Revert "SERVER-16133 Use RESOURCE_METADATA X lock to set the multiKey index value"

This reverts commit 58e49b2726807b7e7c2f0309607ffa454befbff6.

3 files changed, 29 insertions, 20 deletions

diff --git a/src/mongo/db/catalog/index_catalog.cpp b/src/mongo/db/catalog/index_catalog.cpp
index 0bd3810db97..3087523fe97 100644
--- a/src/mongo/db/catalog/index_catalog.cpp
+++ b/src/mongo/db/catalog/index_catalog.cpp
@@ -497,6 +497,10 @@ namespace {
         IndexCatalogEntry* entry = _catalog->_entries.find( desc );
         fassert( 17331, entry && entry == _entry );
 
+        if ( entry->wantToSetIsMultikey() ) {
+            entry->setMultikey(_txn);
+        }
+
         entry->setIsReady( true );
     }
 
diff --git a/src/mongo/db/catalog/index_catalog_entry.cpp b/src/mongo/db/catalog/index_catalog_entry.cpp
index 2d403072dd6..28fb57d5de2 100644
--- a/src/mongo/db/catalog/index_catalog_entry.cpp
+++ b/src/mongo/db/catalog/index_catalog_entry.cpp
@@ -75,8 +75,8 @@ namespace mongo {
           _accessMethod( NULL ),
           _headManager(new HeadManagerImpl(this)),
           _ordering( Ordering::make( descriptor->keyPattern() ) ),
-          _isReady( false ) {
-
+          _isReady( false ),
+          _wantToSetIsMultikey( false ) {
         _descriptor->_cachedEntry = this;
     }
 
@@ -146,30 +146,32 @@ namespace mongo {
             invariant(!_ice->_isMultikey);
         }
 
-        virtual void commit() { _ice->_isMultikey = true; }
-        virtual void rollback() { }
+        virtual void commit() {}
+        virtual void rollback() { _ice->_isMultikey = false; }
 
-    private:
-        IndexCatalogEntry* const _ice;
+        IndexCatalogEntry* _ice;
     };
 
-    void IndexCatalogEntry::setMultikey(OperationContext* txn) {
-        if (isMultikey(txn)) {
+    void IndexCatalogEntry::setMultikey( OperationContext* txn ) {
+        if ( isMultikey( txn ) )
             return;
-        }
-
-        // Only one thread should set the multi-key value per collection, because the metadata for
-        // a collection is one large document.
-        Lock::ResourceLock collMDLock(txn->lockState(),
-                                      ResourceId(RESOURCE_METADATA, _collection->ns()),
-                                      MODE_X);
 
-        // Check again in case we blocked on the MD lock and another thread beat us to setting the
-        // multiKey metadata for this index.
-        if (isMultikey(txn)) {
+        if ( !_isReady && txn->lockState() &&
+             !txn->lockState()->isCollectionLockedForMode( _ns, MODE_X ) ) {
+            // We don't have an exclusive lock, so can't set is multi key.
+            // But, we're building it in an IX lock, so we keep track and will set it later
+            _wantToSetIsMultikey = true;
             return;
         }
 
+        const ResourceId collRes = ResourceId(RESOURCE_COLLECTION, _ns);
+        LockResult res = txn->lockState()->lock(collRes, MODE_X, UINT_MAX, true);
+        if (res == LOCK_DEADLOCK) throw WriteConflictException();
+        invariant(res == LOCK_OK);
+
+        // Lock will be held until end of WUOW to ensure rollback safety.
+        ON_BLOCK_EXIT(&Locker::unlock, txn->lockState(), collRes);
+
         if ( _collection->setIndexIsMultikey( txn,
                                               _descriptor->indexName(),
                                               true ) ) {
@@ -180,9 +182,8 @@ namespace mongo {
             }
         }
 
-        // We should only enable the multi-key value after the transaction has committed and the
-        // multi-key property has been persisted.
         txn->recoveryUnit()->registerChange(new SetMultikeyChange(this));
+        _isMultikey = true;
     }
 
     // ----
diff --git a/src/mongo/db/catalog/index_catalog_entry.h b/src/mongo/db/catalog/index_catalog_entry.h
index cc086b73ec9..b40904d42da 100644
--- a/src/mongo/db/catalog/index_catalog_entry.h
+++ b/src/mongo/db/catalog/index_catalog_entry.h
@@ -87,6 +87,8 @@ namespace mongo {
         // if this ready is ready for queries
         bool isReady( OperationContext* txn ) const;
 
+        bool wantToSetIsMultikey() const { return _wantToSetIsMultikey; }
+
     private:
 
         class SetMultikeyChange;
@@ -117,6 +119,8 @@ namespace mongo {
         bool _isReady; // cache of NamespaceDetails info
         DiskLoc _head; // cache of IndexDetails
         bool _isMultikey; // cache of NamespaceDetails info
+
+        bool _wantToSetIsMultikey; // see ::setMultikey
     };
 
     class IndexCatalogEntryContainer {