Handle task exceptions in ThreadedExecutor

Summary: Make it consistent with the other executors.

Reviewed By: yfeldblum

Differential Revision: D25926045

fbshipit-source-id: ad2f101fbba918fe2a421e394870bf67c0a044b9

folly/executors/ThreadedExecutor.cpp

@@ -76,7 +76,14 @@ void ThreadedExecutor::controlWait() {
 }
 
 void ThreadedExecutor::work(Func& func) {
+  try {
     func();
+  } catch (const std::exception& e) {
+    LOG(ERROR) << "ThreadedExecutor: func threw unhandled " << typeid(e).name()
+               << " exception: " << e.what();
+  } catch (...) {
+    LOG(ERROR) << "ThreadedExecutor: func threw unhandled non-exception object";
+  }
   auto id = std::this_thread::get_id();
   with_unique_lock(finishedm_, [&] { finished_.push_back(id); });
   notify();

folly/executors/test/ThreadedExecutorTest.cpp

@@ -16,6 +16,8 @@
 
 #include <folly/executors/ThreadedExecutor.h>
 
+#include <stdexcept>
+
 #include <folly/Conv.h>
 #include <folly/futures/Future.h>
 #include <folly/gen/Base.h>
@@ -36,6 +38,11 @@ TEST_F(ThreadedExecutorTest, example) {
   EXPECT_EQ("42", ret);
 }
 
+TEST_F(ThreadedExecutorTest, exception) {
+  folly::ThreadedExecutor x;
+  x.add([] { throw std::runtime_error("This should not crash the program"); });
+}
+
 TEST_F(ThreadedExecutorTest, dtor_waits) {
   constexpr auto kDelay = std::chrono::milliseconds(100);
   auto x = std::make_unique<folly::ThreadedExecutor>();