryDefault *copy;
guint8 *data;
GstMemory *copy;
guint8 *data, *dest;
gsize msize;
data = gst_memory_map (mem, &msize, NULL, GST_MAP_READ);
if (size == -1)
size = msize > offset ? msize - offset : 0;
copy = _default_mem_new_block (size, 0, 0, size);
memcpy (copy->data, data + offset, size);
/* use the same allocator as the memory we copy, FIXME, alignment? */
copy = gst_memory_allocator_alloc (mem->allocator, size, 1);
dest = gst_memory_map (copy, NULL, NULL, GST_MAP_WRITE);
memcpy (dest, data + offset, size);
gst_memory_unmap (copy, dest, size);
gst_memory_unmap (mem, data, msize);
return (GstMemory *) copy;
......@@ -581,6 +591,12 @@ gst_memory_is_span (GstMemory * mem1, GstMemory * mem2, gsize * offset)
* Registers the memory allocator with @name and implementation functions
* @info.
*
* All functions in @info are mandatory exept the copy, share and is_span
* functions, which will have a default implementation when left NULL.
*
* The user_data field in @info will be passed to all calls of the alloc
* function.
*
* Returns: a new #GstMemoryAllocator.
*/
const GstMemoryAllocator *
......@@ -593,6 +609,7 @@ gst_memory_allocator_register (const gchar * name, const GstMemoryInfo * info)
g_return_val_if_fail (name != NULL, NULL);
g_return_val_if_fail (info != NULL, NULL);
g_return_val_if_fail (info->alloc != NULL, NULL);
g_return_val_if_fail (info->get_sizes != NULL, NULL);
g_return_val_if_fail (info->resize != NULL, NULL);
g_return_val_if_fail (info->map != NULL, NULL);
......@@ -620,7 +637,8 @@ gst_memory_allocator_register (const gchar * name, const GstMemoryInfo * info)
* gst_memory_allocator_find:
* @name: the name of the allocator
*
* Find a previously registered allocator with @name.
* Find a previously registered allocator with @name. When @name is NULL, the
* default allocator will be returned.
*
* Returns: a #GstMemoryAllocator or NULL when the allocator with @name was not
* registered.
......@@ -628,30 +646,19 @@ gst_memory_allocator_register (const gchar * name, const GstMemoryInfo * info)
const GstMemoryAllocator *
gst_memory_allocator_find (const gchar * name)
{
GstMemoryAllocator *allocator;
g_return_val_if_fail (name != NULL, NULL);
const GstMemoryAllocator *allocator;
g_static_rw_lock_writer_lock (&lock);
allocator = g_hash_table_lookup (memoryimpl, (gconstpointer) name);
g_static_rw_lock_writer_unlock (&lock);
g_static_rw_lock_reader_lock (&lock);
if (name) {
allocator = g_hash_table_lookup (memoryimpl, (gconstpointer) name);
} else {
allocator = _default_allocator;
}
g_static_rw_lock_reader_unlock (&lock);
return allocator;
}
/**
* gst_memory_allocator_get_default:
*
* Get the default allocator.
*
* Returns: the default #GstMemoryAllocator
*/
const GstMemoryAllocator *
gst_memory_allocator_get_default (void)
{
return _default_allocator;
}
/**
* gst_memory_allocator_set_default:
* @allocator: a ##GstMemoryAllocator
......@@ -663,7 +670,9 @@ gst_memory_allocator_set_default (const GstMemoryAllocator * allocator)
{
g_return_if_fail (allocator != NULL);
g_static_rw_lock_writer_lock (&lock);
_default_allocator = allocator;
g_static_rw_lock_writer_unlock (&lock);
}
/**
......@@ -675,6 +684,8 @@ gst_memory_allocator_set_default (const GstMemoryAllocator * allocator)
* Use @allocator to allocate a new memory block with memory that is at least
* @maxsize big and has the given alignment.
*
* When @allocator is NULL, the default allocator will be used.
*
* @align is given as a bitmask so that @align + 1 equals the amount of bytes to
* align to. For example, to align to 8 bytes, use an alignment of 7.
*
......@@ -684,8 +695,6 @@ GstMemory *
gst_memory_allocator_alloc (const GstMemoryAllocator * allocator,
gsize maxsize, gsize align)
{
g_return_val_if_fail (allocator == NULL
|| allocator->info.alloc != NULL, NULL);
g_return_val_if_fail (((align + 1) & align) == 0, NULL);
if (allocator == NULL)
......
......@@ -267,7 +267,6 @@ void _gst_memory_init (void);
const GstMemoryAllocator * gst_memory_allocator_register (const gchar *name, const GstMemoryInfo *info);
const GstMemoryAllocator * gst_memory_allocator_find (const gchar *name);
const GstMemoryAllocator * gst_memory_allocator_get_default (void);
void gst_memory_allocator_set_default (const GstMemoryAllocator * allocator);
/* allocating memory blocks */
......@@ -296,9 +295,6 @@ GstMemory * gst_memory_share (GstMemory *mem, gsize offset, gsize size);
/* span memory */
gboolean gst_memory_is_span (GstMemory *mem1, GstMemory *mem2, gsize *offset);
GstMemory * gst_memory_span (GstMemory **mem1, gsize len1, gsize offset,
GstMemory **mem2, gsize len2, gsize size);
G_END_DECLS
#endif /* __GST_MEMORY_H__ */
......@@ -1806,6 +1806,9 @@ gst_query_add_allocation_memory (GstQuery * query, const gchar * alloc)
* Retrieve the number of values currently stored in the
* allocator array of the query's structure.
*
* If no memory allocator is specified, the downstream element can handle
* the default memory allocator.
*
* Returns: the allocator array size as a #guint.
*/
guint
......
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