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mutter-performance-source/cogl/cogl-memory-stack.c
Neil Roberts 534e535a28 Use the Wayland embedded linked list implementation instead of BSD's
This removes cogl-queue.h and adds a copy of Wayland's embedded list
implementation. The advantage of the Wayland model is that it is much
simpler and so it is easier to follow. It also doesn't require
defining a typedef for every list type.

The downside is that there is only one list type which is a
doubly-linked list where the head has a pointer to both the beginning
and the end. The BSD implementation has many more combinations some of
which we were taking advantage of to reduce the size of critical
structs where we didn't need a pointer to the end of the list.

The corresponding changes to uses of cogl-queue.h are:

• COGL_STAILQ_* was used for onscreen the list of events and dirty
  notifications. This makes the size of the CoglContext grow by one
  pointer.

• COGL_TAILQ_* was used for fences.

• COGL_LIST_* for CoglClosures. In this case the list head now has an
  extra pointer which means CoglOnscreen will grow by the size of
  three pointers, but this doesn't seem like a particularly important
  struct to optimise for size anyway.

• COGL_LIST_* was used for the list of foreign GLES2 offscreens.

• COGL_TAILQ_* was used for the list of sub stacks in a
  CoglMemoryStack.

• COGL_LIST_* was used to track the list of layers that haven't had
  code generated yet while generating a fragment shader for a
  pipeline.

• COGL_LIST_* was used to track the pipeline hierarchy in CoglNode.

The last part is a bit more controversial because it increases the
size of CoglPipeline and CoglPipelineLayer by one pointer in order to
have the redundant tail pointer for the list head. Normally we try to
be very careful about the size of the CoglPipeline struct. Because
CoglPipeline is slice-allocated, this effectively ends up adding two
pointers to the size because GSlice rounds up to the size of two
pointers.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit 13abf613b15f571ba1fcf6d2eb831ffc6fa31324)

Conflicts:
	cogl/cogl-context-private.h
	cogl/cogl-context.c
	cogl/driver/gl/cogl-pipeline-fragend-glsl.c
	doc/reference/cogl-2.0-experimental/Makefile.am
2013-06-13 13:45:47 +01:00

186 lines
5.4 KiB
C

/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2011 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 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, see
* <http://www.gnu.org/licenses/>.
*
*
* CoglMemoryStack provides a really simple, but lightning fast
* memory stack allocation strategy:
*
* - The underlying pool of memory is grow-only.
* - The pool is considered to be a stack which may be comprised
* of multiple smaller stacks. Allocation is done as follows:
* - If there's enough memory in the current sub-stack then the
* stack-pointer will be returned as the allocation and the
* stack-pointer will be incremented by the allocation size.
* - If there isn't enough memory in the current sub-stack
* then a new sub-stack is allocated twice as big as the current
* sub-stack or twice as big as the requested allocation size if
* that's bigger and the stack-pointer is set to the start of the
* new sub-stack.
* - Allocations can't be freed in a random-order, you can only
* rewind the entire stack back to the start. There is no
* the concept of stack frames to allow partial rewinds.
*
* For example; we plan to use this in our tesselator which has to
* allocate lots of small vertex, edge and face structures because
* when tesselation has been finished we just want to free the whole
* lot in one go.
*
*
* Authors:
* Robert Bragg <robert@linux.intel.com>
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "cogl-memory-stack-private.h"
#include "cogl-list.h"
#include <stdint.h>
#include <glib.h>
typedef struct _CoglMemorySubStack
{
CoglList link;
size_t bytes;
uint8_t *data;
} CoglMemorySubStack;
struct _CoglMemoryStack
{
CoglList sub_stacks;
CoglMemorySubStack *sub_stack;
size_t sub_stack_offset;
};
static CoglMemorySubStack *
_cogl_memory_sub_stack_alloc (size_t bytes)
{
CoglMemorySubStack *sub_stack = g_slice_new (CoglMemorySubStack);
sub_stack->bytes = bytes;
sub_stack->data = g_malloc (bytes);
return sub_stack;
}
static void
_cogl_memory_stack_add_sub_stack (CoglMemoryStack *stack,
size_t sub_stack_bytes)
{
CoglMemorySubStack *sub_stack =
_cogl_memory_sub_stack_alloc (sub_stack_bytes);
_cogl_list_insert (stack->sub_stacks.prev, &sub_stack->link);
stack->sub_stack = sub_stack;
stack->sub_stack_offset = 0;
}
CoglMemoryStack *
_cogl_memory_stack_new (size_t initial_size_bytes)
{
CoglMemoryStack *stack = g_slice_new0 (CoglMemoryStack);
_cogl_list_init (&stack->sub_stacks);
_cogl_memory_stack_add_sub_stack (stack, initial_size_bytes);
return stack;
}
void *
_cogl_memory_stack_alloc (CoglMemoryStack *stack, size_t bytes)
{
CoglMemorySubStack *sub_stack;
void *ret;
sub_stack = stack->sub_stack;
if (G_LIKELY (sub_stack->bytes - stack->sub_stack_offset >= bytes))
{
ret = sub_stack->data + stack->sub_stack_offset;
stack->sub_stack_offset += bytes;
return ret;
}
/* If the stack has been rewound and then a large initial allocation
* is made then we may need to skip over one or more of the
* sub-stacks that are too small for the requested allocation
* size... */
for (sub_stack = _cogl_container_of (sub_stack->link.next, sub_stack, link);
&sub_stack->link != &stack->sub_stacks;
sub_stack = _cogl_container_of (sub_stack->link.next, sub_stack, link))
{
if (sub_stack->bytes >= bytes)
{
ret = sub_stack->data;
stack->sub_stack = sub_stack;
stack->sub_stack_offset = bytes;
return ret;
}
}
/* Finally if we couldn't find a free sub-stack with enough space
* for the requested allocation we allocate another sub-stack that's
* twice as big as the last sub-stack or twice as big as the
* requested allocation if that's bigger.
*/
sub_stack = _cogl_container_of (stack->sub_stacks.prev, sub_stack, link);
_cogl_memory_stack_add_sub_stack (stack, MAX (sub_stack->bytes, bytes) * 2);
sub_stack = _cogl_container_of (stack->sub_stacks.prev, sub_stack, link);
stack->sub_stack_offset += bytes;
return sub_stack->data;
}
void
_cogl_memory_stack_rewind (CoglMemoryStack *stack)
{
stack->sub_stack = _cogl_container_of (stack->sub_stacks.next,
stack->sub_stack,
link);
stack->sub_stack_offset = 0;
}
static void
_cogl_memory_sub_stack_free (CoglMemorySubStack *sub_stack)
{
g_free (sub_stack->data);
g_slice_free (CoglMemorySubStack, sub_stack);
}
void
_cogl_memory_stack_free (CoglMemoryStack *stack)
{
while (!_cogl_list_empty (&stack->sub_stacks))
{
CoglMemorySubStack *sub_stack =
_cogl_container_of (stack->sub_stacks.next, sub_stack, link);
_cogl_list_remove (&sub_stack->link);
_cogl_memory_sub_stack_free (sub_stack);
}
g_slice_free (CoglMemoryStack, stack);
}