Image thread safe improvements

This commit makes BKE_image_acquire_ibuf referencing result, which means once
some area requested for image buffer, it'll be guaranteed this buffer wouldn't
be freed by image signal.

To de-reference buffer BKE_image_release_ibuf should now always be used.

To make referencing working correct we can not rely on result of
image_get_ibuf_threadsafe called outside from thread lock. This is so because
we need to guarantee getting image buffer from list of loaded buffers and it's
referencing happens atomic. Without lock here it is possible that between call
of image_get_ibuf_threadsafe and referencing the buffer IMA_SIGNAL_FREE would
be called. Image signal handling too is blocking now to prevent such a
situation.

Threads are locking by spinlock, which are faster than mutexes. There were some
slowdown reports in the past about render slowdown when using OSX on Xeon CPU.
It shouldn't happen with spin locks, but more tests on different hardware would
be really welcome. So far can not see speed regressions on own computers.

This commit also removes BKE_image_get_ibuf, because it was not so intuitive
when get_ibuf and acquire_ibuf should be used.

Thanks to Ton and Brecht for discussion/review :)

7 files changed, 28 insertions, 11 deletions

diff --git a/source/blender/nodes/composite/nodes/node_composite_image.c b/source/blender/nodes/composite/nodes/node_composite_image.c
index 150382c1f8f..88d78df190f 100644
--- a/source/blender/nodes/composite/nodes/node_composite_image.c
+++ b/source/blender/nodes/composite/nodes/node_composite_image.c
@@ -173,9 +173,10 @@ static void cmp_node_image_create_outputs(bNodeTree *ntree, bNode *node)
 	Image *ima= (Image *)node->id;
 	if (ima) {
 		ImageUser *iuser= node->storage;
+		ImBuf *ibuf;
 		
 		/* make sure ima->type is correct */
-		BKE_image_get_ibuf(ima, iuser);
+		ibuf = BKE_image_acquire_ibuf(ima, iuser, NULL);
 		
 		if (ima->rr) {
 			RenderLayer *rl= BLI_findlink(&ima->rr->layers, iuser->layer);
@@ -191,6 +192,8 @@ static void cmp_node_image_create_outputs(bNodeTree *ntree, bNode *node)
 		}
 		else
 			cmp_node_image_add_render_pass_outputs(ntree, node, RRES_OUT_IMAGE|RRES_OUT_ALPHA|RRES_OUT_Z);
+		
+		BKE_image_release_ibuf(ima, ibuf, NULL);
 	}
 	else
 		cmp_node_image_add_render_pass_outputs(ntree, node, RRES_OUT_IMAGE|RRES_OUT_ALPHA);
@@ -312,7 +315,7 @@ float *node_composit_get_float_buffer(RenderData *rd, ImBuf *ibuf, int *alloc)
 }
 
 /* note: this function is used for multilayer too, to ensure uniform 
- * handling with BKE_image_get_ibuf() */
+ * handling with BKE_image_acquire_ibuf() */
 static CompBuf *node_composit_get_image(RenderData *rd, Image *ima, ImageUser *iuser)
 {
 	ImBuf *ibuf;
@@ -322,7 +325,7 @@ static CompBuf *node_composit_get_image(RenderData *rd, Image *ima, ImageUser *i
 	float *rect;
 	int alloc= FALSE;
 
-	ibuf= BKE_image_get_ibuf(ima, iuser);
+	ibuf= BKE_image_acquire_ibuf(ima, iuser, NULL);
 	if (ibuf==NULL || (ibuf->rect==NULL && ibuf->rect_float==NULL)) {
 		return NULL;
 	}
@@ -374,12 +377,15 @@ static CompBuf *node_composit_get_image(RenderData *rd, Image *ima, ImageUser *i
 		}
 	}
 #endif
+
+	BKE_image_release_ibuf(ima, ibuf, NULL);
+
 	return stackbuf;
 }
 
 static CompBuf *node_composit_get_zimage(bNode *node, RenderData *rd)
 {
-	ImBuf *ibuf= BKE_image_get_ibuf((Image *)node->id, node->storage);
+	ImBuf *ibuf= BKE_image_acquire_ibuf((Image *)node->id, node->storage, NULL);
 	CompBuf *zbuf= NULL;
 	
 	if (ibuf && ibuf->zbuf_float) {
@@ -391,6 +397,9 @@ static CompBuf *node_composit_get_zimage(bNode *node, RenderData *rd)
 			zbuf->rect= ibuf->zbuf_float;
 		}
 	}
+
+	BKE_image_release_ibuf((Image *)node->id, ibuf, NULL);
+
 	return zbuf;
 }
 
@@ -418,13 +427,14 @@ static void node_composit_exec_image(void *data, bNode *node, bNodeStack **UNUSE
 		RenderData *rd= data;
 		Image *ima= (Image *)node->id;
 		ImageUser *iuser= (ImageUser *)node->storage;
+		ImBuf *ibuf = NULL;
 		
 		/* first set the right frame number in iuser */
 		BKE_image_user_frame_calc(iuser, rd->cfra, 0);
 		
 		/* force a load, we assume iuser index will be set OK anyway */
 		if (ima->type==IMA_TYPE_MULTILAYER)
-			BKE_image_get_ibuf(ima, iuser);
+			ibuf = BKE_image_acquire_ibuf(ima, iuser, NULL);
 		
 		if (ima->type==IMA_TYPE_MULTILAYER && ima->rr) {
 			RenderLayer *rl= BLI_findlink(&ima->rr->layers, iuser->layer);
@@ -505,6 +515,8 @@ static void node_composit_exec_image(void *data, bNode *node, bNodeStack **UNUSE
 				generate_preview(data, node, stackbuf);
 			}
 		}
+
+		BKE_image_release_ibuf(ima, ibuf, NULL);
 	}
 }
 
diff --git a/source/blender/nodes/composite/nodes/node_composite_splitViewer.c b/source/blender/nodes/composite/nodes/node_composite_splitViewer.c
index 73cf039c6df..81f2f9b05a9 100644
--- a/source/blender/nodes/composite/nodes/node_composite_splitViewer.c
+++ b/source/blender/nodes/composite/nodes/node_composite_splitViewer.c
@@ -128,7 +128,7 @@ static void node_composit_exec_splitviewer(void *data, bNode *node, bNodeStack *
 		
 		composit3_pixel_processor(node, cbuf, buf1, in[0]->vec, buf2, in[1]->vec, mask, NULL, do_copy_split_rgba, CB_RGBA, CB_RGBA, CB_VAL);
 		
-		BKE_image_release_ibuf(ima, lock);
+		BKE_image_release_ibuf(ima, ibuf, lock);
 		
 		generate_preview(data, node, cbuf);
 		free_compbuf(cbuf);
diff --git a/source/blender/nodes/composite/nodes/node_composite_viewer.c b/source/blender/nodes/composite/nodes/node_composite_viewer.c
index 938f75cf3f5..b186a9aeaf9 100644
--- a/source/blender/nodes/composite/nodes/node_composite_viewer.c
+++ b/source/blender/nodes/composite/nodes/node_composite_viewer.c
@@ -112,7 +112,7 @@ static void node_composit_exec_viewer(void *data, bNode *node, bNodeStack **in,
 			free_compbuf(zbuf);
 		}
 
-		BKE_image_release_ibuf(ima, lock);
+		BKE_image_release_ibuf(ima, ibuf, lock);
 
 		generate_preview(data, node, cbuf);
 		free_compbuf(cbuf);
diff --git a/source/blender/nodes/shader/nodes/node_shader_tex_environment.c b/source/blender/nodes/shader/nodes/node_shader_tex_environment.c
index abe8e0190c8..d2d0870e2ed 100644
--- a/source/blender/nodes/shader/nodes/node_shader_tex_environment.c
+++ b/source/blender/nodes/shader/nodes/node_shader_tex_environment.c
@@ -75,12 +75,13 @@ static int node_shader_gpu_tex_environment(GPUMaterial *mat, bNode *node, GPUNod
 	ret = GPU_stack_link(mat, "node_tex_environment", in, out, GPU_image(ima, iuser, isdata));
 
 	if (ret) {
-		ImBuf *ibuf = BKE_image_get_ibuf(ima, iuser);
+		ImBuf *ibuf = BKE_image_acquire_ibuf(ima, iuser, NULL);
 		if (ibuf && (ibuf->colormanage_flag & IMB_COLORMANAGE_IS_DATA) == 0 &&
 		    GPU_material_do_color_management(mat))
 		{
 			GPU_link(mat, "srgb_to_linearrgb", out[0].link, &out[0].link);
 		}
+		BKE_image_release_ibuf(ima, ibuf, NULL);
 	}
 
 	return ret;
diff --git a/source/blender/nodes/shader/nodes/node_shader_tex_image.c b/source/blender/nodes/shader/nodes/node_shader_tex_image.c
index 9b17f76bd47..49b38434246 100644
--- a/source/blender/nodes/shader/nodes/node_shader_tex_image.c
+++ b/source/blender/nodes/shader/nodes/node_shader_tex_image.c
@@ -75,12 +75,13 @@ static int node_shader_gpu_tex_image(GPUMaterial *mat, bNode *node, GPUNodeStack
 	ret = GPU_stack_link(mat, "node_tex_image", in, out, GPU_image(ima, iuser, isdata));
 
 	if (ret) {
-		ImBuf *ibuf = BKE_image_get_ibuf(ima, iuser);
+		ImBuf *ibuf = BKE_image_acquire_ibuf(ima, iuser, NULL);
 		if (ibuf && (ibuf->colormanage_flag & IMB_COLORMANAGE_IS_DATA) == 0 &&
 		    GPU_material_do_color_management(mat))
 		{
 			GPU_link(mat, "srgb_to_linearrgb", out[0].link, &out[0].link);
 		}
+		BKE_image_release_ibuf(ima, ibuf, NULL);
 	}
 
 	return ret;
diff --git a/source/blender/nodes/shader/nodes/node_shader_texture.c b/source/blender/nodes/shader/nodes/node_shader_texture.c
index 6d1b3ff6dba..b77c7d07407 100644
--- a/source/blender/nodes/shader/nodes/node_shader_texture.c
+++ b/source/blender/nodes/shader/nodes/node_shader_texture.c
@@ -128,12 +128,13 @@ static int gpu_shader_texture(GPUMaterial *mat, bNode *node, GPUNodeStack *in, G
 		int ret = GPU_stack_link(mat, "texture_image", in, out, texlink);
 
 		if (ret) {
-			ImBuf *ibuf = BKE_image_get_ibuf(tex->ima, &tex->iuser);
+			ImBuf *ibuf = BKE_image_acquire_ibuf(tex->ima, &tex->iuser, NULL);
 			if (ibuf && (ibuf->colormanage_flag & IMB_COLORMANAGE_IS_DATA) ==0 &&
 			    GPU_material_do_color_management(mat))
 			{
 				GPU_link(mat, "srgb_to_linearrgb", out[1].link, &out[1].link);
 			}
+			BKE_image_release_ibuf(tex->ima, ibuf, NULL);
 		}
 
 		return ret;
diff --git a/source/blender/nodes/texture/nodes/node_texture_image.c b/source/blender/nodes/texture/nodes/node_texture_image.c
index f3fdaf0bb64..2ef1669a266 100644
--- a/source/blender/nodes/texture/nodes/node_texture_image.c
+++ b/source/blender/nodes/texture/nodes/node_texture_image.c
@@ -46,7 +46,7 @@ static void colorfn(float *out, TexParams *p, bNode *node, bNodeStack **UNUSED(i
 	ImageUser *iuser= (ImageUser *)node->storage;
 	
 	if ( ima ) {
-		ImBuf *ibuf = BKE_image_get_ibuf(ima, iuser);
+		ImBuf *ibuf = BKE_image_acquire_ibuf(ima, iuser, NULL);
 		if ( ibuf ) {
 			float xsize, ysize;
 			float xoff, yoff;
@@ -77,6 +77,8 @@ static void colorfn(float *out, TexParams *p, bNode *node, bNodeStack **UNUSED(i
 			
 			result = ibuf->rect_float + py*ibuf->x*4 + px*4;
 			copy_v4_v4(out, result);
+
+			BKE_image_release_ibuf(ima, ibuf, NULL);
 		}
 	}
 }