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1 package org.apache.lucene.store;
2
3
18
19 import java.io.IOException  ;
20 import java.io.File ;
21 import java.io.RandomAccessFile ;
22 import java.nio.ByteBuffer ;
23 import java.nio.channels.FileChannel ;
24 import java.nio.channels.FileChannel.MapMode;
25
26
33 public class MMapDirectory extends FSDirectory {
34
35 private static class MMapIndexInput extends IndexInput {
36
37 private ByteBuffer buffer;
38 private final long length;
39
40 private MMapIndexInput(RandomAccessFile raf) throws IOException {
41 this.length = raf.length();
42 this.buffer = raf.getChannel().map(MapMode.READ_ONLY, 0, length);
43 }
44
45 public byte readByte() throws IOException {
46 return buffer.get();
47 }
48
49 public void readBytes(byte[] b, int offset, int len)
50 throws IOException {
51 buffer.get(b, offset, len);
52 }
53
54 public long getFilePointer() {
55 return buffer.position();
56 }
57
58 public void seek(long pos) throws IOException {
59 buffer.position((int)pos);
60 }
61
62 public long length() {
63 return length;
64 }
65
66 public Object clone() {
67 MMapIndexInput clone = (MMapIndexInput)super.clone();
68 clone.buffer = buffer.duplicate();
69 return clone;
70 }
71
72 public void close() throws IOException {}
73 }
74
75
79 private static class MultiMMapIndexInput extends IndexInput {
80
81 private ByteBuffer [] buffers;
82 private int[] bufSizes;
84 private final long length;
85
86 private int curBufIndex;
87 private final int maxBufSize;
88
89 private ByteBuffer curBuf; private int curAvail;
92
93 public MultiMMapIndexInput(RandomAccessFile raf, int maxBufSize)
94 throws IOException {
95 this.length = raf.length();
96 this.maxBufSize = maxBufSize;
97
98 if (maxBufSize <= 0)
99 throw new IllegalArgumentException ("Non positive maxBufSize: "
100 + maxBufSize);
101
102 if ((length / maxBufSize) > Integer.MAX_VALUE)
103 throw new IllegalArgumentException
104 ("RandomAccessFile too big for maximum buffer size: "
105 + raf.toString());
106
107 int nrBuffers = (int) (length / maxBufSize);
108 if ((nrBuffers * maxBufSize) < length) nrBuffers++;
109
110 this.buffers = new ByteBuffer [nrBuffers];
111 this.bufSizes = new int[nrBuffers];
112
113 long bufferStart = 0;
114 FileChannel rafc = raf.getChannel();
115 for (int bufNr = 0; bufNr < nrBuffers; bufNr++) {
116 int bufSize = (length > (bufferStart + maxBufSize))
117 ? maxBufSize
118 : (int) (length - bufferStart);
119 this.buffers[bufNr] = rafc.map(MapMode.READ_ONLY,bufferStart,bufSize);
120 this.bufSizes[bufNr] = bufSize;
121 bufferStart += bufSize;
122 }
123 seek(0L);
124 }
125
126 public byte readByte() throws IOException {
127 if (curAvail == 0) {
130 curBufIndex++;
131 curBuf = buffers[curBufIndex]; curBuf.position(0);
133 curAvail = bufSizes[curBufIndex];
134 }
135 curAvail--;
136 return curBuf.get();
137 }
138
139 public void readBytes(byte[] b, int offset, int len) throws IOException {
140 while (len > curAvail) {
141 curBuf.get(b, offset, curAvail);
142 len -= curAvail;
143 offset += curAvail;
144 curBufIndex++;
145 curBuf = buffers[curBufIndex]; curBuf.position(0);
147 curAvail = bufSizes[curBufIndex];
148 }
149 curBuf.get(b, offset, len);
150 curAvail -= len;
151 }
152
153 public long getFilePointer() {
154 return (curBufIndex * (long) maxBufSize) + curBuf.position();
155 }
156
157 public void seek(long pos) throws IOException {
158 curBufIndex = (int) (pos / maxBufSize);
159 curBuf = buffers[curBufIndex];
160 int bufOffset = (int) (pos - (curBufIndex * maxBufSize));
161 curBuf.position(bufOffset);
162 curAvail = bufSizes[curBufIndex] - bufOffset;
163 }
164
165 public long length() {
166 return length;
167 }
168
169 public Object clone() {
170 MultiMMapIndexInput clone = (MultiMMapIndexInput)super.clone();
171 clone.buffers = new ByteBuffer [buffers.length];
172 for (int bufNr = 0; bufNr < buffers.length; bufNr++) {
176 clone.buffers[bufNr] = buffers[bufNr].duplicate();
177 }
178 try {
179 clone.seek(getFilePointer());
180 } catch(IOException ioe) {
181 throw new RuntimeException (ioe);
182 };
183 return clone;
184 }
185
186 public void close() throws IOException {}
187 }
188
189 private final int MAX_BBUF = Integer.MAX_VALUE;
190
191 public IndexInput openInput(String name) throws IOException {
192 File f = new File (getFile(), name);
193 RandomAccessFile raf = new RandomAccessFile (f, "r");
194 try {
195 return (raf.length() <= MAX_BBUF)
196 ? (IndexInput) new MMapIndexInput(raf)
197 : (IndexInput) new MultiMMapIndexInput(raf, MAX_BBUF);
198 } finally {
199 raf.close();
200 }
201 }
202 }
203 |
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