SERVER-32397: Notify waiters on any movement of the oplog read timest…

…amp.

src/mongo/db/storage/wiredtiger/wiredtiger_oplog_manager.cpp

@@ -53,7 +53,7 @@ void WiredTigerOplogManager::start(OperationContext* opCtx,
     invariant(!_isRunning);
     // Prime the oplog read timestamp.
     auto sessionCache = WiredTigerRecoveryUnit::get(opCtx)->getSessionCache();
-    _setOplogReadTimestamp(_fetchAllCommittedValue(sessionCache->conn()));
+    setOplogReadTimestamp(Timestamp(_fetchAllCommittedValue(sessionCache->conn())));
 
     std::unique_ptr<SeekableRecordCursor> reverseOplogCursor =
         oplogRecordStore->getCursor(opCtx, false /* false = reverse cursor */);
@@ -187,10 +187,8 @@ void WiredTigerOplogManager::_oplogJournalThreadLoop(WiredTigerSessionCache* ses
         sessionCache->waitUntilDurable(/*forceCheckpoint=*/false, false);
 
         lk.lock();
-
         // Publish the new timestamp value.
-        _setOplogReadTimestamp(newTimestamp);
-        _opsBecameVisibleCV.notify_all();
+        _setOplogReadTimestamp(lk, newTimestamp);
         lk.unlock();
 
         // Wake up any await_data cursors and tell them more data might be visible now.
@@ -209,11 +207,13 @@ std::uint64_t WiredTigerOplogManager::getOplogReadTimestamp() const {
 }
 
 void WiredTigerOplogManager::setOplogReadTimestamp(Timestamp ts) {
-    _oplogReadTimestamp.store(ts.asULL());
+    stdx::lock_guard<stdx::mutex> lk(_oplogVisibilityStateMutex);
+    _setOplogReadTimestamp(lk, ts.asULL());
 }
 
-void WiredTigerOplogManager::_setOplogReadTimestamp(uint64_t newTimestamp) {
+void WiredTigerOplogManager::_setOplogReadTimestamp(WithLock, uint64_t newTimestamp) {
     _oplogReadTimestamp.store(newTimestamp);
+    _opsBecameVisibleCV.notify_all();
     LOG(2) << "setting new oplogReadTimestamp: " << newTimestamp;
 }
 

src/mongo/db/storage/wiredtiger/wiredtiger_oplog_manager.h

@@ -35,6 +35,7 @@
 #include "mongo/stdx/condition_variable.h"
 #include "mongo/stdx/mutex.h"
 #include "mongo/stdx/thread.h"
+#include "mongo/util/concurrency/with_lock.h"
 
 namespace mongo {
 
@@ -83,7 +84,7 @@ class WiredTigerOplogManager {
                                  WiredTigerRecordStore* oplogRecordStore,
                                  bool isMasterSlave) noexcept;
 
-    void _setOplogReadTimestamp(uint64_t newTimestamp);
+    void _setOplogReadTimestamp(WithLock, uint64_t newTimestamp);
 
     uint64_t _fetchAllCommittedValue(WT_CONNECTION* conn);