OpenSubdiv: Use pool for delayed OpenGL buffers free when freeing from non-main thread

This is really similar to what GPU module was already doing. There are number of
possible improvements still:

- Re-use allocated VAOs when requesting new ones instead of going to the trouble
  of freeing VAO and then re-creating it again.

- Move VAO handling to GPU module.

Fixes T46589: OpenSubdiv crash with drivers

1 files changed, 85 insertions, 3 deletions

diff --git a/source/blender/blenkernel/intern/CCGSubSurf_opensubdiv.c b/source/blender/blenkernel/intern/CCGSubSurf_opensubdiv.c
index 9d5ef1079b8..0f61a50ed13 100644
--- a/source/blender/blenkernel/intern/CCGSubSurf_opensubdiv.c
+++ b/source/blender/blenkernel/intern/CCGSubSurf_opensubdiv.c
@@ -28,12 +28,15 @@
 #include "BLI_sys_types.h" // for intptr_t support
 
 #include "BLI_utildefines.h" /* for BLI_assert */
+#include "BLI_listbase.h"
 #include "BLI_math.h"
+#include "BLI_threads.h"
 
 #include "CCGSubSurf.h"
 #include "CCGSubSurf_intern.h"
 
 #include "BKE_DerivedMesh.h"
+#include "BKE_subsurf.h"
 
 #include "DNA_userdef_types.h"
 
@@ -236,7 +239,7 @@ bool ccgSubSurf_prepareGLMesh(CCGSubSurf *ss, bool use_osd_glsl)
 
 	if (ss->osd_mesh_invalid) {
 		if (ss->osd_mesh != NULL) {
-			openSubdiv_deleteOsdGLMesh(ss->osd_mesh);
+			ccgSubSurf__delete_osdGLMesh(ss->osd_mesh);
 			ss->osd_mesh = NULL;
 		}
 		ss->osd_mesh_invalid = false;
@@ -897,8 +900,7 @@ void ccgSubSurf__sync_opensubdiv(CCGSubSurf *ss)
 void ccgSubSurf_free_osd_mesh(CCGSubSurf *ss)
 {
 	if (ss->osd_mesh != NULL) {
-		/* TODO(sergey): Make sure free happens form the main thread! */
-		openSubdiv_deleteOsdGLMesh(ss->osd_mesh);
+		ccgSubSurf__delete_osdGLMesh(ss->osd_mesh);
 		ss->osd_mesh = NULL;
 	}
 	if (ss->osd_vao != 0) {
@@ -921,4 +923,84 @@ void ccgSubSurf_getMinMax(CCGSubSurf *ss, float r_min[3], float r_max[3])
 	}
 }
 
+/* ** Delayed delete routines ** */
+
+typedef struct OsdDeletePendingItem {
+	struct OsdDeletePendingItem *next, *prev;
+	OpenSubdiv_GLMesh *osd_mesh;
+	unsigned int vao;
+} OsdDeletePendingItem;
+
+static SpinLock delete_spin;
+static ListBase delete_pool = {NULL, NULL};
+
+static void delete_pending_push(OpenSubdiv_GLMesh *osd_mesh,
+                                unsigned int vao)
+{
+	OsdDeletePendingItem *new_entry = MEM_mallocN(sizeof(OsdDeletePendingItem),
+	                                              "opensubdiv delete entry");
+	new_entry->osd_mesh = osd_mesh;
+	new_entry->vao = vao;
+	BLI_spin_lock(&delete_spin);
+	BLI_addtail(&delete_pool, new_entry);
+	BLI_spin_unlock(&delete_spin);
+}
+
+void ccgSubSurf__delete_osdGLMesh(OpenSubdiv_GLMesh *osd_mesh)
+{
+	if (BLI_thread_is_main()) {
+		openSubdiv_deleteOsdGLMesh(osd_mesh);
+	}
+	else {
+		delete_pending_push(osd_mesh, 0);
+	}
+}
+
+void ccgSubSurf__delete_vertex_array(unsigned int vao)
+{
+	if (BLI_thread_is_main()) {
+		glDeleteVertexArrays(1, &vao);
+	}
+	else {
+		delete_pending_push(NULL, vao);
+	}
+}
+
+void ccgSubSurf__delete_pending(void)
+{
+	OsdDeletePendingItem *entry;
+	BLI_assert(BLI_thread_is_main());
+	BLI_spin_lock(&delete_spin);
+	for (entry = delete_pool.first; entry != NULL; entry = entry->next) {
+		if (entry->osd_mesh != NULL) {
+			openSubdiv_deleteOsdGLMesh(entry->osd_mesh);
+		}
+		if (entry->vao != 0) {
+			glDeleteVertexArrays(1, &entry->vao);
+		}
+	}
+	BLI_freelistN(&delete_pool);
+	BLI_spin_unlock(&delete_spin);
+}
+
+/* ** Public API ** */
+
+void BKE_subsurf_osd_init(void)
+{
+	openSubdiv_init();
+	BLI_spin_init(&delete_spin);
+}
+
+void BKE_subsurf_free_unused_buffers(void)
+{
+	ccgSubSurf__delete_pending();
+}
+
+void BKE_subsurf_osd_cleanup(void)
+{
+	openSubdiv_cleanup();
+	ccgSubSurf__delete_pending();
+	BLI_spin_end(&delete_spin);
+}
+
 #endif  /* WITH_OPENSUBDIV */