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Add promise to wait for closure of server socket

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This may fix the issues that a websocket server may crash or hang when quitting
This commit is contained in:
abitmore 2020-06-20 11:36:21 -04:00
parent 9ae294293f
commit aa671d61b5
1 changed files with 48 additions and 31 deletions
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79
src/network/http/websocket.cpp
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@ -322,66 +322,82 @@ namespace fc { namespace http {
{
_connections[hdl]->closed();
_connections.erase( hdl );
if( _connections.empty() && _all_connections_closed )
_all_connections_closed->set_value();
}
else
{
wlog( "unknown connection closed" );
}
if( _connections.empty() && _closed )
_closed->set_value();
}).wait();
});
_server.set_fail_handler( [this]( connection_hdl hdl ){
if( _server.is_listening() )
{
_server_thread.async( [this,hdl](){
if( _connections.find(hdl) != _connections.end() )
{
_connections[hdl]->closed();
_connections.erase( hdl );
}
_server_thread.async( [this,hdl](){
if( _connections.find(hdl) != _connections.end() )
{
_connections[hdl]->closed();
_connections.erase( hdl );
if( _connections.empty() && _all_connections_closed )
_all_connections_closed->set_value();
}
else
{
// if the server is shutting down, assume this hdl is the server socket
if( _server_socket_closed )
_server_socket_closed->set_value();
else
{
wlog( "unknown connection failed" );
}
if( _connections.empty() && _closed )
_closed->set_value();
}).wait();
}
}
}).wait();
});
}
virtual ~generic_websocket_server_impl()
{
if( _server.is_listening() )
{
// _server.stop_listening() may trigger the on_fail callback function (the lambda function set by
// _server.set_fail_handler(...) ) for the listening server socket (note: the connection handle
// associated with the server socket is not in our connection map),
// the on_fail callback function may fire (async) a new task which may run really late
// and it will try to access the member variables of this server object,
// so we need to wait for it before destructing this object.
_server_socket_closed = promise<void>::create();
_server.stop_listening();
}
// Note: since _connections can be modified by lambda functions in set_*_handler, which are running
// in another thread, perhaps we need to wait for them (especially the one in set_open_handler)
// being processed. Otherwise `_closed.wait()` may hang.
if( _connections.size() )
// in other tasks, perhaps we need to wait for them (especially the one in set_open_handler)
// being processed. Otherwise `_all_connections_closed.wait()` may hang.
if( !_connections.empty() )
{
_closed = promise<void>::create();
_all_connections_closed = promise<void>::create();
auto cpy_con = _connections;
websocketpp::lib::error_code ec;
for( auto& item : cpy_con )
_server.close( item.first, 0, "server exit" );
_server.close( item.first, 0, "server exit", ec );
_closed->wait();
_all_connections_closed->wait();
}
if( _server_socket_closed )
_server_socket_closed->wait();
}
typedef std::map<connection_hdl, websocket_connection_ptr, std::owner_less<connection_hdl> > con_map;
con_map _connections; // Note: std::map is not thread-safe nor task-safe, we may need
// to use a mutex or similar to avoid concurrent access.
fc::thread& _server_thread;
websocketpp::server<T> _server;
on_connection_handler _on_connection;
fc::promise<void>::ptr _closed;
uint32_t _pending_messages = 0;
std::string _forward_header_key; // A header like "X-Forwarded-For" (XFF), with data IP:port
// Note: std::map is not thread-safe nor task-safe, we may need
// to use a mutex or similar to avoid concurrent access.
con_map _connections; ///< Holds accepted connections
fc::thread& _server_thread; ///< The thread that runs the server
websocketpp::server<T> _server; ///< The server
on_connection_handler _on_connection; ///< A handler to be called when a new connection is accepted
fc::promise<void>::ptr _all_connections_closed; ///< Promise to wait for all connections to be closed
fc::promise<void>::ptr _server_socket_closed; ///< Promise to wait for the server socket to be closed
uint32_t _pending_messages = 0; ///< Number of messages not processed, for rate limiting
std::string _forward_header_key; ///< A header like "X-Forwarded-For" (XFF) with data IP:port
};
class websocket_server_impl : public generic_websocket_server_impl<asio_with_stub_log>
@ -649,8 +665,9 @@ namespace fc { namespace http {
void websocket_server::close()
{
websocketpp::lib::error_code ec;
for( auto& connection : my->_connections )
my->_server.close( connection.first, websocketpp::close::status::normal, "Goodbye" );
my->_server.close( connection.first, websocketpp::close::status::normal, "Goodbye", ec );
}
websocket_tls_server::websocket_tls_server( const string& server_pem, const string& ssl_password,