udp: update docs for transport, create common header for wait implementation

Reimplemented simple udp transport with one impl class.
Moved wait for ready/select implementation into common header.
Important note on select, timeval should have usecs < 1 second
or it may error on some platforms. Fixed in this implementation.

5 files changed, 99 insertions, 151 deletions

diff --git a/host/docs/transport.rst b/host/docs/transport.rst
index 6b9d28bfa..2371d2497 100644
--- a/host/docs/transport.rst
+++ b/host/docs/transport.rst
@@ -17,13 +17,9 @@ that are known to perform well on a variety of systems.
 The transport parameters are defined below for the various transports in the UHD:
 
 ------------------------------------------------------------------------
-UDP transport (ASIO)
+UDP transport (sockets)
 ------------------------------------------------------------------------
-The UDP transport is implemented with Boost's ASIO library.
-ASIO provides an asynchronous API for user-space sockets.
-The transport implementation allocates a number of buffers
-and submits asynchronous requests for send and receive.
-IO service threads run in the background to process these requests.
+The UDP transport is implemented with standard user-space/Berkeley sockets.
 
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 Transport parameters
@@ -35,8 +31,12 @@ The following parameters can be used to alter the transport's default behavior:
 * **send_frame_size:** The size of a single send buffer in bytes
 * **num_send_frames:** The number of send buffers to allocate
 
-**Note:** num_recv_frames and num_send_frames will not have an effect
-as the asynchronous send implementation is currently unimplemented.
+**Note1:** num_recv_frames and num_send_frames do not affect performance.
+
+**Note2:** recv_frame_size and send_frame_size can be used to
+increase or decrease the maximum number of samples per packet.
+The frame sizes default to an MTU of 1472 bytes per IP/UDP packet,
+and may be increased if permitted by your network hardware.
 
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 Flow control parameters
diff --git a/host/lib/transport/CMakeLists.txt b/host/lib/transport/CMakeLists.txt
index a98bcc14e..e58957154 100644
--- a/host/lib/transport/CMakeLists.txt
+++ b/host/lib/transport/CMakeLists.txt
@@ -80,6 +80,6 @@ LIBUHD_APPEND_SOURCES(
     ${CMAKE_CURRENT_SOURCE_DIR}/buffer_pool.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/if_addrs.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/udp_simple.cpp
-    ${CMAKE_CURRENT_SOURCE_DIR}/udp_zero_copy_asio.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/udp_zero_copy.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/vrt_packet_handler.hpp
 )
diff --git a/host/lib/transport/udp_common.hpp b/host/lib/transport/udp_common.hpp
new file mode 100644
index 000000000..44067b5dc
--- /dev/null
+++ b/host/lib/transport/udp_common.hpp
@@ -0,0 +1,51 @@
+//
+// Copyright 2011 Ettus Research LLC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+
+#ifndef INCLUDED_LIBUHD_TRANSPORT_VRT_PACKET_HANDLER_HPP
+#define INCLUDED_LIBUHD_TRANSPORT_VRT_PACKET_HANDLER_HPP
+
+#include <uhd/config.hpp>
+#include <boost/asio.hpp>
+
+namespace uhd{ namespace transport{
+
+    /*!
+     * Wait for the socket to become ready for a receive operation.
+     * \param sock_fd the open socket file descriptor
+     * \param timeout the timeout duration in seconds
+     * \return true when the socket is ready for receive
+     */
+    UHD_INLINE bool wait_for_recv(int sock_fd, double timeout){
+        //setup timeval for timeout
+        timeval tv;
+        //If the tv_usec > 1 second on some platforms, select will
+        //error EINVAL: An invalid timeout interval was specified.
+        tv.tv_sec = int(timeout);
+        tv.tv_usec = int(timeout*1000000)%1000000;
+
+        //setup rset for timeout
+        fd_set rset;
+        FD_ZERO(&rset);
+        FD_SET(sock_fd, &rset);
+
+        //call select with timeout on receive socket
+        return ::select(sock_fd+1, &rset, NULL, NULL, &tv) > 0;
+    }
+
+}} //namespace uhd::transport
+
+#endif /* INCLUDED_LIBUHD_TRANSPORT_VRT_PACKET_HANDLER_HPP */
diff --git a/host/lib/transport/udp_simple.cpp b/host/lib/transport/udp_simple.cpp
index 6799ac7b2..094f570ff 100644
--- a/host/lib/transport/udp_simple.cpp
+++ b/host/lib/transport/udp_simple.cpp
@@ -1,5 +1,5 @@
 //
-// Copyright 2010 Ettus Research LLC
+// Copyright 2010-2011 Ettus Research LLC
 //
 // This program is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
@@ -15,159 +15,71 @@
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 //
 
+#include "udp_common.hpp"
 #include <uhd/transport/udp_simple.hpp>
-#include <boost/asio.hpp>
-#include <boost/thread.hpp>
 #include <boost/format.hpp>
 #include <iostream>
 
 using namespace uhd::transport;
+namespace asio = boost::asio;
 
 /***********************************************************************
- * Helper Functions
+ * UDP simple implementation: connected and broadcast
  **********************************************************************/
-/*!
- * Wait for available data or timeout.
- * \param socket the asio socket
- * \param timeout the timeout in seconds
- * \return false for timeout, true for data
- */
-static bool wait_available(
-    boost::asio::ip::udp::socket &socket, double timeout
-){
-    #if defined(UHD_PLATFORM_LINUX) || defined(UHD_PLATFORM_WIN32)
-
-    //setup timeval for timeout
-    timeval tv;
-    tv.tv_sec = 0;
-    tv.tv_usec = long(timeout*1e6);
-
-    //setup rset for timeout
-    fd_set rset;
-    FD_ZERO(&rset);
-    FD_SET(socket.native(), &rset);
-
-    return ::select(socket.native()+1, &rset, NULL, NULL, &tv) > 0;
-
-    #else /*defined(UHD_PLATFORM_LINUX) || defined(UHD_PLATFORM_WIN32)*/
-
-    //FIXME: why does select fail on macintosh?
-    for (size_t i = 0; i < size_t(timeout*1e3); i++){
-        if (socket.available()) return true;
-        boost::this_thread::sleep(boost::posix_time::milliseconds(1));
-    }
-    return false;
-
-    #endif /*defined(UHD_PLATFORM_LINUX) || defined(UHD_PLATFORM_WIN32)*/
-}
-
-/***********************************************************************
- * UDP connected implementation class
- **********************************************************************/
-class udp_connected_impl : public udp_simple{
+class udp_simple_impl : public udp_simple{
 public:
-    //structors
-    udp_connected_impl(const std::string &addr, const std::string &port);
-    ~udp_connected_impl(void);
+    typedef boost::shared_ptr<asio::ip::udp::socket> socket_sptr;
 
-    //send/recv
-    size_t send(const boost::asio::const_buffer &);
-    size_t recv(const boost::asio::mutable_buffer &, double);
+    udp_simple_impl(
+        const std::string &addr, const std::string &port, bool bcast, bool connect
+    ):_connected(connect){
+        //std::cout << boost::format("Creating udp transport for %s %s") % addr % port << std::endl;
 
-private:
-    boost::asio::ip::udp::socket   *_socket;
-    boost::asio::io_service        _io_service;
-};
+        //resolve the address
+        asio::ip::udp::resolver resolver(_io_service);
+        asio::ip::udp::resolver::query query(asio::ip::udp::v4(), addr, port);
+        _receiver_endpoint = *resolver.resolve(query);
 
-udp_connected_impl::udp_connected_impl(const std::string &addr, const std::string &port){
-    //std::cout << boost::format("Creating udp transport for %s %s") % addr % port << std::endl;
+        //create and open the socket
+        _socket = socket_sptr(new asio::ip::udp::socket(_io_service));
+        _socket->open(asio::ip::udp::v4());
 
-    // resolve the address
-    boost::asio::ip::udp::resolver resolver(_io_service);
-    boost::asio::ip::udp::resolver::query query(boost::asio::ip::udp::v4(), addr, port);
-    boost::asio::ip::udp::endpoint receiver_endpoint = *resolver.resolve(query);
+        //allow broadcasting
+        _socket->set_option(asio::socket_base::broadcast(bcast));
 
-    // Create, open, and connect the socket
-    _socket = new boost::asio::ip::udp::socket(_io_service);
-    _socket->open(boost::asio::ip::udp::v4());
-    _socket->connect(receiver_endpoint);
-}
-
-udp_connected_impl::~udp_connected_impl(void){
-    delete _socket;
-}
-
-size_t udp_connected_impl::send(const boost::asio::const_buffer &buff){
-    return _socket->send(boost::asio::buffer(buff));
-}
+        //connect the socket
+        if (connect) _socket->connect(_receiver_endpoint);
 
-size_t udp_connected_impl::recv(const boost::asio::mutable_buffer &buff, double timeout){
-    if (not wait_available(*_socket, timeout)) return 0;
-    return _socket->receive(boost::asio::buffer(buff));
-}
+    }
 
-/***********************************************************************
- * UDP broadcast implementation class
- **********************************************************************/
-class udp_broadcast_impl : public udp_simple{
-public:
-    //structors
-    udp_broadcast_impl(const std::string &addr, const std::string &port);
-    ~udp_broadcast_impl(void);
+    size_t send(const asio::const_buffer &buff){
+        if (_connected) return _socket->send(asio::buffer(buff));
+        return _socket->send_to(asio::buffer(buff), _receiver_endpoint);
+    }
 
-    //send/recv
-    size_t send(const boost::asio::const_buffer &);
-    size_t recv(const boost::asio::mutable_buffer &, double);
+    size_t recv(const asio::mutable_buffer &buff, double timeout){
+        if (not wait_for_recv(_socket->native(), timeout)) return 0;
+        return _socket->receive(asio::buffer(buff));
+    }
 
 private:
-    boost::asio::ip::udp::socket   *_socket;
-    boost::asio::ip::udp::endpoint _receiver_endpoint;
-    boost::asio::io_service        _io_service;
+    bool                    _connected;
+    asio::io_service        _io_service;
+    socket_sptr             _socket;
+    asio::ip::udp::endpoint _receiver_endpoint;
 };
 
-udp_broadcast_impl::udp_broadcast_impl(const std::string &addr, const std::string &port){
-    //std::cout << boost::format("Creating udp transport for %s %s") % addr % port << std::endl;
-
-    // resolve the address
-    boost::asio::ip::udp::resolver resolver(_io_service);
-    boost::asio::ip::udp::resolver::query query(boost::asio::ip::udp::v4(), addr, port);
-    _receiver_endpoint = *resolver.resolve(query);
-
-    // Create and open the socket
-    _socket = new boost::asio::ip::udp::socket(_io_service);
-    _socket->open(boost::asio::ip::udp::v4());
-
-    // Allow broadcasting
-    boost::asio::socket_base::broadcast option(true);
-    _socket->set_option(option);
-
-}
-
-udp_broadcast_impl::~udp_broadcast_impl(void){
-    delete _socket;
-}
-
-size_t udp_broadcast_impl::send(const boost::asio::const_buffer &buff){
-    return _socket->send_to(boost::asio::buffer(buff), _receiver_endpoint);
-}
-
-size_t udp_broadcast_impl::recv(const boost::asio::mutable_buffer &buff, double timeout){
-    if (not wait_available(*_socket, timeout)) return 0;
-    boost::asio::ip::udp::endpoint sender_endpoint;
-    return _socket->receive_from(boost::asio::buffer(buff), sender_endpoint);
-}
-
 /***********************************************************************
  * UDP public make functions
  **********************************************************************/
 udp_simple::sptr udp_simple::make_connected(
     const std::string &addr, const std::string &port
 ){
-    return sptr(new udp_connected_impl(addr, port));
+    return sptr(new udp_simple_impl(addr, port, false, true /* no bcast, connect */));
 }
 
 udp_simple::sptr udp_simple::make_broadcast(
     const std::string &addr, const std::string &port
 ){
-    return sptr(new udp_broadcast_impl(addr, port));
+    return sptr(new udp_simple_impl(addr, port, true, false /* bcast, no connect */));
 }
diff --git a/host/lib/transport/udp_zero_copy_asio.cpp b/host/lib/transport/udp_zero_copy.cpp
index 05352ffce..793fc6fba 100644
--- a/host/lib/transport/udp_zero_copy_asio.cpp
+++ b/host/lib/transport/udp_zero_copy.cpp
@@ -15,13 +15,12 @@
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 //
 
+#include "udp_common.hpp"
 #include <uhd/transport/udp_zero_copy.hpp>
 #include <uhd/transport/udp_simple.hpp> //mtu
 #include <uhd/transport/bounded_buffer.hpp>
 #include <uhd/transport/buffer_pool.hpp>
-#include <uhd/utils/assert.hpp>
 #include <uhd/utils/warning.hpp>
-#include <boost/asio.hpp>
 #include <boost/format.hpp>
 #include <iostream>
 #include <list>
@@ -188,24 +187,10 @@ public:
      * When the caller is finished with the managed buffer,
      * the managed receive buffer is released back into the queue.
      ******************************************************************/
-    UHD_INLINE bool is_recv_ready(double timeout){
-        //setup timeval for timeout
-        timeval tv;
-        tv.tv_sec = 0;
-        tv.tv_usec = long(timeout*1e6);
-
-        //setup rset for timeout
-        fd_set rset;
-        FD_ZERO(&rset);
-        FD_SET(_sock_fd, &rset);
-
-        //call select with timeout on receive socket
-        return ::select(_sock_fd+1, &rset, NULL, NULL, &tv) > 0;
-    }
-
     managed_recv_buffer::sptr get_recv_buff(double timeout){
         udp_zero_copy_asio_mrb *mrb = NULL;
-        if (is_recv_ready(timeout) and _pending_recv_buffs.pop_with_timed_wait(mrb, timeout)){
+        bool recv_ready = wait_for_recv(_sock_fd, timeout);
+        if (recv_ready and _pending_recv_buffs.pop_with_timed_wait(mrb, timeout)){
             return mrb->get_new(::recv(_sock_fd, mrb->cast<char *>(), _recv_frame_size, 0));
         }
         return managed_recv_buffer::sptr();