Fixing thread pool shutdown so the kill flag is set inside the mutex, preventing a race. This could cause very rare lockups on the previous code.

Also for more safety to prevent lockups on buggy C run-times, adding a 1s timeout in the thread pool condition variable wait.

encoder/basisu_enc.cpp

@@ -2248,7 +2248,10 @@ namespace basisu
 		debug_printf("job_pool::~job_pool\n");
 		
 		// Notify all workers that they need to die right now.
-		m_kill_flag.store(true);
+		{
+			std::lock_guard<std::mutex> lk(m_mutex);
+			m_kill_flag.store(true);
+		}
 		
 		m_has_work.notify_all();
 
@@ -2338,17 +2341,27 @@ namespace basisu
 
 		m_num_active_workers.fetch_add(1);
 		
-		while (true)
+		while (!m_kill_flag)
 		{
 			std::unique_lock<std::mutex> lock(m_mutex);
 
 			// Wait for any jobs to be issued.
+#if 0
 			m_has_work.wait(lock, [this] { return m_kill_flag || m_queue.size(); } );
+#else
+			// For more safety vs. buggy RTL's. Worse case we stall for a second vs. locking up forever if something goes wrong.
+			m_has_work.wait_for(lock, std::chrono::milliseconds(1000), [this] {
+				return m_kill_flag || !m_queue.empty();
+				});
+#endif
 
 			// Check to see if we're supposed to exit.
 			if (m_kill_flag)
 				break;
 
+			if (m_queue.empty())
+				continue;
+
 			// Get the job and execute it.
 			std::function<void()> job(m_queue.back());
 			m_queue.pop_back();