-
Notifications
You must be signed in to change notification settings - Fork 2.3k
/
SegmentFile.java
273 lines (234 loc) · 8.23 KB
/
SegmentFile.java
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
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
/*
* Copyright (c) 2002-2016 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.coreedge.raft.log.segmented;
import java.io.File;
import java.io.IOException;
import org.neo4j.coreedge.helper.StatUtil.StatContext;
import org.neo4j.coreedge.raft.log.EntryRecord;
import org.neo4j.coreedge.raft.log.LogPosition;
import org.neo4j.coreedge.raft.log.RaftLogEntry;
import org.neo4j.coreedge.raft.replication.ReplicatedContent;
import org.neo4j.coreedge.raft.state.ChannelMarshal;
import org.neo4j.coreedge.raft.state.EndOfStreamException;
import org.neo4j.cursor.IOCursor;
import org.neo4j.io.fs.FileSystemAbstraction;
import org.neo4j.io.fs.StoreChannel;
import org.neo4j.kernel.impl.transaction.log.PhysicalFlushableChannel;
import org.neo4j.logging.Log;
import org.neo4j.logging.LogProvider;
import static java.lang.String.format;
/**
* Keeps track of a segment of the RAFT log, i.e. a consecutive set of entries.
* Concurrent reading is thread-safe.
*/
class SegmentFile implements AutoCloseable
{
private static final SegmentHeader.Marshal headerMarshal = new SegmentHeader.Marshal();
private final Log log;
private final FileSystemAbstraction fileSystem;
private final File file;
private final ReaderPool readerPool;
private final ChannelMarshal<ReplicatedContent> contentMarshal;
private final PositionCache positionCache;
private final ReferenceCounter refCount;
private final SegmentHeader header;
private final long version;
private PhysicalFlushableChannel bufferedWriter;
private final StatContext scanStats;
SegmentFile( FileSystemAbstraction fileSystem, File file, ReaderPool readerPool, long version,
ChannelMarshal<ReplicatedContent> contentMarshal, LogProvider logProvider, SegmentHeader header )
{
this( fileSystem, file, readerPool, version, contentMarshal, logProvider, header, null );
}
SegmentFile( FileSystemAbstraction fileSystem, File file, ReaderPool readerPool, long version,
ChannelMarshal<ReplicatedContent> contentMarshal, LogProvider logProvider, SegmentHeader header, StatContext scanStats )
{
this.fileSystem = fileSystem;
this.file = file;
this.readerPool = readerPool;
this.contentMarshal = contentMarshal;
this.header = header;
this.version = version;
this.scanStats = scanStats;
this.positionCache = new PositionCache();
this.refCount = new ReferenceCounter();
this.log = logProvider.getLog( getClass() );
}
static SegmentFile create( FileSystemAbstraction fileSystem, File file, ReaderPool readerPool, long version,
ChannelMarshal<ReplicatedContent> contentMarshal, LogProvider logProvider, SegmentHeader header ) throws IOException
{
return create( fileSystem, file, readerPool, version, contentMarshal, logProvider, header, null );
}
static SegmentFile create( FileSystemAbstraction fileSystem, File file, ReaderPool readerPool, long version,
ChannelMarshal<ReplicatedContent> contentMarshal, LogProvider logProvider, SegmentHeader header, StatContext scanStats )
throws IOException
{
if ( fileSystem.fileExists( file ) )
{
throw new IllegalStateException( "File was not expected to exist" );
}
SegmentFile segment = new SegmentFile( fileSystem, file, readerPool, version, contentMarshal, logProvider, header, scanStats );
headerMarshal.marshal( header, segment.getOrCreateWriter() );
segment.flush();
return segment;
}
/**
* Channels must be closed when no longer used, so that they are released back to the pool of readers.
*/
IOCursor<EntryRecord> getCursor( long logIndex ) throws IOException, DisposedException
{
assert logIndex > header.prevIndex();
if ( !refCount.increase() )
{
throw new DisposedException();
}
/* This is the relative index within the file, starting from zero. */
long offsetIndex = logIndex - (header.prevIndex() + 1);
LogPosition position = positionCache.lookup( offsetIndex );
Reader reader = readerPool.acquire( version, position.byteOffset );
try
{
long currentIndex = position.logIndex;
if ( scanStats != null )
{
scanStats.collect( offsetIndex - currentIndex );
}
return new EntryRecordCursor( reader, contentMarshal, currentIndex, offsetIndex, this );
}
catch ( EndOfStreamException e )
{
readerPool.release( reader );
refCount.decrease();
return IOCursor.getEmpty();
}
catch ( IOException e )
{
reader.close();
refCount.decrease();
throw e;
}
}
private synchronized PhysicalFlushableChannel getOrCreateWriter() throws IOException
{
if ( bufferedWriter == null )
{
if ( !refCount.increase() )
{
throw new IOException( "Writer has been closed" );
}
StoreChannel channel = fileSystem.open( file, "rw" );
channel.position( channel.size() );
bufferedWriter = new PhysicalFlushableChannel( channel );
}
return bufferedWriter;
}
synchronized long position() throws IOException
{
return getOrCreateWriter().position();
}
/**
* Idempotently closes the writer.
*/
synchronized void closeWriter()
{
if ( bufferedWriter != null )
{
try
{
flush();
bufferedWriter.close();
}
catch ( IOException e )
{
log.error( "Failed to close writer for: " + file, e );
}
bufferedWriter = null;
refCount.decrease();
}
}
public synchronized void write( long logIndex, RaftLogEntry entry ) throws IOException
{
EntryRecord.write( getOrCreateWriter(), contentMarshal, logIndex, entry.term(), entry.content() );
}
synchronized void flush() throws IOException
{
bufferedWriter.prepareForFlush().flush();
}
public boolean delete()
{
return fileSystem.deleteFile( file );
}
public SegmentHeader header()
{
return header;
}
public long size()
{
return fileSystem.getFileSize( file );
}
String getFilename()
{
return file.getName();
}
/**
* Called by the pruner when it wants to prune this segment. If there are no open
* readers or writers then the segment will be closed.
*
* @return True if the segment can be pruned at this time, false otherwise.
*/
boolean tryClose()
{
if ( refCount.tryDispose() )
{
close();
return true;
}
return false;
}
@Override
public void close()
{
closeWriter();
if ( !refCount.tryDispose() )
{
throw new IllegalStateException( format( "Segment still referenced. Value: %d", refCount.get() ) );
}
}
@Override
public String toString()
{
return "SegmentFile{" +
"file=" + file.getName() +
", header=" + header +
'}';
}
ReferenceCounter refCount()
{
return refCount;
}
PositionCache positionCache()
{
return positionCache;
}
public ReaderPool readerPool()
{
return readerPool;
}
}