ClickHouse/src/Interpreters/DDLWorker.h
2022-10-31 10:50:33 +01:00

168 lines
5.5 KiB
C++

#pragma once
#include <Common/CurrentThread.h>
#include <Common/DNSResolver.h>
#include <Common/ThreadPool.h>
#include <Common/ZooKeeper/IKeeper.h>
#include <Storages/IStorage_fwd.h>
#include <Parsers/IAST_fwd.h>
#include <Interpreters/Context.h>
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <mutex>
#include <thread>
namespace zkutil
{
class ZooKeeper;
}
namespace Poco
{
class Logger;
namespace Util { class AbstractConfiguration; }
}
namespace Coordination
{
struct Stat;
}
namespace zkutil
{
class ZooKeeperLock;
}
namespace DB
{
class ASTAlterQuery;
struct DDLLogEntry;
struct DDLTaskBase;
using DDLTaskPtr = std::unique_ptr<DDLTaskBase>;
using ZooKeeperPtr = std::shared_ptr<zkutil::ZooKeeper>;
class AccessRightsElements;
class DDLWorker
{
public:
DDLWorker(int pool_size_, const std::string & zk_root_dir, ContextPtr context_, const Poco::Util::AbstractConfiguration * config, const String & prefix,
const String & logger_name = "DDLWorker", const CurrentMetrics::Metric * max_entry_metric_ = nullptr, const CurrentMetrics::Metric * max_pushed_entry_metric_ = nullptr);
virtual ~DDLWorker();
/// Pushes query into DDL queue, returns path to created node
virtual String enqueueQuery(DDLLogEntry & entry);
/// Host ID (name:port) for logging purposes
/// Note that in each task hosts are identified individually by name:port from initiator server cluster config
std::string getCommonHostID() const
{
return host_fqdn_id;
}
std::string getQueueDir() const
{
return queue_dir;
}
void startup();
virtual void shutdown();
bool isCurrentlyActive() const { return initialized && !stop_flag; }
/// Returns cached ZooKeeper session (possibly expired).
ZooKeeperPtr tryGetZooKeeper() const;
/// If necessary, creates a new session and caches it.
ZooKeeperPtr getAndSetZooKeeper();
protected:
/// Iterates through queue tasks in ZooKeeper, runs execution of new tasks
void scheduleTasks(bool reinitialized);
DDLTaskBase & saveTask(DDLTaskPtr && task);
/// Reads entry and check that the host belongs to host list of the task
/// Returns non-empty DDLTaskPtr if entry parsed and the check is passed
virtual DDLTaskPtr initAndCheckTask(const String & entry_name, String & out_reason, const ZooKeeperPtr & zookeeper);
void processTask(DDLTaskBase & task, const ZooKeeperPtr & zookeeper);
void updateMaxDDLEntryID(const String & entry_name);
/// Check that query should be executed on leader replica only
static bool taskShouldBeExecutedOnLeader(const ASTPtr & ast_ddl, StoragePtr storage);
/// Executes query only on leader replica in case of replicated table.
/// Queries like TRUNCATE/ALTER .../OPTIMIZE have to be executed only on one node of shard.
/// Most of these queries can be executed on non-leader replica, but actually they still send
/// query via RemoteQueryExecutor to leader, so to avoid such "2-phase" query execution we
/// execute query directly on leader.
bool tryExecuteQueryOnLeaderReplica(
DDLTaskBase & task,
StoragePtr storage,
const String & node_path,
const ZooKeeperPtr & zookeeper,
std::unique_ptr<zkutil::ZooKeeperLock> & execute_on_leader_lock);
bool tryExecuteQuery(DDLTaskBase & task, const ZooKeeperPtr & zookeeper);
/// Checks and cleanups queue's nodes
void cleanupQueue(Int64 current_time_seconds, const ZooKeeperPtr & zookeeper);
virtual bool canRemoveQueueEntry(const String & entry_name, const Coordination::Stat & stat);
/// Init task node
void createStatusDirs(const std::string & node_path, const ZooKeeperPtr & zookeeper);
/// Return false if the worker was stopped (stop_flag = true)
virtual bool initializeMainThread();
void runMainThread();
void runCleanupThread();
ContextMutablePtr context;
Poco::Logger * log;
std::string host_fqdn; /// current host domain name
std::string host_fqdn_id; /// host_name:port
std::string queue_dir; /// dir with queue of queries
mutable std::mutex zookeeper_mutex;
ZooKeeperPtr current_zookeeper TSA_GUARDED_BY(zookeeper_mutex);
/// Save state of executed task to avoid duplicate execution on ZK error
std::optional<String> last_skipped_entry_name;
std::optional<String> first_failed_task_name;
std::list<DDLTaskPtr> current_tasks;
/// This flag is needed for debug assertions only
bool queue_fully_loaded_after_initialization_debug_helper = false;
Coordination::Stat queue_node_stat;
std::shared_ptr<Poco::Event> queue_updated_event = std::make_shared<Poco::Event>();
std::shared_ptr<Poco::Event> cleanup_event = std::make_shared<Poco::Event>();
std::atomic<bool> initialized = false;
std::atomic<bool> stop_flag = true;
ThreadFromGlobalPool main_thread;
ThreadFromGlobalPool cleanup_thread;
/// Size of the pool for query execution.
size_t pool_size = 1;
std::unique_ptr<ThreadPool> worker_pool;
/// Cleaning starts after new node event is received if the last cleaning wasn't made sooner than N seconds ago
Int64 cleanup_delay_period = 60; // minute (in seconds)
/// Delete node if its age is greater than that
Int64 task_max_lifetime = 7 * 24 * 60 * 60; // week (in seconds)
/// How many tasks could be in the queue
size_t max_tasks_in_queue = 1000;
std::atomic<UInt32> max_id = 0;
const CurrentMetrics::Metric * max_entry_metric;
const CurrentMetrics::Metric * max_pushed_entry_metric;
};
}