1 | #pragma once |
2 | |
3 | #include <Poco/Event.h> |
4 | #include <common/logger_useful.h> |
5 | #include <Core/BackgroundSchedulePool.h> |
6 | #include <Core/Types.h> |
7 | #include <thread> |
8 | #include <atomic> |
9 | |
10 | |
11 | namespace DB |
12 | { |
13 | |
14 | class StorageReplicatedMergeTree; |
15 | |
16 | |
17 | /** Initializes ZK session. |
18 | * Exposes ephemeral nodes. It sets the node values that are required for replica detection. |
19 | * Starts participation in the leader selection. Starts all background threads. |
20 | * Then monitors whether the session has expired. And if it expired, it will reinitialize it. |
21 | */ |
22 | class ReplicatedMergeTreeRestartingThread |
23 | { |
24 | public: |
25 | ReplicatedMergeTreeRestartingThread(StorageReplicatedMergeTree & storage_); |
26 | |
27 | void start() { task->activateAndSchedule(); } |
28 | |
29 | void wakeup() { task->schedule(); } |
30 | |
31 | void shutdown(); |
32 | |
33 | private: |
34 | StorageReplicatedMergeTree & storage; |
35 | String log_name; |
36 | Logger * log; |
37 | std::atomic<bool> need_stop {false}; |
38 | |
39 | /// The random data we wrote into `/replicas/me/is_active`. |
40 | String active_node_identifier; |
41 | |
42 | BackgroundSchedulePool::TaskHolder task; |
43 | Int64 check_period_ms; /// The frequency of checking expiration of session in ZK. |
44 | bool first_time = true; /// Activate replica for the first time. |
45 | time_t prev_time_of_check_delay = 0; |
46 | bool startup_completed = false; |
47 | |
48 | void run(); |
49 | |
50 | /// Start or stop background threads. Used for partial reinitialization when re-creating a session in ZooKeeper. |
51 | bool tryStartup(); /// Returns false if ZooKeeper is not available. |
52 | |
53 | /// Note in ZooKeeper that this replica is currently active. |
54 | void activateReplica(); |
55 | |
56 | /// Delete the parts for which the quorum has failed (for the time when the replica was inactive). |
57 | void removeFailedQuorumParts(); |
58 | |
59 | /// If there is an unreachable quorum, and we have a part, then add this replica to the quorum. |
60 | void updateQuorumIfWeHavePart(); |
61 | |
62 | void partialShutdown(); |
63 | }; |
64 | |
65 | |
66 | } |
67 | |