SERVER-33614 add ApplierHelpers

Contains utility class to group insert operations on the same namespace
assigned to the current writer thread.

1 files changed, 95 insertions, 0 deletions

diff --git a/src/mongo/db/repl/applier_helpers.h b/src/mongo/db/repl/applier_helpers.h
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index 00000000000..c31e12724bc
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+++ b/src/mongo/db/repl/applier_helpers.h
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+/**
+ *    Copyright (C) 2018 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+
+#pragma once
+
+#include "mongo/base/disallow_copying.h"
+#include "mongo/base/status_with.h"
+#include "mongo/db/repl/multiapplier.h"
+#include "mongo/db/repl/sync_tail.h"
+
+namespace mongo {
+namespace repl {
+
+/**
+ * Collection of helper functions and classes for oplog application.
+ */
+class ApplierHelpers {
+public:
+    using OperationPtrs = MultiApplier::OperationPtrs;
+
+    /**
+     * Sorts the oplog entries by namespace, so that entries from the same namespace will be next to
+     * each other in the list.
+     */
+    static void stableSortByNamespace(OperationPtrs* oplogEntryPointers);
+
+    class InsertGroup;
+};
+
+/**
+ * Groups consecutive insert operations on the same namespace and applies the combined operation
+ * as a single oplog entry.
+ * Advances the the MultiApplier::OperationPtrs iterator if the grouped insert is applied
+ * successfully.
+ */
+class ApplierHelpers::InsertGroup {
+    MONGO_DISALLOW_COPYING(InsertGroup);
+
+public:
+    using ConstIterator = OperationPtrs::const_iterator;
+    using Mode = OplogApplication::Mode;
+
+    InsertGroup(OperationPtrs* ops, const SyncApplyFn& applyFn, OperationContext* opCtx, Mode mode);
+
+    /**
+     * Attempts to group insert operations starting at 'iter'.
+     * If the grouped insert is applied successfully, returns the iterator to the last standalone
+     * insert operation included in the applied grouped insert.
+     */
+    StatusWith<ConstIterator> groupAndApplyInserts(ConstIterator oplogEntriesIterator);
+
+private:
+    // _doNotGroupBeforePoint is used to prevent retrying bad group inserts by marking the final op
+    // of a failed group and not allowing further group inserts until that op has been processed.
+    ConstIterator _doNotGroupBeforePoint;
+
+    // Used for constructing search bounds when grouping inserts.
+    ConstIterator _end;
+
+    // Used to apply the grouped insert oplog entry.
+    const SyncApplyFn _applyFn;
+
+    // Passed to _syncApply when applying grouped inserts.
+    OperationContext* _opCtx;
+    Mode _mode;
+};
+
+}  // namespace repl
+}  // namespace mongo