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cogl-journal: Use a pool of vertex arrays

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Previously whenever the journal is flushed a new vertex array would be
created to contain the vertices. To avoid the overhead of reallocating
a buffer every time, this patch makes it use a pool of 8 buffers which
are cycled in turn. The buffers are never destroyed but instead the
data is replaced. The journal should only ever be using one buffer at
a time but we cache more than one buffer anyway in case the GL driver
is internally using the buffer in which case mapping the buffer may
cause it to create a new buffer anyway.
This commit is contained in:
Neil Roberts 2011-06-01 14:30:45 +01:00
parent 54f94a0ed0
commit efadc439a4
2 changed files with 63 additions and 7 deletions
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12
cogl/cogl-journal-private.h
View File

@ -28,6 +28,8 @@
#include "cogl-handle.h"
#include "cogl-clip-stack.h"
#define COGL_JOURNAL_VBO_POOL_SIZE 8
typedef struct _CoglJournal
{
CoglObject _parent;
@ -36,6 +38,16 @@ typedef struct _CoglJournal
GArray *vertices;
size_t needed_vbo_len;
/* A pool of attribute buffers is used so that we can avoid repeatedly
reallocating buffers. Only one of these buffers at a time will be
used by Cogl but we keep more than one alive anyway in case the
GL driver is internally using the buffer and it would have to
allocate a new one when we start writing to it */
CoglAttributeBuffer *vbo_pool[COGL_JOURNAL_VBO_POOL_SIZE];
/* The next vbo to use from the pool. We just cycle through them in
order */
unsigned int next_vbo_in_pool;
int fast_read_pixel_count;
} CoglJournal;

52
cogl/cogl-journal.c
View File

@ -125,10 +125,17 @@ COGL_OBJECT_DEFINE (Journal, journal);
static void
_cogl_journal_free (CoglJournal *journal)
{
int i;
if (journal->entries)
g_array_free (journal->entries, TRUE);
if (journal->vertices)
g_array_free (journal->vertices, TRUE);
for (i = 0; i < COGL_JOURNAL_VBO_POOL_SIZE; i++)
if (journal->vbo_pool[i])
cogl_object_unref (journal->vbo_pool[i]);
g_slice_free (CoglJournal, journal);
}
@ -1095,8 +1102,44 @@ compare_entry_clip_stacks (CoglJournalEntry *entry0, CoglJournalEntry *entry1)
return entry0->clip_stack == entry1->clip_stack;
}
/* Gets a new vertex array from the pool. A reference is taken on the
array so it can be treated as if it was just newly allocated */
static CoglAttributeBuffer *
upload_vertices (const CoglJournalEntry *entries,
create_attribute_buffer (CoglJournal *journal,
gsize n_bytes)
{
CoglAttributeBuffer *vbo;
/* If CoglBuffers are being emulated with malloc then there's not
really any point in using the pool so we'll just allocate the
buffer directly */
if (!cogl_features_available (COGL_FEATURE_VBOS))
return cogl_attribute_buffer_new (n_bytes, NULL);
vbo = journal->vbo_pool[journal->next_vbo_in_pool];
if (vbo == NULL)
{
vbo = cogl_attribute_buffer_new (n_bytes, NULL);
journal->vbo_pool[journal->next_vbo_in_pool] = vbo;
}
else if (cogl_buffer_get_size (COGL_BUFFER (vbo)) < n_bytes)
{
/* If the buffer is too small then we'll just recreate it */
cogl_object_unref (vbo);
vbo = cogl_attribute_buffer_new (n_bytes, NULL);
journal->vbo_pool[journal->next_vbo_in_pool] = vbo;
}
journal->next_vbo_in_pool = ((journal->next_vbo_in_pool + 1) %
COGL_JOURNAL_VBO_POOL_SIZE);
return cogl_object_ref (vbo);
}
static CoglAttributeBuffer *
upload_vertices (CoglJournal *journal,
const CoglJournalEntry *entries,
int n_entries,
size_t needed_vbo_len,
GArray *vertices)
@ -1110,7 +1153,7 @@ upload_vertices (const CoglJournalEntry *entries,
g_assert (needed_vbo_len);
attribute_buffer = cogl_attribute_buffer_new (needed_vbo_len * 4, NULL);
attribute_buffer = create_attribute_buffer (journal, needed_vbo_len * 4);
buffer = COGL_BUFFER (attribute_buffer);
cogl_buffer_set_update_hint (buffer, COGL_BUFFER_UPDATE_HINT_STATIC);
@ -1343,8 +1386,9 @@ _cogl_journal_flush (CoglJournal *journal,
/* We upload the vertices after the clip stack pass in case it
modifies the entries */
state.attribute_buffer = upload_vertices (&g_array_index (journal->entries,
CoglJournalEntry, 0),
state.attribute_buffer =
upload_vertices (journal,
&g_array_index (journal->entries, CoglJournalEntry, 0),
journal->entries->len,
journal->needed_vbo_len,
journal->vertices);