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/**
* Copyright (C) 2022-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.
*/
#include "mongo/s/transaction_router_resource_yielder.h"
#include "mongo/db/session/session_catalog.h"
#include "mongo/logv2/log.h"
#include "mongo/s/is_mongos.h"
#include "mongo/s/session_catalog_router.h"
#include "mongo/util/exit.h"
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kTransaction
namespace mongo {
namespace {
MONGO_FAIL_POINT_DEFINE(hangBeforeUnyieldingTransactionRouter);
}
std::unique_ptr<TransactionRouterResourceYielder>
TransactionRouterResourceYielder::makeForLocalHandoff() {
return std::make_unique<TransactionRouterResourceYielder>();
}
std::unique_ptr<TransactionRouterResourceYielder>
TransactionRouterResourceYielder::makeForRemoteCommand() {
if (isMongos()) {
// Mongos cannot target itself so it does not need to yield for remote commands.
return nullptr;
}
return std::make_unique<TransactionRouterResourceYielder>();
}
void TransactionRouterResourceYielder::yield(OperationContext* opCtx) {
Session* const session = OperationContextSession::get(opCtx);
if (session) {
LOGV2_DEBUG(6753700,
5,
"TransactionRouterResourceYielder yielding",
"lsid"_attr = opCtx->getLogicalSessionId(),
"txnNumber"_attr = opCtx->getTxnNumber());
RouterOperationContextSession::checkIn(opCtx,
OperationContextSession::CheckInReason::kYield);
}
_yielded = (session != nullptr);
}
void TransactionRouterResourceYielder::unyield(OperationContext* opCtx) {
if (_yielded) {
hangBeforeUnyieldingTransactionRouter.pauseWhileSet();
LOGV2_DEBUG(6753701,
5,
"TransactionRouterResourceYielder unyielding",
"lsid"_attr = opCtx->getLogicalSessionId(),
"txnNumber"_attr = opCtx->getTxnNumber());
// Code that uses the TransactionRouter assumes it will only run with it, so check back out
// the session ignoring interruptions, except at global shutdown to prevent stalling
// shutdown. Unyield should always run with no resources held, so there shouldn't be a risk
// of deadlock.
try {
opCtx->runWithoutInterruptionExceptAtGlobalShutdown(
[&] { RouterOperationContextSession::checkOut(opCtx); });
} catch (const DBException&) {
// This can throw at global shutdown, so calling code that catches errors may
// unexpectedly run without a session checked out. This is assumed safe because the
// process is shutting down and can't do any meaningful work. This invariant is to
// safeguard that assumption.
invariant(globalInShutdownDeprecated());
throw;
}
}
}
} // namespace mongo
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