最終回は、予定を変えてReactorフレームワークを詳解します。
TCPServerはスレッドプールによるマルチスレッドのソケット通信ですが、クライアントの数が巨大なシステムではC10K問題を起こしてしまいます。それを解決するノンブロッキングI/Oを実現するのにPocoではReactorフレームワークを提供しています。
Reactorフレームワークを使うNetライブラリのサンプルとして、EchoServerプロジェクトがPOCOに付属しています。EchoServerプロジェクトを、Reactorフレームワークが提供するすべてのイベントハンドラをサポートするように改造してみます。
まずは、サンプルをそのままコンパイルして実行してみましょう。
$ EchoServer
これで、サーバが起動されたので、telnetでサーバと通信してみます。
$ telnet 127.0.0.1 9977
以下のように、接続したあと入力した文字をエコーすると思います。
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$ telnet localhost 9977
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
hello
hello |
それでは、何も入力しないで30秒経つとタイムアウトして接続を切断するように変更します。
変更したソースを以下に記載します。
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#include "Poco/Net/SocketReactor.h"
#include "Poco/Net/SocketAcceptor.h"
#include "Poco/Net/SocketNotification.h"
#include "Poco/Net/StreamSocket.h"
#include "Poco/Net/ServerSocket.h"
#include "Poco/NObserver.h"
#include "Poco/Exception.h"
#include "Poco/Thread.h"
#include "Poco/Timespan.h"
#include "Poco/Util/ServerApplication.h"
#include "Poco/Util/Option.h"
#include "Poco/Util/OptionSet.h"
#include "Poco/Util/HelpFormatter.h"
#include <iostream>
#include <sstream>
using Poco::Net::SocketReactor;
using Poco::Net::SocketAcceptor;
using Poco::Net::ReadableNotification;
using Poco::Net::ShutdownNotification;
using Poco::Net::WritableNotification;
using Poco::Net::ErrorNotification;
using Poco::Net::TimeoutNotification;
using Poco::Net::IdleNotification;
using Poco::Net::ServerSocket;
using Poco::Net::StreamSocket;
using Poco::NObserver;
using Poco::AutoPtr;
using Poco::Thread;
using Poco::Timespan;
using Poco::Util::ServerApplication;
using Poco::Util::Application;
using Poco::Util::Option;
using Poco::Util::OptionSet;
using Poco::Util::HelpFormatter;
class EchoServiceHandler
{
public:
EchoServiceHandler(StreamSocket& socket, SocketReactor& reactor)
:_socket(socket)
,_reactor(reactor)
,_pBuffer(new char[BUFFER_SIZE])
,_onWritableAdded(false)
,_onTimeoutAdded(false)
{
Application& app = Application::instance();
app.logger().information("Connection from " + socket.peerAddress().toString());
_reactor.addEventHandler(_socket, NObserver<EchoServiceHandler, ReadableNotification>(*this, &EchoServiceHandler::onReadable));
_reactor.addEventHandler(_socket, NObserver<EchoServiceHandler, ShutdownNotification>(*this, &EchoServiceHandler::onShutdown));
_reactor.addEventHandler(_socket, NObserver<EchoServiceHandler, ErrorNotification>(*this, &EchoServiceHandler::onError));
_reactor.addEventHandler(_socket, NObserver<EchoServiceHandler, IdleNotification>(*this, &EchoServiceHandler::onIdle));
}
~EchoServiceHandler()
{
Application& app = Application::instance();
try
{
app.logger().information("Disconnecting " + _socket.peerAddress().toString());
}
catch (...)
{
}
_reactor.removeEventHandler(_socket, NObserver<EchoServiceHandler, ReadableNotification>(*this, &EchoServiceHandler::onReadable));
_reactor.removeEventHandler(_socket, NObserver<EchoServiceHandler, ShutdownNotification>(*this, &EchoServiceHandler::onShutdown));
_reactor.removeEventHandler(_socket, NObserver<EchoServiceHandler, ErrorNotification>(*this, &EchoServiceHandler::onError));
_reactor.removeEventHandler(_socket, NObserver<EchoServiceHandler, IdleNotification>(*this, &EchoServiceHandler::onIdle));
if (_onWritableAdded)
_reactor.removeEventHandler(_socket, NObserver<EchoServiceHandler, WritableNotification>(*this, &EchoServiceHandler::onWritable));
if (_onTimeoutAdded)
_reactor.removeEventHandler(_socket, NObserver<EchoServiceHandler, TimeoutNotification>(*this, &EchoServiceHandler::onTimeout));
delete [] _pBuffer;
}
void onReadable(const AutoPtr<ReadableNotification>& pNf)
{
int n = _socket.receiveBytes(_pBuffer, BUFFER_SIZE);
if (n > 0) {
std::stringstream str;
str.write(_pBuffer, n);
_data = str.str();
_reactor.addEventHandler(_socket, NObserver<EchoServiceHandler, WritableNotification>(*this, &EchoServiceHandler::onWritable));
_onWritableAdded = true;
}
else {
delete this;
}
}
void onShutdown(const AutoPtr<ShutdownNotification>& pNf)
{
delete this;
}
void onWritable(const AutoPtr<WritableNotification>& pNf)
{
Application::instance().logger().information("onWritable called");
std::string data = Poco::format("received %s", _data);
_socket.sendBytes(data.data(), data.length());
_reactor.removeEventHandler(_socket, NObserver<EchoServiceHandler, WritableNotification>(*this, &EchoServiceHandler::onWritable));
if (_onTimeoutAdded) {
_reactor.removeEventHandler(_socket, NObserver<EchoServiceHandler, TimeoutNotification>(*this, &EchoServiceHandler::onTimeout));
}
_reactor.addEventHandler(_socket, NObserver<EchoServiceHandler, TimeoutNotification>(*this, &EchoServiceHandler::onTimeout));
_onTimeoutAdded = true;
}
void onError(const AutoPtr<ErrorNotification>& pNf)
{
Application::instance().logger().information("onError called");
}
void onTimeout(const AutoPtr<TimeoutNotification>& pNf)
{
Application::instance().logger().information("onTimeout called");
_reactor.removeEventHandler(_socket, NObserver<EchoServiceHandler, TimeoutNotification>(*this, &EchoServiceHandler::onTimeout));
delete this;
}
void onIdle(const AutoPtr<IdleNotification>& pNf)
{
Application::instance().logger().information("onIdle called");
}
private:
enum
{
BUFFER_SIZE = 1024
};
StreamSocket _socket;
SocketReactor& _reactor;
char* _pBuffer;
std::string _data;
bool _onWritableAdded;
bool _onTimeoutAdded;
};
class EchoServer: public Poco::Util::ServerApplication
/// The main application class.
///
/// This class handles command-line arguments and
/// configuration files.
/// Start the EchoServer executable with the help
/// option (/help on Windows, --help on Unix) for
/// the available command line options.
///
/// To use the sample configuration file (EchoServer.properties),
/// copy the file to the directory where the EchoServer executable
/// resides. If you start the debug version of the EchoServer
/// (EchoServerd[.exe]), you must also create a copy of the configuration
/// file named EchoServerd.properties. In the configuration file, you
/// can specify the port on which the server is listening (default
/// 9977) and the format of the date/time string sent back to the client.
///
/// To test the EchoServer you can use any telnet client (telnet localhost 9977).
{
public:
EchoServer(): _helpRequested(false)
{
}
~EchoServer()
{
}
protected:
void initialize(Application& self)
{
loadConfiguration(); // load default configuration files, if present
ServerApplication::initialize(self);
}
void uninitialize()
{
ServerApplication::uninitialize();
}
void defineOptions(OptionSet& options)
{
ServerApplication::defineOptions(options);
options.addOption(
Option("help", "h", "display help information on command line arguments")
.required(false)
.repeatable(false));
}
void handleOption(const std::string& name, const std::string& value)
{
ServerApplication::handleOption(name, value);
if (name == "help")
_helpRequested = true;
}
void displayHelp()
{
HelpFormatter helpFormatter(options());
helpFormatter.setCommand(commandName());
helpFormatter.setUsage("OPTIONS");
helpFormatter.setHeader("An echo server implemented using the Reactor and Acceptor patterns.");
helpFormatter.format(std::cout);
}
int main(const std::vector<std::string>& args)
{
if (_helpRequested)
{
displayHelp();
}
else
{
// get parameters from configuration file
unsigned short port = (unsigned short) config().getInt("EchoServer.port", 9977);
// set-up a server socket
ServerSocket svs(port);
// set-up a SocketReactor...
Timespan timeout(30000000); // timeout is set to 30sec
SocketReactor reactor(timeout);
// ... and a SocketAcceptor
SocketAcceptor<EchoServiceHandler> acceptor(svs, reactor);
// run the reactor in its own thread so that we can wait for
// a termination request
Thread thread;
thread.start(reactor);
// wait for CTRL-C or kill
waitForTerminationRequest();
// Stop the SocketReactor
reactor.stop();
thread.join();
}
return Application::EXIT_OK;
}
private:
bool _helpRequested;
};
int main(int argc, char** argv)
{
EchoServer app;
return app.run(argc, argv);
} |