SERVER-44393 split IndexBuildsCoordinator::_buildIndex() by index build protocol (single or two phase)

2 files changed, 52 insertions, 0 deletions

diff --git a/src/mongo/db/index_builds_coordinator.cpp b/src/mongo/db/index_builds_coordinator.cpp
index a1bed562111..102a431fc2c 100644
--- a/src/mongo/db/index_builds_coordinator.cpp
+++ b/src/mongo/db/index_builds_coordinator.cpp
@@ -1248,6 +1248,36 @@ void IndexBuildsCoordinator::_buildIndex(
     std::shared_ptr<ReplIndexBuildState> replState,
     const IndexBuildOptions& indexBuildOptions,
     boost::optional<Lock::CollectionLock>* exclusiveCollectionLock) {
+
+    if (IndexBuildProtocol::kSinglePhase == replState->protocol) {
+        _buildIndexSinglePhase(
+            opCtx, dbAndUUID, replState, indexBuildOptions, exclusiveCollectionLock);
+        return;
+    }
+
+    invariant(IndexBuildProtocol::kTwoPhase == replState->protocol,
+              str::stream() << replState->buildUUID);
+    _buildIndexTwoPhase(opCtx, dbAndUUID, replState, indexBuildOptions, exclusiveCollectionLock);
+}
+
+void IndexBuildsCoordinator::_buildIndexSinglePhase(
+    OperationContext* opCtx,
+    const NamespaceStringOrUUID& dbAndUUID,
+    std::shared_ptr<ReplIndexBuildState> replState,
+    const IndexBuildOptions& indexBuildOptions,
+    boost::optional<Lock::CollectionLock>* exclusiveCollectionLock) {
+    _scanCollectionAndInsertKeysIntoSorter(opCtx, dbAndUUID, replState, exclusiveCollectionLock);
+    _insertKeysFromSideTablesWithoutBlockingWrites(opCtx, dbAndUUID, replState);
+    _insertKeysFromSideTablesAndCommit(
+        opCtx, dbAndUUID, replState, indexBuildOptions, exclusiveCollectionLock, {});
+}
+
+void IndexBuildsCoordinator::_buildIndexTwoPhase(
+    OperationContext* opCtx,
+    const NamespaceStringOrUUID& dbAndUUID,
+    std::shared_ptr<ReplIndexBuildState> replState,
+    const IndexBuildOptions& indexBuildOptions,
+    boost::optional<Lock::CollectionLock>* exclusiveCollectionLock) {
     _scanCollectionAndInsertKeysIntoSorter(opCtx, dbAndUUID, replState, exclusiveCollectionLock);
     auto nss = _insertKeysFromSideTablesWithoutBlockingWrites(opCtx, dbAndUUID, replState);
     auto commitIndexBuildTimestamp = _waitForCommitOrAbort(opCtx, nss, replState);
diff --git a/src/mongo/db/index_builds_coordinator.h b/src/mongo/db/index_builds_coordinator.h
index 3c909c3f2c9..2183b1f1e5f 100644
--- a/src/mongo/db/index_builds_coordinator.h
+++ b/src/mongo/db/index_builds_coordinator.h
@@ -421,6 +421,28 @@ protected:
                      boost::optional<Lock::CollectionLock>* collLock);
 
     /**
+     * Builds the indexes single-phased.
+     * This method matches pre-4.4 behavior for a background index build driven by a single
+     * createIndexes oplog entry.
+     */
+    void _buildIndexSinglePhase(OperationContext* opCtx,
+                                const NamespaceStringOrUUID& dbAndUUID,
+                                std::shared_ptr<ReplIndexBuildState> replState,
+                                const IndexBuildOptions& indexBuildOptions,
+                                boost::optional<Lock::CollectionLock>* collLock);
+
+    /**
+     * Builds the indexes two-phased.
+     * The beginning and completion of a index build is driven by the startIndexBuild and
+     * commitIndexBuild oplog entries, respectively.
+     */
+    void _buildIndexTwoPhase(OperationContext* opCtx,
+                             const NamespaceStringOrUUID& dbAndUUID,
+                             std::shared_ptr<ReplIndexBuildState> replState,
+                             const IndexBuildOptions& indexBuildOptions,
+                             boost::optional<Lock::CollectionLock>* collLock);
+
+    /**
      * First phase is the collection scan and insertion of the keys into the sorter.
      */
     void _scanCollectionAndInsertKeysIntoSorter(