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
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
|
/**
* 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 <boost/optional.hpp>
#include <cstddef>
#include <vector>
#include "mongo/base/counter.h"
#include "mongo/base/disallow_copying.h"
#include "mongo/bson/bsonobj.h"
#include "mongo/util/time_support.h"
namespace mongo {
class OperationContext;
namespace repl {
/**
* Interface for temporary container of oplog entries (in BSON format) from sync source by
* OplogFetcher that will be read by applier in the InitialSyncer.
*
* Implementations are only required to support one pusher and one popper.
*/
class OplogBuffer {
MONGO_DISALLOW_COPYING(OplogBuffer);
public:
/**
* Type of item held in the oplog buffer;
*/
using Value = BSONObj;
/**
* Batch of oplog entries (in BSON format) for bulk read/write operations.
*/
using Batch = std::vector<Value>;
/**
* Counters for this oplog buffer.
*/
class Counters;
OplogBuffer() = default;
virtual ~OplogBuffer() = default;
/**
* Causes the oplog buffer to initialize its internal state (start threads if appropriate,
* create backing storage, etc). This method may be called at most once for the lifetime of an
* oplog buffer.
*/
virtual void startup(OperationContext* opCtx) = 0;
/**
* Signals to the oplog buffer that it should shut down. This method may block. After
* calling shutdown, it is illegal to perform read/write operations on this oplog buffer.
*
* It is legal to call this method multiple times, but it should only be called after startup
* has been called.
*/
virtual void shutdown(OperationContext* opCtx) = 0;
/**
* Pushes operation into oplog buffer, ignoring any size constraints. Does not block.
* If the oplog buffer is already full, this will cause the size of the oplog buffer to exceed
* the limit returned by getMaxSize() but should not otherwise adversely affect normal
* functionality such as pushing and popping operations from the oplog buffer.
*/
virtual void pushEvenIfFull(OperationContext* opCtx, const Value& value) = 0;
/**
* Pushes operation into oplog buffer.
* If there are size constraints on the oplog buffer, this may block until sufficient space
* is made available (by popping) to complete this operation.
*/
virtual void push(OperationContext* opCtx, const Value& value) = 0;
/**
* Pushes operations in the iterator range [begin, end) into the oplog buffer without blocking.
*/
virtual void pushAllNonBlocking(OperationContext* opCtx,
Batch::const_iterator begin,
Batch::const_iterator end) = 0;
/**
* Returns when enough space is available.
*/
virtual void waitForSpace(OperationContext* opCtx, std::size_t size) = 0;
/**
* Returns true if oplog buffer is empty.
*/
virtual bool isEmpty() const = 0;
/**
* Maximum size of all oplog entries that can be stored in this oplog buffer as measured by the
* BSONObj::objsize() function.
*
* Returns 0 if this oplog buffer has no size constraints.
*/
virtual std::size_t getMaxSize() const = 0;
/**
* Total size of all oplog entries in this oplog buffer as measured by the BSONObj::objsize()
* function.
*/
virtual std::size_t getSize() const = 0;
/**
* Returns the number/count of items in the oplog buffer.
*/
virtual std::size_t getCount() const = 0;
/**
* Clears oplog buffer.
*/
virtual void clear(OperationContext* opCtx) = 0;
/**
* Returns false if oplog buffer is empty. "value" is left unchanged.
* Otherwise, removes last item (saves in "value") from the oplog buffer and returns true.
*/
virtual bool tryPop(OperationContext* opCtx, Value* value) = 0;
/**
* Waits "waitDuration" for an operation to be pushed into the oplog buffer.
* Returns false if oplog buffer is still empty after "waitDuration".
* Otherwise, returns true.
*/
virtual bool waitForData(Seconds waitDuration) = 0;
/**
* Returns false if oplog buffer is empty.
* Otherwise, returns true and sets "value" to last item in oplog buffer.
*/
virtual bool peek(OperationContext* opCtx, Value* value) = 0;
/**
* Returns the item most recently added to the oplog buffer or nothing if the buffer is empty.
*/
virtual boost::optional<Value> lastObjectPushed(OperationContext* opCtx) const = 0;
};
class OplogBuffer::Counters {
public:
/**
* Sets maximum size of operations for this OplogBuffer.
* This function should only be called by a single thread.
*/
void setMaxSize(std::size_t newMaxSize) {
maxSize.increment(newMaxSize - maxSize.get());
}
/**
* Clears counters.
* This function should only be called by a single thread.
*/
void clear() {
count.decrement(count.get());
size.decrement(size.get());
}
void increment(const Value& value) {
count.increment(1);
size.increment(std::size_t(value.objsize()));
}
void decrement(const Value& value) {
count.decrement(1);
size.decrement(std::size_t(value.objsize()));
}
// Number of operations in this OplogBuffer.
Counter64 count;
// Total size of operations in this OplogBuffer. Measured in bytes.
Counter64 size;
// Maximum size of operations in this OplogBuffer. Measured in bytes.
Counter64 maxSize;
};
} // namespace repl
} // namespace mongo
|
