450 lines
18 KiB
Java
450 lines
18 KiB
Java
/*
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* Copyright (C) 2010 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may not
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* use this file except in compliance with the License. You may obtain a copy of
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* the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations under
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* the License.
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*/
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package com.android.inputmethod.latin;
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import android.content.ContentValues;
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import android.content.Context;
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import android.database.Cursor;
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import android.database.sqlite.SQLiteDatabase;
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import android.database.sqlite.SQLiteOpenHelper;
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import android.database.sqlite.SQLiteQueryBuilder;
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import android.os.AsyncTask;
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import android.provider.BaseColumns;
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import android.util.Log;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.Iterator;
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/**
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* Locally gathers stats about the words user types and various other signals like auto-correction
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* cancellation or manual picks. This allows the keyboard to adapt to the typist over time.
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*/
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public class UserHistoryDictionary extends ExpandableDictionary {
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private static final String TAG = "UserHistoryDictionary";
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/** Any pair being typed or picked */
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private static final int FREQUENCY_FOR_TYPED = 2;
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/** Maximum frequency for all pairs */
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private static final int FREQUENCY_MAX = 127;
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/** Maximum number of pairs. Pruning will start when databases goes above this number. */
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private static int sMaxHistoryBigrams = 10000;
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/**
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* When it hits maximum bigram pair, it will delete until you are left with
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* only (sMaxHistoryBigrams - sDeleteHistoryBigrams) pairs.
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* Do not keep this number small to avoid deleting too often.
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*/
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private static int sDeleteHistoryBigrams = 1000;
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/**
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* Database version should increase if the database structure changes
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*/
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private static final int DATABASE_VERSION = 1;
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private static final String DATABASE_NAME = "userbigram_dict.db";
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/** Name of the words table in the database */
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private static final String MAIN_TABLE_NAME = "main";
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// TODO: Consume less space by using a unique id for locale instead of the whole
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// 2-5 character string.
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private static final String MAIN_COLUMN_ID = BaseColumns._ID;
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private static final String MAIN_COLUMN_WORD1 = "word1";
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private static final String MAIN_COLUMN_WORD2 = "word2";
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private static final String MAIN_COLUMN_LOCALE = "locale";
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/** Name of the frequency table in the database */
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private static final String FREQ_TABLE_NAME = "frequency";
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private static final String FREQ_COLUMN_ID = BaseColumns._ID;
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private static final String FREQ_COLUMN_PAIR_ID = "pair_id";
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private static final String FREQ_COLUMN_FREQUENCY = "freq";
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/** Locale for which this auto dictionary is storing words */
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private String mLocale;
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private HashSet<Bigram> mPendingWrites = new HashSet<Bigram>();
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private final Object mPendingWritesLock = new Object();
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private static volatile boolean sUpdatingDB = false;
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private final static HashMap<String, String> sDictProjectionMap;
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static {
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sDictProjectionMap = new HashMap<String, String>();
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sDictProjectionMap.put(MAIN_COLUMN_ID, MAIN_COLUMN_ID);
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sDictProjectionMap.put(MAIN_COLUMN_WORD1, MAIN_COLUMN_WORD1);
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sDictProjectionMap.put(MAIN_COLUMN_WORD2, MAIN_COLUMN_WORD2);
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sDictProjectionMap.put(MAIN_COLUMN_LOCALE, MAIN_COLUMN_LOCALE);
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sDictProjectionMap.put(FREQ_COLUMN_ID, FREQ_COLUMN_ID);
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sDictProjectionMap.put(FREQ_COLUMN_PAIR_ID, FREQ_COLUMN_PAIR_ID);
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sDictProjectionMap.put(FREQ_COLUMN_FREQUENCY, FREQ_COLUMN_FREQUENCY);
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}
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private static DatabaseHelper sOpenHelper = null;
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private static class Bigram {
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public final String mWord1;
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public final String mWord2;
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public final int mFrequency;
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Bigram(String word1, String word2, int frequency) {
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this.mWord1 = word1;
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this.mWord2 = word2;
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this.mFrequency = frequency;
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}
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@Override
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public boolean equals(Object bigram) {
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if (!(bigram instanceof Bigram)) {
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return false;
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}
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final Bigram bigram2 = (Bigram) bigram;
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final boolean eq1 =
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mWord1 == null ? bigram2.mWord1 == null : mWord1.equals(bigram2.mWord1);
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if (!eq1) {
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return false;
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}
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return mWord2 == null ? bigram2.mWord2 == null : mWord2.equals(bigram2.mWord2);
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}
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@Override
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public int hashCode() {
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return (mWord1 + " " + mWord2).hashCode();
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}
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}
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public void setDatabaseMax(int maxHistoryBigram) {
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sMaxHistoryBigrams = maxHistoryBigram;
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}
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public void setDatabaseDelete(int deleteHistoryBigram) {
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sDeleteHistoryBigrams = deleteHistoryBigram;
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}
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public UserHistoryDictionary(final Context context, final String locale, final int dicTypeId) {
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super(context, dicTypeId);
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mLocale = locale;
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if (sOpenHelper == null) {
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sOpenHelper = new DatabaseHelper(getContext());
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}
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if (mLocale != null && mLocale.length() > 1) {
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loadDictionary();
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}
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}
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@Override
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public void close() {
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flushPendingWrites();
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// Don't close the database as locale changes will require it to be reopened anyway
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// Also, the database is written to somewhat frequently, so it needs to be kept alive
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// throughout the life of the process.
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// mOpenHelper.close();
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super.close();
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}
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/**
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* Return whether the passed charsequence is in the dictionary.
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*/
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@Override
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public synchronized boolean isValidWord(final CharSequence word) {
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// TODO: figure out what is the correct thing to do here.
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return false;
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}
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/**
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* Pair will be added to the user history dictionary.
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*
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* The first word may be null. That means we don't know the context, in other words,
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* it's only a unigram. The first word may also be an empty string : this means start
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* context, as in beginning of a sentence for example.
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* The second word may not be null (a NullPointerException would be thrown).
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*/
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public int addToUserHistory(final String word1, String word2) {
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super.addWord(word2, null /* shortcut */, FREQUENCY_FOR_TYPED);
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// Do not insert a word as a bigram of itself
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if (word2.equals(word1)) {
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return 0;
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}
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int freq;
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if (null == word1) {
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freq = FREQUENCY_FOR_TYPED;
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} else {
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freq = super.addBigram(word1, word2, FREQUENCY_FOR_TYPED);
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}
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if (freq > FREQUENCY_MAX) freq = FREQUENCY_MAX;
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synchronized (mPendingWritesLock) {
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if (freq == FREQUENCY_FOR_TYPED || mPendingWrites.isEmpty()) {
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mPendingWrites.add(new Bigram(word1, word2, freq));
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} else {
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Bigram bi = new Bigram(word1, word2, freq);
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mPendingWrites.remove(bi);
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mPendingWrites.add(bi);
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}
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}
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return freq;
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}
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/**
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* Schedules a background thread to write any pending words to the database.
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*/
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public void flushPendingWrites() {
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synchronized (mPendingWritesLock) {
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// Nothing pending? Return
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if (mPendingWrites.isEmpty()) return;
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// Create a background thread to write the pending entries
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new UpdateDbTask(sOpenHelper, mPendingWrites, mLocale).execute();
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// Create a new map for writing new entries into while the old one is written to db
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mPendingWrites = new HashSet<Bigram>();
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}
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}
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/** Used for testing purpose **/
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void waitUntilUpdateDBDone() {
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synchronized (mPendingWritesLock) {
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while (sUpdatingDB) {
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try {
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Thread.sleep(100);
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} catch (InterruptedException e) {
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}
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}
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return;
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}
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}
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@Override
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public void loadDictionaryAsync() {
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// Load the words that correspond to the current input locale
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final Cursor cursor = query(MAIN_COLUMN_LOCALE + "=?", new String[] { mLocale });
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if (null == cursor) return;
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try {
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if (cursor.moveToFirst()) {
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int word1Index = cursor.getColumnIndex(MAIN_COLUMN_WORD1);
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int word2Index = cursor.getColumnIndex(MAIN_COLUMN_WORD2);
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int frequencyIndex = cursor.getColumnIndex(FREQ_COLUMN_FREQUENCY);
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while (!cursor.isAfterLast()) {
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String word1 = cursor.getString(word1Index);
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String word2 = cursor.getString(word2Index);
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int frequency = cursor.getInt(frequencyIndex);
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// Safeguard against adding really long words. Stack may overflow due
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// to recursive lookup
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if (null == word1) {
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super.addWord(word2, null /* shortcut */, frequency);
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} else if (word1.length() < BinaryDictionary.MAX_WORD_LENGTH
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&& word2.length() < BinaryDictionary.MAX_WORD_LENGTH) {
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super.setBigram(word1, word2, frequency);
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}
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cursor.moveToNext();
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}
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}
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} finally {
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cursor.close();
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}
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}
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/**
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* Query the database
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*/
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private static Cursor query(String selection, String[] selectionArgs) {
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SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
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// main INNER JOIN frequency ON (main._id=freq.pair_id)
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qb.setTables(MAIN_TABLE_NAME + " INNER JOIN " + FREQ_TABLE_NAME + " ON ("
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+ MAIN_TABLE_NAME + "." + MAIN_COLUMN_ID + "=" + FREQ_TABLE_NAME + "."
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+ FREQ_COLUMN_PAIR_ID +")");
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qb.setProjectionMap(sDictProjectionMap);
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// Get the database and run the query
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try {
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SQLiteDatabase db = sOpenHelper.getReadableDatabase();
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Cursor c = qb.query(db,
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new String[] { MAIN_COLUMN_WORD1, MAIN_COLUMN_WORD2, FREQ_COLUMN_FREQUENCY },
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selection, selectionArgs, null, null, null);
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return c;
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} catch (android.database.sqlite.SQLiteCantOpenDatabaseException e) {
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// Can't open the database : presumably we can't access storage. That may happen
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// when the device is wedged; do a best effort to still start the keyboard.
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return null;
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}
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}
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/**
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* This class helps open, create, and upgrade the database file.
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*/
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private static class DatabaseHelper extends SQLiteOpenHelper {
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DatabaseHelper(Context context) {
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super(context, DATABASE_NAME, null, DATABASE_VERSION);
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}
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@Override
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public void onCreate(SQLiteDatabase db) {
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db.execSQL("PRAGMA foreign_keys = ON;");
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db.execSQL("CREATE TABLE " + MAIN_TABLE_NAME + " ("
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+ MAIN_COLUMN_ID + " INTEGER PRIMARY KEY,"
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+ MAIN_COLUMN_WORD1 + " TEXT,"
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+ MAIN_COLUMN_WORD2 + " TEXT,"
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+ MAIN_COLUMN_LOCALE + " TEXT"
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+ ");");
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db.execSQL("CREATE TABLE " + FREQ_TABLE_NAME + " ("
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+ FREQ_COLUMN_ID + " INTEGER PRIMARY KEY,"
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+ FREQ_COLUMN_PAIR_ID + " INTEGER,"
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+ FREQ_COLUMN_FREQUENCY + " INTEGER,"
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+ "FOREIGN KEY(" + FREQ_COLUMN_PAIR_ID + ") REFERENCES " + MAIN_TABLE_NAME
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+ "(" + MAIN_COLUMN_ID + ")" + " ON DELETE CASCADE"
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+ ");");
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}
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@Override
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public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
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Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
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+ newVersion + ", which will destroy all old data");
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db.execSQL("DROP TABLE IF EXISTS " + MAIN_TABLE_NAME);
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db.execSQL("DROP TABLE IF EXISTS " + FREQ_TABLE_NAME);
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onCreate(db);
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}
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}
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/**
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* Async task to write pending words to the database so that it stays in sync with
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* the in-memory trie.
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*/
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private static class UpdateDbTask extends AsyncTask<Void, Void, Void> {
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private final HashSet<Bigram> mMap;
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private final DatabaseHelper mDbHelper;
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private final String mLocale;
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public UpdateDbTask(DatabaseHelper openHelper, HashSet<Bigram> pendingWrites,
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String locale) {
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mMap = pendingWrites;
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mLocale = locale;
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mDbHelper = openHelper;
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}
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/** Prune any old data if the database is getting too big. */
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private static void checkPruneData(SQLiteDatabase db) {
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db.execSQL("PRAGMA foreign_keys = ON;");
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Cursor c = db.query(FREQ_TABLE_NAME, new String[] { FREQ_COLUMN_PAIR_ID },
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null, null, null, null, null);
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try {
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int totalRowCount = c.getCount();
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// prune out old data if we have too much data
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if (totalRowCount > sMaxHistoryBigrams) {
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int numDeleteRows = (totalRowCount - sMaxHistoryBigrams) + sDeleteHistoryBigrams;
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int pairIdColumnId = c.getColumnIndex(FREQ_COLUMN_PAIR_ID);
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c.moveToFirst();
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int count = 0;
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while (count < numDeleteRows && !c.isAfterLast()) {
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String pairId = c.getString(pairIdColumnId);
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// Deleting from MAIN table will delete the frequencies
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// due to FOREIGN KEY .. ON DELETE CASCADE
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db.delete(MAIN_TABLE_NAME, MAIN_COLUMN_ID + "=?",
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new String[] { pairId });
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c.moveToNext();
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count++;
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}
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}
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} finally {
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c.close();
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}
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}
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@Override
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protected void onPreExecute() {
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sUpdatingDB = true;
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}
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@Override
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protected Void doInBackground(Void... v) {
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SQLiteDatabase db = null;
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try {
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db = mDbHelper.getWritableDatabase();
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} catch (android.database.sqlite.SQLiteCantOpenDatabaseException e) {
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// If we can't open the db, don't do anything. Exit through the next test
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// for non-nullity of the db variable.
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}
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if (null == db) {
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// Not much we can do. Just exit.
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sUpdatingDB = false;
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return null;
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}
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db.execSQL("PRAGMA foreign_keys = ON;");
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// Write all the entries to the db
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Iterator<Bigram> iterator = mMap.iterator();
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while (iterator.hasNext()) {
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// TODO: this process of making a text search for each pair each time
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// is terribly inefficient. Optimize this.
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Bigram bi = iterator.next();
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// find pair id
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final Cursor c;
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if (null != bi.mWord1) {
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c = db.query(MAIN_TABLE_NAME, new String[] { MAIN_COLUMN_ID },
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MAIN_COLUMN_WORD1 + "=? AND " + MAIN_COLUMN_WORD2 + "=? AND "
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+ MAIN_COLUMN_LOCALE + "=?",
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new String[] { bi.mWord1, bi.mWord2, mLocale }, null, null, null);
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} else {
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c = db.query(MAIN_TABLE_NAME, new String[] { MAIN_COLUMN_ID },
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MAIN_COLUMN_WORD1 + " IS NULL AND " + MAIN_COLUMN_WORD2 + "=? AND "
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+ MAIN_COLUMN_LOCALE + "=?",
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new String[] { bi.mWord2, mLocale }, null, null, null);
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}
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int pairId;
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if (c.moveToFirst()) {
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// existing pair
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pairId = c.getInt(c.getColumnIndex(MAIN_COLUMN_ID));
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db.delete(FREQ_TABLE_NAME, FREQ_COLUMN_PAIR_ID + "=?",
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new String[] { Integer.toString(pairId) });
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} else {
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// new pair
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Long pairIdLong = db.insert(MAIN_TABLE_NAME, null,
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getContentValues(bi.mWord1, bi.mWord2, mLocale));
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pairId = pairIdLong.intValue();
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}
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c.close();
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// insert new frequency
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db.insert(FREQ_TABLE_NAME, null, getFrequencyContentValues(pairId, bi.mFrequency));
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}
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checkPruneData(db);
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sUpdatingDB = false;
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return null;
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}
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private static ContentValues getContentValues(String word1, String word2, String locale) {
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ContentValues values = new ContentValues(3);
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values.put(MAIN_COLUMN_WORD1, word1);
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values.put(MAIN_COLUMN_WORD2, word2);
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values.put(MAIN_COLUMN_LOCALE, locale);
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return values;
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}
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private static ContentValues getFrequencyContentValues(int pairId, int frequency) {
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ContentValues values = new ContentValues(2);
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values.put(FREQ_COLUMN_PAIR_ID, pairId);
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values.put(FREQ_COLUMN_FREQUENCY, frequency);
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return values;
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}
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}
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}
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