allow waiting for task completion.

src/thread.cpp

@@ -98,6 +98,12 @@ void Thread::wait_for_search_finished() {
 }
 
 
+void Thread::wait_for_task_finished() {
+
+  std::unique_lock<std::mutex> lk(mutex);
+  cv.wait(lk, [&]{ return !task; });
+}
+
 /// Thread::idle_loop() is where the thread is parked, blocked on the
 /// condition variable, when it has no work to do.
 
@@ -293,3 +299,10 @@ void ThreadPool::wait_for_search_finished() const {
         if (th != front())
             th->wait_for_search_finished();
 }
+
+
+void ThreadPool::wait_for_tasks_finished() const {
+
+    for (Thread* th : *this)
+        th->wait_for_task_finished();
+}

src/thread.h

@@ -56,6 +56,7 @@ public:
   void idle_loop();
   void start_searching();
   void wait_for_search_finished();
+  void wait_for_task_finished();
   size_t thread_idx() const { return idx; }
 
   Pawns::Table pawnsTable;
@@ -121,6 +122,7 @@ struct ThreadPool : public std::vector<Thread*> {
   Thread* get_best_thread() const;
   void start_searching();
   void wait_for_search_finished() const;
+  void wait_for_tasks_finished() const;
 
   std::atomic_bool stop, increaseDepth;