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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.
*/
#pragma once
#include "mongo/db/catalog/collection.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/query/canonical_query.h"
#include "mongo/db/query/plan_yield_policy.h"
#include "mongo/db/repl/optime.h"
#include "mongo/db/repl/wait_for_majority_service.h"
#include "mongo/logv2/log.h"
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kQuery
namespace mongo::insert_listener {
// An abstract class used to notify on new insert events.
class Notifier {
public:
virtual ~Notifier(){};
// Performs the necessary work needed for waiting. Should be called prior calling waitUntil().
virtual void prepareForWait(OperationContext* opCtx) = 0;
// Blocks the caller until an insert event is fired or the deadline is hit.
virtual void waitUntil(OperationContext* opCtx, Date_t deadline) = 0;
};
// Class used to notify listeners of local inserts into the capped collection.
class LocalCappedInsertNotifier final : public Notifier {
public:
LocalCappedInsertNotifier(std::shared_ptr<CappedInsertNotifier> notifier)
: _notifier(notifier) {}
void prepareForWait(OperationContext* opCtx) final {
invariant(_notifier);
}
void waitUntil(OperationContext* opCtx, Date_t deadline) final {
auto currentVersion = _notifier->getVersion();
_notifier->waitUntil(opCtx, _lastEOFVersion, deadline);
_lastEOFVersion = currentVersion;
}
private:
std::shared_ptr<CappedInsertNotifier> _notifier;
uint64_t _lastEOFVersion = ~uint64_t(0);
};
// Class used to notify listeners on majority committed point advancement events.
class MajorityCommittedPointNotifier final : public Notifier {
public:
MajorityCommittedPointNotifier(repl::OpTime opTime = repl::OpTime())
: _opTimeToBeMajorityCommitted(opTime) {}
// Computes the OpTime to wait on by incrementing the current read timestamp.
void prepareForWait(OperationContext* opCtx) final {
auto readTs = opCtx->recoveryUnit()->getPointInTimeReadTimestamp(opCtx);
invariant(readTs);
_opTimeToBeMajorityCommitted =
repl::OpTime(*readTs + 1, repl::ReplicationCoordinator::get(opCtx)->getTerm());
}
void waitUntil(OperationContext* opCtx, Date_t deadline) final {
auto majorityCommittedFuture = WaitForMajorityService::get(opCtx->getServiceContext())
.waitUntilMajorityForRead(_opTimeToBeMajorityCommitted,
opCtx->getCancellationToken());
opCtx->runWithDeadline(deadline, opCtx->getTimeoutError(), [&] {
auto status = majorityCommittedFuture.getNoThrow(opCtx);
if (!status.isOK()) {
LOGV2_DEBUG(7455500,
3,
"Failure waiting for the majority committed event",
"status"_attr = status.toString());
}
});
}
private:
repl::OpTime _opTimeToBeMajorityCommitted;
};
/**
* Returns true if the PlanExecutor should listen for inserts, which is when a getMore is called
* on a tailable and awaitData cursor that still has time left and hasn't been interrupted.
*/
bool shouldListenForInserts(OperationContext* opCtx, CanonicalQuery* cq);
/**
* Returns true if the PlanExecutor should wait for data to be inserted, which is when a getMore
* is called on a tailable and awaitData cursor on a capped collection. Returns false if an EOF
* should be returned immediately.
*/
bool shouldWaitForInserts(OperationContext* opCtx,
CanonicalQuery* cq,
PlanYieldPolicy* yieldPolicy);
/**
* Returns an insert notifier for a capped collection.
*/
std::unique_ptr<Notifier> getCappedInsertNotifier(OperationContext* opCtx,
const NamespaceString& nss,
PlanYieldPolicy* yieldPolicy);
/**
* Called for tailable and awaitData cursors in order to yield locks and waits for inserts to
* the collection being tailed. Returns control to the caller once there has been an insertion
* and there may be new results. If the PlanExecutor was killed during a yield, throws an
* exception.
*/
void waitForInserts(OperationContext* opCtx,
PlanYieldPolicy* yieldPolicy,
std::unique_ptr<Notifier>& notifier);
} // namespace mongo::insert_listener
#undef MONGO_LOGV2_DEFAULT_COMPONENT
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