db-lab1/bserv.cpp

375 lines
12 KiB
C++

/**
* bserv - Boost-based HTTP Server
*
* reference:
* https://www.boost.org/doc/libs/1_75_0/libs/beast/example/http/server/async/http_server_async.cpp
* https://www.boost.org/doc/libs/1_75_0/libs/beast/example/advanced/server/advanced_server.cpp
*
*/
#include <boost/beast.hpp>
#include <boost/asio.hpp>
#include <boost/optional.hpp>
#include <boost/json/src.hpp>
#include <iostream>
#include <string>
#include <cstddef>
#include <cstdlib>
#include <vector>
#include <optional>
#include <memory>
#include <thread>
#include <chrono>
#include <pqxx/pqxx>
#include "config.hpp"
#include "logging.hpp"
#include "utils.hpp"
#include "routing.hpp"
#include "database.hpp"
namespace bserv {
namespace beast = boost::beast;
namespace http = beast::http;
namespace asio = boost::asio;
namespace json = boost::json;
using asio::ip::tcp;
void fail(const beast::error_code& ec, const char* what) {
lgerror << what << ": " << ec.message() << std::endl;
}
// this function produces an HTTP response for the given
// request. The type of the response object depends on the
// contents of the request, so the interface requires the
// caller to pass a generic lambda for receiving the response.
// NOTE: `send` should be called only once!
template <class Body, class Allocator, class Send>
void handle_request(
http::request<Body, http::basic_fields<Allocator>>&& req,
Send&& send) {
const auto bad_request = [&req](beast::string_view why) {
http::response<http::string_body> res{
http::status::bad_request, req.version()};
res.set(http::field::server, NAME);
res.set(http::field::content_type, "text/html");
res.keep_alive(req.keep_alive());
res.body() = std::string{why};
res.prepare_payload();
return res;
};
const auto not_found = [&req](beast::string_view target) {
http::response<http::string_body> res{
http::status::not_found, req.version()};
res.set(http::field::server, NAME);
res.set(http::field::content_type, "text/html");
res.keep_alive(req.keep_alive());
res.body() = "The requested url '"
+ std::string{target} + "' does not exist.";
res.prepare_payload();
return res;
};
const auto server_error = [&req](beast::string_view what) {
http::response<http::string_body> res{
http::status::internal_server_error, req.version()};
res.set(http::field::server, NAME);
res.set(http::field::content_type, "text/html");
res.keep_alive(req.keep_alive());
res.body() = "Internal server error: " + std::string{what};
res.prepare_payload();
return res;
};
boost::string_view target = req.target();
auto pos = target.find('?');
boost::string_view url;
if (pos == boost::string_view::npos) url = target;
else url = target.substr(0, pos);
http::response<http::string_body> res{
http::status::ok, req.version()};
res.set(http::field::server, NAME);
res.set(http::field::content_type, "application/json");
res.keep_alive(req.keep_alive());
std::optional<boost::json::value> val;
try {
val = routes(std::string{url}, req, res);
} catch (const url_not_found_exception& e) {
send(not_found(url));
return;
} catch (const bad_request_exception& e) {
send(bad_request("Request body is not a valid JSON string."));
return;
} catch (const std::exception& e) {
send(server_error(e.what()));
return;
} catch (...) {
send(server_error("Unknown exception."));
return;
}
if (val.has_value()) {
res.body() = json::serialize(val.value());
res.prepare_payload();
}
send(std::move(res));
}
// std::string get_address(const tcp::socket& socket) {
// tcp::endpoint end_point = socket.remote_endpoint();
// std::string addr = end_point.address().to_string()
// + ':' + std::to_string(end_point.port());
// return addr;
// }
// handles an HTTP server connection
class http_session
: public std::enable_shared_from_this<http_session> {
private:
// the function object is used to send an HTTP message.
class send_lambda {
private:
http_session& self_;
public:
send_lambda(http_session& self)
: self_{self} {}
template <bool isRequest, class Body, class Fields>
void operator()(
http::message<isRequest, Body, Fields>&& msg) const {
// the lifetime of the message has to extend
// for the duration of the async operation so
// we use a shared_ptr to manage it.
auto sp = std::make_shared<
http::message<isRequest, Body, Fields>>(
std::move(msg));
// stores a type-erased version of the shared
// pointer in the class to keep it alive.
self_.res_ = sp;
// writes the response
http::async_write(
self_.stream_, *sp,
beast::bind_front_handler(
&http_session::on_write,
self_.shared_from_this(),
sp->need_eof()));
}
} lambda_;
beast::tcp_stream stream_;
beast::flat_buffer buffer_;
boost::optional<
http::request_parser<http::string_body>> parser_;
std::shared_ptr<void> res_;
// const std::string address_;
void do_read() {
// constructs a new parser for each message
parser_.emplace();
// applies a reasonable limit to the allowed size
// of the body in bytes to prevent abuse.
parser_->body_limit(PAYLOAD_LIMIT);
// sets the timeout.
stream_.expires_after(std::chrono::seconds(30));
// reads a request using the parser-oriented interface
http::async_read(
stream_, buffer_, *parser_,
beast::bind_front_handler(
&http_session::on_read,
shared_from_this()));
}
void on_read(
beast::error_code ec,
std::size_t bytes_transferred) {
boost::ignore_unused(bytes_transferred);
// lgtrace << "received " << bytes_transferred << " byte(s) from: " << address_;
// this means they closed the connection
if (ec == http::error::end_of_stream) {
do_close();
return;
}
if (ec) {
fail(ec, "http_session async_read");
return;
}
// handles the request and sends the response
handle_request(parser_->release(), lambda_);
// at this point the parser can be reset
}
void on_write(
bool close, beast::error_code ec,
std::size_t bytes_transferred) {
boost::ignore_unused(bytes_transferred);
// we're done with the response so delete it
res_.reset();
if (ec) {
fail(ec, "http_session async_write");
return;
}
// lgtrace << "sent " << bytes_transferred << " byte(s) to: " << address_;
if (close) {
// this means we should close the connection, usually because
// the response indicated the "Connection: close" semantic.
do_close();
return;
}
// reads another request
do_read();
}
void do_close() {
// sends a TCP shutdown
beast::error_code ec;
stream_.socket().shutdown(tcp::socket::shutdown_send, ec);
// at this point the connection is closed gracefully
// lgtrace << "socket connection closed: " << address_;
}
public:
http_session(tcp::socket&& socket)
: lambda_{*this}, stream_{std::move(socket)} /*,
address_{get_address(stream_.socket())} */ {
// lgtrace << "http session opened: " << address_;
}
~http_session() {
// lgtrace << "http session closed: " << address_;
}
void run() {
asio::dispatch(
stream_.get_executor(),
beast::bind_front_handler(
&http_session::do_read,
shared_from_this()));
}
};
// accepts incoming connections and launches the sessions
class listener
: public std::enable_shared_from_this<listener> {
private:
asio::io_context& ioc_;
tcp::acceptor acceptor_;
void do_accept() {
acceptor_.async_accept(
asio::make_strand(ioc_),
beast::bind_front_handler(
&listener::on_accept,
shared_from_this()));
}
void on_accept(beast::error_code ec, tcp::socket socket) {
if (ec) {
fail(ec, "listener::acceptor async_accept");
} else {
// lgtrace << "listener accepts: " << get_address(socket);
std::make_shared<http_session>(
std::move(socket))->run();
}
do_accept();
}
public:
listener(
asio::io_context& ioc,
tcp::endpoint endpoint)
: ioc_{ioc},
acceptor_{asio::make_strand(ioc)} {
beast::error_code ec;
acceptor_.open(endpoint.protocol(), ec);
if (ec) {
fail(ec, "listener::acceptor open");
return;
}
acceptor_.set_option(
asio::socket_base::reuse_address(true), ec);
if (ec) {
fail(ec, "listener::acceptor set_option");
return;
}
acceptor_.bind(endpoint, ec);
if (ec) {
fail(ec, "listener::acceptor bind");
return;
}
acceptor_.listen(
asio::socket_base::max_listen_connections, ec);
if (ec) {
fail(ec, "listener::acceptor listen");
return;
}
}
void run() {
asio::dispatch(
acceptor_.get_executor(),
beast::bind_front_handler(
&listener::do_accept,
shared_from_this()));
}
};
void show_config() {
lginfo << NAME << " config:"
<< "\nport: " << PORT
<< "\nthreads: " << NUM_THREADS
<< "\ndb-conn: " << NUM_DB_CONN
<< "\npayload: " << PAYLOAD_LIMIT / 1024 / 1024
<< "\nrotation: " << LOG_ROTATION_SIZE / 1024 / 1024
<< "\nlog path: " << LOG_PATH
<< "\nconn-str: " << DB_CONN_STR << std::endl;
}
} // bserv
int main(int argc, char* argv[]) {
using namespace bserv;
if (parse_arguments(argc, argv))
return EXIT_FAILURE;
init_logging();
show_config();
// some initializations must be done after parsing the arguments
// e.g. database connection
try {
db_conn_mgr = std::make_shared<
db_connection_manager>(DB_CONN_STR, NUM_DB_CONN);
} catch (const std::exception& e) {
lgfatal << "db connection initialization failed: " << e.what() << std::endl;
return EXIT_FAILURE;
}
session_mgr = std::make_shared<memory_session>();
// io_context for all I/O
asio::io_context ioc{NUM_THREADS};
// creates and launches a listening port
std::make_shared<listener>(
ioc, tcp::endpoint{tcp::v4(), PORT})->run();
// captures SIGINT and SIGTERM to perform a clean shutdown
asio::signal_set signals{ioc, SIGINT, SIGTERM};
signals.async_wait(
[&](const boost::system::error_code&, int) {
// stops the `io_context`. This will cause `run()`
// to return immediately, eventually destroying the
// `io_context` and all of the sockets in it.
ioc.stop();
});
lginfo << NAME << " started";
// runs the I/O service on the requested number of threads
std::vector<std::thread> v;
v.reserve(NUM_THREADS - 1);
for (int i = 1; i < NUM_THREADS; ++i)
v.emplace_back([&]{ ioc.run(); });
ioc.run();
// if we get here, it means we got a SIGINT or SIGTERM
lginfo << "exiting " << NAME;
// blocks until all the threads exit
for (auto & t : v) t.join();
return EXIT_SUCCESS;
}