From 8148d7b1df54f103eec60fcae12fb5000e225c7b Mon Sep 17 00:00:00 2001
From: Brecht Van Lommel <brechtvanlommel@pandora.be>
Date: Thu, 10 May 2012 22:31:16 +0000
Subject: Cycles: reviewed the task scheduler code and fixed (hopefully all)
 windows threading problems.

---
 intern/cycles/util/util_task.cpp | 75 ++++++++++++++++++++++++----------------
 intern/cycles/util/util_task.h   |  9 ++---
 2 files changed, 50 insertions(+), 34 deletions(-)

(limited to 'intern')

diff --git a/intern/cycles/util/util_task.cpp b/intern/cycles/util/util_task.cpp
index fc806275ea4..023630e8fae 100644
--- a/intern/cycles/util/util_task.cpp
+++ b/intern/cycles/util/util_task.cpp
@@ -28,8 +28,6 @@ CCL_NAMESPACE_BEGIN
 TaskPool::TaskPool()
 {
 	num = 0;
-	num_done = 0;
-
 	do_cancel = false;
 }
 
@@ -55,9 +53,11 @@ void TaskPool::push(const TaskRunFunction& run, bool front)
 
 void TaskPool::wait_work()
 {
-	thread_scoped_lock done_lock(done_mutex);
+	thread_scoped_lock num_lock(num_mutex);
+
+	while(num != 0) {
+		num_lock.unlock();
 
-	while(num_done != num) {
 		thread_scoped_lock queue_lock(TaskScheduler::queue_mutex);
 
 		/* find task from this pool. if we get a task from another pool,
@@ -81,8 +81,6 @@ void TaskPool::wait_work()
 
 		/* if found task, do it, otherwise wait until other tasks are done */
 		if(found_entry) {
-			done_lock.unlock();
-
 			/* run task */
 			work_entry.task->run();
 
@@ -90,26 +88,31 @@ void TaskPool::wait_work()
 			delete work_entry.task;
 
 			/* notify pool task was done */
-			done_increase(1);
-
-			done_lock.lock();
+			num_decrease(1);
 		}
-		else
-			done_cond.wait(done_lock);
+
+		num_lock.lock();
+		if(num == 0)
+			break;
+
+		if(!found_entry)
+			num_cond.wait(num_lock);
 	}
 }
 
 void TaskPool::cancel()
 {
-	TaskScheduler::clear(this);
-
 	do_cancel = true;
+
+	TaskScheduler::clear(this);
+	
 	{
-		thread_scoped_lock lock(done_mutex);
+		thread_scoped_lock num_lock(num_mutex);
 
-		while(num_done != num)
-			done_cond.wait(lock);
+		while(num)
+			num_cond.wait(num_lock);
 	}
+
 	do_cancel = false;
 }
 
@@ -117,7 +120,7 @@ void TaskPool::stop()
 {
 	TaskScheduler::clear(this);
 
-	assert(num_done == num);
+	assert(num == 0);
 }
 
 bool TaskPool::cancelled()
@@ -125,14 +128,23 @@ bool TaskPool::cancelled()
 	return do_cancel;
 }
 
-void TaskPool::done_increase(int done)
+void TaskPool::num_decrease(int done)
 {
-	done_mutex.lock();
-	num_done += done;
-	done_mutex.unlock();
+	num_mutex.lock();
+	num -= done;
+
+	assert(num >= 0);
+	if(num == 0)
+		num_cond.notify_all();
+
+	num_mutex.unlock();
+}
 
-	assert(num_done <= num);
-	done_cond.notify_all();
+void TaskPool::num_increase()
+{
+	thread_scoped_lock num_lock(num_mutex);
+	num++;
+	num_cond.notify_all();
 }
 
 /* Task Scheduler */
@@ -196,10 +208,10 @@ void TaskScheduler::exit()
 
 bool TaskScheduler::thread_wait_pop(Entry& entry)
 {
-	thread_scoped_lock lock(queue_mutex);
+	thread_scoped_lock queue_lock(queue_mutex);
 
 	while(queue.empty() && !do_exit)
-		queue_cond.wait(lock);
+		queue_cond.wait(queue_lock);
 
 	if(queue.empty()) {
 		assert(do_exit);
@@ -227,27 +239,28 @@ void TaskScheduler::thread_run(int thread_id)
 		delete entry.task;
 
 		/* notify pool task was done */
-		entry.pool->done_increase(1);
+		entry.pool->num_decrease(1);
 	}
 }
 
 void TaskScheduler::push(Entry& entry, bool front)
 {
+	entry.pool->num_increase();
+
 	/* add entry to queue */
 	TaskScheduler::queue_mutex.lock();
 	if(front)
 		TaskScheduler::queue.push_front(entry);
 	else
 		TaskScheduler::queue.push_back(entry);
-	entry.pool->num++;
-	TaskScheduler::queue_mutex.unlock();
 
 	TaskScheduler::queue_cond.notify_one();
+	TaskScheduler::queue_mutex.unlock();
 }
 
 void TaskScheduler::clear(TaskPool *pool)
 {
-	thread_scoped_lock lock(queue_mutex);
+	thread_scoped_lock queue_lock(TaskScheduler::queue_mutex);
 
 	/* erase all tasks from this pool from the queue */
 	list<Entry>::iterator it = queue.begin();
@@ -266,8 +279,10 @@ void TaskScheduler::clear(TaskPool *pool)
 			it++;
 	}
 
+	queue_lock.unlock();
+
 	/* notify done */
-	pool->done_increase(done);
+	pool->num_decrease(done);
 }
 
 CCL_NAMESPACE_END
diff --git a/intern/cycles/util/util_task.h b/intern/cycles/util/util_task.h
index 6b7562c2267..401a503f540 100644
--- a/intern/cycles/util/util_task.h
+++ b/intern/cycles/util/util_task.h
@@ -73,12 +73,13 @@ public:
 protected:
 	friend class TaskScheduler;
 
-	void done_increase(int done);
+	void num_decrease(int done);
+	void num_increase();
 
-	thread_mutex done_mutex;
-	thread_condition_variable done_cond;
+	thread_mutex num_mutex;
+	thread_condition_variable num_cond;
 
-	volatile int num, num_done;
+	volatile int num;
 	volatile bool do_cancel;
 };
 
-- 
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