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/**
* Copyright (C) 2016 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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 <cstdint>
#include "mongo/base/disallow_copying.h"
#include "mongo/s/catalog/type_settings.h"
#include "mongo/s/migration_secondary_throttle_options.h"
#include "mongo/stdx/mutex.h"
#include "mongo/platform/atomic_word.h"
namespace mongo {
class MigrationSecondaryThrottleOptions;
class OperationContext;
class Status;
/**
* Contains settings, which control the behaviour of the balancer.
*/
class BalancerConfiguration {
MONGO_DISALLOW_COPYING(BalancerConfiguration);
public:
// Default value used for the max chunk size if one is not specified in the balancer
// configuration
static const uint64_t kDefaultMaxChunkSizeBytes;
/**
* Primes the balancer configuration with some default values. These settings may change at a
* later time after a call to refresh().
*/
BalancerConfiguration(uint64_t defaultMaxChunkSizeBytes);
~BalancerConfiguration();
/**
* Returns whether balancing is allowed based on both the enabled state of the balancer and the
* balancing window.
*/
bool isBalancerActive() const;
/**
* Returns the secondary throttle options for the balancer.
*/
MigrationSecondaryThrottleOptions getSecondaryThrottle() const;
/**
* Returns whether the balancer should wait for deletion of orphaned chunk data at the end of
* each migration.
*/
bool waitForDelete() const;
/**
* Returns the max chunk size after which a chunk would be considered jumbo.
*/
uint64_t getMaxChunkSizeBytes() const {
return _maxChunkSizeBytes.loadRelaxed();
}
/**
* Blocking method, which refreshes the balancer configuration from the settings in the
* config.settings collection. It will stop at the first bad configuration value and return an
* error indicating what failed.
*
* This method is thread-safe but it doesn't make sense to be called from more than one thread
* at a time.
*/
Status refreshAndCheck(OperationContext* txn);
/**
* Validates that the specified max chunk size value (in bytes) is allowed.
*/
static bool checkMaxChunkSizeValid(uint64_t maxChunkSizeBytes);
private:
/**
* Reloads the balancer configuration from the settings document. Fails if the settings document
* cannot be read, in which case the values will remain unchanged.
*/
Status _refreshBalancerSettings(OperationContext* txn);
/**
* If the balancer settings document is missing, these are the defaults, which will be used.
*/
void _useDefaultBalancerSettings();
/**
* Reloads the chunk sizes configuration from the settings document. Fails if the settings
* document cannot be read or if any setting contains invalid value, in which case the offending
* value will remain unchanged.
*/
Status _refreshChunkSizeSettings(OperationContext* txn);
/**
* If the chunk size settings document is missing, these are the defaults, which will be used.
*/
void _useDefaultChunkSizeSettings();
// Whether auto-balancing of chunks should happen
AtomicBool _shouldBalance{true};
// The latest read balancer settings (used for the balancer window and secondary throttle) and a
// mutex to protect its changes
mutable stdx::mutex _balancerSettingsMutex;
SettingsType _balancerSettings;
bool _waitForDelete{false};
MigrationSecondaryThrottleOptions _secondaryThrottle;
// Default value for use for the max chunk size if the setting is not present in the balancer
// configuration
const uint64_t _defaultMaxChunkSizeBytes;
// Max chunk size after which a chunk would be considered jumbo and won't be moved
AtomicUInt64 _maxChunkSizeBytes;
};
} // namespace mongo
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