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/*
* Copyright 2011, Blender Foundation.
*
* 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.
*/
#include "util_debug.h"
#include "util_foreach.h"
#include "util_system.h"
#include "util_task.h"
//#define THREADING_DEBUG_ENABLED
#ifdef THREADING_DEBUG_ENABLED
#include <stdio.h>
#define THREADING_DEBUG(...) do { printf(__VA_ARGS__); fflush(stdout); } while(0)
#else
#define THREADING_DEBUG(...)
#endif
CCL_NAMESPACE_BEGIN
/* Task Pool */
TaskPool::TaskPool()
{
num = 0;
do_cancel = false;
}
TaskPool::~TaskPool()
{
stop();
}
void TaskPool::push(Task *task, bool front)
{
TaskScheduler::Entry entry;
entry.task = task;
entry.pool = this;
TaskScheduler::push(entry, front);
}
void TaskPool::push(const TaskRunFunction& run, bool front)
{
push(new Task(run), front);
}
void TaskPool::wait_work()
{
thread_scoped_lock num_lock(num_mutex);
while(num != 0) {
num_lock.unlock();
thread_scoped_lock queue_lock(TaskScheduler::queue_mutex);
/* find task from this pool. if we get a task from another pool,
* we can get into deadlock */
TaskScheduler::Entry work_entry;
bool found_entry = false;
list<TaskScheduler::Entry>::iterator it;
for(it = TaskScheduler::queue.begin(); it != TaskScheduler::queue.end(); it++) {
TaskScheduler::Entry& entry = *it;
if(entry.pool == this) {
work_entry = entry;
found_entry = true;
TaskScheduler::queue.erase(it);
break;
}
}
queue_lock.unlock();
/* if found task, do it, otherwise wait until other tasks are done */
if(found_entry) {
/* run task */
work_entry.task->run();
/* delete task */
delete work_entry.task;
/* notify pool task was done */
num_decrease(1);
}
num_lock.lock();
if(num == 0)
break;
if(!found_entry) {
THREADING_DEBUG("num==%d, Waiting for condition in TaskPool::wait_work !found_entry\n", num);
num_cond.wait(num_lock);
THREADING_DEBUG("num==%d, condition wait done in TaskPool::wait_work !found_entry\n", num);
}
}
}
void TaskPool::cancel()
{
do_cancel = true;
TaskScheduler::clear(this);
{
thread_scoped_lock num_lock(num_mutex);
while(num) {
THREADING_DEBUG("num==%d, Waiting for condition in TaskPool::cancel\n", num);
num_cond.wait(num_lock);
THREADING_DEBUG("num==%d condition wait done in TaskPool::cancel\n", num);
}
}
do_cancel = false;
}
void TaskPool::stop()
{
TaskScheduler::clear(this);
assert(num == 0);
}
bool TaskPool::cancelled()
{
return do_cancel;
}
void TaskPool::num_decrease(int done)
{
num_mutex.lock();
num -= done;
assert(num >= 0);
if(num == 0) {
THREADING_DEBUG("num==%d, notifying all in TaskPool::num_decrease\n", num);
num_cond.notify_all();
}
num_mutex.unlock();
}
void TaskPool::num_increase()
{
thread_scoped_lock num_lock(num_mutex);
num++;
THREADING_DEBUG("num==%d, notifying all in TaskPool::num_increase\n", num);
num_cond.notify_all();
}
/* Task Scheduler */
thread_mutex TaskScheduler::mutex;
int TaskScheduler::users = 0;
vector<thread*> TaskScheduler::threads;
volatile bool TaskScheduler::do_exit = false;
list<TaskScheduler::Entry> TaskScheduler::queue;
thread_mutex TaskScheduler::queue_mutex;
thread_condition_variable TaskScheduler::queue_cond;
void TaskScheduler::init(int num_threads)
{
thread_scoped_lock lock(mutex);
/* multiple cycles instances can use this task scheduler, sharing the same
* threads, so we keep track of the number of users. */
if(users == 0) {
do_exit = false;
if(num_threads == 0) {
/* automatic number of threads will be main thread + num cores */
num_threads = system_cpu_thread_count();
}
else {
/* main thread will also work, for fixed threads we count it too */
num_threads -= 1;
}
/* launch threads that will be waiting for work */
threads.resize(num_threads);
for(size_t i = 0; i < threads.size(); i++)
threads[i] = new thread(function_bind(&TaskScheduler::thread_run, i));
}
users++;
}
void TaskScheduler::exit()
{
thread_scoped_lock lock(mutex);
users--;
if(users == 0) {
/* stop all waiting threads */
do_exit = true;
TaskScheduler::queue_cond.notify_all();
/* delete threads */
foreach(thread *t, threads) {
t->join();
delete t;
}
threads.clear();
}
}
bool TaskScheduler::thread_wait_pop(Entry& entry)
{
thread_scoped_lock queue_lock(queue_mutex);
while(queue.empty() && !do_exit)
queue_cond.wait(queue_lock);
if(queue.empty()) {
assert(do_exit);
return false;
}
entry = queue.front();
queue.pop_front();
return true;
}
void TaskScheduler::thread_run(int thread_id)
{
Entry entry;
/* todo: test affinity/denormal mask */
/* keep popping off tasks */
while(thread_wait_pop(entry)) {
/* run task */
entry.task->run();
/* delete task */
delete entry.task;
/* notify pool task was done */
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);
TaskScheduler::queue_cond.notify_one();
TaskScheduler::queue_mutex.unlock();
}
void TaskScheduler::clear(TaskPool *pool)
{
thread_scoped_lock queue_lock(TaskScheduler::queue_mutex);
/* erase all tasks from this pool from the queue */
list<Entry>::iterator it = queue.begin();
int done = 0;
while(it != queue.end()) {
Entry& entry = *it;
if(entry.pool == pool) {
done++;
delete entry.task;
it = queue.erase(it);
}
else
it++;
}
queue_lock.unlock();
/* notify done */
pool->num_decrease(done);
}
CCL_NAMESPACE_END
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