SERVER-24242 Lock::ParallelBatchWriterMode sets isBatchWriter while in scope

3 files changed, 12 insertions, 2 deletions

diff --git a/src/mongo/db/concurrency/d_concurrency.cpp b/src/mongo/db/concurrency/d_concurrency.cpp
index cf66b2e5620..0879f8bda4f 100644
--- a/src/mongo/db/concurrency/d_concurrency.cpp
+++ b/src/mongo/db/concurrency/d_concurrency.cpp
@@ -185,7 +185,14 @@ void Lock::OplogIntentWriteLock::serializeIfNeeded() {
 }
 
 Lock::ParallelBatchWriterMode::ParallelBatchWriterMode(Locker* lockState)
-    : _pbwm(lockState, resourceIdParallelBatchWriterMode, MODE_X) {}
+    : _pbwm(lockState, resourceIdParallelBatchWriterMode, MODE_X), _lockState(lockState) {
+    invariant(!_lockState->isBatchWriter());  // Otherwise we couldn't clear in destructor.
+    _lockState->setIsBatchWriter(true);
+}
+
+Lock::ParallelBatchWriterMode::~ParallelBatchWriterMode() {
+    _lockState->setIsBatchWriter(false);
+}
 
 void Lock::ResourceLock::lock(LockMode mode) {
     invariant(_result == LOCK_INVALID);
diff --git a/src/mongo/db/concurrency/d_concurrency.h b/src/mongo/db/concurrency/d_concurrency.h
index bbaae4630b0..c9849f7b21f 100644
--- a/src/mongo/db/concurrency/d_concurrency.h
+++ b/src/mongo/db/concurrency/d_concurrency.h
@@ -335,9 +335,11 @@ public:
 
     public:
         explicit ParallelBatchWriterMode(Locker* lockState);
+        ~ParallelBatchWriterMode();
 
     private:
         ResourceLock _pbwm;
+        Locker* const _lockState;
     };
 };
 
diff --git a/src/mongo/db/concurrency/locker.h b/src/mongo/db/concurrency/locker.h
index a858a5b0d79..2bd075ff2a3 100644
--- a/src/mongo/db/concurrency/locker.h
+++ b/src/mongo/db/concurrency/locker.h
@@ -302,7 +302,8 @@ public:
      */
     virtual bool hasLockPending() const = 0;
 
-    // Used for the replication parallel log op application threads
+    // Used for the replication parallel oplog application threads to prevent any other threads from
+    // using the system while it is in an inconsistent state.
     virtual void setIsBatchWriter(bool newValue) = 0;
     virtual bool isBatchWriter() const = 0;