added exception guard on wait_for_all

tsung-wei-huang · tsung-wei-huang · commit 8f6bfe676947 · 2018-09-03T10:04:42.000-05:00
diff --git a/taskflow/threadpool/threadpool.hpp b/taskflow/threadpool/threadpool.hpp
@@ -250,26 +250,28 @@ auto Threadpool::async(C&& c, Signal sig) {
 // After this method returns, all previously-scheduled tasks in the pool
 // will have been executed.
 inline void Threadpool::wait_for_all() {
+  
+  if(is_worker()) {
+    throw std::runtime_error("Worker thread cannot wait for all");
+  }
 
   std::mutex barrier_mutex;
   std::condition_variable barrier_cv;
   auto threads_to_sync{_threads.size()};
   std::vector<std::future<void>> futures;
 
-  auto barrier_task = [&] {
-    std::unique_lock<std::mutex> lock(barrier_mutex);
-    if (--threads_to_sync == 0) {
-      barrier_cv.notify_all();
-    }
-    else {
-      barrier_cv.wait(lock, [&threads_to_sync] {
-        return threads_to_sync == 0;
-      });
-    }
-  };
-
   for(size_t i=0; i<_threads.size(); ++i) {
-    futures.emplace_back(async(barrier_task));
+    futures.emplace_back(async([&] () {
+      std::unique_lock<std::mutex> lock(barrier_mutex);
+      if (--threads_to_sync; threads_to_sync == 0) {
+        barrier_cv.notify_all();
+      }
+      else {
+        barrier_cv.wait(lock, [&threads_to_sync] {
+          return threads_to_sync == 0;
+        });
+      }
+    }));
   }
 
   // Wait for all threads to have finished synchronization
diff --git a/taskflow/threadpool/threadpool_cxx14.hpp b/taskflow/threadpool/threadpool_cxx14.hpp
@@ -1,7 +1,9 @@
 // A C++-14 based threadpool implementation inspired by Taskflow Threadpool.
-
-// 2018/08/27 - contributed by Glen Fraser
+// 
+// 2018/09/02 - contributed by Glen Fraser
+//   - added wait_for_all method
 //
+// 2018/08/27 - contributed by Glen Fraser
 // taskflow.hpp was modified by Glen Fraser to produce this file
 // (threadpool_cxx14.hpp), which is a "light" version of the library with
 // restricted functionality -- it only exposes the tf::Threadpool class.
@@ -347,6 +349,10 @@ std::enable_if_t<
 // will have been executed.
 inline void Threadpool::wait_for_all() {
 
+  if(is_worker()) {
+    throw std::runtime_error("Worker thread cannot wait for all");
+  }
+
   std::mutex barrier_mutex;
   std::condition_variable barrier_cv;
   auto threads_to_sync{_threads.size()};
diff --git a/unittest/threadpool_cxx14.cpp b/unittest/threadpool_cxx14.cpp
@@ -1,4 +1,8 @@
+// 2018/09/02 - contributed by Glen Fraser
+//   - added wait_for_all test
+//
 // 2018/08/28 - contributed by Glen Fraser
+//   - added basic test
 
 #define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
 
