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1
18 package org.apache.activemq.kaha.impl.async;
19
20 import java.io.File  ;
21 import java.io.IOException ;
22 import java.io.RandomAccessFile ;
23 import java.nio.channels.FileLock ;
24
25 import org.apache.activemq.util.ByteSequence;
26
27
35 final public class ControlFile {
36
37 private final static boolean DISABLE_FILE_LOCK = "true".equals(System.getProperty("java.nio.channels.FileLock.broken", "false"));
38 private final File file;
39
40
41 private final RandomAccessFile randomAccessFile;
42 private final int maxRecordSize;
43
44 private long version=0;
45 private FileLock lock;
46 private boolean disposed;
47
48
49 public ControlFile(File file, int recordSize) throws IOException {
50 this.file = file;
51 this.maxRecordSize = recordSize+4;
52 randomAccessFile = new RandomAccessFile (file, "rw");
53 }
54
55
59 public void lock() throws IOException {
60 if( DISABLE_FILE_LOCK )
61 return;
62
63 if( lock == null ) {
64 lock = randomAccessFile.getChannel().tryLock();
65 if (lock == null) {
66 throw new IOException ("Control file '"+file+"' could not be locked.");
67 }
68 }
69 }
70
71
76 public void unlock() throws IOException {
77 if( DISABLE_FILE_LOCK )
78 return;
79
80 if (lock != null) {
81 lock.release();
82 lock = null;
83 }
84 }
85
86 public void dispose() {
87 if( disposed )
88 return;
89 disposed=true;
90 try {
91 unlock();
92 } catch (IOException e) {
93 }
94 try {
95 randomAccessFile.close();
96 } catch (IOException e) {
97 }
98 }
99
100 synchronized public ByteSequence load() throws IOException {
101 long l = randomAccessFile.length();
102 if( l < maxRecordSize ) {
103 return null;
104 }
105
106 randomAccessFile.seek(0);
107 long v1 = randomAccessFile.readLong();
108 randomAccessFile.seek(maxRecordSize+8);
109 long v1check = randomAccessFile.readLong();
110
111 randomAccessFile.seek(maxRecordSize+16);
112 long v2 = randomAccessFile.readLong();
113 randomAccessFile.seek((maxRecordSize*2)+24);
114 long v2check = randomAccessFile.readLong();
115
116 byte[] data=null;
117 if( v2 == v2check ) {
118 version = v2;
119 randomAccessFile.seek(maxRecordSize+24);
120 int size = randomAccessFile.readInt();
121 data = new byte[size];
122 randomAccessFile.readFully(data);
123 } else if ( v1 == v1check ){
124 version = v1;
125 randomAccessFile.seek(maxRecordSize+8);
126 int size = randomAccessFile.readInt();
127 data = new byte[size];
128 randomAccessFile.readFully(data);
129 } else {
130 throw new IOException ("Control data corrupted.");
134 }
135 return new ByteSequence(data,0,data.length);
136 }
137
138 public void store(ByteSequence data, boolean sync) throws IOException {
139
140 version++;
141 randomAccessFile.setLength((maxRecordSize*2)+32);
142 randomAccessFile.seek(0);
143
144 randomAccessFile.writeLong(version);
146 randomAccessFile.writeInt(data.getLength());
147 randomAccessFile.write(data.getData());
148 randomAccessFile.writeLong(version);
149
150 randomAccessFile.writeLong(version);
152 randomAccessFile.writeInt(data.getLength());
153 randomAccessFile.write(data.getData());
154 randomAccessFile.writeLong(version);
155
156 if( sync ) {
157 randomAccessFile.getFD().sync();
158 }
159 }
160
161 }
162 |
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