uhd: implemented a double timeout (in seconds) for send and recv chains

converted all size_t timeout_ms to double timeout

bounded and alignment buffer now take double timeout

added timeout to device::send and zero_copy_if::get_send_buff

17 files changed, 140 insertions, 137 deletions

diff --git a/host/include/uhd/device.hpp b/host/include/uhd/device.hpp
index 2077cae62..992276928 100644
--- a/host/include/uhd/device.hpp
+++ b/host/include/uhd/device.hpp
@@ -41,9 +41,6 @@ public:
     typedef boost::function<device_addrs_t(const device_addr_t &)> find_t;
     typedef boost::function<sptr(const device_addr_t &)> make_t;
 
-    //! A reasonable default timeout for receive
-    static const size_t default_recv_timeout_ms = 100;
-
     /*!
      * Register a device into the discovery and factory system.
      *
@@ -112,12 +109,15 @@ public:
      *
      * This is a blocking call and will not return until the number
      * of samples returned have been read out of each buffer.
+     * Under a timeout condition, the number of samples returned
+     * may be less than the number of samples specified.
      *
      * \param buffs a vector of read-only memory containing IF data
      * \param nsamps_per_buff the number of samples to send, per buffer
      * \param metadata data describing the buffer's contents
      * \param io_type the type of data loaded in the buffer
      * \param send_mode tells send how to unload the buffer
+     * \param timeout the timeout in seconds to wait on a packet
      * \return the number of samples sent
      */
     virtual size_t send(
@@ -125,7 +125,8 @@ public:
         size_t nsamps_per_buff,
         const tx_metadata_t &metadata,
         const io_type_t &io_type,
-        send_mode_t send_mode
+        send_mode_t send_mode,
+        double timeout = 0.1
     ) = 0;
 
     /*!
@@ -136,7 +137,8 @@ public:
         size_t nsamps_per_buff,
         const tx_metadata_t &metadata,
         const io_type_t &io_type,
-        send_mode_t send_mode
+        send_mode_t send_mode,
+        double timeout = 0.1
     );
 
     /*!
@@ -154,7 +156,9 @@ public:
      * See the rx metadata fragment flags and offset fields for details.
      *
      * This is a blocking call and will not return until the number
-     * of samples returned have been written into each buffer or timeout.
+     * of samples returned have been written into each buffer.
+     * Under a timeout condition, the number of samples returned
+     * may be less than the number of samples specified.
      *
      * When using the full buffer recv mode, the metadata only applies
      * to the first packet received and written into the recv buffers.
@@ -165,7 +169,7 @@ public:
      * \param metadata data to fill describing the buffer
      * \param io_type the type of data to fill into the buffer
      * \param recv_mode tells recv how to load the buffer
-     * \param timeout_ms the timeout in milliseconds to wait for a packet
+     * \param timeout the timeout in seconds to wait for a packet
      * \return the number of samples received or 0 on error
      */
     virtual size_t recv(
@@ -174,7 +178,7 @@ public:
         rx_metadata_t &metadata,
         const io_type_t &io_type,
         recv_mode_t recv_mode,
-        size_t timeout_ms = default_recv_timeout_ms
+        double timeout = 0.1
     ) = 0;
 
     /*!
@@ -186,7 +190,7 @@ public:
         rx_metadata_t &metadata,
         const io_type_t &io_type,
         recv_mode_t recv_mode,
-        size_t timeout_ms = default_recv_timeout_ms
+        double timeout = 0.1
     );
 
     /*!
@@ -204,12 +208,11 @@ public:
     /*!
      * Receive and asynchronous message from the device.
      * \param async_metadata the metadata to be filled in
-     * \param timeout_ms the timeout in milliseconds to wait for a message
+     * \param timeout the timeout in seconds to wait for a message
      * \return true when the async_metadata is valid, false for timeout
      */
     virtual bool recv_async_msg(
-        async_metadata_t &async_metadata,
-        size_t timeout_ms = default_recv_timeout_ms
+        async_metadata_t &async_metadata, double timeout = 0.1
     ) = 0;
 
 };
diff --git a/host/include/uhd/device.ipp b/host/include/uhd/device.ipp
index 60a3f535d..e2e51ecd0 100644
--- a/host/include/uhd/device.ipp
+++ b/host/include/uhd/device.ipp
@@ -25,12 +25,13 @@ namespace uhd{
         size_t nsamps_per_buff,
         const tx_metadata_t &metadata,
         const io_type_t &io_type,
-        send_mode_t send_mode
+        send_mode_t send_mode,
+        double timeout
     ){
         return this->send(
             std::vector<const void *>(1, buff),
             nsamps_per_buff, metadata,
-            io_type, send_mode
+            io_type, send_mode, timeout
         );
     }
 
@@ -40,12 +41,12 @@ namespace uhd{
         rx_metadata_t &metadata,
         const io_type_t &io_type,
         recv_mode_t recv_mode,
-        size_t timeout_ms
+        double timeout
     ){
         return this->recv(
             std::vector<void *>(1, buff),
             nsamps_per_buff, metadata,
-            io_type, recv_mode, timeout_ms
+            io_type, recv_mode, timeout
         );
     }
 
diff --git a/host/include/uhd/transport/alignment_buffer.hpp b/host/include/uhd/transport/alignment_buffer.hpp
index 29ba74efc..f44a037f8 100644
--- a/host/include/uhd/transport/alignment_buffer.hpp
+++ b/host/include/uhd/transport/alignment_buffer.hpp
@@ -48,20 +48,17 @@ namespace uhd{ namespace transport{
          * \return true if the element fit without popping for space
          */
         virtual bool push_with_pop_on_full(
-            const elem_type &elem,
-            const seq_type &seq,
-            size_t index
+            const elem_type &elem, const seq_type &seq, size_t index
         ) = 0;
 
         /*!
          * Pop an aligned set of elements from this alignment buffer.
          * \param elems a collection to store the aligned elements
-         * \param time the timeout time
+         * \param timeout the timeout in seconds
          * \return false when the operation times out
          */
         virtual bool pop_elems_with_timed_wait(
-            std::vector<elem_type> &elems,
-            const time_duration_t &time
+            std::vector<elem_type> &elems, double timeout
         ) = 0;
     };
 
diff --git a/host/include/uhd/transport/alignment_buffer.ipp b/host/include/uhd/transport/alignment_buffer.ipp
index 61b3b60f5..5f09de0d9 100644
--- a/host/include/uhd/transport/alignment_buffer.ipp
+++ b/host/include/uhd/transport/alignment_buffer.ipp
@@ -41,9 +41,7 @@ namespace uhd{ namespace transport{ namespace{ /*anon*/
         }
 
         UHD_INLINE bool push_with_pop_on_full(
-            const elem_type &elem,
-            const seq_type &seq,
-            size_t index
+            const elem_type &elem, const seq_type &seq, size_t index
         ){
             //clear the buffer for this index if the seqs are mis-ordered
             if (seq < _last_seqs[index]){
@@ -54,17 +52,16 @@ namespace uhd{ namespace transport{ namespace{ /*anon*/
         }
 
         UHD_INLINE bool pop_elems_with_timed_wait(
-            std::vector<elem_type> &elems,
-            const time_duration_t &time
+            std::vector<elem_type> &elems, double timeout
         ){
-            boost::system_time exit_time = boost::get_system_time() + time;
+            boost::system_time exit_time = boost::get_system_time() + boost::posix_time::microseconds(long(timeout*1e6));
             buff_contents_type buff_contents_tmp;
             std::list<size_t> indexes_to_do(_all_indexes);
 
             //do an initial pop to load an initial sequence id
             size_t index = indexes_to_do.front();
             if (not _buffs[index]->pop_with_timed_wait(
-                buff_contents_tmp, exit_time - boost::get_system_time()
+                buff_contents_tmp, 1e-6*(exit_time - boost::get_system_time()).total_microseconds()
             )) return false;
             elems[index] = buff_contents_tmp.first;
             seq_type expected_seq_id = buff_contents_tmp.second;
@@ -79,7 +76,7 @@ namespace uhd{ namespace transport{ namespace{ /*anon*/
                     indexes_to_do = _all_indexes;
                     index = indexes_to_do.front();
                     if (not _buffs[index]->pop_with_timed_wait(
-                        buff_contents_tmp, exit_time - boost::get_system_time()
+                        buff_contents_tmp, 1e-6*(exit_time - boost::get_system_time()).total_microseconds()
                     )) return false;
                     elems[index] = buff_contents_tmp.first;
                     expected_seq_id = buff_contents_tmp.second;
@@ -89,7 +86,7 @@ namespace uhd{ namespace transport{ namespace{ /*anon*/
                 //pop an element off for this index
                 index = indexes_to_do.front();
                 if (not _buffs[index]->pop_with_timed_wait(
-                    buff_contents_tmp, exit_time - boost::get_system_time()
+                    buff_contents_tmp, 1e-6*(exit_time - boost::get_system_time()).total_microseconds()
                 )) return false;
 
                 //if the sequence id matches:
diff --git a/host/include/uhd/transport/bounded_buffer.hpp b/host/include/uhd/transport/bounded_buffer.hpp
index d1deece96..aca93b071 100644
--- a/host/include/uhd/transport/bounded_buffer.hpp
+++ b/host/include/uhd/transport/bounded_buffer.hpp
@@ -20,13 +20,9 @@
 
 #include <uhd/config.hpp>
 #include <boost/shared_ptr.hpp>
-#include <boost/date_time/posix_time/posix_time_types.hpp>
 
 namespace uhd{ namespace transport{
 
-    //! typedef for the time duration type for wait operations
-    typedef boost::posix_time::time_duration time_duration_t;
-
     /*!
      * Implement a templated bounded buffer:
      * Used for passing elements between threads in a producer-consumer model.
@@ -64,10 +60,10 @@ namespace uhd{ namespace transport{
          * Push a new element into the bounded_buffer.
          * Wait until the bounded_buffer becomes non-full or timeout.
          * \param elem the new element to push
-         * \param time the timeout time
+         * \param timeout the timeout in seconds
          * \return false when the operation times out
          */
-        virtual bool push_with_timed_wait(const elem_type &elem, const time_duration_t &time) = 0;
+        virtual bool push_with_timed_wait(const elem_type &elem, double timeout) = 0;
 
         /*!
          * Pop an element from the bounded_buffer.
@@ -80,10 +76,10 @@ namespace uhd{ namespace transport{
          * Pop an element from the bounded_buffer.
          * Wait until the bounded_buffer becomes non-empty or timeout.
          * \param elem the element reference pop to
-         * \param time the timeout time
+         * \param timeout the timeout in seconds
          * \return false when the operation times out
          */
-        virtual bool pop_with_timed_wait(elem_type &elem, const time_duration_t &time) = 0;
+        virtual bool pop_with_timed_wait(elem_type &elem, double timeout) = 0;
 
         /*!
          * Clear all elements from the bounded_buffer.
diff --git a/host/include/uhd/transport/bounded_buffer.ipp b/host/include/uhd/transport/bounded_buffer.ipp
index e106e229e..71143741e 100644
--- a/host/include/uhd/transport/bounded_buffer.ipp
+++ b/host/include/uhd/transport/bounded_buffer.ipp
@@ -21,6 +21,7 @@
 #include <boost/bind.hpp>
 #include <boost/circular_buffer.hpp>
 #include <boost/thread/condition.hpp>
+#include <boost/date_time/posix_time/posix_time_types.hpp>
 
 namespace uhd{ namespace transport{ namespace{ /*anon*/
 
@@ -57,9 +58,12 @@ namespace uhd{ namespace transport{ namespace{ /*anon*/
             _empty_cond.notify_one();
         }
 
-        bool push_with_timed_wait(const elem_type &elem, const time_duration_t &time){
+        bool push_with_timed_wait(const elem_type &elem, double timeout){
             boost::unique_lock<boost::mutex> lock(_mutex);
-            if (not _full_cond.timed_wait(lock, time, boost::bind(&bounded_buffer_impl<elem_type>::not_full, this))) return false;
+            if (not _full_cond.timed_wait(
+                lock, boost::posix_time::microseconds(long(timeout*1e6)),
+                boost::bind(&bounded_buffer_impl<elem_type>::not_full, this)
+            )) return false;
             _buffer.push_front(elem);
             lock.unlock();
             _empty_cond.notify_one();
@@ -74,9 +78,12 @@ namespace uhd{ namespace transport{ namespace{ /*anon*/
             _full_cond.notify_one();
         }
 
-        bool pop_with_timed_wait(elem_type &elem, const time_duration_t &time){
+        bool pop_with_timed_wait(elem_type &elem, double timeout){
             boost::unique_lock<boost::mutex> lock(_mutex);
-            if (not _empty_cond.timed_wait(lock, time, boost::bind(&bounded_buffer_impl<elem_type>::not_empty, this))) return false;
+            if (not _empty_cond.timed_wait(
+                lock, boost::posix_time::microseconds(long(timeout*1e6)),
+                boost::bind(&bounded_buffer_impl<elem_type>::not_empty, this)
+            )) return false;
             elem = _buffer.back(); _buffer.pop_back();
             lock.unlock();
             _full_cond.notify_one();
diff --git a/host/include/uhd/transport/zero_copy.hpp b/host/include/uhd/transport/zero_copy.hpp
index 8ecafd3fb..ba19b193c 100644
--- a/host/include/uhd/transport/zero_copy.hpp
+++ b/host/include/uhd/transport/zero_copy.hpp
@@ -122,10 +122,10 @@ namespace uhd{ namespace transport{
 
         /*!
          * Get a new receive buffer from this transport object.
-         * \param timeout_ms the timeout to get the buffer in ms
+         * \param timeout the timeout to get the buffer in seconds
          * \return a managed buffer, or null sptr on timeout/error
          */
-        virtual managed_recv_buffer::sptr get_recv_buff(size_t timeout_ms) = 0;
+        virtual managed_recv_buffer::sptr get_recv_buff(double timeout = 0.1) = 0;
 
         /*!
          * Get the maximum number of receive frames:
@@ -138,9 +138,10 @@ namespace uhd{ namespace transport{
 
         /*!
          * Get a new send buffer from this transport object.
+         * \param timeout the timeout to get the buffer in seconds
          * \return a managed buffer, or null sptr on timeout/error
          */
-        virtual managed_send_buffer::sptr get_send_buff(void) = 0;
+        virtual managed_send_buffer::sptr get_send_buff(double timeout = 0.1) = 0;
 
         /*!
          * Get the maximum number of send frames:
@@ -172,19 +173,19 @@ namespace uhd{ namespace transport{
 
         /*!
          * Get a new receive buffer from this transport object.
-         * \param timeout_ms the timeout to get the buffer in ms
+         * \param timeout the timeout to get the buffer in seconds
          * \return a managed buffer, or null sptr on timeout/error
          */
-        managed_recv_buffer::sptr get_recv_buff(size_t timeout_ms);
+        managed_recv_buffer::sptr get_recv_buff(double timeout);
 
     private:
         /*!
          * Perform a private copying recv.
          * \param buff the buffer to write data into
-         * \param timeout_ms the timeout to get the buffer in ms
+         * \param timeout the timeout to get the buffer in seconds
          * \return the number of bytes written to buff, 0 for timeout, negative for error
          */
-        virtual ssize_t recv(const boost::asio::mutable_buffer &buff, size_t timeout_ms) = 0;
+        virtual ssize_t recv(const boost::asio::mutable_buffer &buff, double timeout) = 0;
 
         UHD_PIMPL_DECL(impl) _impl;
     };
@@ -208,9 +209,10 @@ namespace uhd{ namespace transport{
 
         /*!
          * Get a new send buffer from this transport object.
+         * \param timeout the timeout to get the buffer in seconds
          * \return a managed buffer, or null sptr on timeout/error
          */
-        managed_send_buffer::sptr get_send_buff(void);
+        managed_send_buffer::sptr get_send_buff(double timeout);
 
     private:
         /*!
diff --git a/host/lib/transport/libusb1_zero_copy.cpp b/host/lib/transport/libusb1_zero_copy.cpp
index f9beb0b4c..7f2bc3468 100644
--- a/host/lib/transport/libusb1_zero_copy.cpp
+++ b/host/lib/transport/libusb1_zero_copy.cpp
@@ -24,12 +24,10 @@
 #include <boost/thread.hpp>
 #include <vector>
 #include <iostream>
-#include <iomanip>
 
 using namespace uhd::transport;
 
-const int libusb_timeout = 0;
-
+static const double CLEANUP_TIMEOUT   = 0.2;    //seconds
 static const size_t DEFAULT_NUM_XFERS = 16;     //num xfers
 static const size_t DEFAULT_XFER_SIZE = 32*512; //bytes
 
@@ -84,10 +82,10 @@ public:
      * Get an available transfer:
      * For inputs, this is a just filled transfer.
      * For outputs, this is a just emptied transfer.
-     * \param timeout_ms the timeout to wait for a lut
+     * \param timeout the timeout to wait for a lut
      * \return the transfer pointer or NULL if timeout
      */
-    libusb_transfer *get_lut_with_wait(size_t timeout_ms = 100);
+    libusb_transfer *get_lut_with_wait(double timeout);
 
     //Callback use only
     void callback_handle_transfer(libusb_transfer *lut);
@@ -187,7 +185,7 @@ usb_endpoint::~usb_endpoint(void){
     }
 
     //collect canceled transfers (drain the queue)
-    while (this->get_lut_with_wait() != NULL){};
+    while (this->get_lut_with_wait(CLEANUP_TIMEOUT) != NULL){};
 
     //free all transfers
     BOOST_FOREACH(libusb_transfer *lut, _all_luts){
@@ -274,12 +272,10 @@ void usb_endpoint::print_transfer_status(libusb_transfer *lut){
     }
 }
 
-libusb_transfer *usb_endpoint::get_lut_with_wait(size_t timeout_ms){
+libusb_transfer *usb_endpoint::get_lut_with_wait(double timeout){
     boost::this_thread::disable_interruption di; //disable because the wait can throw
     libusb_transfer *lut;
-    if (_completed_list->pop_with_timed_wait(
-        lut, boost::posix_time::milliseconds(timeout_ms)
-    )) return lut;
+    if (_completed_list->pop_with_timed_wait(lut, timeout)) return lut;
     return NULL;
 }
 
@@ -399,8 +395,8 @@ public:
         size_t send_xfer_size, size_t send_num_xfers
     );
 
-    managed_recv_buffer::sptr get_recv_buff(size_t timeout_ms);
-    managed_send_buffer::sptr get_send_buff(void);
+    managed_recv_buffer::sptr get_recv_buff(double);
+    managed_send_buffer::sptr get_send_buff(double);
 
     size_t get_num_recv_frames(void) const { return _recv_num_frames; }
     size_t get_num_send_frames(void) const { return _send_num_frames; }
@@ -459,8 +455,8 @@ libusb_zero_copy_impl::libusb_zero_copy_impl(
  * Return empty pointer if no transfer is available (timeout or error).
  * \return pointer to a managed receive buffer
  */
-managed_recv_buffer::sptr libusb_zero_copy_impl::get_recv_buff(size_t timeout_ms){
-    libusb_transfer *lut = _recv_ep->get_lut_with_wait(timeout_ms);
+managed_recv_buffer::sptr libusb_zero_copy_impl::get_recv_buff(double timeout){
+    libusb_transfer *lut = _recv_ep->get_lut_with_wait(timeout);
     if (lut == NULL) {
         return managed_recv_buffer::sptr();
     }
@@ -478,8 +474,8 @@ managed_recv_buffer::sptr libusb_zero_copy_impl::get_recv_buff(size_t timeout_ms
  * (timeout or error).
  * \return pointer to a managed send buffer
  */
-managed_send_buffer::sptr libusb_zero_copy_impl::get_send_buff(void){
-    libusb_transfer *lut = _send_ep->get_lut_with_wait(/* TODO timeout API */);
+managed_send_buffer::sptr libusb_zero_copy_impl::get_send_buff(double timeout){
+    libusb_transfer *lut = _send_ep->get_lut_with_wait(timeout);
     if (lut == NULL) {
         return managed_send_buffer::sptr();
     }
@@ -494,18 +490,18 @@ managed_send_buffer::sptr libusb_zero_copy_impl::get_send_buff(void){
  * USB zero_copy make functions
  **********************************************************************/
 usb_zero_copy::sptr usb_zero_copy::make(
-	usb_device_handle::sptr handle,
+    usb_device_handle::sptr handle,
     unsigned int recv_endpoint, unsigned int send_endpoint,
-	size_t recv_xfer_size, size_t recv_num_xfers,
-	size_t send_xfer_size, size_t send_num_xfers
+    size_t recv_xfer_size, size_t recv_num_xfers,
+    size_t send_xfer_size, size_t send_num_xfers
 ){
     libusb::device_handle::sptr dev_handle(libusb::device_handle::get_cached_handle(
         boost::static_pointer_cast<libusb::special_handle>(handle)->get_device()
     ));
     return sptr(new libusb_zero_copy_impl(
-		dev_handle,
-		recv_endpoint,  send_endpoint,
-		recv_xfer_size, recv_num_xfers,
-		send_xfer_size, send_num_xfers
+        dev_handle,
+        recv_endpoint,  send_endpoint,
+        recv_xfer_size, recv_num_xfers,
+        send_xfer_size, send_num_xfers
     ));
 }
diff --git a/host/lib/transport/udp_zero_copy_asio.cpp b/host/lib/transport/udp_zero_copy_asio.cpp
index 0a6c9f2af..3130830a5 100644
--- a/host/lib/transport/udp_zero_copy_asio.cpp
+++ b/host/lib/transport/udp_zero_copy_asio.cpp
@@ -109,11 +109,11 @@ private:
     boost::asio::io_service        _io_service;
     int                            _sock_fd;
 
-    ssize_t recv(const boost::asio::mutable_buffer &buff, size_t timeout_ms){
+    ssize_t recv(const boost::asio::mutable_buffer &buff, double timeout){
         //setup timeval for timeout
         timeval tv;
         tv.tv_sec = 0;
-        tv.tv_usec = timeout_ms*1000;
+        tv.tv_usec = long(timeout*1e6);
 
         //setup rset for timeout
         fd_set rset;
diff --git a/host/lib/transport/vrt_packet_handler.hpp b/host/lib/transport/vrt_packet_handler.hpp
index b603f1371..e11afff30 100644
--- a/host/lib/transport/vrt_packet_handler.hpp
+++ b/host/lib/transport/vrt_packet_handler.hpp
@@ -303,18 +303,18 @@ template <typename T> UHD_INLINE T get_context_code(
      * Pack a vrt header, copy-convert the data, and send it.
      *  - helper function for vrt_packet_handler::send
      ******************************************************************/
-    static UHD_INLINE void _send1(
+    static UHD_INLINE size_t _send1(
         send_state &state,
         const std::vector<const void *> &buffs,
-        size_t offset_bytes,
-        size_t num_samps,
+        const size_t offset_bytes,
+        const size_t num_samps,
         uhd::transport::vrt::if_packet_info_t &if_packet_info,
         const uhd::io_type_t &io_type,
         const uhd::otw_type_t &otw_type,
         const vrt_packer_t &vrt_packer,
         const get_send_buffs_t &get_send_buffs,
-        size_t vrt_header_offset_words32,
-        size_t chans_per_otw_buff
+        const size_t vrt_header_offset_words32,
+        const size_t chans_per_otw_buff
     ){
         //load the rest of the if_packet_info in here
         if_packet_info.num_payload_words32 = (num_samps*chans_per_otw_buff*otw_type.get_sample_size())/sizeof(boost::uint32_t);
@@ -322,7 +322,7 @@ template <typename T> UHD_INLINE T get_context_code(
 
         //get send buffers for each channel
         managed_send_buffs_t send_buffs(buffs.size()/chans_per_otw_buff);
-        UHD_ASSERT_THROW(get_send_buffs(send_buffs));
+        if (not get_send_buffs(send_buffs)) return 0;
 
         std::vector<const void *> io_buffs(chans_per_otw_buff);
         for (size_t i = 0; i < buffs.size(); i+=chans_per_otw_buff){
@@ -347,6 +347,7 @@ template <typename T> UHD_INLINE T get_context_code(
                 std::cerr << "commit to send buffer returned less than commit size" << std::endl;
             }
         }
+        return num_samps;
     }
 
     /*******************************************************************
@@ -381,7 +382,6 @@ template <typename T> UHD_INLINE T get_context_code(
         ////////////////////////////////////////////////////////////////
         case uhd::device::SEND_MODE_ONE_PACKET:{
         ////////////////////////////////////////////////////////////////
-            size_t num_samps = std::min(total_num_samps, max_samples_per_packet);
 
             //fill in parts of the packet info overwrote in full buff mode
             if_packet_info.has_tsi = metadata.has_time_spec;
@@ -389,10 +389,10 @@ template <typename T> UHD_INLINE T get_context_code(
             if_packet_info.sob = metadata.start_of_burst;
             if_packet_info.eob = metadata.end_of_burst;
 
-            _send1(
+            return _send1(
                 state,
                 buffs, 0,
-                num_samps,
+                std::min(total_num_samps, max_samples_per_packet),
                 if_packet_info,
                 io_type, otw_type,
                 vrt_packer,
@@ -400,31 +400,32 @@ template <typename T> UHD_INLINE T get_context_code(
                 vrt_header_offset_words32,
                 chans_per_otw_buff
             );
-            return num_samps;
         }
 
         ////////////////////////////////////////////////////////////////
         case uhd::device::SEND_MODE_FULL_BUFF:{
         ////////////////////////////////////////////////////////////////
-            //calculate constants for fragmentation
-            const size_t num_fragments = (total_num_samps+max_samples_per_packet-1)/max_samples_per_packet;
-            static const size_t first_fragment_index = 0;
-            const size_t final_fragment_index = num_fragments-1;
+            size_t total_num_samps_sent = 0;
 
             //loop through the following fragment indexes
-            for (size_t n = first_fragment_index; n <= final_fragment_index; n++){
+            while(total_num_samps_sent < total_num_samps){
+
+                //calculate per-loop-iteration variables
+                const size_t total_num_samps_unsent = total_num_samps - total_num_samps_sent;
+                const bool first_fragment = (total_num_samps_sent == 0);
+                const bool final_fragment = (total_num_samps_unsent <= max_samples_per_packet);
 
                 //calculate new flags for the fragments
-                if_packet_info.has_tsi = metadata.has_time_spec  and (n == first_fragment_index);
-                if_packet_info.has_tsf = metadata.has_time_spec  and (n == first_fragment_index);
-                if_packet_info.sob     = metadata.start_of_burst and (n == first_fragment_index);
-                if_packet_info.eob     = metadata.end_of_burst   and (n == final_fragment_index);
+                if_packet_info.has_tsi = metadata.has_time_spec  and first_fragment;
+                if_packet_info.has_tsf = if_packet_info.has_tsi;
+                if_packet_info.sob     = metadata.start_of_burst and first_fragment;
+                if_packet_info.eob     = metadata.end_of_burst   and final_fragment;
 
                 //send the fragment with the helper function
-                _send1(
+                const size_t num_samps_sent = _send1(
                     state,
-                    buffs, n*max_samples_per_packet*io_type.size,
-                    (n == final_fragment_index)?(total_num_samps%max_samples_per_packet):max_samples_per_packet,
+                    buffs, total_num_samps_sent*io_type.size,
+                    std::min(total_num_samps_unsent, max_samples_per_packet),
                     if_packet_info,
                     io_type, otw_type,
                     vrt_packer,
@@ -432,8 +433,10 @@ template <typename T> UHD_INLINE T get_context_code(
                     vrt_header_offset_words32,
                     chans_per_otw_buff
                 );
+                total_num_samps_sent += num_samps_sent;
+                if (num_samps_sent == 0) return total_num_samps_sent;
             }
-            return total_num_samps;
+            return total_num_samps_sent;
         }
 
         default: throw std::runtime_error("unknown send mode");
diff --git a/host/lib/transport/zero_copy.cpp b/host/lib/transport/zero_copy.cpp
index 1fcf846a0..dfb65951f 100644
--- a/host/lib/transport/zero_copy.cpp
+++ b/host/lib/transport/zero_copy.cpp
@@ -68,12 +68,12 @@ phony_zero_copy_recv_if::~phony_zero_copy_recv_if(void){
     /* NOP */
 }
 
-managed_recv_buffer::sptr phony_zero_copy_recv_if::get_recv_buff(size_t timeout_ms){
+managed_recv_buffer::sptr phony_zero_copy_recv_if::get_recv_buff(double timeout){
     //allocate memory
     boost::uint8_t *recv_mem = new boost::uint8_t[_impl->max_buff_size];
 
     //call recv() with timeout option
-    ssize_t num_bytes = this->recv(boost::asio::buffer(recv_mem, _impl->max_buff_size), timeout_ms);
+    ssize_t num_bytes = this->recv(boost::asio::buffer(recv_mem, _impl->max_buff_size), timeout);
 
     if (num_bytes <= 0) return managed_recv_buffer::sptr(); //NULL sptr
 
@@ -138,6 +138,6 @@ phony_zero_copy_send_if::~phony_zero_copy_send_if(void){
     delete [] _impl->send_mem;
 }
 
-managed_send_buffer::sptr phony_zero_copy_send_if::get_send_buff(void){
+managed_send_buffer::sptr phony_zero_copy_send_if::get_send_buff(double){
     return _impl->send_buff; //FIXME there is only ever one send buff, we assume that the caller doesnt hang onto these
 }
diff --git a/host/lib/usrp/usrp1/io_impl.cpp b/host/lib/usrp/usrp1/io_impl.cpp
index aee760a83..8d9c68961 100644
--- a/host/lib/usrp/usrp1/io_impl.cpp
+++ b/host/lib/usrp/usrp1/io_impl.cpp
@@ -94,12 +94,13 @@ struct usrp1_impl::io_impl{
     //all of this to ensure only full buffers are committed
     managed_send_buffer::sptr send_buff;
     size_t num_bytes_committed;
+    double send_timeout;
     boost::uint8_t pseudo_buff[BYTES_PER_PACKET];
     ssize_t phony_commit_pseudo_buff(size_t num_bytes);
     ssize_t phony_commit_send_buff(size_t num_bytes);
     ssize_t commit_send_buff(void);
     void flush_send_buff(void);
-    bool get_send_buffs(vrt_packet_handler::managed_send_buffs_t &);
+    bool get_send_buffs(vrt_packet_handler::managed_send_buffs_t &, double);
 
     //helpers to get at the send buffer + offset
     inline void *get_send_mem_ptr(void){
@@ -159,14 +160,15 @@ void usrp1_impl::io_impl::flush_send_buff(void){
  */
 ssize_t usrp1_impl::io_impl::commit_send_buff(void){
     ssize_t ret = send_buff->commit(num_bytes_committed);
-    send_buff = data_transport->get_send_buff();
+    send_buff = data_transport->get_send_buff(send_timeout);
     num_bytes_committed = 0;
     return ret;
 }
 
 bool usrp1_impl::io_impl::get_send_buffs(
-    vrt_packet_handler::managed_send_buffs_t &buffs
+    vrt_packet_handler::managed_send_buffs_t &buffs, double timeout
 ){
+    send_timeout = timeout;
     UHD_ASSERT_THROW(buffs.size() == 1);
 
     //not enough bytes free -> use the pseudo buffer
@@ -216,7 +218,7 @@ static void usrp1_bs_vrt_packer(
 size_t usrp1_impl::send(
     const std::vector<const void *> &buffs, size_t num_samps,
     const tx_metadata_t &metadata, const io_type_t &io_type,
-    send_mode_t send_mode
+    send_mode_t send_mode, double timeout
 ){
     size_t num_samps_sent = vrt_packet_handler::send(
         _io_impl->packet_handler_send_state,       //last state of the send handler
@@ -225,7 +227,7 @@ size_t usrp1_impl::send(
         io_type, _tx_otw_type,                     //input and output types to convert
         _clock_ctrl->get_master_clock_freq(),      //master clock tick rate
         &usrp1_bs_vrt_packer,
-        boost::bind(&usrp1_impl::io_impl::get_send_buffs, _io_impl.get(), _1),
+        boost::bind(&usrp1_impl::io_impl::get_send_buffs, _io_impl.get(), _1, timeout),
         get_max_send_samps_per_packet(),
         0,                                         //vrt header offset
         _tx_subdev_spec.size()                     //num channels
@@ -272,18 +274,18 @@ static void usrp1_bs_vrt_unpacker(
 }
 
 static bool get_recv_buffs(
-    zero_copy_if::sptr zc_if, size_t timeout_ms,
+    zero_copy_if::sptr zc_if, double timeout,
     vrt_packet_handler::managed_recv_buffs_t &buffs
 ){
     UHD_ASSERT_THROW(buffs.size() == 1);
-    buffs[0] = zc_if->get_recv_buff(timeout_ms);
+    buffs[0] = zc_if->get_recv_buff(timeout);
     return buffs[0].get() != NULL;
 }
 
 size_t usrp1_impl::recv(
     const std::vector<void *> &buffs, size_t num_samps,
     rx_metadata_t &metadata, const io_type_t &io_type,
-    recv_mode_t recv_mode, size_t timeout_ms
+    recv_mode_t recv_mode, double timeout
 ){
     size_t num_samps_recvd = vrt_packet_handler::recv(
         _io_impl->packet_handler_recv_state,       //last state of the recv handler
@@ -292,7 +294,7 @@ size_t usrp1_impl::recv(
         io_type, _rx_otw_type,                     //input and output types to convert
         _clock_ctrl->get_master_clock_freq(),      //master clock tick rate
         &usrp1_bs_vrt_unpacker,
-        boost::bind(&get_recv_buffs, _data_transport, timeout_ms, _1),
+        boost::bind(&get_recv_buffs, _data_transport, timeout, _1),
         &vrt_packet_handler::handle_overflow_nop,
         0,                                         //vrt header offset
         _rx_subdev_spec.size()                     //num channels
diff --git a/host/lib/usrp/usrp1/usrp1_impl.cpp b/host/lib/usrp/usrp1/usrp1_impl.cpp
index 156fc119f..6ebd6bb09 100644
--- a/host/lib/usrp/usrp1/usrp1_impl.cpp
+++ b/host/lib/usrp/usrp1/usrp1_impl.cpp
@@ -209,9 +209,9 @@ usrp1_impl::~usrp1_impl(void){
     /* NOP */
 }
 
-bool usrp1_impl::recv_async_msg(uhd::async_metadata_t &, size_t timeout_ms){
+bool usrp1_impl::recv_async_msg(uhd::async_metadata_t &, double timeout){
     //dummy fill-in for the recv_async_msg
-    boost::this_thread::sleep(boost::posix_time::milliseconds(timeout_ms));
+    boost::this_thread::sleep(boost::posix_time::microseconds(long(timeout*1e6)));
     return false;
 }
 
diff --git a/host/lib/usrp/usrp1/usrp1_impl.hpp b/host/lib/usrp/usrp1/usrp1_impl.hpp
index 20ae3c02a..f2c464610 100644
--- a/host/lib/usrp/usrp1/usrp1_impl.hpp
+++ b/host/lib/usrp/usrp1/usrp1_impl.hpp
@@ -83,13 +83,12 @@ public:
                 size_t,
                 const uhd::tx_metadata_t &,
                 const uhd::io_type_t &,
-                send_mode_t);
+                send_mode_t, double);
 
     size_t recv(const std::vector<void *> &,
                 size_t, uhd::rx_metadata_t &,
                 const uhd::io_type_t &,
-                recv_mode_t,
-                size_t timeout);
+                recv_mode_t, double);
 
     static const size_t BYTES_PER_PACKET = 512*4; //under the transfer size
 
@@ -101,7 +100,7 @@ public:
         return BYTES_PER_PACKET/_rx_otw_type.get_sample_size()/_rx_subdev_spec.size();
     }
 
-    bool recv_async_msg(uhd::async_metadata_t &, size_t);
+    bool recv_async_msg(uhd::async_metadata_t &, double);
 
 private:
     /*!
diff --git a/host/lib/usrp/usrp2/io_impl.cpp b/host/lib/usrp/usrp2/io_impl.cpp
index 3395f94e2..c0d8ab029 100644
--- a/host/lib/usrp/usrp2/io_impl.cpp
+++ b/host/lib/usrp/usrp2/io_impl.cpp
@@ -33,7 +33,6 @@ using namespace uhd::transport;
 namespace asio = boost::asio;
 
 static const int underflow_flags = async_metadata_t::EVENT_CODE_UNDERFLOW | async_metadata_t::EVENT_CODE_UNDERFLOW_IN_PACKET;
-static const double RECV_TIMEOUT_MS = 100;
 
 /***********************************************************************
  * io impl details (internal to this file)
@@ -59,9 +58,9 @@ struct usrp2_impl::io_impl{
         recv_pirate_crew.join_all();
     }
 
-    bool get_recv_buffs(vrt_packet_handler::managed_recv_buffs_t &buffs, size_t timeout_ms){
+    bool get_recv_buffs(vrt_packet_handler::managed_recv_buffs_t &buffs, double timeout){
         boost::this_thread::disable_interruption di; //disable because the wait can throw
-        return recv_pirate_booty->pop_elems_with_timed_wait(buffs, boost::posix_time::milliseconds(timeout_ms));
+        return recv_pirate_booty->pop_elems_with_timed_wait(buffs, timeout);
     }
 
     //state management for the vrt packet handler code
@@ -91,7 +90,7 @@ void usrp2_impl::io_impl::recv_pirate_loop(
     size_t next_packet_seq = 0;
 
     while(recv_pirate_crew_raiding){
-        managed_recv_buffer::sptr buff = zc_if->get_recv_buff(RECV_TIMEOUT_MS);
+        managed_recv_buffer::sptr buff = zc_if->get_recv_buff();
         if (not buff.get()) continue; //ignore timeout/error buffers
 
         try{
@@ -151,7 +150,7 @@ void usrp2_impl::io_init(void){
         std::memcpy(send_buff->cast<void*>(), &data, sizeof(data));
         send_buff->commit(sizeof(data));
         //drain the recv buffers (may have junk)
-        while (data_transport->get_recv_buff(RECV_TIMEOUT_MS).get()){};
+        while (data_transport->get_recv_buff().get()){};
     }
 
     //the number of recv frames is the number for the first transport
@@ -179,12 +178,10 @@ void usrp2_impl::io_init(void){
  * Async Data
  **********************************************************************/
 bool usrp2_impl::recv_async_msg(
-    async_metadata_t &async_metadata, size_t timeout_ms
+    async_metadata_t &async_metadata, double timeout
 ){
     boost::this_thread::disable_interruption di; //disable because the wait can throw
-    return _io_impl->async_msg_fifo->pop_with_timed_wait(
-        async_metadata, boost::posix_time::milliseconds(timeout_ms)
-    );
+    return _io_impl->async_msg_fifo->pop_with_timed_wait(async_metadata, timeout);
 }
 
 /***********************************************************************
@@ -192,19 +189,22 @@ bool usrp2_impl::recv_async_msg(
  **********************************************************************/
 static bool get_send_buffs(
     const std::vector<udp_zero_copy::sptr> &trans,
-    vrt_packet_handler::managed_send_buffs_t &buffs
+    vrt_packet_handler::managed_send_buffs_t &buffs,
+    double timeout
 ){
     UHD_ASSERT_THROW(trans.size() == buffs.size());
+    bool good = true;
     for (size_t i = 0; i < buffs.size(); i++){
-        buffs[i] = trans[i]->get_send_buff();
+        buffs[i] = trans[i]->get_send_buff(timeout);
+        good = good and (buffs[i].get() != NULL);
     }
-    return true;
+    return good;
 }
 
 size_t usrp2_impl::send(
     const std::vector<const void *> &buffs, size_t num_samps,
     const tx_metadata_t &metadata, const io_type_t &io_type,
-    send_mode_t send_mode
+    send_mode_t send_mode, double timeout
 ){
     return vrt_packet_handler::send(
         _io_impl->packet_handler_send_state,       //last state of the send handler
@@ -213,7 +213,7 @@ size_t usrp2_impl::send(
         io_type, _io_helper.get_tx_otw_type(),     //input and output types to convert
         _mboards.front()->get_master_clock_freq(), //master clock tick rate
         uhd::transport::vrt::if_hdr_pack_be,
-        boost::bind(&get_send_buffs, _data_transports, _1),
+        boost::bind(&get_send_buffs, _data_transports, _1, timeout),
         get_max_send_samps_per_packet()
     );
 }
@@ -224,7 +224,7 @@ size_t usrp2_impl::send(
 size_t usrp2_impl::recv(
     const std::vector<void *> &buffs, size_t num_samps,
     rx_metadata_t &metadata, const io_type_t &io_type,
-    recv_mode_t recv_mode, size_t timeout_ms
+    recv_mode_t recv_mode, double timeout
 ){
     return vrt_packet_handler::recv(
         _io_impl->packet_handler_recv_state,       //last state of the recv handler
@@ -233,6 +233,6 @@ size_t usrp2_impl::recv(
         io_type, _io_helper.get_rx_otw_type(),     //input and output types to convert
         _mboards.front()->get_master_clock_freq(), //master clock tick rate
         uhd::transport::vrt::if_hdr_unpack_be,
-        boost::bind(&usrp2_impl::io_impl::get_recv_buffs, _io_impl.get(), _1, timeout_ms)
+        boost::bind(&usrp2_impl::io_impl::get_recv_buffs, _io_impl.get(), _1, timeout)
     );
 }
diff --git a/host/lib/usrp/usrp2/usrp2_impl.hpp b/host/lib/usrp/usrp2/usrp2_impl.hpp
index 157d17057..e8763b284 100644
--- a/host/lib/usrp/usrp2/usrp2_impl.hpp
+++ b/host/lib/usrp/usrp2/usrp2_impl.hpp
@@ -234,7 +234,7 @@ public:
     size_t send(
         const std::vector<const void *> &, size_t,
         const uhd::tx_metadata_t &, const uhd::io_type_t &,
-        uhd::device::send_mode_t
+        uhd::device::send_mode_t, double
     );
     size_t get_max_recv_samps_per_packet(void) const{
         return _io_helper.get_max_recv_samps_per_packet();
@@ -242,9 +242,9 @@ public:
     size_t recv(
         const std::vector<void *> &, size_t,
         uhd::rx_metadata_t &, const uhd::io_type_t &,
-        uhd::device::recv_mode_t, size_t
+        uhd::device::recv_mode_t, double
     );
-    bool recv_async_msg(uhd::async_metadata_t &, size_t);
+    bool recv_async_msg(uhd::async_metadata_t &, double);
 
 private:
     //device properties interface
diff --git a/host/test/buffer_test.cpp b/host/test/buffer_test.cpp
index aadb3f951..8445412e7 100644
--- a/host/test/buffer_test.cpp
+++ b/host/test/buffer_test.cpp
@@ -23,7 +23,7 @@
 using namespace boost::assign;
 using namespace uhd::transport;
 
-static const boost::posix_time::milliseconds timeout(10);
+static const double timeout = 0.01/*secs*/;
 
 BOOST_AUTO_TEST_CASE(test_bounded_buffer_with_timed_wait){
     bounded_buffer<int>::sptr bb(bounded_buffer<int>::make(3));