Source Code Cross Referenced for TermInfosReader.java in  » Net » lucene-connector » org » apache » lucene » index » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Net » lucene connector » org.apache.lucene.index 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        package org.apache.lucene.index;
002:
003:        /**
004:         * Licensed to the Apache Software Foundation (ASF) under one or more
005:         * contributor license agreements.  See the NOTICE file distributed with
006:         * this work for additional information regarding copyright ownership.
007:         * The ASF licenses this file to You under the Apache License, Version 2.0
008:         * (the "License"); you may not use this file except in compliance with
009:         * the License.  You may obtain a copy of the License at
010:         *
011:         *     http://www.apache.org/licenses/LICENSE-2.0
012:         *
013:         * Unless required by applicable law or agreed to in writing, software
014:         * distributed under the License is distributed on an "AS IS" BASIS,
015:         * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
016:         * See the License for the specific language governing permissions and
017:         * limitations under the License.
018:         */
019:
020:        import java.io.IOException;
021:
022:        import org.apache.lucene.store.Directory;
023:        import org.apache.lucene.store.BufferedIndexInput;
024:
025:        /** This stores a monotonically increasing set of <Term, TermInfo> pairs in a
026:         * Directory.  Pairs are accessed either by Term or by ordinal position the
027:         * set.  */
028:
029:        final class TermInfosReader {
030:            private Directory directory;
031:            private String segment;
032:            private FieldInfos fieldInfos;
033:
034:            private ThreadLocal enumerators = new ThreadLocal();
035:            private SegmentTermEnum origEnum;
036:            private long size;
037:
038:            private Term[] indexTerms = null;
039:            private TermInfo[] indexInfos;
040:            private long[] indexPointers;
041:
042:            private SegmentTermEnum indexEnum;
043:
044:            private int indexDivisor = 1;
045:            private int totalIndexInterval;
046:
047:            TermInfosReader(Directory dir, String seg, FieldInfos fis)
048:                    throws CorruptIndexException, IOException {
049:                this (dir, seg, fis, BufferedIndexInput.BUFFER_SIZE);
050:            }
051:
052:            TermInfosReader(Directory dir, String seg, FieldInfos fis,
053:                    int readBufferSize) throws CorruptIndexException,
054:                    IOException {
055:                boolean success = false;
056:
057:                try {
058:                    directory = dir;
059:                    segment = seg;
060:                    fieldInfos = fis;
061:
062:                    origEnum = new SegmentTermEnum(directory.openInput(segment
063:                            + ".tis", readBufferSize), fieldInfos, false);
064:                    size = origEnum.size;
065:                    totalIndexInterval = origEnum.indexInterval;
066:
067:                    indexEnum = new SegmentTermEnum(directory.openInput(segment
068:                            + ".tii", readBufferSize), fieldInfos, true);
069:
070:                    success = true;
071:                } finally {
072:                    // With lock-less commits, it's entirely possible (and
073:                    // fine) to hit a FileNotFound exception above. In
074:                    // this case, we want to explicitly close any subset
075:                    // of things that were opened so that we don't have to
076:                    // wait for a GC to do so.
077:                    if (!success) {
078:                        close();
079:                    }
080:                }
081:            }
082:
083:            public int getSkipInterval() {
084:                return origEnum.skipInterval;
085:            }
086:
087:            public int getMaxSkipLevels() {
088:                return origEnum.maxSkipLevels;
089:            }
090:
091:            /**
092:             * <p>Sets the indexDivisor, which subsamples the number
093:             * of indexed terms loaded into memory.  This has a
094:             * similar effect as {@link
095:             * IndexWriter#setTermIndexInterval} except that setting
096:             * must be done at indexing time while this setting can be
097:             * set per reader.  When set to N, then one in every
098:             * N*termIndexInterval terms in the index is loaded into
099:             * memory.  By setting this to a value > 1 you can reduce
100:             * memory usage, at the expense of higher latency when
101:             * loading a TermInfo.  The default value is 1.</p>
102:             *
103:             * <b>NOTE:</b> you must call this before the term
104:             * index is loaded.  If the index is already loaded,
105:             * an IllegalStateException is thrown.
106:             *
107:             + @throws IllegalStateException if the term index has
108:             * already been loaded into memory.
109:             */
110:            public void setIndexDivisor(int indexDivisor)
111:                    throws IllegalStateException {
112:                if (indexDivisor < 1)
113:                    throw new IllegalArgumentException(
114:                            "indexDivisor must be > 0: got " + indexDivisor);
115:
116:                if (indexTerms != null)
117:                    throw new IllegalStateException(
118:                            "index terms are already loaded");
119:
120:                this .indexDivisor = indexDivisor;
121:                totalIndexInterval = origEnum.indexInterval * indexDivisor;
122:            }
123:
124:            /** Returns the indexDivisor.
125:             * @see #setIndexDivisor
126:             */
127:            public int getIndexDivisor() {
128:                return indexDivisor;
129:            }
130:
131:            final void close() throws IOException {
132:                if (origEnum != null)
133:                    origEnum.close();
134:                if (indexEnum != null)
135:                    indexEnum.close();
136:                enumerators.set(null);
137:            }
138:
139:            /** Returns the number of term/value pairs in the set. */
140:            final long size() {
141:                return size;
142:            }
143:
144:            private SegmentTermEnum getEnum() {
145:                SegmentTermEnum termEnum = (SegmentTermEnum) enumerators.get();
146:                if (termEnum == null) {
147:                    termEnum = terms();
148:                    enumerators.set(termEnum);
149:                }
150:                return termEnum;
151:            }
152:
153:            private synchronized void ensureIndexIsRead() throws IOException {
154:                if (indexTerms != null) // index already read
155:                    return; // do nothing
156:                try {
157:                    int indexSize = 1 + ((int) indexEnum.size - 1)
158:                            / indexDivisor; // otherwise read index
159:
160:                    indexTerms = new Term[indexSize];
161:                    indexInfos = new TermInfo[indexSize];
162:                    indexPointers = new long[indexSize];
163:
164:                    for (int i = 0; indexEnum.next(); i++) {
165:                        indexTerms[i] = indexEnum.term();
166:                        indexInfos[i] = indexEnum.termInfo();
167:                        indexPointers[i] = indexEnum.indexPointer;
168:
169:                        for (int j = 1; j < indexDivisor; j++)
170:                            if (!indexEnum.next())
171:                                break;
172:                    }
173:                } finally {
174:                    indexEnum.close();
175:                    indexEnum = null;
176:                }
177:            }
178:
179:            /** Returns the offset of the greatest index entry which is less than or equal to term.*/
180:            private final int getIndexOffset(Term term) {
181:                int lo = 0; // binary search indexTerms[]
182:                int hi = indexTerms.length - 1;
183:
184:                while (hi >= lo) {
185:                    int mid = (lo + hi) >> 1;
186:                    int delta = term.compareTo(indexTerms[mid]);
187:                    if (delta < 0)
188:                        hi = mid - 1;
189:                    else if (delta > 0)
190:                        lo = mid + 1;
191:                    else
192:                        return mid;
193:                }
194:                return hi;
195:            }
196:
197:            private final void seekEnum(int indexOffset) throws IOException {
198:                getEnum().seek(indexPointers[indexOffset],
199:                        (indexOffset * totalIndexInterval) - 1,
200:                        indexTerms[indexOffset], indexInfos[indexOffset]);
201:            }
202:
203:            /** Returns the TermInfo for a Term in the set, or null. */
204:            TermInfo get(Term term) throws IOException {
205:                if (size == 0)
206:                    return null;
207:
208:                ensureIndexIsRead();
209:
210:                // optimize sequential access: first try scanning cached enum w/o seeking
211:                SegmentTermEnum enumerator = getEnum();
212:                if (enumerator.term() != null // term is at or past current
213:                        && ((enumerator.prev() != null && term
214:                                .compareTo(enumerator.prev()) > 0) || term
215:                                .compareTo(enumerator.term()) >= 0)) {
216:                    int enumOffset = (int) (enumerator.position / totalIndexInterval) + 1;
217:                    if (indexTerms.length == enumOffset // but before end of block
218:                            || term.compareTo(indexTerms[enumOffset]) < 0)
219:                        return scanEnum(term); // no need to seek
220:                }
221:
222:                // random-access: must seek
223:                seekEnum(getIndexOffset(term));
224:                return scanEnum(term);
225:            }
226:
227:            /** Scans within block for matching term. */
228:            private final TermInfo scanEnum(Term term) throws IOException {
229:                SegmentTermEnum enumerator = getEnum();
230:                enumerator.scanTo(term);
231:                if (enumerator.term() != null
232:                        && term.compareTo(enumerator.term()) == 0)
233:                    return enumerator.termInfo();
234:                else
235:                    return null;
236:            }
237:
238:            /** Returns the nth term in the set. */
239:            final Term get(int position) throws IOException {
240:                if (size == 0)
241:                    return null;
242:
243:                SegmentTermEnum enumerator = getEnum();
244:                if (enumerator != null
245:                        && enumerator.term() != null
246:                        && position >= enumerator.position
247:                        && position < (enumerator.position + totalIndexInterval))
248:                    return scanEnum(position); // can avoid seek
249:
250:                seekEnum(position / totalIndexInterval); // must seek
251:                return scanEnum(position);
252:            }
253:
254:            private final Term scanEnum(int position) throws IOException {
255:                SegmentTermEnum enumerator = getEnum();
256:                while (enumerator.position < position)
257:                    if (!enumerator.next())
258:                        return null;
259:
260:                return enumerator.term();
261:            }
262:
263:            /** Returns the position of a Term in the set or -1. */
264:            final long getPosition(Term term) throws IOException {
265:                if (size == 0)
266:                    return -1;
267:
268:                ensureIndexIsRead();
269:                int indexOffset = getIndexOffset(term);
270:                seekEnum(indexOffset);
271:
272:                SegmentTermEnum enumerator = getEnum();
273:                while (term.compareTo(enumerator.term()) > 0
274:                        && enumerator.next()) {
275:                }
276:
277:                if (term.compareTo(enumerator.term()) == 0)
278:                    return enumerator.position;
279:                else
280:                    return -1;
281:            }
282:
283:            /** Returns an enumeration of all the Terms and TermInfos in the set. */
284:            public SegmentTermEnum terms() {
285:                return (SegmentTermEnum) origEnum.clone();
286:            }
287:
288:            /** Returns an enumeration of terms starting at or after the named term. */
289:            public SegmentTermEnum terms(Term term) throws IOException {
290:                get(term);
291:                return (SegmentTermEnum) getEnum().clone();
292:            }
293:        }
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