1 | /** |
---|
2 | * Licensed to the Apache Software Foundation (ASF) under one |
---|
3 | * or more contributor license agreements. See the NOTICE file |
---|
4 | * distributed with this work for additional information |
---|
5 | * regarding copyright ownership. The ASF licenses this file |
---|
6 | * to you under the Apache License, Version 2.0 (the |
---|
7 | * "License"); you may not use this file except in compliance |
---|
8 | * with the License. You may obtain a copy of the License at |
---|
9 | * |
---|
10 | * http://www.apache.org/licenses/LICENSE-2.0 |
---|
11 | * |
---|
12 | * Unless required by applicable law or agreed to in writing, software |
---|
13 | * distributed under the License is distributed on an "AS IS" BASIS, |
---|
14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
---|
15 | * See the License for the specific language governing permissions and |
---|
16 | * limitations under the License. |
---|
17 | */ |
---|
18 | |
---|
19 | package org.apache.hadoop.io; |
---|
20 | |
---|
21 | import java.io.*; |
---|
22 | |
---|
23 | import org.apache.commons.logging.Log; |
---|
24 | import org.apache.commons.logging.LogFactory; |
---|
25 | import org.apache.hadoop.fs.*; |
---|
26 | import org.apache.hadoop.conf.*; |
---|
27 | import org.apache.hadoop.util.Progressable; |
---|
28 | import org.apache.hadoop.util.ReflectionUtils; |
---|
29 | import org.apache.hadoop.io.SequenceFile.CompressionType; |
---|
30 | import org.apache.hadoop.io.compress.CompressionCodec; |
---|
31 | import org.apache.hadoop.io.compress.DefaultCodec; |
---|
32 | |
---|
33 | /** A file-based map from keys to values. |
---|
34 | * |
---|
35 | * <p>A map is a directory containing two files, the <code>data</code> file, |
---|
36 | * containing all keys and values in the map, and a smaller <code>index</code> |
---|
37 | * file, containing a fraction of the keys. The fraction is determined by |
---|
38 | * {@link Writer#getIndexInterval()}. |
---|
39 | * |
---|
40 | * <p>The index file is read entirely into memory. Thus key implementations |
---|
41 | * should try to keep themselves small. |
---|
42 | * |
---|
43 | * <p>Map files are created by adding entries in-order. To maintain a large |
---|
44 | * database, perform updates by copying the previous version of a database and |
---|
45 | * merging in a sorted change list, to create a new version of the database in |
---|
46 | * a new file. Sorting large change lists can be done with {@link |
---|
47 | * SequenceFile.Sorter}. |
---|
48 | */ |
---|
49 | public class MapFile { |
---|
50 | private static final Log LOG = LogFactory.getLog(MapFile.class); |
---|
51 | |
---|
52 | /** The name of the index file. */ |
---|
53 | public static final String INDEX_FILE_NAME = "index"; |
---|
54 | |
---|
55 | /** The name of the data file. */ |
---|
56 | public static final String DATA_FILE_NAME = "data"; |
---|
57 | |
---|
58 | protected MapFile() {} // no public ctor |
---|
59 | |
---|
60 | /** Writes a new map. */ |
---|
61 | public static class Writer implements java.io.Closeable { |
---|
62 | private SequenceFile.Writer data; |
---|
63 | private SequenceFile.Writer index; |
---|
64 | |
---|
65 | final private static String INDEX_INTERVAL = "io.map.index.interval"; |
---|
66 | private int indexInterval = 128; |
---|
67 | |
---|
68 | private long size; |
---|
69 | private LongWritable position = new LongWritable(); |
---|
70 | |
---|
71 | // the following fields are used only for checking key order |
---|
72 | private WritableComparator comparator; |
---|
73 | private DataInputBuffer inBuf = new DataInputBuffer(); |
---|
74 | private DataOutputBuffer outBuf = new DataOutputBuffer(); |
---|
75 | private WritableComparable lastKey; |
---|
76 | |
---|
77 | |
---|
78 | /** Create the named map for keys of the named class. */ |
---|
79 | public Writer(Configuration conf, FileSystem fs, String dirName, |
---|
80 | Class<? extends WritableComparable> keyClass, Class valClass) |
---|
81 | throws IOException { |
---|
82 | this(conf, fs, dirName, |
---|
83 | WritableComparator.get(keyClass), valClass, |
---|
84 | SequenceFile.getCompressionType(conf)); |
---|
85 | } |
---|
86 | |
---|
87 | /** Create the named map for keys of the named class. */ |
---|
88 | public Writer(Configuration conf, FileSystem fs, String dirName, |
---|
89 | Class<? extends WritableComparable> keyClass, Class valClass, |
---|
90 | CompressionType compress, Progressable progress) |
---|
91 | throws IOException { |
---|
92 | this(conf, fs, dirName, WritableComparator.get(keyClass), valClass, |
---|
93 | compress, progress); |
---|
94 | } |
---|
95 | |
---|
96 | /** Create the named map for keys of the named class. */ |
---|
97 | public Writer(Configuration conf, FileSystem fs, String dirName, |
---|
98 | Class<? extends WritableComparable> keyClass, Class valClass, |
---|
99 | CompressionType compress, CompressionCodec codec, |
---|
100 | Progressable progress) |
---|
101 | throws IOException { |
---|
102 | this(conf, fs, dirName, WritableComparator.get(keyClass), valClass, |
---|
103 | compress, codec, progress); |
---|
104 | } |
---|
105 | |
---|
106 | /** Create the named map for keys of the named class. */ |
---|
107 | public Writer(Configuration conf, FileSystem fs, String dirName, |
---|
108 | Class<? extends WritableComparable> keyClass, Class valClass, |
---|
109 | CompressionType compress) |
---|
110 | throws IOException { |
---|
111 | this(conf, fs, dirName, WritableComparator.get(keyClass), valClass, compress); |
---|
112 | } |
---|
113 | |
---|
114 | /** Create the named map using the named key comparator. */ |
---|
115 | public Writer(Configuration conf, FileSystem fs, String dirName, |
---|
116 | WritableComparator comparator, Class valClass) |
---|
117 | throws IOException { |
---|
118 | this(conf, fs, dirName, comparator, valClass, |
---|
119 | SequenceFile.getCompressionType(conf)); |
---|
120 | } |
---|
121 | /** Create the named map using the named key comparator. */ |
---|
122 | public Writer(Configuration conf, FileSystem fs, String dirName, |
---|
123 | WritableComparator comparator, Class valClass, |
---|
124 | SequenceFile.CompressionType compress) |
---|
125 | throws IOException { |
---|
126 | this(conf, fs, dirName, comparator, valClass, compress, null); |
---|
127 | } |
---|
128 | /** Create the named map using the named key comparator. */ |
---|
129 | public Writer(Configuration conf, FileSystem fs, String dirName, |
---|
130 | WritableComparator comparator, Class valClass, |
---|
131 | SequenceFile.CompressionType compress, |
---|
132 | Progressable progress) |
---|
133 | throws IOException { |
---|
134 | this(conf, fs, dirName, comparator, valClass, |
---|
135 | compress, new DefaultCodec(), progress); |
---|
136 | } |
---|
137 | /** Create the named map using the named key comparator. */ |
---|
138 | public Writer(Configuration conf, FileSystem fs, String dirName, |
---|
139 | WritableComparator comparator, Class valClass, |
---|
140 | SequenceFile.CompressionType compress, CompressionCodec codec, |
---|
141 | Progressable progress) |
---|
142 | throws IOException { |
---|
143 | |
---|
144 | this.indexInterval = conf.getInt(INDEX_INTERVAL, this.indexInterval); |
---|
145 | |
---|
146 | this.comparator = comparator; |
---|
147 | this.lastKey = comparator.newKey(); |
---|
148 | |
---|
149 | Path dir = new Path(dirName); |
---|
150 | if (!fs.mkdirs(dir)) { |
---|
151 | throw new IOException("Mkdirs failed to create directory " + dir.toString()); |
---|
152 | } |
---|
153 | Path dataFile = new Path(dir, DATA_FILE_NAME); |
---|
154 | Path indexFile = new Path(dir, INDEX_FILE_NAME); |
---|
155 | |
---|
156 | Class keyClass = comparator.getKeyClass(); |
---|
157 | this.data = |
---|
158 | SequenceFile.createWriter |
---|
159 | (fs, conf, dataFile, keyClass, valClass, compress, codec, progress); |
---|
160 | this.index = |
---|
161 | SequenceFile.createWriter |
---|
162 | (fs, conf, indexFile, keyClass, LongWritable.class, |
---|
163 | CompressionType.BLOCK, progress); |
---|
164 | } |
---|
165 | |
---|
166 | /** The number of entries that are added before an index entry is added.*/ |
---|
167 | public int getIndexInterval() { return indexInterval; } |
---|
168 | |
---|
169 | /** Sets the index interval. |
---|
170 | * @see #getIndexInterval() |
---|
171 | */ |
---|
172 | public void setIndexInterval(int interval) { indexInterval = interval; } |
---|
173 | |
---|
174 | /** Sets the index interval and stores it in conf |
---|
175 | * @see #getIndexInterval() |
---|
176 | */ |
---|
177 | public static void setIndexInterval(Configuration conf, int interval) { |
---|
178 | conf.setInt(INDEX_INTERVAL, interval); |
---|
179 | } |
---|
180 | |
---|
181 | /** Close the map. */ |
---|
182 | public synchronized void close() throws IOException { |
---|
183 | data.close(); |
---|
184 | index.close(); |
---|
185 | } |
---|
186 | |
---|
187 | /** Append a key/value pair to the map. The key must be greater or equal |
---|
188 | * to the previous key added to the map. */ |
---|
189 | public synchronized void append(WritableComparable key, Writable val) |
---|
190 | throws IOException { |
---|
191 | |
---|
192 | checkKey(key); |
---|
193 | |
---|
194 | if (size % indexInterval == 0) { // add an index entry |
---|
195 | position.set(data.getLength()); // point to current eof |
---|
196 | index.append(key, position); |
---|
197 | } |
---|
198 | |
---|
199 | data.append(key, val); // append key/value to data |
---|
200 | size++; |
---|
201 | } |
---|
202 | |
---|
203 | private void checkKey(WritableComparable key) throws IOException { |
---|
204 | // check that keys are well-ordered |
---|
205 | if (size != 0 && comparator.compare(lastKey, key) > 0) |
---|
206 | throw new IOException("key out of order: "+key+" after "+lastKey); |
---|
207 | |
---|
208 | // update lastKey with a copy of key by writing and reading |
---|
209 | outBuf.reset(); |
---|
210 | key.write(outBuf); // write new key |
---|
211 | |
---|
212 | inBuf.reset(outBuf.getData(), outBuf.getLength()); |
---|
213 | lastKey.readFields(inBuf); // read into lastKey |
---|
214 | } |
---|
215 | |
---|
216 | } |
---|
217 | |
---|
218 | /** Provide access to an existing map. */ |
---|
219 | public static class Reader implements java.io.Closeable { |
---|
220 | |
---|
221 | /** Number of index entries to skip between each entry. Zero by default. |
---|
222 | * Setting this to values larger than zero can facilitate opening large map |
---|
223 | * files using less memory. */ |
---|
224 | private int INDEX_SKIP = 0; |
---|
225 | |
---|
226 | private WritableComparator comparator; |
---|
227 | |
---|
228 | private WritableComparable nextKey; |
---|
229 | private long seekPosition = -1; |
---|
230 | private int seekIndex = -1; |
---|
231 | private long firstPosition; |
---|
232 | |
---|
233 | // the data, on disk |
---|
234 | private SequenceFile.Reader data; |
---|
235 | private SequenceFile.Reader index; |
---|
236 | |
---|
237 | // whether the index Reader was closed |
---|
238 | private boolean indexClosed = false; |
---|
239 | |
---|
240 | // the index, in memory |
---|
241 | private int count = -1; |
---|
242 | private WritableComparable[] keys; |
---|
243 | private long[] positions; |
---|
244 | |
---|
245 | /** Returns the class of keys in this file. */ |
---|
246 | public Class<?> getKeyClass() { return data.getKeyClass(); } |
---|
247 | |
---|
248 | /** Returns the class of values in this file. */ |
---|
249 | public Class<?> getValueClass() { return data.getValueClass(); } |
---|
250 | |
---|
251 | /** Construct a map reader for the named map.*/ |
---|
252 | public Reader(FileSystem fs, String dirName, Configuration conf) throws IOException { |
---|
253 | this(fs, dirName, null, conf); |
---|
254 | INDEX_SKIP = conf.getInt("io.map.index.skip", 0); |
---|
255 | } |
---|
256 | |
---|
257 | /** Construct a map reader for the named map using the named comparator.*/ |
---|
258 | public Reader(FileSystem fs, String dirName, WritableComparator comparator, Configuration conf) |
---|
259 | throws IOException { |
---|
260 | this(fs, dirName, comparator, conf, true); |
---|
261 | } |
---|
262 | |
---|
263 | /** |
---|
264 | * Hook to allow subclasses to defer opening streams until further |
---|
265 | * initialization is complete. |
---|
266 | * @see #createDataFileReader(FileSystem, Path, Configuration) |
---|
267 | */ |
---|
268 | protected Reader(FileSystem fs, String dirName, |
---|
269 | WritableComparator comparator, Configuration conf, boolean open) |
---|
270 | throws IOException { |
---|
271 | |
---|
272 | if (open) { |
---|
273 | open(fs, dirName, comparator, conf); |
---|
274 | } |
---|
275 | } |
---|
276 | |
---|
277 | protected synchronized void open(FileSystem fs, String dirName, |
---|
278 | WritableComparator comparator, Configuration conf) throws IOException { |
---|
279 | Path dir = new Path(dirName); |
---|
280 | Path dataFile = new Path(dir, DATA_FILE_NAME); |
---|
281 | Path indexFile = new Path(dir, INDEX_FILE_NAME); |
---|
282 | |
---|
283 | // open the data |
---|
284 | this.data = createDataFileReader(fs, dataFile, conf); |
---|
285 | this.firstPosition = data.getPosition(); |
---|
286 | |
---|
287 | if (comparator == null) |
---|
288 | this.comparator = WritableComparator.get(data.getKeyClass().asSubclass(WritableComparable.class)); |
---|
289 | else |
---|
290 | this.comparator = comparator; |
---|
291 | |
---|
292 | // open the index |
---|
293 | this.index = new SequenceFile.Reader(fs, indexFile, conf); |
---|
294 | } |
---|
295 | |
---|
296 | /** |
---|
297 | * Override this method to specialize the type of |
---|
298 | * {@link SequenceFile.Reader} returned. |
---|
299 | */ |
---|
300 | protected SequenceFile.Reader createDataFileReader(FileSystem fs, |
---|
301 | Path dataFile, Configuration conf) throws IOException { |
---|
302 | return new SequenceFile.Reader(fs, dataFile, conf); |
---|
303 | } |
---|
304 | |
---|
305 | private void readIndex() throws IOException { |
---|
306 | // read the index entirely into memory |
---|
307 | if (this.keys != null) |
---|
308 | return; |
---|
309 | this.count = 0; |
---|
310 | this.keys = new WritableComparable[1024]; |
---|
311 | this.positions = new long[1024]; |
---|
312 | try { |
---|
313 | int skip = INDEX_SKIP; |
---|
314 | LongWritable position = new LongWritable(); |
---|
315 | WritableComparable lastKey = null; |
---|
316 | while (true) { |
---|
317 | WritableComparable k = comparator.newKey(); |
---|
318 | |
---|
319 | if (!index.next(k, position)) |
---|
320 | break; |
---|
321 | |
---|
322 | // check order to make sure comparator is compatible |
---|
323 | if (lastKey != null && comparator.compare(lastKey, k) > 0) |
---|
324 | throw new IOException("key out of order: "+k+" after "+lastKey); |
---|
325 | lastKey = k; |
---|
326 | |
---|
327 | if (skip > 0) { |
---|
328 | skip--; |
---|
329 | continue; // skip this entry |
---|
330 | } else { |
---|
331 | skip = INDEX_SKIP; // reset skip |
---|
332 | } |
---|
333 | |
---|
334 | if (count == keys.length) { // time to grow arrays |
---|
335 | int newLength = (keys.length*3)/2; |
---|
336 | WritableComparable[] newKeys = new WritableComparable[newLength]; |
---|
337 | long[] newPositions = new long[newLength]; |
---|
338 | System.arraycopy(keys, 0, newKeys, 0, count); |
---|
339 | System.arraycopy(positions, 0, newPositions, 0, count); |
---|
340 | keys = newKeys; |
---|
341 | positions = newPositions; |
---|
342 | } |
---|
343 | |
---|
344 | keys[count] = k; |
---|
345 | positions[count] = position.get(); |
---|
346 | count++; |
---|
347 | } |
---|
348 | } catch (EOFException e) { |
---|
349 | LOG.warn("Unexpected EOF reading " + index + |
---|
350 | " at entry #" + count + ". Ignoring."); |
---|
351 | } finally { |
---|
352 | indexClosed = true; |
---|
353 | index.close(); |
---|
354 | } |
---|
355 | } |
---|
356 | |
---|
357 | /** Re-positions the reader before its first key. */ |
---|
358 | public synchronized void reset() throws IOException { |
---|
359 | data.seek(firstPosition); |
---|
360 | } |
---|
361 | |
---|
362 | /** Get the key at approximately the middle of the file. |
---|
363 | * |
---|
364 | * @throws IOException |
---|
365 | */ |
---|
366 | public synchronized WritableComparable midKey() throws IOException { |
---|
367 | |
---|
368 | readIndex(); |
---|
369 | int pos = ((count - 1) / 2); // middle of the index |
---|
370 | if (pos < 0) { |
---|
371 | throw new IOException("MapFile empty"); |
---|
372 | } |
---|
373 | |
---|
374 | return keys[pos]; |
---|
375 | } |
---|
376 | |
---|
377 | /** Reads the final key from the file. |
---|
378 | * |
---|
379 | * @param key key to read into |
---|
380 | */ |
---|
381 | public synchronized void finalKey(WritableComparable key) |
---|
382 | throws IOException { |
---|
383 | |
---|
384 | long originalPosition = data.getPosition(); // save position |
---|
385 | try { |
---|
386 | readIndex(); // make sure index is valid |
---|
387 | if (count > 0) { |
---|
388 | data.seek(positions[count-1]); // skip to last indexed entry |
---|
389 | } else { |
---|
390 | reset(); // start at the beginning |
---|
391 | } |
---|
392 | while (data.next(key)) {} // scan to eof |
---|
393 | |
---|
394 | } finally { |
---|
395 | data.seek(originalPosition); // restore position |
---|
396 | } |
---|
397 | } |
---|
398 | |
---|
399 | /** Positions the reader at the named key, or if none such exists, at the |
---|
400 | * first entry after the named key. Returns true iff the named key exists |
---|
401 | * in this map. |
---|
402 | */ |
---|
403 | public synchronized boolean seek(WritableComparable key) throws IOException { |
---|
404 | return seekInternal(key) == 0; |
---|
405 | } |
---|
406 | |
---|
407 | /** |
---|
408 | * Positions the reader at the named key, or if none such exists, at the |
---|
409 | * first entry after the named key. |
---|
410 | * |
---|
411 | * @return 0 - exact match found |
---|
412 | * < 0 - positioned at next record |
---|
413 | * 1 - no more records in file |
---|
414 | */ |
---|
415 | private synchronized int seekInternal(WritableComparable key) |
---|
416 | throws IOException { |
---|
417 | return seekInternal(key, false); |
---|
418 | } |
---|
419 | |
---|
420 | /** |
---|
421 | * Positions the reader at the named key, or if none such exists, at the |
---|
422 | * key that falls just before or just after dependent on how the |
---|
423 | * <code>before</code> parameter is set. |
---|
424 | * |
---|
425 | * @param before - IF true, and <code>key</code> does not exist, position |
---|
426 | * file at entry that falls just before <code>key</code>. Otherwise, |
---|
427 | * position file at record that sorts just after. |
---|
428 | * @return 0 - exact match found |
---|
429 | * < 0 - positioned at next record |
---|
430 | * 1 - no more records in file |
---|
431 | */ |
---|
432 | private synchronized int seekInternal(WritableComparable key, |
---|
433 | final boolean before) |
---|
434 | throws IOException { |
---|
435 | readIndex(); // make sure index is read |
---|
436 | |
---|
437 | if (seekIndex != -1 // seeked before |
---|
438 | && seekIndex+1 < count |
---|
439 | && comparator.compare(key, keys[seekIndex+1])<0 // before next indexed |
---|
440 | && comparator.compare(key, nextKey) |
---|
441 | >= 0) { // but after last seeked |
---|
442 | // do nothing |
---|
443 | } else { |
---|
444 | seekIndex = binarySearch(key); |
---|
445 | if (seekIndex < 0) // decode insertion point |
---|
446 | seekIndex = -seekIndex-2; |
---|
447 | |
---|
448 | if (seekIndex == -1) // belongs before first entry |
---|
449 | seekPosition = firstPosition; // use beginning of file |
---|
450 | else |
---|
451 | seekPosition = positions[seekIndex]; // else use index |
---|
452 | } |
---|
453 | data.seek(seekPosition); |
---|
454 | |
---|
455 | if (nextKey == null) |
---|
456 | nextKey = comparator.newKey(); |
---|
457 | |
---|
458 | // If we're looking for the key before, we need to keep track |
---|
459 | // of the position we got the current key as well as the position |
---|
460 | // of the key before it. |
---|
461 | long prevPosition = -1; |
---|
462 | long curPosition = seekPosition; |
---|
463 | |
---|
464 | while (data.next(nextKey)) { |
---|
465 | int c = comparator.compare(key, nextKey); |
---|
466 | if (c <= 0) { // at or beyond desired |
---|
467 | if (before && c != 0) { |
---|
468 | if (prevPosition == -1) { |
---|
469 | // We're on the first record of this index block |
---|
470 | // and we've already passed the search key. Therefore |
---|
471 | // we must be at the beginning of the file, so seek |
---|
472 | // to the beginning of this block and return c |
---|
473 | data.seek(curPosition); |
---|
474 | } else { |
---|
475 | // We have a previous record to back up to |
---|
476 | data.seek(prevPosition); |
---|
477 | data.next(nextKey); |
---|
478 | // now that we've rewound, the search key must be greater than this key |
---|
479 | return 1; |
---|
480 | } |
---|
481 | } |
---|
482 | return c; |
---|
483 | } |
---|
484 | if (before) { |
---|
485 | prevPosition = curPosition; |
---|
486 | curPosition = data.getPosition(); |
---|
487 | } |
---|
488 | } |
---|
489 | |
---|
490 | return 1; |
---|
491 | } |
---|
492 | |
---|
493 | private int binarySearch(WritableComparable key) { |
---|
494 | int low = 0; |
---|
495 | int high = count-1; |
---|
496 | |
---|
497 | while (low <= high) { |
---|
498 | int mid = (low + high) >>> 1; |
---|
499 | WritableComparable midVal = keys[mid]; |
---|
500 | int cmp = comparator.compare(midVal, key); |
---|
501 | |
---|
502 | if (cmp < 0) |
---|
503 | low = mid + 1; |
---|
504 | else if (cmp > 0) |
---|
505 | high = mid - 1; |
---|
506 | else |
---|
507 | return mid; // key found |
---|
508 | } |
---|
509 | return -(low + 1); // key not found. |
---|
510 | } |
---|
511 | |
---|
512 | /** Read the next key/value pair in the map into <code>key</code> and |
---|
513 | * <code>val</code>. Returns true if such a pair exists and false when at |
---|
514 | * the end of the map */ |
---|
515 | public synchronized boolean next(WritableComparable key, Writable val) |
---|
516 | throws IOException { |
---|
517 | return data.next(key, val); |
---|
518 | } |
---|
519 | |
---|
520 | /** Return the value for the named key, or null if none exists. */ |
---|
521 | public synchronized Writable get(WritableComparable key, Writable val) |
---|
522 | throws IOException { |
---|
523 | if (seek(key)) { |
---|
524 | data.getCurrentValue(val); |
---|
525 | return val; |
---|
526 | } else |
---|
527 | return null; |
---|
528 | } |
---|
529 | |
---|
530 | /** |
---|
531 | * Finds the record that is the closest match to the specified key. |
---|
532 | * Returns <code>key</code> or if it does not exist, at the first entry |
---|
533 | * after the named key. |
---|
534 | * |
---|
535 | - * @param key - key that we're trying to find |
---|
536 | - * @param val - data value if key is found |
---|
537 | - * @return - the key that was the closest match or null if eof. |
---|
538 | */ |
---|
539 | public synchronized WritableComparable getClosest(WritableComparable key, |
---|
540 | Writable val) |
---|
541 | throws IOException { |
---|
542 | return getClosest(key, val, false); |
---|
543 | } |
---|
544 | |
---|
545 | /** |
---|
546 | * Finds the record that is the closest match to the specified key. |
---|
547 | * |
---|
548 | * @param key - key that we're trying to find |
---|
549 | * @param val - data value if key is found |
---|
550 | * @param before - IF true, and <code>key</code> does not exist, return |
---|
551 | * the first entry that falls just before the <code>key</code>. Otherwise, |
---|
552 | * return the record that sorts just after. |
---|
553 | * @return - the key that was the closest match or null if eof. |
---|
554 | */ |
---|
555 | public synchronized WritableComparable getClosest(WritableComparable key, |
---|
556 | Writable val, final boolean before) |
---|
557 | throws IOException { |
---|
558 | |
---|
559 | int c = seekInternal(key, before); |
---|
560 | |
---|
561 | // If we didn't get an exact match, and we ended up in the wrong |
---|
562 | // direction relative to the query key, return null since we |
---|
563 | // must be at the beginning or end of the file. |
---|
564 | if ((!before && c > 0) || |
---|
565 | (before && c < 0)) { |
---|
566 | return null; |
---|
567 | } |
---|
568 | |
---|
569 | data.getCurrentValue(val); |
---|
570 | return nextKey; |
---|
571 | } |
---|
572 | |
---|
573 | /** Close the map. */ |
---|
574 | public synchronized void close() throws IOException { |
---|
575 | if (!indexClosed) { |
---|
576 | index.close(); |
---|
577 | } |
---|
578 | data.close(); |
---|
579 | } |
---|
580 | |
---|
581 | } |
---|
582 | |
---|
583 | /** Renames an existing map directory. */ |
---|
584 | public static void rename(FileSystem fs, String oldName, String newName) |
---|
585 | throws IOException { |
---|
586 | Path oldDir = new Path(oldName); |
---|
587 | Path newDir = new Path(newName); |
---|
588 | if (!fs.rename(oldDir, newDir)) { |
---|
589 | throw new IOException("Could not rename " + oldDir + " to " + newDir); |
---|
590 | } |
---|
591 | } |
---|
592 | |
---|
593 | /** Deletes the named map file. */ |
---|
594 | public static void delete(FileSystem fs, String name) throws IOException { |
---|
595 | Path dir = new Path(name); |
---|
596 | Path data = new Path(dir, DATA_FILE_NAME); |
---|
597 | Path index = new Path(dir, INDEX_FILE_NAME); |
---|
598 | |
---|
599 | fs.delete(data, true); |
---|
600 | fs.delete(index, true); |
---|
601 | fs.delete(dir, true); |
---|
602 | } |
---|
603 | |
---|
604 | /** |
---|
605 | * This method attempts to fix a corrupt MapFile by re-creating its index. |
---|
606 | * @param fs filesystem |
---|
607 | * @param dir directory containing the MapFile data and index |
---|
608 | * @param keyClass key class (has to be a subclass of Writable) |
---|
609 | * @param valueClass value class (has to be a subclass of Writable) |
---|
610 | * @param dryrun do not perform any changes, just report what needs to be done |
---|
611 | * @return number of valid entries in this MapFile, or -1 if no fixing was needed |
---|
612 | * @throws Exception |
---|
613 | */ |
---|
614 | public static long fix(FileSystem fs, Path dir, |
---|
615 | Class<? extends Writable> keyClass, |
---|
616 | Class<? extends Writable> valueClass, boolean dryrun, |
---|
617 | Configuration conf) throws Exception { |
---|
618 | String dr = (dryrun ? "[DRY RUN ] " : ""); |
---|
619 | Path data = new Path(dir, DATA_FILE_NAME); |
---|
620 | Path index = new Path(dir, INDEX_FILE_NAME); |
---|
621 | int indexInterval = 128; |
---|
622 | if (!fs.exists(data)) { |
---|
623 | // there's nothing we can do to fix this! |
---|
624 | throw new Exception(dr + "Missing data file in " + dir + ", impossible to fix this."); |
---|
625 | } |
---|
626 | if (fs.exists(index)) { |
---|
627 | // no fixing needed |
---|
628 | return -1; |
---|
629 | } |
---|
630 | SequenceFile.Reader dataReader = new SequenceFile.Reader(fs, data, conf); |
---|
631 | if (!dataReader.getKeyClass().equals(keyClass)) { |
---|
632 | throw new Exception(dr + "Wrong key class in " + dir + ", expected" + keyClass.getName() + |
---|
633 | ", got " + dataReader.getKeyClass().getName()); |
---|
634 | } |
---|
635 | if (!dataReader.getValueClass().equals(valueClass)) { |
---|
636 | throw new Exception(dr + "Wrong value class in " + dir + ", expected" + valueClass.getName() + |
---|
637 | ", got " + dataReader.getValueClass().getName()); |
---|
638 | } |
---|
639 | long cnt = 0L; |
---|
640 | Writable key = ReflectionUtils.newInstance(keyClass, conf); |
---|
641 | Writable value = ReflectionUtils.newInstance(valueClass, conf); |
---|
642 | SequenceFile.Writer indexWriter = null; |
---|
643 | if (!dryrun) indexWriter = SequenceFile.createWriter(fs, conf, index, keyClass, LongWritable.class); |
---|
644 | try { |
---|
645 | long pos = 0L; |
---|
646 | LongWritable position = new LongWritable(); |
---|
647 | while(dataReader.next(key, value)) { |
---|
648 | cnt++; |
---|
649 | if (cnt % indexInterval == 0) { |
---|
650 | position.set(pos); |
---|
651 | if (!dryrun) indexWriter.append(key, position); |
---|
652 | } |
---|
653 | pos = dataReader.getPosition(); |
---|
654 | } |
---|
655 | } catch(Throwable t) { |
---|
656 | // truncated data file. swallow it. |
---|
657 | } |
---|
658 | dataReader.close(); |
---|
659 | if (!dryrun) indexWriter.close(); |
---|
660 | return cnt; |
---|
661 | } |
---|
662 | |
---|
663 | |
---|
664 | public static void main(String[] args) throws Exception { |
---|
665 | String usage = "Usage: MapFile inFile outFile"; |
---|
666 | |
---|
667 | if (args.length != 2) { |
---|
668 | System.err.println(usage); |
---|
669 | System.exit(-1); |
---|
670 | } |
---|
671 | |
---|
672 | String in = args[0]; |
---|
673 | String out = args[1]; |
---|
674 | |
---|
675 | Configuration conf = new Configuration(); |
---|
676 | FileSystem fs = FileSystem.getLocal(conf); |
---|
677 | MapFile.Reader reader = new MapFile.Reader(fs, in, conf); |
---|
678 | MapFile.Writer writer = |
---|
679 | new MapFile.Writer(conf, fs, out, |
---|
680 | reader.getKeyClass().asSubclass(WritableComparable.class), |
---|
681 | reader.getValueClass()); |
---|
682 | |
---|
683 | WritableComparable key = |
---|
684 | ReflectionUtils.newInstance(reader.getKeyClass().asSubclass(WritableComparable.class), conf); |
---|
685 | Writable value = |
---|
686 | ReflectionUtils.newInstance(reader.getValueClass().asSubclass(Writable.class), conf); |
---|
687 | |
---|
688 | while (reader.next(key, value)) // copy all entries |
---|
689 | writer.append(key, value); |
---|
690 | |
---|
691 | writer.close(); |
---|
692 | } |
---|
693 | |
---|
694 | } |
---|