Improve efficiency of time measurement in tight loops

This patch instantiate a clock_t instance for each XS
socket. Thus, it is shared between subsequent calls
to xs_recv (and xs_send). That in turn significantly
limits the number of invocations of  getimeofday (or similar)
when timeouts are used and recv/send is called in a
tight loop.

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

2 files changed, 4 insertions, 3 deletions

diff --git a/src/socket_base.cpp b/src/socket_base.cpp
index 1f45fd6..39881d5 100644
--- a/src/socket_base.cpp
+++ b/src/socket_base.cpp
@@ -42,7 +42,6 @@
 #include "io_thread.hpp"
 #include "session_base.hpp"
 #include "config.hpp"
-#include "clock.hpp"
 #include "pipe.hpp"
 #include "err.hpp"
 #include "ctx.hpp"
@@ -558,7 +557,6 @@ int xs::socket_base_t::send (msg_t *msg_, int flags_)
 
     //  Compute the time when the timeout should occur.
     //  If the timeout is infite, don't care. 
-    clock_t clock ;
     uint64_t end = timeout < 0 ? 0 : (clock.now_ms () + timeout);
 
     //  Oops, we couldn't send the message. Wait for the next
@@ -643,7 +641,6 @@ int xs::socket_base_t::recv (msg_t *msg_, int flags_)
 
     //  Compute the time when the timeout should occur.
     //  If the timeout is infite, don't care. 
-    clock_t clock ;
     uint64_t end = timeout < 0 ? 0 : (clock.now_ms () + timeout);
 
     //  In blocking scenario, commands are processed over and over again until
diff --git a/src/socket_base.hpp b/src/socket_base.hpp
index 9225ce7..0f7dca8 100644
--- a/src/socket_base.hpp
+++ b/src/socket_base.hpp
@@ -32,6 +32,7 @@
 #include "atomic_counter.hpp"
 #include "mailbox.hpp"
 #include "stdint.hpp"
+#include "clock.hpp"
 #include "pipe.hpp"
 
 namespace xs
@@ -202,6 +203,9 @@ namespace xs
         //  True if the last message received had MORE flag set.
         bool rcvmore;
 
+        //  Improves efficiency of time measurement.
+        clock_t clock;
+
         socket_base_t (const socket_base_t&);
         const socket_base_t &operator = (const socket_base_t&);
     };