uhd: reworked the zero copy interface

- recv buffers have a release call
- safe make function for recv buffers (buff + release callback)
- send buffer commits now have a void return
- safe make function for send buffers (buff + commit callback)

The reason for the void return from commit is that ssize_t num_bytes was never returning anything of use.
That is for all of the zero copy implementations so far, commit cannot really error (being asynchronous).

libusb zero copy impl was reworked to support the new interface.
USRP1 io_impl with the psuedo managed buffer was replaced with safe_make.
Also, usrp1 io_impl was simplified greatly due to commit returning void now.
UDP zero copy asio was disabled (in this commit, until its reworked).
Phony send and recv interfaces were removed completely.

1 files changed, 16 insertions, 49 deletions

diff --git a/host/lib/usrp/usrp1/io_impl.cpp b/host/lib/usrp/usrp1/io_impl.cpp
index 8d9c68961..676b1536a 100644
--- a/host/lib/usrp/usrp1/io_impl.cpp
+++ b/host/lib/usrp/usrp1/io_impl.cpp
@@ -34,35 +34,6 @@ using namespace uhd::transport;
 namespace asio = boost::asio;
 
 /***********************************************************************
- * Pseudo send buffer implementation
- **********************************************************************/
-class pseudo_managed_send_buffer : public managed_send_buffer{
-public:
-
-    pseudo_managed_send_buffer(
-        const boost::asio::mutable_buffer &buff,
-        const boost::function<ssize_t(size_t)> &commit
-    ):
-        _buff(buff),
-        _commit(commit)
-    {
-        /* NOP */
-    }
-
-    ssize_t commit(size_t num_bytes){
-        return _commit(num_bytes);
-    }
-
-private:
-    const boost::asio::mutable_buffer &get(void) const{
-        return _buff;
-    }
-
-    const boost::asio::mutable_buffer      _buff;
-    const boost::function<ssize_t(size_t)> _commit;
-};
-
-/***********************************************************************
  * IO Implementation Details
  **********************************************************************/
 struct usrp1_impl::io_impl{
@@ -96,9 +67,9 @@ struct usrp1_impl::io_impl{
     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 phony_commit_pseudo_buff(size_t num_bytes);
+    void phony_commit_send_buff(size_t num_bytes);
+    void commit_send_buff(void);
     void flush_send_buff(void);
     bool get_send_buffs(vrt_packet_handler::managed_send_buffs_t &, double);
 
@@ -119,28 +90,25 @@ struct usrp1_impl::io_impl{
  *   The first loop iteration will fill the remainder of the send buffer.
  *   The second loop iteration will empty the pseudo buffer remainder.
  */
-ssize_t usrp1_impl::io_impl::phony_commit_pseudo_buff(size_t num_bytes){
+void usrp1_impl::io_impl::phony_commit_pseudo_buff(size_t num_bytes){
     size_t bytes_to_copy = num_bytes, bytes_copied = 0;
     while(bytes_to_copy){
         size_t bytes_copied_here = std::min(bytes_to_copy, get_send_mem_size());
         std::memcpy(get_send_mem_ptr(), pseudo_buff + bytes_copied, bytes_copied_here);
-        ssize_t ret = phony_commit_send_buff(bytes_copied_here);
-        if (ret < 0) return ret;
-        bytes_to_copy -= ret;
-        bytes_copied += ret;
+        phony_commit_send_buff(bytes_copied_here);
+        bytes_to_copy -= bytes_copied_here;
+        bytes_copied += bytes_copied_here;
     }
-    return bytes_copied;
 }
 
 /*!
  * Accept a commit of num bytes to the send buffer.
  * Conditionally commit the send buffer if full.
  */
-ssize_t usrp1_impl::io_impl::phony_commit_send_buff(size_t num_bytes){
+void usrp1_impl::io_impl::phony_commit_send_buff(size_t num_bytes){
     num_bytes_committed += num_bytes;
-    if (num_bytes_committed != send_buff->size()) return num_bytes;
-    ssize_t ret = commit_send_buff();
-    return (ret < 0)? ret : num_bytes;
+    if (num_bytes_committed != send_buff->size()) return;
+    commit_send_buff();
 }
 
 /*!
@@ -158,11 +126,10 @@ void usrp1_impl::io_impl::flush_send_buff(void){
  * Perform an actual commit on the send buffer:
  * Commit the contents of the send buffer and request a new buffer.
  */
-ssize_t usrp1_impl::io_impl::commit_send_buff(void){
-    ssize_t ret = send_buff->commit(num_bytes_committed);
+void usrp1_impl::io_impl::commit_send_buff(void){
+    send_buff->commit(num_bytes_committed);
     send_buff = data_transport->get_send_buff(send_timeout);
     num_bytes_committed = 0;
-    return ret;
 }
 
 bool usrp1_impl::io_impl::get_send_buffs(
@@ -173,17 +140,17 @@ bool usrp1_impl::io_impl::get_send_buffs(
 
     //not enough bytes free -> use the pseudo buffer
     if (get_send_mem_size() < BYTES_PER_PACKET){
-        buffs[0] = managed_send_buffer::sptr(new pseudo_managed_send_buffer(
+        buffs[0] = managed_send_buffer::make_safe(
             boost::asio::buffer(pseudo_buff),
             boost::bind(&usrp1_impl::io_impl::phony_commit_pseudo_buff, this, _1)
-        ));
+        );
     }
     //otherwise use the send buffer offset by the bytes written
     else{
-        buffs[0] = managed_send_buffer::sptr(new pseudo_managed_send_buffer(
+        buffs[0] = managed_send_buffer::make_safe(
             boost::asio::buffer(get_send_mem_ptr(), get_send_mem_size()),
             boost::bind(&usrp1_impl::io_impl::phony_commit_send_buff, this, _1)
-        ));
+        );
     }
 
     return buffs[0].get() != NULL;