Add support for non libevent based backends in the AsyncSignalHandler

Summary: Add support for non libevent based backends in the AsyncSignalHandler

Reviewed By: kevin-vigor

Differential Revision: D20524116

fbshipit-source-id: fdd49cf75bd51599055239270dd704c496d567e3

folly/io/async/AsyncSignalHandler.cpp

@@ -32,7 +32,7 @@ AsyncSignalHandler::AsyncSignalHandler(EventBase* eventBase)
 AsyncSignalHandler::~AsyncSignalHandler() {
   // Unregister any outstanding events
   for (auto& signalEvent : signalEvents_) {
-    event_del(&signalEvent.second);
+    signalEvent.second->eb_event_del();
   }
 }
 
@@ -49,23 +49,23 @@ void AsyncSignalHandler::detachEventBase() {
 }
 
 void AsyncSignalHandler::registerSignalHandler(int signum) {
-  pair<SignalEventMap::iterator, bool> ret =
-      signalEvents_.insert(make_pair(signum, event()));
+  pair<SignalEventMap::iterator, bool> ret = signalEvents_.insert(
+      make_pair(signum, std::make_unique<EventBaseEvent>()));
   if (!ret.second) {
     // This signal has already been registered
     throw std::runtime_error(
         folly::to<string>("handler already registered for signal ", signum));
   }
 
-  struct event* ev = &(ret.first->second);
+  EventBaseEvent* ev = ret.first->second.get();
   try {
-    signal_set(ev, signum, libeventCallback, this);
-    if (event_base_set(eventBase_->getLibeventBase(), ev) != 0) {
+    ev->eb_signal_set(signum, libeventCallback, this);
+    if (ev->eb_event_base_set(eventBase_) != 0) {
       throw std::runtime_error(folly::to<string>(
           "error initializing event handler for signal ", signum));
     }
 
-    if (event_add(ev, nullptr) != 0) {
+    if (ev->eb_event_add(nullptr) != 0) {
       throw std::runtime_error(
           folly::to<string>("error adding event handler for signal ", signum));
     }
@@ -84,7 +84,7 @@ void AsyncSignalHandler::unregisterSignalHandler(int signum) {
         ": signal not registered"));
   }
 
-  event_del(&it->second);
+  it->second->eb_event_del();
   signalEvents_.erase(it);
 }
 

folly/io/async/AsyncSignalHandler.h

@@ -103,7 +103,10 @@ class AsyncSignalHandler {
   virtual void signalReceived(int signum) noexcept = 0;
 
  private:
-  typedef std::map<int, struct event> SignalEventMap;
+  // we cannot copy the EventBaseEvent instances
+  // so we need to store ptrs to them
+  // Also some backends store ptrs to the EventBaseEvent instances
+  using SignalEventMap = std::map<int, std::unique_ptr<EventBaseEvent>>;
 
   // Forbidden copy constructor and assignment operator
   AsyncSignalHandler(AsyncSignalHandler const&);