SERVER-31912 use a private WT_SESSION in waitUntilDurable instead of one from the session cache

2 files changed, 11 insertions, 4 deletions

diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.cpp
index 11cd1594b02..90d9dff9f08 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.cpp
@@ -250,20 +250,24 @@ void WiredTigerSessionCache::waitUntilDurable(bool forceCheckpoint, bool stableC
     _lastSyncTime.store(current + 1);
 
     // Nobody has synched yet, so we have to sync ourselves.
-    auto session = getSession();
-    WT_SESSION* s = session->getSession();
 
     // This gets the token (OpTime) from the last write, before flushing (either the journal, or a
     // checkpoint), and then reports that token (OpTime) as a durable write.
     stdx::unique_lock<stdx::mutex> jlk(_journalListenerMutex);
     JournalListener::Token token = _journalListener->getToken();
 
+    // Initialize on first use.
+    if (!_waitUntilDurableSession) {
+        invariantWTOK(
+            _conn->open_session(_conn, NULL, "isolation=snapshot", &_waitUntilDurableSession));
+    }
+
     // Use the journal when available, or a checkpoint otherwise.
     if (_engine && _engine->isDurable()) {
-        invariantWTOK(s->log_flush(s, "sync=on"));
+        invariantWTOK(_waitUntilDurableSession->log_flush(_waitUntilDurableSession, "sync=on"));
         LOG(4) << "flushed journal";
     } else {
-        invariantWTOK(s->checkpoint(s, NULL));
+        invariantWTOK(_waitUntilDurableSession->checkpoint(_waitUntilDurableSession, NULL));
         LOG(4) << "created checkpoint";
     }
     _journalListener->onDurable(token);
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.h b/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.h
index 5f8045ee2de..12c61fb0db3 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.h
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.h
@@ -248,6 +248,9 @@ private:
     // Notified when we commit to the journal.
     JournalListener* _journalListener = &NoOpJournalListener::instance;
 
+    WT_SESSION* _waitUntilDurableSession = nullptr;  // owned, and never explicitly closed
+                                                     // (uses connection close to clean up)
+
     /**
      * Returns a session to the cache for later reuse. If closeAll was called between getting this
      * session and releasing it, the session is directly released. This method is thread safe.