Merge pull request #550 from gaudryc/fix_webserver_graceful_stop

Fix webserver graceful stop

Author: gizmocuz

webserver/cWebem.cpp

@@ -98,14 +98,8 @@ void cWebem::Stop() {
 		_log.Log(LOG_ERROR, "[web:%s] exception thrown while stopping session cleaner", GetPort().c_str());
 	}
 	// Stop Web server
-	if ((myServer != NULL) && !myServer->stopped()) {
-		myServer->stop(); // asynchronous stop
-		while(true) {
-			if (myServer->stopped()) {
-				break;
-			}
-			sleep_milliseconds(500);
-		}
+	if (myServer != NULL) {
+		myServer->stop();
 	}
 }
 

webserver/connection.cpp

@@ -119,6 +119,9 @@ void connection::start()
 
 void connection::stop()
 {
+	// Timers should be cancelled before stopping to remove tasks from the io_service.
+	// The io_service will stop naturally when every tasks are removed.
+	// If timers are not cancelled, the exception ERROR_ABANDONED_WAIT_0 is thrown up to the io_service::run() caller.
 	cancel_abandoned_timeout();
 	cancel_read_timeout();
 
@@ -384,7 +387,7 @@ void connection::stop_gracefully() {
 			(status_ == WAITING_READ) ||
 			(status_ == WAITING_HANDSHAKE)) {
 		// avoid to wait until timeout
-		connection_manager_.stop(shared_from_this());
+		stop(); // stop with clearing, it will be done in connection_manager::stop
 	}
 }
 

webserver/server.cpp

@@ -7,6 +7,8 @@
 #include "server.hpp"
 #include <fstream>
 #include "../main/Logger.h"
+#include "../main/Helper.h"
+#include "../main/localtime_r.h"
 
 namespace http {
 namespace server {
@@ -18,7 +20,8 @@ server_base::server_base(const server_settings & settings, request_handler & use
 		settings_(settings),
 		request_handler_(user_request_handler),
 		timeout_(20), // default read timeout in seconds
-		is_running(false) {
+		is_running(false),
+		is_stop_complete(false) {
 	if (!settings.is_enabled()) {
 		throw std::invalid_argument("cannot initialize a disabled server (listening port cannot be empty or 0)");
 	}
@@ -75,13 +78,27 @@ void server_base::run() {
 
 /// Ask the server to stop using asynchronous command
 void server_base::stop() {
-	// Post a call to the stop function so that server_base::stop() is safe to call from any thread.
-	io_service_.post(boost::bind(&server_base::handle_stop, this));
-}
+	if (is_running) {
+		// Post a call to the stop function so that server_base::stop() is safe to call from any thread.
+		io_service_.post(boost::bind(&server_base::handle_stop, this));
+	} else {
+		// if io_service is not running then the post call will not be performed
+		handle_stop();
+	}
 
-/// Returns true if the server is stopped.
-bool server_base::stopped() {
-	return !is_running;
+	// Wait for acceptor and connections to stop
+	int timeout = 15; // force stop after 15 seconds
+	time_t start = mytime(NULL);
+	while(true) {
+		if (!is_running && is_stop_complete) {
+			break;
+		}
+		if ((mytime(NULL) - start) > timeout) {
+			// timeout occurred
+			break;
+		}
+		sleep_milliseconds(500);
+	}
 }
 
 void server_base::handle_stop() {
@@ -92,6 +109,7 @@ void server_base::handle_stop() {
 		_log.Log(LOG_ERROR, "[web:%s] exception occurred while closing acceptor", settings_.listening_port.c_str());
 	}
 	connection_manager_.stop_all(false);
+	is_stop_complete = true;
 }
 
 server::server(const server_settings & settings, request_handler & user_request_handler) :

webserver/server.hpp

@@ -33,9 +33,6 @@ class server_base : private boost::noncopyable {
 	/// Stop the server.
 	void stop();
 
-	/// Check if the server is running
-	bool stopped();
-
 	/// Print server settings to string (debug purpose)
 	virtual std::string to_string() const {
 		return "'server_base[" + settings_.to_string() + "]'";
@@ -65,6 +62,9 @@ class server_base : private boost::noncopyable {
 	/// indicate if the server is running
 	bool is_running;
 
+	/// indicate if the server is stopped (acceptor and connections)
+	bool is_stop_complete;
+
 private:
 	/// Handle a request to stop the server.
 	void handle_stop();