1/*
2 * Copyright (C) 2013 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.inputmethod.latin;
18
19import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
20import com.android.inputmethod.latin.common.ComposedData;
21import com.android.inputmethod.latin.settings.SettingsValuesForSuggestion;
22
23import java.util.ArrayList;
24import java.util.Locale;
25import java.util.concurrent.locks.ReentrantReadWriteLock;
26
27/**
28 * This class provides binary dictionary reading operations with locking. An instance of this class
29 * can be used by multiple threads. Note that different session IDs must be used when multiple
30 * threads get suggestions using this class.
31 */
32public final class ReadOnlyBinaryDictionary extends Dictionary {
33    /**
34     * A lock for accessing binary dictionary. Only closing binary dictionary is the operation
35     * that change the state of dictionary.
36     */
37    private final ReentrantReadWriteLock mLock = new ReentrantReadWriteLock();
38
39    private final BinaryDictionary mBinaryDictionary;
40
41    public ReadOnlyBinaryDictionary(final String filename, final long offset, final long length,
42            final boolean useFullEditDistance, final Locale locale, final String dictType) {
43        super(dictType, locale);
44        mBinaryDictionary = new BinaryDictionary(filename, offset, length, useFullEditDistance,
45                locale, dictType, false /* isUpdatable */);
46    }
47
48    public boolean isValidDictionary() {
49        return mBinaryDictionary.isValidDictionary();
50    }
51
52    @Override
53    public ArrayList<SuggestedWordInfo> getSuggestions(final ComposedData composedData,
54            final NgramContext ngramContext, final long proximityInfoHandle,
55            final SettingsValuesForSuggestion settingsValuesForSuggestion,
56            final int sessionId, final float weightForLocale,
57            final float[] inOutWeightOfLangModelVsSpatialModel) {
58        if (mLock.readLock().tryLock()) {
59            try {
60                return mBinaryDictionary.getSuggestions(composedData, ngramContext,
61                        proximityInfoHandle, settingsValuesForSuggestion, sessionId,
62                        weightForLocale, inOutWeightOfLangModelVsSpatialModel);
63            } finally {
64                mLock.readLock().unlock();
65            }
66        }
67        return null;
68    }
69
70    @Override
71    public boolean isInDictionary(final String word) {
72        if (mLock.readLock().tryLock()) {
73            try {
74                return mBinaryDictionary.isInDictionary(word);
75            } finally {
76                mLock.readLock().unlock();
77            }
78        }
79        return false;
80    }
81
82    @Override
83    public boolean shouldAutoCommit(final SuggestedWordInfo candidate) {
84        if (mLock.readLock().tryLock()) {
85            try {
86                return mBinaryDictionary.shouldAutoCommit(candidate);
87            } finally {
88                mLock.readLock().unlock();
89            }
90        }
91        return false;
92    }
93
94    @Override
95    public int getFrequency(final String word) {
96        if (mLock.readLock().tryLock()) {
97            try {
98                return mBinaryDictionary.getFrequency(word);
99            } finally {
100                mLock.readLock().unlock();
101            }
102        }
103        return NOT_A_PROBABILITY;
104    }
105
106    @Override
107    public int getMaxFrequencyOfExactMatches(final String word) {
108        if (mLock.readLock().tryLock()) {
109            try {
110                return mBinaryDictionary.getMaxFrequencyOfExactMatches(word);
111            } finally {
112                mLock.readLock().unlock();
113            }
114        }
115        return NOT_A_PROBABILITY;
116    }
117
118    @Override
119    public void close() {
120        mLock.writeLock().lock();
121        try {
122            mBinaryDictionary.close();
123        } finally {
124            mLock.writeLock().unlock();
125        }
126    }
127}
128