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/**
* Copyright (C) 2014 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.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kStorage
#include "mongo/platform/basic.h"
#include <set>
#include "mongo/base/checked_cast.h"
#include "mongo/base/init.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/db/catalog/database.h"
#include "mongo/db/catalog/database_holder.h"
#include "mongo/db/client.h"
#include "mongo/db/concurrency/d_concurrency.h"
#include "mongo/db/db_raii.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/service_context.h"
#include "mongo/db/storage/wiredtiger/wiredtiger_kv_engine.h"
#include "mongo/db/storage/wiredtiger/wiredtiger_record_store.h"
#include "mongo/db/storage/wiredtiger/wiredtiger_recovery_unit.h"
#include "mongo/stdx/mutex.h"
#include "mongo/util/background.h"
#include "mongo/util/exit.h"
#include "mongo/util/log.h"
namespace mongo {
namespace {
std::set<NamespaceString> _backgroundThreadNamespaces;
stdx::mutex _backgroundThreadMutex;
class OplogTruncaterThread : public BackgroundJob {
public:
OplogTruncaterThread(const NamespaceString& ns)
: BackgroundJob(true /* deleteSelf */), _ns(ns) {
_name = std::string("WT OplogTruncaterThread: ") + _ns.toString();
}
virtual std::string name() const {
return _name;
}
/**
* Returns true iff there was an oplog to delete from.
*/
bool _deleteExcessDocuments() {
if (!getGlobalServiceContext()->getStorageEngine()) {
LOG(2) << "no global storage engine yet";
return false;
}
const ServiceContext::UniqueOperationContext opCtx = cc().makeOperationContext();
try {
// A Global IX lock should be good enough to protect the oplog truncation from
// interruptions such as restartCatalog. PBWM, database lock or collection lock is not
// needed. This improves concurrency if oplog truncation takes long time.
ShouldNotConflictWithSecondaryBatchApplicationBlock shouldNotConflictBlock(
opCtx.get()->lockState());
Lock::GlobalLock lk(opCtx.get(), MODE_IX);
WiredTigerRecordStore* rs = nullptr;
{
// Release the database lock right away because we don't want to
// block other operations on the local database and given the
// fact that oplog collection is so special, Global IX lock can
// make sure the collection exists.
Lock::DBLock dbLock(opCtx.get(), _ns.db(), MODE_IX);
Database* db = DatabaseHolder::getDatabaseHolder().get(opCtx.get(), _ns.db());
if (!db) {
LOG(2) << "no local database yet";
return false;
}
// We need to hold the database lock while getting the collection. Otherwise a
// concurrent collection creation would write to the map in the Database object
// while we concurrently read the map.
Collection* collection = db->getCollection(opCtx.get(), _ns);
if (!collection) {
LOG(2) << "no collection " << _ns;
return false;
}
rs = checked_cast<WiredTigerRecordStore*>(collection->getRecordStore());
}
if (!rs->yieldAndAwaitOplogDeletionRequest(opCtx.get())) {
return false; // Oplog went away.
}
rs->reclaimOplog(opCtx.get());
} catch (const ExceptionForCat<ErrorCategory::Interruption>&) {
return false;
} catch (const std::exception& e) {
severe() << "error in OplogTruncaterThread: " << e.what();
fassertFailedNoTrace(!"error in OplogTruncaterThread");
} catch (...) {
fassertFailedNoTrace(!"unknown error in OplogTruncaterThread");
}
return true;
}
virtual void run() {
Client::initThread(_name.c_str());
ON_BLOCK_EXIT([] { Client::destroy(); });
while (!globalInShutdownDeprecated()) {
if (!_deleteExcessDocuments()) {
sleepmillis(1000); // Back off in case there were problems deleting.
}
}
}
private:
NamespaceString _ns;
std::string _name;
};
bool initRsOplogBackgroundThread(StringData ns) {
if (!NamespaceString::oplog(ns)) {
return false;
}
if (storageGlobalParams.repair || storageGlobalParams.readOnly) {
LOG(1) << "not starting OplogTruncaterThread for " << ns
<< " because we are either in repair or read-only mode";
return false;
}
stdx::lock_guard<stdx::mutex> lock(_backgroundThreadMutex);
NamespaceString nss(ns);
if (_backgroundThreadNamespaces.count(nss)) {
log() << "OplogTruncaterThread " << ns << " already started";
} else {
log() << "Starting OplogTruncaterThread " << ns;
BackgroundJob* backgroundThread = new OplogTruncaterThread(nss);
backgroundThread->go();
_backgroundThreadNamespaces.insert(nss);
}
return true;
}
MONGO_INITIALIZER(SetInitRsOplogBackgroundThreadCallback)(InitializerContext* context) {
WiredTigerKVEngine::setInitRsOplogBackgroundThreadCallback(initRsOplogBackgroundThread);
return Status::OK();
}
} // namespace
} // namespace mongo
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