Created zero copy interface/framework, made use of it in usrp2 udp transport stuff.

3 files changed, 84 insertions, 44 deletions

diff --git a/host/lib/transport/udp_zero_copy_asio.cpp b/host/lib/transport/udp_zero_copy_asio.cpp
index 1fc8ce14a..13fd50f65 100644
--- a/host/lib/transport/udp_zero_copy_asio.cpp
+++ b/host/lib/transport/udp_zero_copy_asio.cpp
@@ -25,39 +25,74 @@
 using namespace uhd::transport;
 
 /***********************************************************************
- * Smart buffer implementation for udp zerocopy none
- *
- * This smart buffer implemention houses a const buffer.
- * When the smart buffer is deleted, the buffer is freed.
- * The memory in the const buffer is allocated with new [],
- * and so the destructor frees the buffer with delete [].
+ * Managed receive buffer implementation for udp zero-copy asio:
+ *   Frees the memory held by the const buffer on done.
  **********************************************************************/
-class smart_buffer_impl : public smart_buffer{
+class managed_recv_buffer_impl : public managed_recv_buffer{
 public:
-    smart_buffer_impl(const boost::asio::const_buffer &buff){
-        _buff = buff;
+    managed_recv_buffer_impl(const boost::asio::const_buffer &buff) : _buff(buff){
+        _done = false;
     }
 
-    ~smart_buffer_impl(void){
+    ~managed_recv_buffer_impl(void){
+        if (not _done) this->done();
+    }
+
+    void done(void){
+        _done = true;
         delete [] boost::asio::buffer_cast<const boost::uint32_t *>(_buff);
     }
 
-    const boost::asio::const_buffer &get(void) const{
+private:
+    const boost::asio::const_buffer &get(void){
         return _buff;
     }
 
+    const boost::asio::const_buffer _buff;
+    bool _done;
+};
+
+/***********************************************************************
+ * Managed send buffer implementation for udp zero-copy asio:
+ *   Sends and frees the memory held by the mutable buffer on done.
+ **********************************************************************/
+class managed_send_buffer_impl : public managed_send_buffer{
+public:
+    managed_send_buffer_impl(
+        const boost::asio::mutable_buffer &buff,
+        boost::asio::ip::udp::socket *socket
+    ) : _buff(buff){
+        _done = false;
+        _socket = socket;
+    }
+
+    ~managed_send_buffer_impl(void){
+        if (not _done) this->done(0);
+    }
+
+    void done(size_t num_bytes){
+        _done = true;
+        boost::uint32_t *mem = boost::asio::buffer_cast<boost::uint32_t *>(_buff);
+        _socket->send(boost::asio::buffer(mem, num_bytes));
+        delete [] mem;
+    }
+
 private:
-    boost::asio::const_buffer _buff;
+    const boost::asio::mutable_buffer &get(void){
+        return _buff;
+    }
+
+    const boost::asio::mutable_buffer _buff;
+    boost::asio::ip::udp::socket      *_socket;
+    bool _done;
 };
 
 /***********************************************************************
- * UDP zero copy implementation class
- *
- * This is the portable zero copy implementation for systems
- * where a faster, platform specific solution is not available.
- *
- * It uses boost asio udp sockets and the standard recv() class,
- * and in-fact, is not actually doing a zero-copy implementation.
+ * Zero Copy UDP implementation with ASIO:
+ *   This is the portable zero copy implementation for systems
+ *   where a faster, platform specific solution is not available.
+ *   However, it is not a true zero copy implementation as each
+ *   send and recv requires a copy operation to/from userspace.
  **********************************************************************/
 class udp_zero_copy_impl : public udp_zero_copy{
 public:
@@ -66,8 +101,8 @@ public:
     ~udp_zero_copy_impl(void);
 
     //send/recv
-    size_t send(const boost::asio::const_buffer &buff);
-    smart_buffer::sptr recv(void);
+    managed_recv_buffer::sptr get_recv_buff(void);
+    managed_send_buffer::sptr get_send_buff(void);
 
 private:
     boost::asio::ip::udp::socket   *_socket;
@@ -107,31 +142,33 @@ udp_zero_copy_impl::~udp_zero_copy_impl(void){
     delete _socket;
 }
 
-size_t udp_zero_copy_impl::send(const boost::asio::const_buffer &buff){
-    return _socket->send(boost::asio::buffer(buff));
-}
-
-smart_buffer::sptr udp_zero_copy_impl::recv(void){
-    size_t available = 0;
+managed_recv_buffer::sptr udp_zero_copy_impl::get_recv_buff(void){
+    boost::uint32_t *buff_mem = new boost::uint32_t[1500/sizeof(boost::uint32_t)];
 
     //implement timeout through polling and sleeping
+    size_t available = 0;
     boost::asio::deadline_timer timer(_socket->get_io_service());
     timer.expires_from_now(boost::posix_time::milliseconds(100));
     while (not ((available = _socket->available()) or timer.expires_from_now().is_negative())){
         boost::this_thread::sleep(boost::posix_time::milliseconds(1));
     }
 
-    //allocate memory and create buffer
-    boost::uint32_t *buff_mem = new boost::uint32_t[available/sizeof(boost::uint32_t)];
-    boost::asio::mutable_buffer buff(buff_mem, available);
-
     //receive only if data is available
     if (available){
-        _socket->receive(boost::asio::buffer(buff));
+        available = _socket->receive(boost::asio::buffer(buff_mem, available));
     }
 
-    //create a new smart buffer to house the data
-    return smart_buffer::sptr(new smart_buffer_impl(buff));
+    //create a new managed buffer to house the data
+    return managed_recv_buffer::sptr(
+        new managed_recv_buffer_impl(boost::asio::buffer(buff_mem, available))
+    );
+}
+
+managed_send_buffer::sptr udp_zero_copy_impl::get_send_buff(void){
+    boost::uint32_t *buff_mem = new boost::uint32_t[1500/sizeof(boost::uint32_t)];
+    return managed_send_buffer::sptr(
+        new managed_send_buffer_impl(boost::asio::buffer(buff_mem, 1500), _socket)
+    );
 }
 
 size_t udp_zero_copy_impl::get_recv_buff_size(void){
diff --git a/host/lib/usrp/usrp2/io_impl.cpp b/host/lib/usrp/usrp2/io_impl.cpp
index a58e32619..a54c0a409 100644
--- a/host/lib/usrp/usrp2/io_impl.cpp
+++ b/host/lib/usrp/usrp2/io_impl.cpp
@@ -42,11 +42,13 @@ void usrp2_impl::io_init(void){
 
     //send a small data packet so the usrp2 knows the udp source port
     //and the maximum number of lines (32 bit words) per packet
+    managed_send_buffer::sptr send_buff = _data_transport->get_send_buff();
     boost::uint32_t data[2] = {
         htonl(USRP2_INVALID_VRT_HEADER),
         htonl(_max_rx_samples_per_packet)
     };
-    _data_transport->send(asio::buffer(&data, sizeof(data)));
+    memcpy(send_buff->cast<void*>(), data, sizeof(data));
+    send_buff->done(sizeof(data));
 }
 
 #define unrolled_loop(__inst, __len){ \
@@ -127,15 +129,15 @@ static inline void usrp2_items_to_host_items(
  **********************************************************************/
 void usrp2_impl::recv_raw(rx_metadata_t &metadata){
     //do a receive
-    _rx_smart_buff = _data_transport->recv();
+    _rx_smart_buff = _data_transport->get_recv_buff();
 
     //unpack the vrt header
-    size_t num_packet_words32 = asio::buffer_size(_rx_smart_buff->get())/sizeof(boost::uint32_t);
+    size_t num_packet_words32 = _rx_smart_buff->size()/sizeof(boost::uint32_t);
     if (num_packet_words32 == 0){
         _rx_copy_buff = boost::asio::buffer("", 0);
         return; //must exit here after setting the buffer
     }
-    const boost::uint32_t *vrt_hdr = asio::buffer_cast<const boost::uint32_t *>(_rx_smart_buff->get());
+    const boost::uint32_t *vrt_hdr = _rx_smart_buff->cast<const boost::uint32_t *>();
     size_t num_header_words32_out, num_payload_words32_out, packet_count_out;
     try{
         vrt::unpack(
@@ -176,11 +178,12 @@ size_t usrp2_impl::send(
 ){
     tx_metadata_t metadata = metadata_; //rw copy to change later
 
-    boost::uint32_t tx_mem[_mtu/sizeof(boost::uint32_t)];
+    transport::managed_send_buffer::sptr send_buff = _data_transport->get_send_buff();
+    boost::uint32_t *tx_mem = send_buff->cast<boost::uint32_t *>();
     size_t num_samps = std::min(
-        asio::buffer_size(buff)/io_type.size,
-        size_t(_max_tx_samples_per_packet)
-    );
+        asio::buffer_size(buff),
+        send_buff->size()
+    )/io_type.size;
 
     //kill the end of burst flag if this is a fragment
     if (asio::buffer_size(buff)/io_type.size < num_samps)
@@ -214,7 +217,7 @@ size_t usrp2_impl::send(
     }
 
     //send and return number of samples
-    _data_transport->send(asio::buffer(tx_mem, num_packet_words32*sizeof(boost::uint32_t)));
+    send_buff->done(num_packet_words32*sizeof(boost::uint32_t));
     return num_samps;
 }
 
diff --git a/host/lib/usrp/usrp2/usrp2_impl.hpp b/host/lib/usrp/usrp2/usrp2_impl.hpp
index baa6530b8..be09c4ee1 100644
--- a/host/lib/usrp/usrp2/usrp2_impl.hpp
+++ b/host/lib/usrp/usrp2/usrp2_impl.hpp
@@ -136,7 +136,7 @@ private:
         (_mtu - _hdrs)/sizeof(boost::uint32_t) -
         uhd::transport::vrt::max_header_words32
     ;
-    uhd::transport::smart_buffer::sptr _rx_smart_buff;
+    uhd::transport::managed_recv_buffer::sptr _rx_smart_buff;
     boost::asio::const_buffer _rx_copy_buff;
     size_t _fragment_offset_in_samps;
     void io_init(void);