SERVER-18277 Track elapsed time on cursors using microsecond resolution on OperationContext.

This completes the mechanics of moving max-time tracking to OperationContext and
switching the checkForInterrupt checks to use the service context's fast clock
source, while tracking the amount of execution time remaining on a cursor with
microsecond granularity to ensure that remaining execution time always declines,
even for very brief operations on cursors.

This patch does not complete the transition from wait_for waiting to wait_until
waiting in all places that do waiting based on operation deadlines.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/mongo/util/timer.h b/src/mongo/util/timer.h
index c16ac255206..05a5936c69e 100644
--- a/src/mongo/util/timer.h
+++ b/src/mongo/util/timer.h
@@ -29,6 +29,8 @@
 
 #pragma once
 
+#include "mongo/util/time_support.h"
+
 
 namespace mongo {
 
@@ -76,6 +78,10 @@ public:
         return static_cast<long long>((now() - _old) * _microsPerCount);
     }
 
+    Microseconds elapsed() const {
+        return Microseconds{micros()};
+    }
+
     inline void reset() {
         _old = now();
     }