weejobs.h - replace list::size with a safer/faster version to prevent…

… a crash on older compilers
gwaldron · Mar 8, 2024 · 5702f02 · 5702f02
1 parent 194cfb9
commit 5702f02
Showing 1 changed file with 12 additions and 7 deletions.
diff --git a/src/osgEarth/weejobs.h b/src/osgEarth/weejobs.h
@@ -536,6 +536,7 @@ namespace WEEJOBS_NAMESPACE
         {
             std::lock_guard<std::mutex> lock(_queue_mutex);
             _queue.clear();
+            _queue_size = 0;
             _metrics.canceled += _metrics.pending;
             _metrics.pending = 0;
         }
@@ -559,6 +560,8 @@ namespace WEEJOBS_NAMESPACE
                     std::lock_guard<std::mutex> lock(_queue_mutex);
 
                     _queue.emplace_back(detail::job{ context, delegate });
+                    _queue_size++;
+
                     _metrics.pending++;
                     _metrics.total++;
                     _block.notify_one();
@@ -586,7 +589,7 @@ namespace WEEJOBS_NAMESPACE
                 std::lock_guard<std::mutex> lock(_queue_mutex);
                 return _take_job(output, false);
             }
-            else if (!_done && !_queue.empty())
+            else if (!_done && _queue_size > 0)
             {
                 auto ptr = _queue.end();
                 float highest_priority = -FLT_MAX;
@@ -608,6 +611,7 @@ namespace WEEJOBS_NAMESPACE
 
                 output = std::move(*ptr);
                 _queue.erase(ptr);
+                _queue_size--;
                 _metrics.pending--;
                 return true;
             }
@@ -638,6 +642,7 @@ namespace WEEJOBS_NAMESPACE
 
         bool _can_steal_work = true;
         std::list<detail::job> _queue;
+        std::atomic_int _queue_size = { 0 }; // don't use list::size(), it's slow and not atomic
         mutable std::mutex _queue_mutex; // protect access to the queue
         mutable std::mutex _quit_mutex; // protects access to _done
         std::atomic<unsigned> _target_concurrency; // target number of concurrent threads in the pool
@@ -877,7 +882,7 @@ namespace WEEJOBS_NAMESPACE
                         // work-stealing enabled: wait until any queue is non-empty
                         _block.wait(lock, [this]() { return get_metrics()->total_pending() > 0 || _done; });
 
-                        if (!_done && !_queue.empty())
+                        if (!_done && _queue_size > 0)
                         {
                             have_next = _take_job(next, false);
                         }
@@ -893,9 +898,9 @@ namespace WEEJOBS_NAMESPACE
                     std::unique_lock<std::mutex> lock(_queue_mutex);
 
                     // wait until just our local queue is non-empty
-                    _block.wait(lock, [this] { return !_queue.empty() || _done; });
+                    _block.wait(lock, [this] { return (_queue_size > 0) || _done; });
 
-                    if (!_done && !_queue.empty())
+                    if (!_done && _queue_size > 0)
                     {
                         have_next = _take_job(next, false);
                     }
@@ -976,6 +981,7 @@ namespace WEEJOBS_NAMESPACE
             }
         }
         _queue.clear();
+        _queue_size = 0;
 
         // wake up all threads so they can exit
         _block.notify_all();
@@ -1008,10 +1014,9 @@ namespace WEEJOBS_NAMESPACE
             {
                 if (pool != thief)
                 {
-                    auto num_jobs = pool->_queue.size();
-                    if (num_jobs > max_num_jobs)
+                    if (pool->_queue_size > max_num_jobs)
                     {
-                        max_num_jobs = num_jobs;
+                        max_num_jobs = pool->_queue_size;
                         pool_with_most_jobs = pool;
                     }
                 }