[Boost-commit] svn:boost r44678 - trunk/libs/asio/example/porthopper

From: chris_at_[hidden]
Date: 2008-04-21 01:43:43

Author: chris_kohlhoff
Date: 2008-04-21 01:43:42 EDT (Mon, 21 Apr 2008)
New Revision: 44678
URL: http://svn.boost.org/trac/boost/changeset/44678

Log:
Add porthopper example to demonstrate applications that mix synchronous and
asynchronous operations.

Added:
   trunk/libs/asio/example/porthopper/
   trunk/libs/asio/example/porthopper/Jamfile   (contents, props changed)
   trunk/libs/asio/example/porthopper/Jamfile.v2   (contents, props changed)
   trunk/libs/asio/example/porthopper/client.cpp   (contents, props changed)
   trunk/libs/asio/example/porthopper/protocol.hpp   (contents, props changed)
   trunk/libs/asio/example/porthopper/server.cpp   (contents, props changed)

Added: trunk/libs/asio/example/porthopper/Jamfile
==============================================================================
--- (empty file)
+++ trunk/libs/asio/example/porthopper/Jamfile	2008-04-21 01:43:42 EDT (Mon, 21 Apr 2008)
@@ -0,0 +1,45 @@
+#
+# Copyright (c) 2003-2008 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+#
+# Distributed under the Boost Software License, Version 1.0. (See accompanying
+# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#
+
+subproject libs/asio/example/porthopper ;
+
+project boost : $(BOOST_ROOT) ;
+
+if $(UNIX)
+{
+  switch $(JAMUNAME)
+  {
+  case SunOS* :
+    {
+      SOCKET_LIBS = <find-library>socket <find-library>nsl ;
+    }
+  }
+}
+
+exe client
+  : <lib>@boost/libs/system/build/boost_system
+    client.cpp
+  : <include>$(BOOST_ROOT)
+    <include>../../../..
+    <define>BOOST_ALL_NO_LIB=1
+    <threading>multi
+    <mingw><*><find-library>ws2_32
+    <mingw><*><find-library>mswsock
+    $(SOCKET_LIBS)
+  ;
+
+exe server
+  : <lib>@boost/libs/system/build/boost_system
+    server.cpp
+  : <include>$(BOOST_ROOT)
+    <include>../../../..
+    <define>BOOST_ALL_NO_LIB=1
+    <threading>multi
+    <mingw><*><find-library>ws2_32
+    <mingw><*><find-library>mswsock
+    $(SOCKET_LIBS)
+  ;

Added: trunk/libs/asio/example/porthopper/Jamfile.v2
==============================================================================
--- (empty file)
+++ trunk/libs/asio/example/porthopper/Jamfile.v2	2008-04-21 01:43:42 EDT (Mon, 21 Apr 2008)
@@ -0,0 +1,41 @@
+#
+# Copyright (c) 2003-2008 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+#
+# Distributed under the Boost Software License, Version 1.0. (See accompanying
+# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#
+
+import os ;
+
+if [ os.name ] = SOLARIS
+{
+  lib socket ;
+  lib nsl ;
+}
+else if [ os.name ] = NT
+{
+  lib ws2_32 ;
+  lib mswsock ;
+}
+else if [ os.name ] = HPUX
+{
+  lib ipv6 ;
+}
+
+project
+  : requirements
+    <library>/boost/system//boost_system
+    <define>BOOST_ALL_NO_LIB=1
+    <threading>multi
+    <os>SOLARIS:<library>socket
+    <os>SOLARIS:<library>nsl
+    <os>NT:<define>_WIN32_WINNT=0x0501
+    <os>NT,<toolset>gcc:<library>ws2_32
+    <os>NT,<toolset>gcc:<library>mswsock
+    <os>NT,<toolset>gcc-cygwin:<define>__USE_W32_SOCKETS
+    <os>HPUX,<toolset>gcc:<define>_XOPEN_SOURCE_EXTENDED
+    <os>HPUX:<library>ipv6
+  ;
+
+exe client : client.cpp ;
+exe server : server.cpp ;

Added: trunk/libs/asio/example/porthopper/client.cpp
==============================================================================
--- (empty file)
+++ trunk/libs/asio/example/porthopper/client.cpp	2008-04-21 01:43:42 EDT (Mon, 21 Apr 2008)
@@ -0,0 +1,183 @@
+#include <boost/asio.hpp>
+#include <boost/lambda/lambda.hpp>
+#include <boost/lambda/bind.hpp>
+#include <boost/lambda/if.hpp>
+#include <boost/shared_ptr.hpp>
+#include <algorithm>
+#include <cstdlib>
+#include <exception>
+#include <iostream>
+#include <string>
+#include "protocol.hpp"
+
+using namespace boost;
+using boost::asio::ip::tcp;
+using boost::asio::ip::udp;
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 3)
+    {
+      std::cerr << "Usage: client <host> <port>\n";
+      return 1;
+    }
+    using namespace std; // For atoi.
+    std::string host_name = argv[1];
+    std::string port = argv[2];
+
+    boost::asio::io_service io_service;
+
+    // Determine the location of the server.
+    tcp::resolver resolver(io_service);
+    tcp::resolver::query query(host_name, port);
+    tcp::endpoint remote_endpoint = *resolver.resolve(query);
+
+    // Establish the control connection to the server.
+    tcp::socket control_socket(io_service);
+    control_socket.connect(remote_endpoint);
+
+    // Create a datagram socket to receive data from the server.
+    shared_ptr<udp::socket> data_socket(
+        new udp::socket(io_service, udp::endpoint(udp::v4(), 0)));
+
+    // Determine what port we will receive data on.
+    udp::endpoint data_endpoint = data_socket->local_endpoint();
+
+    // Ask the server to start sending us data.
+    control_request start = control_request::start(data_endpoint.port());
+    boost::asio::write(control_socket, start.to_buffers());
+
+    unsigned long last_frame_number = 0;
+    for (;;)
+    {
+      // Receive 50 messages on the current data socket.
+      for (int i = 0; i < 50; ++i)
+      {
+        // Receive a frame from the server.
+        frame f;
+        data_socket->receive(f.to_buffers(), 0);
+        if (f.number() > last_frame_number)
+        {
+          last_frame_number = f.number();
+          std::cout << "\n" << f.payload();
+        }
+      }
+
+      // Time to switch to a new socket. To ensure seamless handover we will
+      // continue to receive packets using the old socket until data arrives on
+      // the new one.
+      std::cout << " Starting renegotiation";
+
+      // Create the new data socket.
+      shared_ptr<udp::socket> new_data_socket(
+          new udp::socket(io_service, udp::endpoint(udp::v4(), 0)));
+
+      // Determine the new port we will use to receive data.
+      udp::endpoint new_data_endpoint = new_data_socket->local_endpoint();
+
+      // Ask the server to switch over to the new port.
+      control_request change = control_request::change(
+          data_endpoint.port(), new_data_endpoint.port());
+      boost::system::error_code control_result;
+      boost::asio::async_write(control_socket, change.to_buffers(),
+          lambda::unlambda((
+            lambda::var(control_result) = lambda::_1
+          )));
+
+      // Try to receive a frame from the server on the new data socket. If we
+      // successfully receive a frame on this new data socket we can consider
+      // the renegotation complete. In that case we will close the old data
+      // socket, which will cause any outstanding receive operation on it to be
+      // cancelled.
+      frame f1;
+      boost::system::error_code new_data_socket_result;
+      new_data_socket->async_receive(f1.to_buffers(),
+          lambda::unlambda((
+            // Note: lambda::_1 is the first argument to the callback handler,
+            // which in this case is the error code for the operation.
+            lambda::var(new_data_socket_result) = lambda::_1,
+            lambda::if_(!lambda::_1)
+            [
+              // We have successfully received a frame on the new data socket,
+              // so we can close the old data socket. This will cancel any
+              // outstanding receive operation on the old data socket.
+              lambda::var(data_socket) = shared_ptr<udp::socket>()
+            ]
+          )));
+
+      // This loop will continue until we have successfully completed the
+      // renegotiation (i.e. received a frame on the new data socket), or some
+      // unrecoverable error occurs.
+      bool done = false;
+      while (!done)
+      {
+        // Even though we're performing a renegotation, we want to continue
+        // receiving data as smoothly as possible. Therefore we will continue to
+        // try to receive a frame from the server on the old data socket. If we
+        // receive a frame on this socket we will interrupt the io_service,
+        // print the frame, and resume waiting for the other operations to
+        // complete.
+        frame f2;
+        done = true; // Let's be optimistic.
+        if (data_socket) // Might have been closed by new_data_socket's handler.
+        {
+          data_socket->async_receive(f2.to_buffers(), 0,
+              lambda::unlambda((
+                lambda::if_(!lambda::_1)
+                [
+                  // We have successfully received a frame on the old data
+                  // socket. Stop the io_service so that we can print it.
+                  lambda::bind(&boost::asio::io_service::stop, &io_service),
+                  lambda::var(done) = false
+                ]
+              )));
+        }
+
+        // Run the operations in parallel. This will block until all operations
+        // have finished, or until the io_service is interrupted. (No threads!)
+        io_service.reset();
+        io_service.run();
+
+        // If the io_service.run() was interrupted then we have received a frame
+        // on the old data socket. We need to keep waiting for the renegotation
+        // operations to complete.
+        if (!done)
+        {
+          if (f2.number() > last_frame_number)
+          {
+            last_frame_number = f2.number();
+            std::cout << "\n" << f2.payload();
+          }
+        }
+      }
+
+      // Since the loop has finished, we have either successfully completed
+      // the renegotation, or an error has occurred. First we'll check for
+      // errors.
+      if (control_result)
+        throw boost::system::system_error(control_result);
+      if (new_data_socket_result)
+        throw boost::system::system_error(new_data_socket_result);
+
+      // If we get here it means we have successfully started receiving data on
+      // the new data socket. This new data socket will be used from now on
+      // (until the next time we renegotiate).
+      std::cout << " Renegotiation complete";
+      data_socket = new_data_socket;
+      data_endpoint = new_data_endpoint;
+      if (f1.number() > last_frame_number)
+      {
+        last_frame_number = f1.number();
+        std::cout << "\n" << f1.payload();
+      }
+    }
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << std::endl;
+  }
+
+  return 0;
+}

Added: trunk/libs/asio/example/porthopper/protocol.hpp
==============================================================================
--- (empty file)
+++ trunk/libs/asio/example/porthopper/protocol.hpp	2008-04-21 01:43:42 EDT (Mon, 21 Apr 2008)
@@ -0,0 +1,145 @@
+#ifndef PORTHOPPER_PROTOCOL_HPP
+#define PORTHOPPER_PROTOCOL_HPP
+
+#include <boost/array.hpp>
+#include <boost/asio.hpp>
+#include <cstring>
+#include <iomanip>
+#include <string>
+#include <strstream>
+
+// This request is sent by the client to the server over a TCP connection.
+// The client uses it to perform three functions:
+// - To request that data start being sent to a given port.
+// - To request that data is no longer sent to a given port.
+// - To change the target port to another.
+class control_request
+{
+public:
+  // Construct an empty request. Used when receiving.
+  control_request()
+  {
+  }
+
+  // Create a request to start sending data to a given port.
+  static const control_request start(unsigned short port)
+  {
+    return control_request(0, port);
+  }
+
+  // Create a request to stop sending data to a given port.
+  static const control_request stop(unsigned short port)
+  {
+    return control_request(port, 0);
+  }
+
+  // Create a request to change the port that data is sent to.
+  static const control_request change(
+      unsigned short old_port, unsigned short new_port)
+  {
+    return control_request(old_port, new_port);
+  }
+
+  // Get the old port. Returns 0 for start requests.
+  unsigned short old_port() const
+  {
+    std::istrstream is(data_, encoded_port_size);
+    unsigned short port = 0;
+    is >> std::setw(encoded_port_size) >> std::hex >> port;
+    return port;
+  }
+
+  // Get the new port. Returns 0 for stop requests.
+  unsigned short new_port() const
+  {
+    std::istrstream is(data_ + encoded_port_size, encoded_port_size);
+    unsigned short port = 0;
+    is >> std::setw(encoded_port_size) >> std::hex >> port;
+    return port;
+  }
+
+  // Obtain buffers for reading from or writing to a socket.
+  boost::array<boost::asio::mutable_buffer, 1> to_buffers()
+  {
+    boost::array<boost::asio::mutable_buffer, 1> buffers
+      = { { boost::asio::buffer(data_) } };
+    return buffers;
+  }
+
+private:
+  // Construct with specified old and new ports.
+  control_request(unsigned short old_port, unsigned short new_port)
+  {
+    std::ostrstream os(data_, control_request_size);
+    os << std::setw(encoded_port_size) << std::hex << old_port;
+    os << std::setw(encoded_port_size) << std::hex << new_port;
+  }
+
+  // The length in bytes of a control_request and its components.
+  enum
+  {
+    encoded_port_size = 4, // 16-bit port in hex.
+    control_request_size = encoded_port_size * 2
+  };
+
+  // The encoded request data.
+  char data_[control_request_size];
+};
+
+// This frame is sent from the server to subscribed clients over UDP.
+class frame
+{
+public:
+  // The maximum allowable length of the payload.
+  enum { payload_size = 32 };
+
+  // Construct an empty frame. Used when receiving.
+  frame()
+  {
+  }
+
+  // Construct a frame with specified frame number and payload.
+  frame(unsigned long number, const std::string& payload)
+  {
+    std::ostrstream os(data_, frame_size);
+    os << std::setw(encoded_number_size) << std::hex << number;
+    os << std::setw(payload_size)
+      << std::setfill(' ') << payload.substr(0, payload_size);
+  }
+
+  // Get the frame number.
+  unsigned long number() const
+  {
+    std::istrstream is(data_, encoded_number_size);
+    unsigned long number = 0;
+    is >> std::setw(encoded_number_size) >> std::hex >> number;
+    return number;
+  }
+
+  // Get the payload data.
+  const std::string payload() const
+  {
+    return std::string(data_ + encoded_number_size, payload_size);
+  }
+
+  // Obtain buffers for reading from or writing to a socket.
+  boost::array<boost::asio::mutable_buffer, 1> to_buffers()
+  {
+    boost::array<boost::asio::mutable_buffer, 1> buffers
+      = { { boost::asio::buffer(data_) } };
+    return buffers;
+  }
+
+private:
+  // The length in bytes of a frame and its components.
+  enum
+  {
+    encoded_number_size = 8, // Frame number in hex.
+    frame_size = encoded_number_size + payload_size
+  };
+
+  // The encoded frame data.
+  char data_[frame_size];
+};
+
+#endif // PORTHOPPER_PROTOCOL_HPP

Added: trunk/libs/asio/example/porthopper/server.cpp
==============================================================================
--- (empty file)
+++ trunk/libs/asio/example/porthopper/server.cpp	2008-04-21 01:43:42 EDT (Mon, 21 Apr 2008)
@@ -0,0 +1,177 @@
+#include <boost/asio.hpp>
+#include <boost/bind.hpp>
+#include <boost/shared_ptr.hpp>
+#include <cmath>
+#include <cstdlib>
+#include <exception>
+#include <iostream>
+#include <set>
+#include "protocol.hpp"
+
+using boost::asio::ip::tcp;
+using boost::asio::ip::udp;
+
+typedef boost::shared_ptr<tcp::socket> tcp_socket_ptr;
+typedef boost::shared_ptr<boost::asio::deadline_timer> timer_ptr;
+typedef boost::shared_ptr<control_request> control_request_ptr;
+
+class server
+{
+public:
+  // Construct the server to wait for incoming control connections.
+  server(boost::asio::io_service& io_service, unsigned short port)
+    : acceptor_(io_service, tcp::endpoint(tcp::v4(), port)),
+      timer_(io_service),
+      udp_socket_(io_service, udp::endpoint(udp::v4(), 0)),
+      next_frame_number_(1)
+  {
+    // Start waiting for a new control connection.
+    tcp_socket_ptr new_socket(new tcp::socket(acceptor_.get_io_service()));
+    acceptor_.async_accept(*new_socket,
+        boost::bind(&server::handle_accept, this,
+          boost::asio::placeholders::error, new_socket));
+
+    // Start the timer used to generate outgoing frames.
+    timer_.expires_from_now(boost::posix_time::milliseconds(100));
+    timer_.async_wait(boost::bind(&server::handle_timer, this));
+  }
+
+  // Handle a new control connection.
+  void handle_accept(const boost::system::error_code& ec, tcp_socket_ptr socket)
+  {
+    if (!ec)
+    {
+      // Start receiving control requests on the connection.
+      control_request_ptr request(new control_request);
+      boost::asio::async_read(*socket, request->to_buffers(),
+          boost::bind(&server::handle_control_request, this,
+            boost::asio::placeholders::error, socket, request));
+
+      // Start waiting for a new control connection.
+      tcp_socket_ptr new_socket(new tcp::socket(acceptor_.get_io_service()));
+      acceptor_.async_accept(*new_socket,
+          boost::bind(&server::handle_accept, this,
+            boost::asio::placeholders::error, new_socket));
+    }
+  }
+
+  // Handle a new control request.
+  void handle_control_request(const boost::system::error_code& ec,
+      tcp_socket_ptr socket, control_request_ptr request)
+  {
+    if (!ec)
+    {
+      // Delay handling of the control request to simulate network latency.
+      timer_ptr delay_timer(
+          new boost::asio::deadline_timer(acceptor_.get_io_service()));
+      delay_timer->expires_from_now(boost::posix_time::seconds(2));
+      delay_timer->async_wait(
+          boost::bind(&server::handle_control_request_timer, this,
+            socket, request, delay_timer));
+    }
+  }
+
+  void handle_control_request_timer(tcp_socket_ptr socket,
+      control_request_ptr request, timer_ptr delay_timer)
+  {
+    // Determine what address this client is connected from, since
+    // subscriptions must be stored on the server as a complete endpoint, not
+    // just a port. We use the non-throwing overload of remote_endpoint() since
+    // it may fail if the socket is no longer connected.
+    boost::system::error_code ec;
+    tcp::endpoint remote_endpoint = socket->remote_endpoint(ec);
+    if (!ec)
+    {
+      // Remove old port subscription, if any.
+      if (unsigned short old_port = request->old_port())
+      {
+        udp::endpoint old_endpoint(remote_endpoint.address(), old_port);
+        subscribers_.erase(old_endpoint);
+        std::cout << "Removing subscription " << old_endpoint << std::endl;
+      }
+
+      // Add new port subscription, if any.
+      if (unsigned short new_port = request->new_port())
+      {
+        udp::endpoint new_endpoint(remote_endpoint.address(), new_port);
+        subscribers_.insert(new_endpoint);
+        std::cout << "Adding subscription " << new_endpoint << std::endl;
+      }
+    }
+
+    // Wait for next control request on this connection.
+    boost::asio::async_read(*socket, request->to_buffers(),
+        boost::bind(&server::handle_control_request, this,
+          boost::asio::placeholders::error, socket, request));
+  }
+
+  // Every time the timer fires we will generate a new frame and send it to all
+  // subscribers.
+  void handle_timer()
+  {
+    // Generate payload.
+    double x = next_frame_number_ * 0.2;
+    double y = std::sin(x);
+    int char_index = static_cast<int>((y + 1.0) * (frame::payload_size / 2));
+    std::string payload;
+    for (int i = 0; i < frame::payload_size; ++i)
+      payload += (i == char_index ? '*' : '.');
+
+    // Create the frame to be sent to all subscribers.
+    frame f(next_frame_number_++, payload);
+
+    // Send frame to all subscribers. We can use synchronous calls here since
+    // UDP send operations typically do not block.
+    std::set<udp::endpoint>::iterator j;
+    for (j = subscribers_.begin(); j != subscribers_.end(); ++j)
+    {
+      boost::system::error_code ec;
+      udp_socket_.send_to(f.to_buffers(), *j, 0, ec);
+    }
+
+    // Wait for next timeout.
+    timer_.expires_from_now(boost::posix_time::milliseconds(100));
+    timer_.async_wait(boost::bind(&server::handle_timer, this));
+  }
+
+private:
+  // The acceptor used to accept incoming control connections.
+  tcp::acceptor acceptor_;
+
+  // The timer used for generating data.
+  boost::asio::deadline_timer timer_;
+
+  // The socket used to send data to subscribers.
+  udp::socket udp_socket_;
+
+  // The next frame number.
+  unsigned long next_frame_number_;
+
+  // The set of endpoints that are subscribed.
+  std::set<udp::endpoint> subscribers_;
+};
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: server <port>\n";
+      return 1;
+    }
+
+    boost::asio::io_service io_service;
+
+    using namespace std; // For atoi.
+    server s(io_service, atoi(argv[1]));
+
+    io_service.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << std::endl;
+  }
+
+  return 0;
+}