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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.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/query/query_yield.h"
#include "mongo/bson/bsonobj.h"
#include "mongo/db/curop.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/storage/record_fetcher.h"
#include "mongo/util/fail_point_service.h"
#include "mongo/util/time_support.h"
namespace mongo {
namespace {
MONGO_FAIL_POINT_DEFINE(setYieldAllLocksHang);
MONGO_FAIL_POINT_DEFINE(setYieldAllLocksWait);
} // namespace
// static
void QueryYield::yieldAllLocks(OperationContext* opCtx,
stdx::function<void()> whileYieldingFn,
const NamespaceString& planExecNS) {
// Things have to happen here in a specific order:
// * Release lock mgr locks
// * Go to sleep
// * Call the whileYieldingFn
// * Reacquire lock mgr locks
Locker* locker = opCtx->lockState();
Locker::LockSnapshot snapshot;
// Nothing was unlocked, just return, yielding is pointless.
if (!locker->saveLockStateAndUnlock(&snapshot)) {
return;
}
// Top-level locks are freed, release any potential low-level (storage engine-specific
// locks). If we are yielding, we are at a safe place to do so.
opCtx->recoveryUnit()->abandonSnapshot();
// Track the number of yields in CurOp.
CurOp::get(opCtx)->yielded();
MONGO_FAIL_POINT_PAUSE_WHILE_SET(setYieldAllLocksHang);
MONGO_FAIL_POINT_BLOCK(setYieldAllLocksWait, customWait) {
const BSONObj& data = customWait.getData();
BSONElement customWaitNS = data["namespace"];
if (!customWaitNS || planExecNS.ns() == customWaitNS.str()) {
sleepFor(Milliseconds(data["waitForMillis"].numberInt()));
}
}
if (whileYieldingFn) {
whileYieldingFn();
}
UninterruptibleLockGuard noInterrupt(locker);
locker->restoreLockState(opCtx, snapshot);
}
} // namespace mongo
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