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/**
* 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.
*/
#pragma once
#include "mongo/db/shard_role.h"
#include "mongo/db/ttl_collection_cache.h"
#include "mongo/util/background.h"
namespace mongo {
class ServiceContext;
/**
* Instantiates the TTLMonitor to periodically remove documents from TTL collections. Safe to call
* again after shutdownTTLMonitor() has been called.
*/
void startTTLMonitor(ServiceContext* serviceContext);
/**
* Shuts down the TTLMonitor if it is running. Safe to call multiple times.
*/
void shutdownTTLMonitor(ServiceContext* serviceContext);
class TTLMonitor : public BackgroundJob {
public:
TTLMonitor();
static TTLMonitor* get(ServiceContext* serviceCtx);
static void set(ServiceContext* serviceCtx, std::unique_ptr<TTLMonitor> monitor);
static Status onUpdateTTLMonitorSleepSeconds(int newSleepSeconds);
std::string name() const {
return "TTLMonitor";
}
void run();
/**
* Signals the thread to quit and then waits until it does.
*/
void shutdown();
/**
* Invoked when the node enters the primary state.
*/
void onStepUp(OperationContext* opCtx);
void updateSleepSeconds(Seconds newSeconds);
long long getTTLPasses_forTest();
long long getTTLSubPasses_forTest();
private:
friend class TTLTest;
/**
* Deletes all expired documents. May consist of several sub-passes.
*/
void _doTTLPass();
/**
* A sub-pass iterates over a list of TTL indexes until there are no more expired documents to
* delete or 'ttlSubPassTargetSecs' is exceeded.
*
* Once it is confirmed there are no more expired documents on an index, the index will not be
* visited again for the remainder of the sub-pass.
*
* The 'collSubpassHistory' tracks the number of consecutive subpasses on a collection that
* completed with more expired documents remaining. It is used to determine when a collection's
* TTL deletes should be raised from 'low' to 'normal' priority to prevent TTL deletes from
* falling behind on TTL inserts.
*
* Returns true if there are more expired documents to delete. False otherwise.
*/
bool _doTTLSubPass(OperationContext* opCtx,
stdx::unordered_map<UUID, long long, UUID::Hash>& collSubpassHistory);
/**
* Given a TTL index, attempts to delete all expired documents through the index until
* - hitting the batched delete document or time limit for a single TTL index
* - removing all expired documents corresponding to the TTLIndex
* - reaching an error
*
* Returns true if there are more expired documents to delete (a batched delete limit is met).
* Returns false if there are no more expired documents to delete at this time - including when
* errors specific to the TTL index are reached.
*
* When batching is disabled, always returns false since all expired documents are guaranteed to
* be removed.
*
* In some cases (i.e: on temporary resharding collections, collections pending to be dropped,
* etc), the TTLMonitor is prohibitied from removing expired documents - returns false in these
* scenarios as well.
*/
bool _doTTLIndexDelete(OperationContext* opCtx,
TTLCollectionCache* ttlCollectionCache,
const UUID& uuid,
const TTLCollectionCache::Info& info);
/**
* Removes documents from the collection using the specified TTL index after a sufficient
* amount of time has passed according to its expiry specification.
*
* Returns true if there are more expired documents to delete through the index at this time.
* False otherwise.
*
* When batching is disabled, always returns false since all expired documents are guaranteed to
* be removed.
*/
bool _deleteExpiredWithIndex(OperationContext* opCtx,
TTLCollectionCache* ttlCollectionCache,
const ScopedCollectionAcquisition& collection,
std::string indexName);
/*
* Removes expired documents from a clustered collection using a bounded collection scan.
* On time-series buckets collections, TTL operates on type 'ObjectId'. On general purpose
* collections, TTL operates on type 'Date'.
*
* Returns true if there are more expired documents to delete through the clustered index at
* this time. False otherwise.
*
* When batching is disabled, always returns false since all expired documents are guaranteed to
* be removed.
*/
bool _deleteExpiredWithCollscan(OperationContext* opCtx,
TTLCollectionCache* ttlCollectionCache,
const ScopedCollectionAcquisition& collection);
// Protects the state below.
mutable Mutex _stateMutex = MONGO_MAKE_LATCH("TTLMonitorStateMutex");
// Signaled to wake up the thread, if the thread is waiting. This condition variable is used to
// notify the thread of either:
// * The server is shutting down.
// * The ttlMonitorSleepSecs variable has changed.
// If the server is shutting down the monitor will stop.
mutable stdx::condition_variable _notificationCV;
bool _shuttingDown = false;
Seconds _ttlMonitorSleepSecs;
};
} // namespace mongo
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