/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed 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 com.android.inputmethod.latin;
import android.content.ContentValues;
import android.content.Context;
import android.content.SharedPreferences;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteQueryBuilder;
import android.os.AsyncTask;
import android.provider.BaseColumns;
import android.util.Log;
import com.android.inputmethod.latin.UserHistoryForgettingCurveUtils.ForgettingCurveParams;
import java.lang.ref.SoftReference;
import java.util.HashMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.locks.ReentrantLock;
/**
* Locally gathers stats about the words user types and various other signals like auto-correction
* cancellation or manual picks. This allows the keyboard to adapt to the typist over time.
*/
public class UserHistoryDictionary extends ExpandableDictionary {
private static final String TAG = "UserHistoryDictionary";
public static final boolean DBG_SAVE_RESTORE = false;
public static final boolean DBG_STRESS_TEST = false;
public static final boolean DBG_ALWAYS_WRITE = false;
public static final boolean PROFILE_SAVE_RESTORE = LatinImeLogger.sDBG;
/** Any pair being typed or picked */
private static final int FREQUENCY_FOR_TYPED = 2;
/** Maximum number of pairs. Pruning will start when databases goes above this number. */
private static int sMaxHistoryBigrams = 10000;
/**
* When it hits maximum bigram pair, it will delete until you are left with
* only (sMaxHistoryBigrams - sDeleteHistoryBigrams) pairs.
* Do not keep this number small to avoid deleting too often.
*/
private static int sDeleteHistoryBigrams = 1000;
/**
* Database version should increase if the database structure changes
*/
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "userbigram_dict.db";
/** Name of the words table in the database */
private static final String MAIN_TABLE_NAME = "main";
// TODO: Consume less space by using a unique id for locale instead of the whole
// 2-5 character string.
private static final String MAIN_COLUMN_ID = BaseColumns._ID;
private static final String MAIN_COLUMN_WORD1 = "word1";
private static final String MAIN_COLUMN_WORD2 = "word2";
private static final String MAIN_COLUMN_LOCALE = "locale";
/** Name of the frequency table in the database */
private static final String FREQ_TABLE_NAME = "frequency";
private static final String FREQ_COLUMN_ID = BaseColumns._ID;
private static final String FREQ_COLUMN_PAIR_ID = "pair_id";
private static final String COLUMN_FORGETTING_CURVE_VALUE = "freq";
/** Locale for which this user history dictionary is storing words */
private final String mLocale;
private final UserHistoryDictionaryBigramList mBigramList =
new UserHistoryDictionaryBigramList();
private final ReentrantLock mBigramListLock = new ReentrantLock();
private final SharedPreferences mPrefs;
private final static HashMap<String, String> sDictProjectionMap;
private final static ConcurrentHashMap<String, SoftReference<UserHistoryDictionary>>
sLangDictCache = new ConcurrentHashMap<String, SoftReference<UserHistoryDictionary>>();
static {
sDictProjectionMap = new HashMap<String, String>();
sDictProjectionMap.put(MAIN_COLUMN_ID, MAIN_COLUMN_ID);
sDictProjectionMap.put(MAIN_COLUMN_WORD1, MAIN_COLUMN_WORD1);
sDictProjectionMap.put(MAIN_COLUMN_WORD2, MAIN_COLUMN_WORD2);
sDictProjectionMap.put(MAIN_COLUMN_LOCALE, MAIN_COLUMN_LOCALE);
sDictProjectionMap.put(FREQ_COLUMN_ID, FREQ_COLUMN_ID);
sDictProjectionMap.put(FREQ_COLUMN_PAIR_ID, FREQ_COLUMN_PAIR_ID);
sDictProjectionMap.put(COLUMN_FORGETTING_CURVE_VALUE, COLUMN_FORGETTING_CURVE_VALUE);
}
private static DatabaseHelper sOpenHelper = null;
public void setDatabaseMax(int maxHistoryBigram) {
sMaxHistoryBigrams = maxHistoryBigram;
}
public void setDatabaseDelete(int deleteHistoryBigram) {
sDeleteHistoryBigrams = deleteHistoryBigram;
}
public synchronized static UserHistoryDictionary getInstance(
final Context context, final String locale, final SharedPreferences sp) {
if (sLangDictCache.containsKey(locale)) {
final SoftReference<UserHistoryDictionary> ref = sLangDictCache.get(locale);
final UserHistoryDictionary dict = ref == null ? null : ref.get();
if (dict != null) {
if (PROFILE_SAVE_RESTORE) {
Log.w(TAG, "Use cached UserHistoryDictionary for " + locale);
}
return dict;
}
}
final UserHistoryDictionary dict =
new UserHistoryDictionary(context, locale, sp);
sLangDictCache.put(locale, new SoftReference<UserHistoryDictionary>(dict));
return dict;
}
private UserHistoryDictionary(final Context context, final String locale,
final SharedPreferences sp) {
super(context, Suggest.DICT_KEY_USER_HISTORY);
mLocale = locale;
mPrefs = sp;
if (sOpenHelper == null) {
sOpenHelper = new DatabaseHelper(getContext());
}
if (mLocale != null && mLocale.length() > 1) {
loadDictionary();
}
}
@Override
public void close() {
flushPendingWrites();
// Don't close the database as locale changes will require it to be reopened anyway
// Also, the database is written to somewhat frequently, so it needs to be kept alive
// throughout the life of the process.
// mOpenHelper.close();
// Ignore close because we cache UserHistoryDictionary for each language. See getInstance()
// above.
// super.close();
}
/**
* Return whether the passed charsequence is in the dictionary.
*/
@Override
public synchronized boolean isValidWord(final CharSequence word) {
// TODO: figure out what is the correct thing to do here.
return false;
}
/**
* Pair will be added to the user history dictionary.
*
* The first word may be null. That means we don't know the context, in other words,
* it's only a unigram. The first word may also be an empty string : this means start
* context, as in beginning of a sentence for example.
* The second word may not be null (a NullPointerException would be thrown).
*/
public int addToUserHistory(final String word1, String word2, boolean isValid) {
if (mBigramListLock.tryLock()) {
try {
super.addWord(
word2, null /* the "shortcut" parameter is null */, FREQUENCY_FOR_TYPED);
// Do not insert a word as a bigram of itself
if (word2.equals(word1)) {
return 0;
}
final int freq;
if (null == word1) {
freq = FREQUENCY_FOR_TYPED;
} else {
freq = super.setBigramAndGetFrequency(
word1, word2, new ForgettingCurveParams(isValid));
}
mBigramList.addBigram(word1, word2);
return freq;
} finally {
mBigramListLock.unlock();
}
}
return -1;
}
public boolean cancelAddingUserHistory(String word1, String word2) {
if (mBigramListLock.tryLock()) {
try {
if (mBigramList.removeBigram(word1, word2)) {
return super.removeBigram(word1, word2);
}
} finally {
mBigramListLock.unlock();
}
}
return false;
}
/**
* Schedules a background thread to write any pending words to the database.
*/
private void flushPendingWrites() {
if (mBigramListLock.isLocked()) {
return;
}
// Create a background thread to write the pending entries
new UpdateDbTask(sOpenHelper, mBigramList, mLocale, this, mPrefs).execute();
}
@Override
public void loadDictionaryAsync() {
// This must be run on non-main thread
mBigramListLock.lock();
try {
loadDictionaryAsyncLocked();
} finally {
mBigramListLock.unlock();
}
}
private void loadDictionaryAsyncLocked() {
if (DBG_STRESS_TEST) {
try {
Log.w(TAG, "Start stress in loading: " + mLocale);
Thread.sleep(15000);
Log.w(TAG, "End stress in loading");
} catch (InterruptedException e) {
}
}
final long last = SettingsValues.getLastUserHistoryWriteTime(mPrefs, mLocale);
final boolean initializing = last == 0;
final long now = System.currentTimeMillis();
// Load the words that correspond to the current input locale
final Cursor cursor = query(MAIN_COLUMN_LOCALE + "=?", new String[] { mLocale });
if (null == cursor) return;
try {
// TODO: Call SQLiteDataBase.beginTransaction / SQLiteDataBase.endTransaction
if (cursor.moveToFirst()) {
final int word1Index = cursor.getColumnIndex(MAIN_COLUMN_WORD1);
final int word2Index = cursor.getColumnIndex(MAIN_COLUMN_WORD2);
final int fcIndex = cursor.getColumnIndex(COLUMN_FORGETTING_CURVE_VALUE);
while (!cursor.isAfterLast()) {
final String word1 = cursor.getString(word1Index);
final String word2 = cursor.getString(word2Index);
final int fc = cursor.getInt(fcIndex);
if (DBG_SAVE_RESTORE) {
Log.d(TAG, "--- Load user history: " + word1 + ", " + word2 + ","
+ mLocale + "," + this);
}
// Safeguard against adding really long words. Stack may overflow due
// to recursive lookup
if (null == word1) {
super.addWord(word2, null /* shortcut */, fc);
} else if (word1.length() < BinaryDictionary.MAX_WORD_LENGTH
&& word2.length() < BinaryDictionary.MAX_WORD_LENGTH) {
super.setBigramAndGetFrequency(
word1, word2, initializing ? new ForgettingCurveParams(true)
: new ForgettingCurveParams(fc, now, last));
}
mBigramList.addBigram(word1, word2, (byte)fc);
cursor.moveToNext();
}
}
} finally {
cursor.close();
if (PROFILE_SAVE_RESTORE) {
final long diff = System.currentTimeMillis() - now;
Log.w(TAG, "PROF: Load User HistoryDictionary: "
+ mLocale + ", " + diff + "ms.");
}
}
}
/**
* Query the database
*/
private static Cursor query(String selection, String[] selectionArgs) {
SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
// main INNER JOIN frequency ON (main._id=freq.pair_id)
qb.setTables(MAIN_TABLE_NAME + " INNER JOIN " + FREQ_TABLE_NAME + " ON ("
+ MAIN_TABLE_NAME + "." + MAIN_COLUMN_ID + "=" + FREQ_TABLE_NAME + "."
+ FREQ_COLUMN_PAIR_ID +")");
qb.setProjectionMap(sDictProjectionMap);
// Get the database and run the query
try {
SQLiteDatabase db = sOpenHelper.getReadableDatabase();
Cursor c = qb.query(db,
new String[] {
MAIN_COLUMN_WORD1, MAIN_COLUMN_WORD2, COLUMN_FORGETTING_CURVE_VALUE },
selection, selectionArgs, null, null, null);
return c;
} catch (android.database.sqlite.SQLiteCantOpenDatabaseException e) {
// Can't open the database : presumably we can't access storage. That may happen
// when the device is wedged; do a best effort to still start the keyboard.
return null;
}
}
/**
* This class helps open, create, and upgrade the database file.
*/
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("PRAGMA foreign_keys = ON;");
db.execSQL("CREATE TABLE " + MAIN_TABLE_NAME + " ("
+ MAIN_COLUMN_ID + " INTEGER PRIMARY KEY,"
+ MAIN_COLUMN_WORD1 + " TEXT,"
+ MAIN_COLUMN_WORD2 + " TEXT,"
+ MAIN_COLUMN_LOCALE + " TEXT"
+ ");");
db.execSQL("CREATE TABLE " + FREQ_TABLE_NAME + " ("
+ FREQ_COLUMN_ID + " INTEGER PRIMARY KEY,"
+ FREQ_COLUMN_PAIR_ID + " INTEGER,"
+ COLUMN_FORGETTING_CURVE_VALUE + " INTEGER,"
+ "FOREIGN KEY(" + FREQ_COLUMN_PAIR_ID + ") REFERENCES " + MAIN_TABLE_NAME
+ "(" + MAIN_COLUMN_ID + ")" + " ON DELETE CASCADE"
+ ");");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS " + MAIN_TABLE_NAME);
db.execSQL("DROP TABLE IF EXISTS " + FREQ_TABLE_NAME);
onCreate(db);
}
}
/**
* Async task to write pending words to the database so that it stays in sync with
* the in-memory trie.
*/
private static class UpdateDbTask extends AsyncTask<Void, Void, Void> {
private final UserHistoryDictionaryBigramList mBigramList;
private final DatabaseHelper mDbHelper;
private final String mLocale;
private final UserHistoryDictionary mUserHistoryDictionary;
private final SharedPreferences mPrefs;
public UpdateDbTask(
DatabaseHelper openHelper, UserHistoryDictionaryBigramList pendingWrites,
String locale, UserHistoryDictionary dict, SharedPreferences prefs) {
mBigramList = pendingWrites;
mLocale = locale;
mDbHelper = openHelper;
mUserHistoryDictionary = dict;
mPrefs = prefs;
}
/** Prune any old data if the database is getting too big. */
private static void checkPruneData(SQLiteDatabase db) {
db.execSQL("PRAGMA foreign_keys = ON;");
Cursor c = db.query(FREQ_TABLE_NAME, new String[] { FREQ_COLUMN_PAIR_ID },
null, null, null, null, null);
try {
int totalRowCount = c.getCount();
// prune out old data if we have too much data
if (totalRowCount > sMaxHistoryBigrams) {
int numDeleteRows = (totalRowCount - sMaxHistoryBigrams)
+ sDeleteHistoryBigrams;
int pairIdColumnId = c.getColumnIndex(FREQ_COLUMN_PAIR_ID);
c.moveToFirst();
int count = 0;
while (count < numDeleteRows && !c.isAfterLast()) {
String pairId = c.getString(pairIdColumnId);
// Deleting from MAIN table will delete the frequencies
// due to FOREIGN KEY .. ON DELETE CASCADE
db.delete(MAIN_TABLE_NAME, MAIN_COLUMN_ID + "=?",
new String[] { pairId });
c.moveToNext();
count++;
}
}
} finally {
c.close();
}
}
@Override
protected Void doInBackground(Void... v) {
SQLiteDatabase db = null;
if (mUserHistoryDictionary.mBigramListLock.tryLock()) {
try {
try {
db = mDbHelper.getWritableDatabase();
} catch (android.database.sqlite.SQLiteCantOpenDatabaseException e) {
// If we can't open the db, don't do anything. Exit through the next test
// for non-nullity of the db variable.
}
if (null == db) {
// Not much we can do. Just exit.
return null;
}
db.beginTransaction();
return doLoadTaskLocked(db);
} finally {
if (db != null) {
db.endTransaction();
}
mUserHistoryDictionary.mBigramListLock.unlock();
}
}
return null;
}
private Void doLoadTaskLocked(SQLiteDatabase db) {
if (DBG_STRESS_TEST) {
try {
Log.w(TAG, "Start stress in closing: " + mLocale);
Thread.sleep(15000);
Log.w(TAG, "End stress in closing");
} catch (InterruptedException e) {
}
}
final long now = PROFILE_SAVE_RESTORE ? System.currentTimeMillis() : 0;
int profTotal = 0;
int profInsert = 0;
int profDelete = 0;
db.execSQL("PRAGMA foreign_keys = ON;");
final boolean addLevel0Bigram = mBigramList.size() <= sMaxHistoryBigrams;
// Write all the entries to the db
for (String word1 : mBigramList.keySet()) {
final HashMap<String, Byte> word1Bigrams = mBigramList.getBigrams(word1);
for (String word2 : word1Bigrams.keySet()) {
if (PROFILE_SAVE_RESTORE) {
++profTotal;
}
// Get new frequency. Do not insert unigrams/bigrams which freq is "-1".
final int freq; // -1, or 0~255
if (word1 == null) { // unigram
freq = FREQUENCY_FOR_TYPED;
final byte prevFc = word1Bigrams.get(word2);
if (prevFc == FREQUENCY_FOR_TYPED) {
// No need to update since we found no changes for this entry.
// Just skip to the next entry.
if (DBG_SAVE_RESTORE) {
Log.d(TAG, "Skip update user history: " + word1 + "," + word2
+ "," + prevFc);
}
if (!DBG_ALWAYS_WRITE) {
continue;
}
}
} else { // bigram
final NextWord nw = mUserHistoryDictionary.getBigramWord(word1, word2);
if (nw != null) {
final ForgettingCurveParams fcp = nw.getFcParams();
final byte prevFc = word1Bigrams.get(word2);
final byte fc = (byte)fcp.getFc();
final boolean isValid = fcp.isValid();
if (prevFc > 0 && prevFc == fc) {
// No need to update since we found no changes for this entry.
// Just skip to the next entry.
if (DBG_SAVE_RESTORE) {
Log.d(TAG, "Skip update user history: " + word1 + ","
+ word2 + "," + prevFc);
}
if (!DBG_ALWAYS_WRITE) {
continue;
} else {
freq = fc;
}
} else if (UserHistoryForgettingCurveUtils.
needsToSave(fc, isValid, addLevel0Bigram)) {
freq = fc;
} else {
freq = -1;
}
} else {
freq = -1;
}
}
// TODO: this process of making a text search for each pair each time
// is terribly inefficient. Optimize this.
// Find pair id
Cursor c = null;
try {
if (null != word1) {
c = db.query(MAIN_TABLE_NAME, new String[] { MAIN_COLUMN_ID },
MAIN_COLUMN_WORD1 + "=? AND " + MAIN_COLUMN_WORD2 + "=? AND "
+ MAIN_COLUMN_LOCALE + "=?",
new String[] { word1, word2, mLocale }, null, null,
null);
} else {
c = db.query(MAIN_TABLE_NAME, new String[] { MAIN_COLUMN_ID },
MAIN_COLUMN_WORD1 + " IS NULL AND " + MAIN_COLUMN_WORD2
+ "=? AND " + MAIN_COLUMN_LOCALE + "=?",
new String[] { word2, mLocale }, null, null, null);
}
final int pairId;
if (c.moveToFirst()) {
if (PROFILE_SAVE_RESTORE) {
++profDelete;
}
// Delete existing pair
pairId = c.getInt(c.getColumnIndex(MAIN_COLUMN_ID));
db.delete(FREQ_TABLE_NAME, FREQ_COLUMN_PAIR_ID + "=?",
new String[] { Integer.toString(pairId) });
} else {
// Create new pair
Long pairIdLong = db.insert(MAIN_TABLE_NAME, null,
getContentValues(word1, word2, mLocale));
pairId = pairIdLong.intValue();
}
if (freq > 0) {
if (PROFILE_SAVE_RESTORE) {
++profInsert;
}
if (DBG_SAVE_RESTORE) {
Log.d(TAG, "--- Save user history: " + word1 + ", " + word2
+ mLocale + "," + this);
}
// Insert new frequency
db.insert(FREQ_TABLE_NAME, null,
getFrequencyContentValues(pairId, freq));
// Update an existing bigram entry in mBigramList too in order to
// synchronize the SQL DB and mBigramList.
mBigramList.updateBigram(word1, word2, (byte)freq);
}
} finally {
if (c != null) {
c.close();
}
}
}
}
checkPruneData(db);
// Save the timestamp after we finish writing the SQL DB.
SettingsValues.setLastUserHistoryWriteTime(mPrefs, mLocale);
if (PROFILE_SAVE_RESTORE) {
final long diff = System.currentTimeMillis() - now;
Log.w(TAG, "PROF: Write User HistoryDictionary: " + mLocale + ", "+ diff
+ "ms. Total: " + profTotal + ". Insert: " + profInsert + ". Delete: "
+ profDelete);
}
db.setTransactionSuccessful();
return null;
}
private static ContentValues getContentValues(String word1, String word2, String locale) {
ContentValues values = new ContentValues(3);
values.put(MAIN_COLUMN_WORD1, word1);
values.put(MAIN_COLUMN_WORD2, word2);
values.put(MAIN_COLUMN_LOCALE, locale);
return values;
}
private static ContentValues getFrequencyContentValues(int pairId, int frequency) {
ContentValues values = new ContentValues(2);
values.put(FREQ_COLUMN_PAIR_ID, pairId);
values.put(COLUMN_FORGETTING_CURVE_VALUE, frequency);
return values;
}
}
}