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GUAC-665: Narrow cost estimation algorithm.

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This commit is contained in:
Michael Jumper 2014-05-01 19:22:47 -07:00
parent 5b2f824097
commit 84fb0d8681
1 changed files with 75 additions and 16 deletions
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91
src/common/guac_surface.c
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@ -30,12 +30,59 @@
#include <stdlib.h>
static int __guac_common_should_combine(guac_common_surface* surface, int x, int y, int w, int h) {
/**
* The width of an update which should be considered negible and thus
* trivial overhead compared ot the cost of two updates.
*/
#define GUAC_SURFACE_NEGLIGIBLE_WIDTH 64
/**
* The height of an update which should be considered negible and thus
* trivial overhead compared ot the cost of two updates.
*/
#define GUAC_SURFACE_NEGLIGIBLE_HEIGHT 64
/**
* The proportional increase in cost contributed by transfer and processing of
* image data, compared to processing an equivalent amount of client-side
* data.
*/
#define GUAC_SURFACE_DATA_FACTOR 16
/**
* The base cost of every update. Each update should be considered to have
* this starting cost, plus any additional cost estimated from its
* content.
*/
#define GUAC_SURFACE_BASE_COST 4096
/**
* An increase in cost is negligible if it is less than
* 1/GUAC_SURFACE_NEGLIGIBLE_INCREASE of the old cost.
*/
#define GUAC_SURFACE_NEGLIGIBLE_INCREASE 4
/**
* Returns whether the given rectangle should be combined into the existing
* dirty rectangle, to be eventually flushed as a "png" instruction.
*
* @param surface The surface to be queried.
* @param x The X coordinate of the upper-left corner of the update rectangle.
* @param y The Y coordinate of the upper-left corner of the update rectangle.
* @param w The width of the update rectangle.
* @param h The height of the update rectangle.
* @param rect_only Non-zero if this update, by its nature, contains only
* metainformation about the update's rectangle, zero if
* the update also contains image data.
* @return Non-zero if the update should be combined with any existing update,
* zero otherwise.
*/
static int __guac_common_should_combine(guac_common_surface* surface, int x, int y, int w, int h, int rect_only) {
if (surface->dirty) {
int new_pixels, dirty_pixels, update_pixels;
int new_width, new_height;
int combined_cost, dirty_cost, update_cost;
int combined_width, combined_height;
/* Calculate extents of existing dirty rect */
int dirty_left = surface->dirty_x;
@ -53,20 +100,32 @@ static int __guac_common_should_combine(guac_common_surface* surface, int x, int
if (right > dirty_right) dirty_right = right;
if (bottom > dirty_bottom) dirty_bottom = bottom;
new_width = dirty_right - dirty_left;
new_height = dirty_bottom - dirty_top;
combined_width = dirty_right - dirty_left;
combined_height = dirty_bottom - dirty_top;
/* Combine if result is still small */
if (new_width <= 64 && new_height <= 64)
if (combined_width <= GUAC_SURFACE_NEGLIGIBLE_WIDTH && combined_height <= GUAC_SURFACE_NEGLIGIBLE_HEIGHT)
return 1;
new_pixels = new_width*new_height;
dirty_pixels = surface->dirty_width*surface->dirty_height;
update_pixels = w*h;
/* Estimate costs of the existing update, new update, and both combined */
combined_cost = GUAC_SURFACE_BASE_COST + combined_width * combined_height;
dirty_cost = GUAC_SURFACE_BASE_COST + surface->dirty_width * surface->dirty_height;
update_cost = GUAC_SURFACE_BASE_COST + w*h;
/* Combine if increase in cost is likely negligible */
if (new_pixels - dirty_pixels <= update_pixels*4) return 1;
if (new_pixels / dirty_pixels <= 2) return 1;
/* Reduce cost if no image data */
if (rect_only)
update_cost /= GUAC_SURFACE_DATA_FACTOR;
/* Combine if cost estimate shows benefit */
if (combined_cost <= update_cost + dirty_cost)
return 1;
/* Combine if increase in cost is negligible */
if (combined_cost - dirty_cost <= dirty_cost / GUAC_SURFACE_NEGLIGIBLE_INCREASE)
return 1;
if (combined_cost - update_cost <= update_cost / GUAC_SURFACE_NEGLIGIBLE_INCREASE)
return 1;
}
@ -351,7 +410,7 @@ void guac_common_surface_draw(guac_common_surface* surface, int x, int y, cairo_
int h = cairo_image_surface_get_height(src);
/* Flush if not combining */
if (!__guac_common_should_combine(surface, x, y, w, h))
if (!__guac_common_should_combine(surface, x, y, w, h, 0))
guac_common_surface_flush(surface);
/* Always defer draws */
@ -374,7 +433,7 @@ void guac_common_surface_copy(guac_common_surface* src, int sx, int sy, int w, i
const guac_layer* dst_layer = dst->layer;
/* Defer if combining */
if (__guac_common_should_combine(dst, dx, dy, w, h))
if (__guac_common_should_combine(dst, dx, dy, w, h, 1))
__guac_common_mark_dirty(dst, dx, dy, w, h);
/* Otherwise, flush and draw immediately */
@ -400,7 +459,7 @@ void guac_common_surface_transfer(guac_common_surface* src, int sx, int sy, int
const guac_layer* dst_layer = dst->layer;
/* Defer if combining */
if (__guac_common_should_combine(dst, dx, dy, w, h))
if (__guac_common_should_combine(dst, dx, dy, w, h, 1))
__guac_common_mark_dirty(dst, dx, dy, w, h);
/* Otherwise, flush and draw immediately */
@ -426,7 +485,7 @@ void guac_common_surface_rect(guac_common_surface* surface,
const guac_layer* layer = surface->layer;
/* Defer if combining */
if (__guac_common_should_combine(surface, x, y, w, h))
if (__guac_common_should_combine(surface, x, y, w, h, 1))
__guac_common_mark_dirty(surface, x, y, w, h);
/* Otherwise, flush and draw immediately */