org.apache.lucene.index.TermStates Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.index;
import java.io.IOException;
import java.util.Arrays;
/**
* Maintains a {@link IndexReader} {@link TermState} view over
* {@link IndexReader} instances containing a single term. The
* {@link TermStates} doesn't track if the given {@link TermState}
* objects are valid, neither if the {@link TermState} instances refer to the
* same terms in the associated readers.
*
* @lucene.experimental
*/
public final class TermStates {
private static final TermState EMPTY_TERMSTATE = new TermState() {
@Override
public void copyFrom(TermState other) {
}
};
// Important: do NOT keep hard references to index readers
private final Object topReaderContextIdentity;
private final TermState[] states;
private final Term term; // null if stats are to be used
private int docFreq;
private long totalTermFreq;
//public static boolean DEBUG = BlockTreeTermsWriter.DEBUG;
private TermStates(Term term, IndexReaderContext context) {
assert context != null && context.isTopLevel;
topReaderContextIdentity = context.identity;
docFreq = 0;
totalTermFreq = 0;
final int len;
if (context.leaves() == null) {
len = 1;
} else {
len = context.leaves().size();
}
states = new TermState[len];
this.term = term;
}
/**
* Creates an empty {@link TermStates} from a {@link IndexReaderContext}
*/
public TermStates(IndexReaderContext context) {
this(null, context);
}
/**
* Expert: Return whether this {@link TermStates} was built for the given
* {@link IndexReaderContext}. This is typically used for assertions.
* @lucene.internal
*/
public boolean wasBuiltFor(IndexReaderContext context) {
return topReaderContextIdentity == context.identity;
}
/**
* Creates a {@link TermStates} with an initial {@link TermState},
* {@link IndexReader} pair.
*/
public TermStates(IndexReaderContext context, TermState state, int ord, int docFreq, long totalTermFreq) {
this(null, context);
register(state, ord, docFreq, totalTermFreq);
}
/**
* Creates a {@link TermStates} from a top-level {@link IndexReaderContext} and the
* given {@link Term}. This method will lookup the given term in all context's leaf readers
* and register each of the readers containing the term in the returned {@link TermStates}
* using the leaf reader's ordinal.
*
* Note: the given context must be a top-level context.
*
* @param needsStats if {@code true} then all leaf contexts will be visited up-front to
* collect term statistics. Otherwise, the {@link TermState} objects
* will be built only when requested
*/
public static TermStates build(IndexReaderContext context, Term term, boolean needsStats)
throws IOException {
assert context != null && context.isTopLevel;
final TermStates perReaderTermState = new TermStates(needsStats ? null : term, context);
if (needsStats) {
for (final LeafReaderContext ctx : context.leaves()) {
//if (DEBUG) System.out.println(" r=" + leaves[i].reader);
TermsEnum termsEnum = loadTermsEnum(ctx, term);
if (termsEnum != null) {
final TermState termState = termsEnum.termState();
//if (DEBUG) System.out.println(" found");
perReaderTermState.register(termState, ctx.ord, termsEnum.docFreq(), termsEnum.totalTermFreq());
}
}
}
return perReaderTermState;
}
private static TermsEnum loadTermsEnum(LeafReaderContext ctx, Term term) throws IOException {
final Terms terms = ctx.reader().terms(term.field());
if (terms != null) {
final TermsEnum termsEnum = terms.iterator();
if (termsEnum.seekExact(term.bytes())) {
return termsEnum;
}
}
return null;
}
/**
* Clears the {@link TermStates} internal state and removes all
* registered {@link TermState}s
*/
public void clear() {
docFreq = 0;
totalTermFreq = 0;
Arrays.fill(states, null);
}
/**
* Registers and associates a {@link TermState} with an leaf ordinal. The leaf ordinal
* should be derived from a {@link IndexReaderContext}'s leaf ord.
*/
public void register(TermState state, final int ord, final int docFreq, final long totalTermFreq) {
register(state, ord);
accumulateStatistics(docFreq, totalTermFreq);
}
/**
* Expert: Registers and associates a {@link TermState} with an leaf ordinal. The
* leaf ordinal should be derived from a {@link IndexReaderContext}'s leaf ord.
* On the contrary to {@link #register(TermState, int, int, long)} this method
* does NOT update term statistics.
*/
public void register(TermState state, final int ord) {
assert state != null : "state must not be null";
assert ord >= 0 && ord < states.length;
assert states[ord] == null : "state for ord: " + ord
+ " already registered";
states[ord] = state;
}
/** Expert: Accumulate term statistics. */
public void accumulateStatistics(final int docFreq, final long totalTermFreq) {
assert docFreq >= 0;
assert totalTermFreq >= 0;
assert docFreq <= totalTermFreq;
this.docFreq += docFreq;
this.totalTermFreq += totalTermFreq;
}
/**
* Returns the {@link TermState} for a leaf reader context or null if no
* {@link TermState} for the context was registered.
*
* @param ctx
* the {@link LeafReaderContext} to get the {@link TermState} for.
* @return the {@link TermState} for the given readers ord or null if no
* {@link TermState} for the reader was registered
*/
public TermState get(LeafReaderContext ctx) throws IOException {
assert ctx.ord >= 0 && ctx.ord < states.length;
if (term == null)
return states[ctx.ord];
if (this.states[ctx.ord] == null) {
TermsEnum te = loadTermsEnum(ctx, term);
this.states[ctx.ord] = te == null ? EMPTY_TERMSTATE : te.termState();
}
if (this.states[ctx.ord] == EMPTY_TERMSTATE)
return null;
return this.states[ctx.ord];
}
/**
* Returns the accumulated document frequency of all {@link TermState}
* instances passed to {@link #register(TermState, int, int, long)}.
* @return the accumulated document frequency of all {@link TermState}
* instances passed to {@link #register(TermState, int, int, long)}.
*/
public int docFreq() {
if (term != null) {
throw new IllegalStateException("Cannot call docFreq() when needsStats=false");
}
return docFreq;
}
/**
* Returns the accumulated term frequency of all {@link TermState}
* instances passed to {@link #register(TermState, int, int, long)}.
* @return the accumulated term frequency of all {@link TermState}
* instances passed to {@link #register(TermState, int, int, long)}.
*/
public long totalTermFreq() {
if (term != null) {
throw new IllegalStateException("Cannot call totalTermFreq() when needsStats=false");
}
return totalTermFreq;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("TermStates\n");
for(TermState termState : states) {
sb.append(" state=");
sb.append(termState);
sb.append('\n');
}
return sb.toString();
}
}