Merge lp:~aacid/qtmir/unlikelyResetStartTime into lp:~aacid/qtmir/timestampsInPast

[Albert Astals Cid]

Provide branch prediction information to the if in compressTimestamp

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Prerequisite

 * Did you perform an exploratory manual test run of your code change and any related functionality?
Yes

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[Albert Astals Cid (aacid)]

This seems a pretty hot path and 99.999% of the times the if evaluates to false so i thought it might make sense telling the compiler to optimize for that.

[lp:~aacid/qtmir/unlikelyResetStartTime]

431. By Albert Astals Cid on 2015-12-15

Use Qt's unlikely define since we're already using Qt here

[Gerry Boland (gerboland)]

review: Approve

Unmerged revisions

431. By Albert Astals Cid on 2015-12-15

Use Qt's unlikely define since we're already using Qt here

430. By Albert Astals Cid on 2015-12-15

Provide branch prediction information to the if in compressTimestamp

=== modified file 'src/common/timestamp_impl.h'
--- src/common/timestamp_impl.h	2015-12-15 11:04:54 +0000
+++ src/common/timestamp_impl.h	2015-12-15 11:25:54 +0000
@@ -15,9 +15,9 @@
 {
     std::chrono::nanoseconds startTime = getStartTime(timestamp);
 
-    if ((std::chrono::nanoseconds::max() > T::max() &&
-         timestamp - startTime > std::chrono::nanoseconds(T::max()))
-        || timestamp < startTime) {
+    if (Q_UNLIKELY((std::chrono::nanoseconds::max() > T::max() &&
+                    timestamp - startTime > std::chrono::nanoseconds(T::max()))
+                   || timestamp < startTime)) {
         // we've overflowed the boundaries of the millisecond type.
         // or the timestamp has travelled to the past
         resetStartTime(timestamp);