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/**
* Copyright (C) 2022-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/operation_context.h"
#include "mongo/db/repl/replica_set_aware_service.h"
#include "mongo/db/service_context.h"
#include "mongo/s/analyze_shard_key_common_gen.h"
#include "mongo/s/analyze_shard_key_util.h"
#include "mongo/util/periodic_runner.h"
namespace mongo {
namespace analyze_shard_key {
/**
* Keeps track of all samplers in the cluster and assigns sample rates to each sampler based on its
* view of the query distribution across the samplers.
*
* Currently, query sampling is only supported on a sharded cluster. So a sampler must be a mongos
* or shardsvr mongod (acting as a router), and the coordinator must be the config server's primary
* mongod.
*/
class QueryAnalysisCoordinator : public ReplicaSetAwareService<QueryAnalysisCoordinator> {
public:
using CollectionQueryAnalyzerConfigurationMap =
stdx::unordered_map<UUID, CollectionQueryAnalyzerConfiguration, UUID::Hash>;
/**
* Stores the last ping time and the last exponential moving average number of queries executed
* per second for a sampler.
*/
class Sampler {
public:
Sampler(std::string name, Date_t lastPingTime) : _name(name), _lastPingTime(lastPingTime){};
std::string getName() const {
return _name;
}
Date_t getLastPingTime() const {
return _lastPingTime;
}
boost::optional<double> getLastNumQueriesExecutedPerSecond() const {
return _lastNumQueriesExecutedPerSecond;
}
void setLastPingTime(Date_t pingTime);
void setLastNumQueriesExecutedPerSecond(double numQueries);
void resetLastNumQueriesExecutedPerSecond();
private:
std::string _name;
Date_t _lastPingTime;
boost::optional<double> _lastNumQueriesExecutedPerSecond;
};
QueryAnalysisCoordinator() = default;
/**
* Obtains the service-wide QueryAnalysisCoordinator instance.
*/
static QueryAnalysisCoordinator* get(OperationContext* opCtx);
static QueryAnalysisCoordinator* get(ServiceContext* serviceContext);
void onStartup(OperationContext* opCtx) override final;
void onStepUpBegin(OperationContext* opCtx, long long term) override final;
/**
* Creates, updates and deletes the configuration for the collection with the given
* config.queryAnalyzers document.
*/
void onConfigurationInsert(const BSONObj& doc);
void onConfigurationUpdate(const BSONObj& doc);
void onConfigurationDelete(const BSONObj& doc);
/**
* Creates, updates and deletes the sampler (i.e. mongos) with the given config.mongos document.
*/
void onSamplerInsert(const BSONObj& doc);
void onSamplerUpdate(const BSONObj& doc);
void onSamplerDelete(const BSONObj& doc);
/**
* Given the average number of queries that a sampler executes, returns the new query analyzer
* configurations for the sampler.
*/
std::vector<CollectionQueryAnalyzerConfiguration> getNewConfigurationsForSampler(
OperationContext* opCtx, StringData samplerName, double numQueriesExecutedPerSecond);
CollectionQueryAnalyzerConfigurationMap getConfigurationsForTest() const {
stdx::lock_guard<Latch> lk(_mutex);
return _configurations;
}
void clearConfigurationsForTest() {
stdx::lock_guard<Latch> lk(_mutex);
_configurations.clear();
}
StringMap<Sampler> getSamplersForTest() const {
stdx::lock_guard<Latch> lk(_mutex);
return _samplers;
}
void clearSamplersForTest() {
stdx::lock_guard<Latch> lk(_mutex);
_samplers.clear();
}
private:
bool shouldRegisterReplicaSetAwareService() const override final;
void onInitialDataAvailable(OperationContext* opCtx,
bool isMajorityDataAvailable) override final {}
void onShutdown() override final {}
void onStepUpComplete(OperationContext* opCtx, long long term) override final {}
void onStepDown() override final {}
void onBecomeArbiter() override final {}
/**
* Returns the minimum last ping time for a sampler to be considered as active.
*/
Date_t _getMinLastPingTime();
mutable Mutex _mutex = MONGO_MAKE_LATCH("QueryAnalysisCoordinator::_mutex");
CollectionQueryAnalyzerConfigurationMap _configurations;
StringMap<Sampler> _samplers;
};
} // namespace analyze_shard_key
} // namespace mongo
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