128 lines
4.0 KiB
C++
128 lines
4.0 KiB
C++
/*
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* Copyright (C) 2021-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: AGPL-3.0-or-later
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*/
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#pragma once
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#include "log.hh"
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#include "seastarx.hh"
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#include <list>
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#include <seastar/core/file-types.hh>
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#include <seastar/core/future.hh>
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#include <seastar/core/gate.hh>
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#include <seastar/net/api.hh>
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#include <seastar/net/tls.hh>
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#include <boost/intrusive/list.hpp>
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namespace generic_server {
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class server;
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// A generic TCP connection.
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//
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// This class is used in tandem with the `server`class to implement a protocol
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// specific TCP connection.
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//
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// Protocol specific classes are expected to override the `process_request`
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// member function to perform request processing. This base class provides a
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// `_read_buf` and a `_write_buf` for reading requests and writing responses.
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class connection : public boost::intrusive::list_base_hook<> {
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protected:
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server& _server;
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connected_socket _fd;
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input_stream<char> _read_buf;
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output_stream<char> _write_buf;
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future<> _ready_to_respond = make_ready_future<>();
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seastar::gate _pending_requests_gate;
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public:
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connection(server& server, connected_socket&& fd);
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virtual ~connection();
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virtual future<> process();
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virtual void handle_error(future<>&& f) = 0;
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virtual future<> process_request() = 0;
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virtual void on_connection_close();
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virtual future<> shutdown();
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};
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// A generic TCP socket server.
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//
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// This class can be used as a base for a protocol specific TCP socket server
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// that listens to incoming connections and processes requests coming over the
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// connection.
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//
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// The provides a `listen` member function that creates a TCP server socket and
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// registers it to the Seastar reactor. The class also provides a `stop` member
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// function that can be used to safely stop the server.
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//
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// Protocol specific classes that inherit `server` are expected to also inherit
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// a connection class from `connection` and override the `make_connection` member
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// function to create a protocol specific connection upon `accept`.
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class server {
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friend class connection;
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protected:
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sstring _server_name;
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logging::logger& _logger;
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bool _stopping = false;
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promise<> _all_connections_stopped;
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uint64_t _current_connections = 0;
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uint64_t _connections_being_accepted = 0;
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uint64_t _total_connections = 0;
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future<> _listeners_stopped = make_ready_future<>();
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using connections_list_t = boost::intrusive::list<connection>;
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connections_list_t _connections_list;
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struct gentle_iterator {
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connections_list_t::iterator iter, end;
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gentle_iterator(server& s) : iter(s._connections_list.begin()), end(s._connections_list.end()) {}
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gentle_iterator(const gentle_iterator&) = delete;
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gentle_iterator(gentle_iterator&&) = delete;
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};
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std::list<gentle_iterator> _gentle_iterators;
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std::vector<server_socket> _listeners;
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public:
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server(const sstring& server_name, logging::logger& logger);
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virtual ~server();
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// Makes sure listening sockets no longer generate new connections and aborts the
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// connected sockets, so that new requests are not served and existing requests don't
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// send responses back.
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//
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// It does _not_ wait for any internal activity started by the established connections
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// to finish. It's the .stop() method that does it
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future<> shutdown();
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future<> stop();
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future<> listen(socket_address addr, std::shared_ptr<seastar::tls::credentials_builder> creds, bool is_shard_aware, bool keepalive, std::optional<file_permissions> unix_domain_socket_permissions);
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future<> do_accepts(int which, bool keepalive, socket_address server_addr);
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protected:
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virtual seastar::shared_ptr<connection> make_connection(socket_address server_addr, connected_socket&& fd, socket_address addr) = 0;
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virtual future<> advertise_new_connection(shared_ptr<connection> conn);
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virtual future<> unadvertise_connection(shared_ptr<connection> conn);
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future<> for_each_gently(noncopyable_function<void(connection&)>);
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void maybe_stop();
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};
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}
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