Files
scylladb/generic_server.hh
Avi Kivity fcb8d040e8 treewide: use Software Package Data Exchange (SPDX) license identifiers
Instead of lengthy blurbs, switch to single-line, machine-readable
standardized (https://spdx.dev) license identifiers. The Linux kernel
switched long ago, so there is strong precedent.

Three cases are handled: AGPL-only, Apache-only, and dual licensed.
For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0),
reasoning that our changes are extensive enough to apply our license.

The changes we applied mechanically with a script, except to
licenses/README.md.

Closes #9937
2022-01-18 12:15:18 +01:00

108 lines
3.0 KiB
C++

/*
* Copyright (C) 2021-present ScyllaDB
*/
/*
* SPDX-License-Identifier: AGPL-3.0-or-later
*/
#pragma once
#include "log.hh"
#include "seastarx.hh"
#include <seastar/core/future.hh>
#include <seastar/core/gate.hh>
#include <seastar/net/api.hh>
#include <seastar/net/tls.hh>
#include <boost/intrusive/list.hpp>
namespace generic_server {
class server;
// A generic TCP connection.
//
// This class is used in tandem with the `server`class to implement a protocol
// specific TCP connection.
//
// Protocol specific classes are expected to override the `process_request`
// member function to perform request processing. This base class provides a
// `_read_buf` and a `_write_buf` for reading requests and writing responses.
class connection : public boost::intrusive::list_base_hook<> {
protected:
server& _server;
connected_socket _fd;
input_stream<char> _read_buf;
output_stream<char> _write_buf;
future<> _ready_to_respond = make_ready_future<>();
seastar::gate _pending_requests_gate;
public:
connection(server& server, connected_socket&& fd);
virtual ~connection();
virtual future<> process();
virtual void handle_error(future<>&& f) = 0;
virtual future<> process_request() = 0;
virtual void on_connection_close();
virtual future<> shutdown();
};
// A generic TCP socket server.
//
// This class can be used as a base for a protocol specific TCP socket server
// that listens to incoming connections and processes requests coming over the
// connection.
//
// The provides a `listen` member function that creates a TCP server socket and
// registers it to the Seastar reactor. The class also provides a `stop` member
// function that can be used to safely stop the server.
//
// Protocol specific classes that inherit `server` are expected to also inherit
// a connection class from `connection` and override the `make_connection` member
// function to create a protocol specific connection upon `accept`.
class server {
friend class connection;
protected:
sstring _server_name;
logging::logger& _logger;
bool _stopping = false;
promise<> _all_connections_stopped;
uint64_t _current_connections = 0;
uint64_t _connections_being_accepted = 0;
uint64_t _total_connections = 0;
future<> _stopped = _all_connections_stopped.get_future();
boost::intrusive::list<connection> _connections_list;
std::vector<server_socket> _listeners;
public:
server(const sstring& server_name, logging::logger& logger);
virtual ~server();
future<> stop();
future<> listen(socket_address addr, std::shared_ptr<seastar::tls::credentials_builder> creds, bool is_shard_aware, bool keepalive);
future<> do_accepts(int which, bool keepalive, socket_address server_addr);
protected:
virtual seastar::shared_ptr<connection> make_connection(socket_address server_addr, connected_socket&& fd, socket_address addr) = 0;
virtual future<> advertise_new_connection(shared_ptr<connection> conn);
virtual future<> unadvertise_connection(shared_ptr<connection> conn);
void maybe_stop();
};
}