Refactor http server module for consideration of a potential core dump

Author: chenneal

sentinel-core/transport/command/http_server.cc

@@ -11,12 +11,7 @@ namespace Transport {
 HttpServer::HttpServer(http_request_callback_t callback)
     : request_callback_(callback) {}
 
-HttpServer::~HttpServer() {
-  if (http_) {
-    evhttp_free(http_);
-    http_ = nullptr;
-  }
-}
+HttpServer::~HttpServer() { Stop(); }
 
 bool HttpServer::Start(int port) {
   auto ret = event_loop_thread_.Start();
@@ -26,11 +21,9 @@ bool HttpServer::Start(int port) {
 
   port_ = port;
 
-  std::promise<bool> start_promise;
-  auto start_future = start_promise.get_future();
-  auto task = [&start_promise, this]() { InternalStart(start_promise); };
-
-  event_loop_thread_.RunTask(task);
+  auto start_future = start_promise_.get_future();
+  event_loop_thread_.RunTask(
+      [this](void) mutable { InternalStart(start_promise_); });
 
   return start_future.get();
 }

sentinel-core/transport/command/http_server.h

@@ -33,6 +33,7 @@ class HttpServer {
 
   struct evhttp *http_ = nullptr;
   http_request_callback_t request_callback_;
+  std::promise<bool> start_promise_;
 
   static void HttpGenCallback(struct evhttp_request *req, void *arg);
 

sentinel-core/transport/common/event_loop_thread.cc

@@ -20,12 +20,11 @@ bool EventLoopThread::Start() {
 }
 
 void EventLoopThread::Stop() {
-  if (stoped_.load()) {
+  bool expected = false;
+  if (!stoped_.compare_exchange_strong(expected, true)) {
     return;
   }
 
-  stoped_ = true;
-
   Wakeup();
 
   thd_->join();