1 files changed, 50 insertions, 5 deletions

diff --git a/src/mongo/db/repl/collection_cloner.cpp b/src/mongo/db/repl/collection_cloner.cpp
index 41968073f89..4d73098c787 100644
--- a/src/mongo/db/repl/collection_cloner.cpp
+++ b/src/mongo/db/repl/collection_cloner.cpp
@@ -200,10 +200,12 @@ void CollectionCloner::runQuery() {
     if (_resumeSupported) {
         if (_resumeToken) {
             // Resume the query from where we left off.
+            LOG(1) << "Collection cloner will resume the last successful query";
             query = QUERY("query" << BSONObj() << "$readOnce" << true << "$_requestResumeToken"
                                   << true << "$_resumeAfter" << _resumeToken.get());
         } else {
             // New attempt at a resumable query.
+            LOG(1) << "Collection cloner will run a new query";
             query = QUERY("query" << BSONObj() << "$readOnce" << true << "$_requestResumeToken"
                                   << true);
         }
@@ -226,13 +228,35 @@ void CollectionCloner::runQuery() {
     } catch (...) {
         auto status = exceptionToStatus();
 
+        // If the collection was dropped at any point, we can just move on to the next cloner.
+        // This applies to both resumable (4.4) and non-resumable (4.2) queries.
+        if (status == ErrorCodes::NamespaceNotFound) {
+            throw;  // This will re-throw the NamespaceNotFound, resulting in a clean exit.
+        }
+
+        // Wire version 4.2 only.
         if (!_resumeSupported) {
-            std::string message = str::stream()
-                << "Collection clone failed and is not resumable. nss: " << _sourceNss;
-            log() << message;
-            uasserted(ErrorCodes::InitialSyncFailure, message);
+            // If we lost our cursor last round, the only time we can can continue is if we find out
+            // this round that the collection was dropped on the source (that scenario is covered
+            // right above). If that is not the case, then the cloner would have more work to do,
+            // but since we cannot resume the query, we must abort initial sync.
+            if (_lostNonResumableCursor) {
+                abortNonResumableClone(status);
+            }
+
+            // Collection has changed upstream. This will trigger the code block above next round,
+            // (unless we find out the collection was dropped via getting a NamespaceNotFound).
+            if (_queryStage.isCursorError(status)) {
+                log() << "Lost cursor during non-resumable query: " << status;
+                _lostNonResumableCursor = true;
+                throw;
+            }
+            // Any other errors (including network errors, but excluding NamespaceNotFound) result
+            // in immediate failure.
+            abortNonResumableClone(status);
         }
 
+        // Re-throw all query errors for resumable (4.4) queries.
         throw;
     }
 }
@@ -249,6 +273,14 @@ void CollectionCloner::handleNextBatch(DBClientCursorBatchIterator& iter) {
         }
     }
 
+    // If this is 'true', it means that something happened to our remote cursor for a reason other
+    // than the collection being dropped, all while we were running a non-resumable (4.2) clone.
+    // We must abort initial sync in that case.
+    if (_lostNonResumableCursor) {
+        // This will be caught in runQuery().
+        uasserted(ErrorCodes::InitialSyncFailure, "Lost remote cursor");
+    }
+
     if (_firstBatchOfQueryRound && _resumeSupported) {
         // Store the cursorId of the remote cursor.
         _remoteCursorId = iter.getCursorId();
@@ -354,7 +386,7 @@ void CollectionCloner::killOldQueryCursor() {
     auto id = _remoteCursorId;
 
     auto cmdObj = BSON("killCursors" << nss.coll() << "cursors" << BSON_ARRAY(id));
-
+    LOG(1) << "Attempting to kill old remote cursor with id: " << id;
     try {
         getClient()->runCommand(nss.db().toString(), cmdObj, infoObj);
     } catch (...) {
@@ -365,6 +397,19 @@ void CollectionCloner::killOldQueryCursor() {
     _remoteCursorId = -1;
 }
 
+void CollectionCloner::forgetOldQueryCursor() {
+    _remoteCursorId = -1;
+}
+
+// Throws.
+void CollectionCloner::abortNonResumableClone(const Status& status) {
+    invariant(!_resumeSupported);
+    log() << "Error during non-resumable clone: " << status;
+    std::string message = str::stream()
+        << "Collection clone failed and is not resumable. nss: " << _sourceNss;
+    uasserted(ErrorCodes::InitialSyncFailure, message);
+}
+
 CollectionCloner::Stats CollectionCloner::getStats() const {
     stdx::lock_guard<Latch> lk(_mutex);
     return _stats;