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/**
* Copyright (C) 2020-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/plan_insert_listener.h"
#include <memory>
#include "mongo/db/catalog/database.h"
#include "mongo/db/catalog/database_holder.h"
#include "mongo/db/curop.h"
#include "mongo/db/query/find_common.h"
#include "mongo/logv2/log.h"
#include "mongo/util/fail_point.h"
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kQuery
namespace mongo::insert_listener {
namespace {
MONGO_FAIL_POINT_DEFINE(planExecutorHangWhileYieldedInWaitForInserts);
}
bool shouldListenForInserts(OperationContext* opCtx, CanonicalQuery* cq) {
return cq && cq->getFindCommandRequest().getTailable() &&
cq->getFindCommandRequest().getAwaitData() && awaitDataState(opCtx).shouldWaitForInserts &&
opCtx->checkForInterruptNoAssert().isOK() &&
awaitDataState(opCtx).waitForInsertsDeadline >
opCtx->getServiceContext()->getPreciseClockSource()->now();
}
bool shouldWaitForInserts(OperationContext* opCtx,
CanonicalQuery* cq,
PlanYieldPolicy* yieldPolicy) {
// If this is an awaitData-respecting operation and we have time left and we're not interrupted,
// we should wait for inserts.
if (shouldListenForInserts(opCtx, cq)) {
// We expect awaitData cursors to be yielding.
invariant(yieldPolicy->canReleaseLocksDuringExecution());
// For operations with a last committed opTime, we should not wait if the replication
// coordinator's lastCommittedOpTime has progressed past the client's lastCommittedOpTime.
// In that case, we will return early so that we can inform the client of the new
// lastCommittedOpTime immediately.
if (!clientsLastKnownCommittedOpTime(opCtx).isNull()) {
auto replCoord = repl::ReplicationCoordinator::get(opCtx);
return clientsLastKnownCommittedOpTime(opCtx) >= replCoord->getLastCommittedOpTime();
}
return true;
}
return false;
}
std::unique_ptr<Notifier> getCappedInsertNotifier(OperationContext* opCtx,
const NamespaceString& nss,
PlanYieldPolicy* yieldPolicy) {
// We don't expect to need a capped insert notifier for non-yielding plans.
invariant(yieldPolicy->canReleaseLocksDuringExecution());
// In case of the read concern majority, return a majority committed point notifier, otherwise,
// a notifier associated with that capped collection
//
// We can only wait on the capped collection insert notifier if the collection is present,
// otherwise we should retry immediately when we hit EOF.
if (opCtx->recoveryUnit()->getTimestampReadSource() == RecoveryUnit::kMajorityCommitted) {
return std::make_unique<MajorityCommittedPointNotifier>();
} else {
auto collection = CollectionCatalog::get(opCtx)->lookupCollectionByNamespace(opCtx, nss);
invariant(collection);
return std::make_unique<LocalCappedInsertNotifier>(
collection->getRecordStore()->getCappedInsertNotifier());
}
}
void waitForInserts(OperationContext* opCtx,
PlanYieldPolicy* yieldPolicy,
std::unique_ptr<Notifier>& notifier) {
// The notifier wait() method will not wait unless the version passed to it matches the
// current version of the notifier. Since the version passed to it is the current version
// of the notifier at the time of the previous EOF, we require two EOFs in a row with no
// notifier version change in order to wait. This is sufficient to ensure we never wait
// when data is available.
auto curOp = CurOp::get(opCtx);
curOp->pauseTimer();
ON_BLOCK_EXIT([curOp] { curOp->resumeTimer(); });
notifier->prepareForWait(opCtx);
auto yieldResult = yieldPolicy->yieldOrInterrupt(opCtx, [opCtx, ¬ifier] {
const auto deadline = awaitDataState(opCtx).waitForInsertsDeadline;
notifier->waitUntil(opCtx, deadline);
if (MONGO_unlikely(planExecutorHangWhileYieldedInWaitForInserts.shouldFail())) {
LOGV2(4452903,
"PlanExecutor - planExecutorHangWhileYieldedInWaitForInserts fail point enabled. "
"Blocking until fail point is disabled");
planExecutorHangWhileYieldedInWaitForInserts.pauseWhileSet();
}
});
uassertStatusOK(yieldResult);
}
} // namespace mongo::insert_listener
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