Task scheduler ported form CYcles to C

Replaces ThreadedWorker and is gonna to be used
for threaded object update in the future and
some more upcoming changes.

But in general, it's to be used for any task
based subsystem in Blender.

Originally written by Brecht, with some fixes
and tweaks by self.

1 files changed, 108 insertions, 0 deletions

diff --git a/source/blender/blenlib/BLI_task.h b/source/blender/blenlib/BLI_task.h
new file mode 100644
index 00000000000..f57d42858c7
--- /dev/null
+++ b/source/blender/blenlib/BLI_task.h
@@ -0,0 +1,108 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+#ifndef __BLI_TASK_H__
+#define __BLI_TASK_H__ 
+
+/** \file BLI_task.h
+ *  \ingroup bli
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "BLI_threads.h"
+#include "BLI_utildefines.h"
+
+/* Task Scheduler
+ * 
+ * Central scheduler that holds running threads ready to execute tasks. A single
+ * queue holds the task from all pools.
+ *
+ * Init/exit must be called before/after any task pools are created/freed, and
+ * must be called from the main threads. All other scheduler and pool functions
+ * are thread-safe. */
+
+typedef struct TaskScheduler TaskScheduler;
+
+enum {
+	TASK_SCHEDULER_AUTO_THREADS = 0,
+	TASK_SCHEDULER_SINGLE_THREAD = 1
+};
+
+TaskScheduler *BLI_task_scheduler_create(int num_threads);
+void BLI_task_scheduler_free(TaskScheduler *scheduler);
+
+int BLI_task_scheduler_num_threads(TaskScheduler *scheduler);
+
+/* Task Pool
+ *
+ * Pool of tasks that will be executed by the central TaskScheduler. For each
+ * pool, we can wait for all tasks to be done, or cancel them before they are
+ * done.
+ *
+ * Running tasks may spawn new tasks.
+ *
+ * Pools may be nested, i.e. a thread running a task can create another task
+ * pool with smaller tasks. When other threads are busy they will continue
+ * working on their own tasks, if not they will join in, no new threads will
+ * be launched.
+ */
+
+typedef enum TaskPriority {
+	TASK_PRIORITY_LOW,
+	TASK_PRIORITY_HIGH
+} TaskPriority;
+
+typedef struct TaskPool TaskPool;
+typedef void (*TaskRunFunction)(TaskPool *pool, void *taskdata, int threadid);
+
+TaskPool *BLI_task_pool_create(TaskScheduler *scheduler, void *userdata);
+void BLI_task_pool_free(TaskPool *pool);
+
+void BLI_task_pool_push(TaskPool *pool, TaskRunFunction run,
+	void *taskdata, bool free_taskdata, TaskPriority priority);
+
+/* work and wait until all tasks are done */
+void BLI_task_pool_work_and_wait(TaskPool *pool);
+/* cancel all tasks, keep worker threads running */
+void BLI_task_pool_cancel(TaskPool *pool);
+/* stop all worker threads */
+void BLI_task_pool_stop(TaskPool *pool);
+
+/* for worker threads, test if cancelled */
+bool BLI_task_pool_cancelled(TaskPool *pool);
+
+/* optional userdata pointer to pass along to run function */
+void *BLI_task_pool_userdata(TaskPool *pool);
+
+/* optional mutex to use from run function */
+ThreadMutex *BLI_task_pool_user_mutex(TaskPool *pool);
+
+/* number of tasks done, for stats, don't use this to make decisions */
+size_t BLI_task_pool_tasks_done(TaskPool *pool);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+