SERVER-37756 add logging for the amount of time spent blocked on a prepare conflict

1 files changed, 15 insertions, 0 deletions

diff --git a/src/mongo/db/prepare_conflict_tracker.cpp b/src/mongo/db/prepare_conflict_tracker.cpp
index 25120459408..1ec1bb9c89a 100644
--- a/src/mongo/db/prepare_conflict_tracker.cpp
+++ b/src/mongo/db/prepare_conflict_tracker.cpp
@@ -40,13 +40,28 @@ bool PrepareConflictTracker::isWaitingOnPrepareConflict() const {
 }
 
 void PrepareConflictTracker::beginPrepareConflict() {
+    invariant(_prepareConflictStartTime == 0);
+    _prepareConflictStartTime = curTimeMicros64();
+
     // Implies that the current read operation is blocked on a prepared transaction.
     _waitOnPrepareConflict.store(true);
 }
 
 void PrepareConflictTracker::endPrepareConflict() {
+    // This function is called regardless whether there was a prepare conflict.
+    if (_prepareConflictStartTime > 0) {
+        invariant(_prepareConflictStartTime <= static_cast<long long>(curTimeMicros64()));
+        _prepareConflictDuration +=
+            Microseconds{static_cast<long long>(curTimeMicros64()) - _prepareConflictStartTime};
+    }
+    _prepareConflictStartTime = 0;
+
     // Implies that the current read operation is not blocked on a prepared transaction.
     _waitOnPrepareConflict.store(false);
 }
 
+Microseconds PrepareConflictTracker::getPrepareConflictDuration() {
+    return _prepareConflictDuration;
+}
+
 }  // namespace mongo