Revert "Implement parallel foreach() for easier multithreading"

This reverts commit e28868e30cd478e878d0a8331e17e2cf90039558.

core/object/worker_thread_pool.h

@@ -202,25 +202,4 @@ public:
 	~WorkerThreadPool();
 };
 
-template <typename F>
-static _FORCE_INLINE_ void for_range(int i_begin, int i_end, bool parallel, String name, F f) {
-	if (!parallel) {
-		for (int i = i_begin; i < i_end; i++) {
-			f(i);
-		}
-		return;
-	}
-
-	auto wrapper = [&](int i, void *unused) {
-		f(i + i_begin);
-	};
-
-	WorkerThreadPool *wtp = WorkerThreadPool::get_singleton();
-	WorkerThreadPool::GroupID gid = wtp->add_template_group_task(
-			&wrapper, &decltype(wrapper)::operator(), nullptr,
-			i_end - i_begin, -1,
-			true, name);
-	wtp->wait_for_group_task_completion(gid);
-}
-
 #endif // WORKER_THREAD_POOL_H

modules/raycast/raycast_occlusion_cull.cpp

@@ -355,14 +355,41 @@ void RaycastOcclusionCull::Scenario::_update_dirty_instance(int p_idx, RID *p_in
 	// Embree requires the last element to be readable by a 16-byte SSE load instruction, so we add padding to be safe.
 	occ_inst->xformed_vertices.resize(vertices_size + 1);
 
-	for_range(0, vertices_size, vertices_size > 1024, SNAME("RaycastOcclusionCull"), [&](const int i) {
-		occ_inst->xformed_vertices[i] = occ_inst->xform.xform(occ->vertices[i]);
-	});
+	const Vector3 *read_ptr = occ->vertices.ptr();
+	Vector3 *write_ptr = occ_inst->xformed_vertices.ptr();
+
+	if (vertices_size > 1024) {
+		TransformThreadData td;
+		td.xform = occ_inst->xform;
+		td.read = read_ptr;
+		td.write = write_ptr;
+		td.vertex_count = vertices_size;
+		td.thread_count = WorkerThreadPool::get_singleton()->get_thread_count();
+		WorkerThreadPool::GroupID group_task = WorkerThreadPool::get_singleton()->add_template_group_task(this, &Scenario::_transform_vertices_thread, &td, td.thread_count, -1, true, SNAME("RaycastOcclusionCull"));
+		WorkerThreadPool::get_singleton()->wait_for_group_task_completion(group_task);
+
+	} else {
+		_transform_vertices_range(read_ptr, write_ptr, occ_inst->xform, 0, vertices_size);
+	}
 
 	occ_inst->indices.resize(occ->indices.size());
 	memcpy(occ_inst->indices.ptr(), occ->indices.ptr(), occ->indices.size() * sizeof(int32_t));
 }
 
+void RaycastOcclusionCull::Scenario::_transform_vertices_thread(uint32_t p_thread, TransformThreadData *p_data) {
+	uint32_t vertex_total = p_data->vertex_count;
+	uint32_t total_threads = p_data->thread_count;
+	uint32_t from = p_thread * vertex_total / total_threads;
+	uint32_t to = (p_thread + 1 == total_threads) ? vertex_total : ((p_thread + 1) * vertex_total / total_threads);
+	_transform_vertices_range(p_data->read, p_data->write, p_data->xform, from, to);
+}
+
+void RaycastOcclusionCull::Scenario::_transform_vertices_range(const Vector3 *p_read, Vector3 *p_write, const Transform3D &p_xform, int p_from, int p_to) {
+	for (int i = p_from; i < p_to; i++) {
+		p_write[i] = p_xform.xform(p_read[i]);
+	}
+}
+
 void RaycastOcclusionCull::Scenario::_commit_scene(void *p_ud) {
 	Scenario *scenario = (Scenario *)p_ud;
 	int commit_idx = 1 - (scenario->current_scene_idx);

modules/raycast/raycast_occlusion_cull.h

@@ -121,6 +121,14 @@ private:
 			const uint32_t *masks;
 		};
 
+		struct TransformThreadData {
+			uint32_t thread_count;
+			uint32_t vertex_count;
+			Transform3D xform;
+			const Vector3 *read;
+			Vector3 *write = nullptr;
+		};
+
 		Thread *commit_thread = nullptr;
 		bool commit_done = true;
 		bool dirty = false;
@@ -136,6 +144,8 @@ private:
 
 		void _update_dirty_instance_thread(int p_idx, RID *p_instances);
 		void _update_dirty_instance(int p_idx, RID *p_instances);
+		void _transform_vertices_thread(uint32_t p_thread, TransformThreadData *p_data);
+		void _transform_vertices_range(const Vector3 *p_read, Vector3 *p_write, const Transform3D &p_xform, int p_from, int p_to);
 		static void _commit_scene(void *p_ud);
 		bool update();
 

tests/core/threads/test_worker_thread_pool.h

@@ -106,32 +106,6 @@ TEST_CASE("[WorkerThreadPool] Process elements using group tasks") {
 	}
 }
 
-TEST_CASE("[WorkerThreadPool] Parallel foreach") {
-	const int count_max = 256;
-
-	for (int midpoint = 0; midpoint < count_max; midpoint++) {
-		LocalVector<int> c;
-		c.resize(count_max);
-
-		for_range(0, count_max, true, String(), [&](int i) {
-			c[i] = 1;
-		});
-		c.sort();
-		CHECK(c[0] == 1);
-		CHECK(c[0] == c[count_max - 1]);
-
-		for_range(0, midpoint, false, String(), [&](int i) {
-			c[i]++;
-		});
-		for_range(midpoint, count_max, true, String(), [&](int i) {
-			c[i]++;
-		});
-		c.sort();
-		CHECK(c[0] == 2);
-		CHECK(c[0] == c[count_max - 1]);
-	}
-}
-
 } // namespace TestWorkerThreadPool
 
 #endif // TEST_WORKER_THREAD_POOL_H