/**
 *    Copyright (C) 2018-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/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/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_BLOCK(setYieldAllLocksHang, config) {
        StringData ns{config.getData().getStringField("namespace")};
        if (ns.empty() || ns == planExecNS.ns()) {
            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