3 files changed, 15 insertions, 4 deletions
diff --git a/host/include/uhd/device.hpp b/host/include/uhd/device.hpp
index 1a52867c9..47dfa4328 100644
--- a/host/include/uhd/device.hpp
+++ b/host/include/uhd/device.hpp
@@ -77,6 +77,9 @@ public:
      * It is up to the caller to call send again on the un-sent
      * portions of the buffer, until the buffer is exhausted.
      *
+     * This is a blocking call and will not return until the number
+     * of samples returned have been read out of the buffer.
+     *
      * \param buff a buffer pointing to some read-only memory
      * \param metadata data describing the buffer's contents
      * \param the type of data loaded in the buffer (32fc, 16sc)
@@ -101,6 +104,14 @@ public:
      * The next call to receive, after the remainder becomes exahausted,
      * will perform an over-the-wire receive as usual.
      *
+     * This is a blocking call and will not return until the number
+     * of samples returned have been written into the buffer.
+     * However, a call to receive may timeout and return zero samples.
+     * The timeout duration is decided by the underlying transport layer.
+     * The caller should assume that the call to receive will not return
+     * immediately when no packets are available to the transport layer,
+     * and that the timeout duration is reasonably tuned for performance.
+     *
      * \param buff the buffer to fill with IF data
      * \param metadata data to fill describing the buffer
      * \param the type of data to fill into the buffer (32fc, 16sc)
diff --git a/host/include/uhd/transport/udp_simple.hpp b/host/include/uhd/transport/udp_simple.hpp
index 8663128ec..0d8fcc5f0 100644
--- a/host/include/uhd/transport/udp_simple.hpp
+++ b/host/include/uhd/transport/udp_simple.hpp
@@ -67,9 +67,9 @@ public:
 
     /*!
      * Receive into the provided buffer.
-     * Returns empty when data is not available.
+     * Blocks until data is received or a timeout occurs.
      * \param buff a mutable buffer to receive into
-     * \return the number of bytes received.
+     * \return the number of bytes received or zero on timeout
      */
     virtual size_t recv(const boost::asio::mutable_buffer &buff) = 0;
 };
diff --git a/host/include/uhd/transport/udp_zero_copy.hpp b/host/include/uhd/transport/udp_zero_copy.hpp
index 9c3505dd6..1a8d822fd 100644
--- a/host/include/uhd/transport/udp_zero_copy.hpp
+++ b/host/include/uhd/transport/udp_zero_copy.hpp
@@ -64,9 +64,9 @@ public:
 
     /*!
      * Receive a buffer.
+     * Blocks until data is received or a timeout occurs.
      * The memory is managed by the implementation.
-     * Returns an empty buffer when data is not available.
-     * \return a smart buffer with memory and size
+     * \return a smart buffer (empty on timeout)
      */
     virtual smart_buffer::sptr recv(void) = 0;
 };