1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
|
/**
* Copyright (C) 2018-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/util/concurrency/thread_pool.h"
#include "mongo/util/periodic_runner.h"
namespace mongo {
class NamespaceString;
class OperationContext;
class ServiceContext;
class ChunkSplitStateDriver;
/**
* Handles asynchronous auto-splitting of chunks.
*/
class ChunkSplitter {
ChunkSplitter(const ChunkSplitter&) = delete;
ChunkSplitter& operator=(const ChunkSplitter&) = delete;
public:
ChunkSplitter();
~ChunkSplitter();
/**
* Obtains the service-wide chunk splitter instance.
*/
static ChunkSplitter& get(OperationContext* opCtx);
static ChunkSplitter& get(ServiceContext* serviceContext);
/**
* Sets the mode of the ChunkSplitter to either primary or secondary.
* The ChunkSplitter is only active when primary.
*/
void onShardingInitialization(bool isPrimary);
/**
* Invoked when the shard server primary enters the 'PRIMARY' state to set up the ChunkSplitter
* to begin accepting split requests.
*/
void onStepUp();
/**
* Invoked when this node which is currently serving as a 'PRIMARY' steps down.
*
* This method might be called multiple times in succession, which is what happens as a result
* of incomplete transition to primary so it is resilient to that.
*/
void onStepDown();
/**
* Blocks until all chunk split tasks in the underlying thread pool have
* completed (that is, until the thread pool is idle)
*/
void waitForIdle();
/**
* Schedules an autosplit task. This function throws on scheduling failure.
*/
void trySplitting(std::shared_ptr<ChunkSplitStateDriver> chunkSplitStateDriver,
const NamespaceString& nss,
const BSONObj& min,
const BSONObj& max,
long dataWritten);
private:
/**
* Determines if the specified chunk should be split and then performs any necessary splits.
*
* It may also perform a 'top chunk' optimization where a resulting chunk that contains either
* MaxKey or MinKey as a range extreme will be moved off to another shard to relieve load on the
* original owner. This optimization presumes that the user is doing writes with increasing or
* decreasing shard key values.
*/
void _runAutosplit(std::shared_ptr<ChunkSplitStateDriver> chunkSplitStateDriver,
const NamespaceString& nss,
const BSONObj& min,
const BSONObj& max,
long dataWritten);
// Protects the state below.
Mutex _mutex = MONGO_MAKE_LATCH("ChunkSplitter::_mutex");
// The ChunkSplitter is only active on a primary node.
bool _isPrimary{false};
// Thread pool for parallelizing splits.
ThreadPool _threadPool;
};
} // namespace mongo
|
