SERVER-43805 Create InitialSyncSharedData structure.

Author: mtrussotto

src/mongo/db/repl/initial_sync_shared_data.h

@@ -0,0 +1,60 @@
+/**
+ *    Copyright (C) 2019-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    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
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    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 Server Side 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 <mutex>
+
+
+#include "mongo/base/status.h"
+#include "mongo/base/string_data.h"
+#include "mongo/db/server_options.h"
+#include "mongo/platform/mutex.h"
+
+namespace mongo {
+struct InitialSyncSharedData {
+    InitialSyncSharedData(ServerGlobalParams::FeatureCompatibility::Version inFCV, int inRollbackId)
+        : FCV(inFCV), rollBackId(inRollbackId) {}
+
+    // The const members above the mutex may be accessed without the mutex.
+
+    // Sync source FCV at start of initial sync.
+    const ServerGlobalParams::FeatureCompatibility::Version FCV;
+
+    // Rollback ID at start of initial sync
+    const int rollBackId;
+
+    // This mutex controls access to all members below it.
+    mutable Mutex mutex = MONGO_MAKE_LATCH("InitialSyncSharedData::mutex"_sd);
+
+    // Status of the entire initial sync.  All initial sync tasks should exit if this becomes
+    // non-OK.
+    Status initialSyncStatus = Status::OK();
+};
+}  // namespace mongo

src/mongo/db/repl/initial_syncer.cpp

@@ -271,6 +271,13 @@ void InitialSyncer::_cancelRemainingWork_inlock() {
     _cancelHandle_inlock(_getNextApplierBatchHandle);
 
     _shutdownComponent_inlock(_oplogFetcher);
+    if (_sharedData) {
+        stdx::lock_guard<Latch>(_sharedData->mutex);
+        if (_sharedData->initialSyncStatus.isOK()) {
+            _sharedData->initialSyncStatus =
+                Status{ErrorCodes::CallbackCanceled, "Initial sync attempt canceled"};
+        }
+    }
     if (_initialSyncState) {
         _shutdownComponent_inlock(_initialSyncState->dbsCloner);
     }
@@ -853,6 +860,7 @@ void InitialSyncer::_fcvFetcherCallback(const StatusWith<Fetcher::QueryResponse>
     // This is where the flow of control starts to split into two parallel tracks:
     // - oplog fetcher
     // - data cloning and applier
+    _sharedData = std::make_unique<InitialSyncSharedData>(version, _rollbackChecker->getBaseRBID());
     auto listDatabasesFilter = [](BSONObj dbInfo) {
         std::string name;
         auto status = mongo::bsonExtractStringField(dbInfo, "name", &name);

src/mongo/db/repl/initial_syncer.h

@@ -44,6 +44,7 @@
 #include "mongo/db/repl/collection_cloner.h"
 #include "mongo/db/repl/data_replicator_external_state.h"
 #include "mongo/db/repl/database_cloner.h"
+#include "mongo/db/repl/initial_sync_shared_data.h"
 #include "mongo/db/repl/multiapplier.h"
 #include "mongo/db/repl/oplog_applier.h"
 #include "mongo/db/repl/oplog_buffer.h"
@@ -640,6 +641,8 @@ class InitialSyncer {
     // Contains stats on the current initial sync request (includes all attempts).
     // To access these stats in a user-readable format, use getInitialSyncProgress().
     Stats _stats;  // (M)
+    // Data shared by cloners and fetcher.  Follow InitialSyncSharedData synchronization rules.
+    std::unique_ptr<InitialSyncSharedData> _sharedData;  // (S)
 };
 
 }  // namespace repl