ClickHouse/src/Storages/MergeTree/ReplicatedMergeTreeRestartingThread.h
2020-10-27 12:04:03 +01:00

69 lines
2.0 KiB
C++

#pragma once
#include <Poco/Event.h>
#include <common/logger_useful.h>
#include <Core/BackgroundSchedulePool.h>
#include <common/types.h>
#include <thread>
#include <atomic>
namespace DB
{
class StorageReplicatedMergeTree;
/** Initializes ZK session.
* Exposes ephemeral nodes. It sets the node values that are required for replica detection.
* Starts participation in the leader selection. Starts all background threads.
* Then monitors whether the session has expired. And if it expired, it will reinitialize it.
*/
class ReplicatedMergeTreeRestartingThread
{
public:
ReplicatedMergeTreeRestartingThread(StorageReplicatedMergeTree & storage_);
void start() { task->activateAndSchedule(); }
void wakeup() { task->schedule(); }
void shutdown();
private:
StorageReplicatedMergeTree & storage;
String log_name;
Poco::Logger * log;
std::atomic<bool> need_stop {false};
// We need it besides `storage.is_readonly`, because `shutdown()` may be called many times, that way `storage.is_readonly` will not change.
bool incr_readonly = false;
/// The random data we wrote into `/replicas/me/is_active`.
String active_node_identifier;
BackgroundSchedulePool::TaskHolder task;
Int64 check_period_ms; /// The frequency of checking expiration of session in ZK.
bool first_time = true; /// Activate replica for the first time.
bool startup_completed = false;
void run();
/// Start or stop background threads. Used for partial reinitialization when re-creating a session in ZooKeeper.
bool tryStartup(); /// Returns false if ZooKeeper is not available.
/// Note in ZooKeeper that this replica is currently active.
void activateReplica();
/// Delete the parts for which the quorum has failed (for the time when the replica was inactive).
void removeFailedQuorumParts();
/// If there is an unreachable quorum, and we have a part, then add this replica to the quorum.
void updateQuorumIfWeHavePart();
void partialShutdown();
};
}