SERVER-51228 dbHash should return SnapshotUnavailable if the _id index is not visible or ready

3 files changed, 27 insertions, 11 deletions

diff --git a/src/mongo/db/catalog/index_catalog_entry.h b/src/mongo/db/catalog/index_catalog_entry.h
index 8abc7000fdb..e34deceab01 100644
--- a/src/mongo/db/catalog/index_catalog_entry.h
+++ b/src/mongo/db/catalog/index_catalog_entry.h
@@ -137,10 +137,26 @@ public:
                              const KeyStringSet& multikeyMetadataKeys,
                              const MultikeyPaths& multikeyPaths) = 0;
 
-    // if this ready is ready for queries
+    /**
+     * Returns whether this index is ready for queries. This is potentially unsafe in that it does
+     * not consider whether the index is visible or ready in the currently storage snapshot. For
+     * that, use isReadyInMySnapshot() or isPresentInMySnapshot().
+     */
     virtual bool isReady(OperationContext* const opCtx) const = 0;
 
     /**
+     * Safely check whether this index is visible in the durable catalog in the current storage
+     * engine snapshot.
+     */
+    virtual bool isPresentInMySnapshot(OperationContext* opCtx) const = 0;
+
+    /**
+     * Safely check whether this index is visible and ready in the durable catalog in the current
+     * storage engine snapshot.
+     */
+    virtual bool isReadyInMySnapshot(OperationContext* opCtx) const = 0;
+
+    /**
      * Returns true if this index is not ready, and it is not currently in the process of being
      * built either.
      */
diff --git a/src/mongo/db/catalog/index_catalog_entry_impl.cpp b/src/mongo/db/catalog/index_catalog_entry_impl.cpp
index 7787183bb59..44458a89187 100644
--- a/src/mongo/db/catalog/index_catalog_entry_impl.cpp
+++ b/src/mongo/db/catalog/index_catalog_entry_impl.cpp
@@ -76,7 +76,7 @@ IndexCatalogEntryImpl::IndexCatalogEntryImpl(OperationContext* const opCtx,
           DurableCatalog::get(opCtx)->getIndexPrefix(opCtx, _catalogId, _descriptor->indexName())) {
 
     _descriptor->_entry = this;
-    _isReady = _catalogIsReady(opCtx);
+    _isReady = isReadyInMySnapshot(opCtx);
 
     {
         stdx::lock_guard<Latch> lk(_indexMultikeyPathsMutex);
@@ -131,7 +131,7 @@ bool IndexCatalogEntryImpl::isReady(OperationContext* opCtx) const {
     // out-of-sync index catalog entries.  To fix this, we uassert if we detect that the
     // in-memory catalog is out-of-sync with the on-disk catalog.
     if (opCtx->inMultiDocumentTransaction()) {
-        if (!_catalogIsPresent(opCtx) || _catalogIsReady(opCtx) != _isReady) {
+        if (!isPresentInMySnapshot(opCtx) || isReadyInMySnapshot(opCtx) != _isReady) {
             uasserted(ErrorCodes::SnapshotUnavailable,
                       str::stream() << "Unable to read from a snapshot due to pending collection"
                                        " catalog changes; please retry the operation.");
@@ -139,7 +139,7 @@ bool IndexCatalogEntryImpl::isReady(OperationContext* opCtx) const {
     }
 
     if (kDebugBuild)
-        invariant(_isReady == _catalogIsReady(opCtx));
+        invariant(_isReady == isReadyInMySnapshot(opCtx));
     return _isReady;
 }
 
@@ -270,7 +270,7 @@ Status IndexCatalogEntryImpl::_setMultikeyInMultiDocumentTransaction(
     // If the index is not visible within the side transaction, the index may have been created,
     // but not committed, in the parent transaction. Therefore, we abandon the side transaction
     // and set the multikey flag in the parent transaction.
-    if (!_catalogIsPresent(opCtx)) {
+    if (!isPresentInMySnapshot(opCtx)) {
         return {ErrorCodes::SnapshotUnavailable, "index not visible in side transaction"};
     }
 
@@ -325,11 +325,11 @@ NamespaceString IndexCatalogEntryImpl::getNSSFromCatalog(OperationContext* opCtx
     return DurableCatalog::get(opCtx)->getEntry(_catalogId).nss;
 }
 
-bool IndexCatalogEntryImpl::_catalogIsReady(OperationContext* opCtx) const {
+bool IndexCatalogEntryImpl::isReadyInMySnapshot(OperationContext* opCtx) const {
     return DurableCatalog::get(opCtx)->isIndexReady(opCtx, _catalogId, _descriptor->indexName());
 }
 
-bool IndexCatalogEntryImpl::_catalogIsPresent(OperationContext* opCtx) const {
+bool IndexCatalogEntryImpl::isPresentInMySnapshot(OperationContext* opCtx) const {
     return DurableCatalog::get(opCtx)->isIndexPresent(opCtx, _catalogId, _descriptor->indexName());
 }
 
diff --git a/src/mongo/db/catalog/index_catalog_entry_impl.h b/src/mongo/db/catalog/index_catalog_entry_impl.h
index f1feb5e0f92..6af6908ef8c 100644
--- a/src/mongo/db/catalog/index_catalog_entry_impl.h
+++ b/src/mongo/db/catalog/index_catalog_entry_impl.h
@@ -159,11 +159,14 @@ public:
                      const KeyStringSet& multikeyMetadataKeys,
                      const MultikeyPaths& multikeyPaths) final;
 
-    // if this ready is ready for queries
     bool isReady(OperationContext* opCtx) const final;
 
     bool isFrozen() const final;
 
+    bool isPresentInMySnapshot(OperationContext* opCtx) const final;
+
+    bool isReadyInMySnapshot(OperationContext* opCtx) const final;
+
     KVPrefix getPrefix() const final {
         return _prefix;
     }
@@ -191,9 +194,6 @@ private:
                                                   const CollectionPtr& collection,
                                                   const MultikeyPaths& multikeyPaths);
 
-    bool _catalogIsReady(OperationContext* opCtx) const;
-    bool _catalogIsPresent(OperationContext* opCtx) const;
-
     /**
      * Retrieves the multikey information associated with this index from '_collection',
      *