SERVER-42357 Add additional state to the IndexCatalogEntry to track when it is dropped

5 files changed, 66 insertions, 2 deletions

diff --git a/src/mongo/db/catalog/index_catalog_entry.h b/src/mongo/db/catalog/index_catalog_entry.h
index 07246e14f03..f4d55c60880 100644
--- a/src/mongo/db/catalog/index_catalog_entry.h
+++ b/src/mongo/db/catalog/index_catalog_entry.h
@@ -90,6 +90,9 @@ public:
 
     virtual void setIsReady(const bool newIsReady) = 0;
 
+    virtual void setDropped() = 0;
+    virtual bool isDropped() const = 0;
+
     // --
 
     /**
diff --git a/src/mongo/db/catalog/index_catalog_entry_impl.cpp b/src/mongo/db/catalog/index_catalog_entry_impl.cpp
index b203f3f1fb2..69da31c0ae2 100644
--- a/src/mongo/db/catalog/index_catalog_entry_impl.cpp
+++ b/src/mongo/db/catalog/index_catalog_entry_impl.cpp
@@ -66,6 +66,7 @@ IndexCatalogEntryImpl::IndexCatalogEntryImpl(OperationContext* const opCtx,
       _queryInfo(queryInfo),
       _ordering(Ordering::make(_descriptor->keyPattern())),
       _isReady(false),
+      _isDropped(false),
       _prefix(DurableCatalog::get(opCtx)->getIndexPrefix(
           opCtx, _descriptor->parentNS(), _descriptor->indexName())) {
     _descriptor->_cachedEntry = this;
diff --git a/src/mongo/db/catalog/index_catalog_entry_impl.h b/src/mongo/db/catalog/index_catalog_entry_impl.h
index e11322d63e3..df7f053537f 100644
--- a/src/mongo/db/catalog/index_catalog_entry_impl.h
+++ b/src/mongo/db/catalog/index_catalog_entry_impl.h
@@ -113,6 +113,14 @@ public:
 
     void setIsReady(bool newIsReady) final;
 
+    void setDropped() final {
+        _isDropped.store(true);
+    }
+
+    bool isDropped() const final {
+        return _isDropped.load();
+    }
+
     // --
 
     /**
@@ -199,8 +207,9 @@ private:
 
     // cached stuff
 
-    Ordering _ordering;  // TODO: this might be b-tree specific
-    bool _isReady;       // cache of NamespaceDetails info
+    Ordering _ordering;           // TODO: this might be b-tree specific
+    bool _isReady;                // cache of NamespaceDetails info
+    AtomicWord<bool> _isDropped;  // Whether the index drop is committed.
 
     // Set to true if this index supports path-level multikey tracking.
     // '_indexTracksPathLevelMultikeyInfo' is effectively const after IndexCatalogEntry::init() is
diff --git a/src/mongo/db/catalog/index_catalog_impl.cpp b/src/mongo/db/catalog/index_catalog_impl.cpp
index 04066249e50..088950236d3 100644
--- a/src/mongo/db/catalog/index_catalog_impl.cpp
+++ b/src/mongo/db/catalog/index_catalog_impl.cpp
@@ -881,6 +881,7 @@ public:
             // future, and we will need to do another write to reach the minimum visible snapshot.
             commitTime = LogicalClock::getClusterTimeForReplicaSet(_opCtx).asTimestamp();
         }
+        _entry->setDropped();
         _collection->setMinimumVisibleSnapshot(commitTime.get());
     }
 
diff --git a/src/mongo/dbtests/indexcatalogtests.cpp b/src/mongo/dbtests/indexcatalogtests.cpp
index 802a200ead9..f51a4e2852a 100644
--- a/src/mongo/dbtests/indexcatalogtests.cpp
+++ b/src/mongo/dbtests/indexcatalogtests.cpp
@@ -108,6 +108,55 @@ private:
     Database* _db;
 };
 
+class IndexCatalogEntryDroppedTest {
+public:
+    IndexCatalogEntryDroppedTest() {
+        const ServiceContext::UniqueOperationContext opCtxPtr = cc().makeOperationContext();
+        OperationContext& opCtx = *opCtxPtr;
+        Lock::DBLock lk(&opCtx, _nss.db(), MODE_X);
+        OldClientContext ctx(&opCtx, _nss.ns());
+        WriteUnitOfWork wuow(&opCtx);
+
+        _db = ctx.db();
+        _coll = _db->createCollection(&opCtx, _nss);
+        _catalog = _coll->getIndexCatalog();
+        wuow.commit();
+    }
+
+    void run() {
+        const ServiceContext::UniqueOperationContext opCtxPtr = cc().makeOperationContext();
+        OperationContext& opCtx = *opCtxPtr;
+        dbtests::WriteContextForTests ctx(&opCtx, _nss.ns());
+
+        const IndexDescriptor* idDesc = _catalog->findIdIndex(&opCtx);
+        std::shared_ptr<const IndexCatalogEntry> entry = _catalog->getEntryShared(idDesc);
+
+        ASSERT_FALSE(entry->isDropped());
+
+        {
+            Lock::CollectionLock lk(&opCtx, _nss, MODE_X);
+            WriteUnitOfWork wuow(&opCtx);
+            ASSERT_OK(_db->dropCollection(&opCtx, _nss));
+            ASSERT_FALSE(entry->isDropped());
+        }
+
+        ASSERT_FALSE(entry->isDropped());
+
+        {
+            Lock::CollectionLock lk(&opCtx, _nss, MODE_X);
+            WriteUnitOfWork wuow(&opCtx);
+            ASSERT_OK(_db->dropCollection(&opCtx, _nss));
+            wuow.commit();
+            ASSERT_TRUE(entry->isDropped());
+        }
+    }
+
+private:
+    IndexCatalog* _catalog;
+    Collection* _coll;
+    Database* _db;
+};
+
 /**
  * Test for IndexCatalog::refreshEntry().
  */
@@ -187,6 +236,7 @@ public:
     IndexCatalogTests() : Suite("indexcatalogtests") {}
     void setupTests() {
         add<IndexIteratorTests>();
+        add<IndexCatalogEntryDroppedTest>();
         add<RefreshEntry>();
     }
 };