Add an expandable binary dictionary that can be modified at runtime and works with native algorithms.

Bug: 6188977
Change-Id: Iec5c4e7d1d3918ac645187bd32dc3f82a95fec1e
main
Tom Ouyang 2012-03-24 15:13:40 +09:00
parent 8834e3dbce
commit ecd2ac93bc
1 changed files with 393 additions and 0 deletions

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/*
* Copyright (C) 2012 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.Context;
import android.os.SystemClock;
import android.util.Log;
import com.android.inputmethod.keyboard.ProximityInfo;
import com.android.inputmethod.latin.makedict.BinaryDictInputOutput;
import com.android.inputmethod.latin.makedict.FusionDictionary;
import com.android.inputmethod.latin.makedict.FusionDictionary.Node;
import com.android.inputmethod.latin.makedict.UnsupportedFormatException;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.concurrent.locks.ReentrantLock;
/**
* Abstract base class for an expandable dictionary that can be created and updated dynamically
* during runtime. When updated it automatically generates a new binary dictionary to handle future
* queries in native code. This binary dictionary is written to internal storage, and potentially
* shared across multiple ExpandableBinaryDictionary instances. Updates to each dictionary filename
* are controlled across multiple instances to ensure that only one instance can update the same
* dictionary at the same time.
*/
abstract public class ExpandableBinaryDictionary extends Dictionary {
/** Used for Log actions from this class */
private static final String TAG = ExpandableBinaryDictionary.class.getSimpleName();
/** Whether to print debug output to log */
private static boolean DEBUG = false;
/**
* The maximum length of a word in this dictionary. This is the same value as the binary
* dictionary.
*/
protected static final int MAX_WORD_LENGTH = BinaryDictionary.MAX_WORD_LENGTH;
/**
* A static map of locks, each of which controls access to a single binary dictionary file. They
* ensure that only one instance can update the same dictionary at the same time. The key for
* this map is the filename and the value is the shared dictionary controller associated with
* that filename.
*/
private static final HashMap<String, DictionaryController> sSharedDictionaryControllers =
new HashMap<String, DictionaryController>();
/** The application context. */
protected final Context mContext;
/**
* The binary dictionary generated dynamically from the fusion dictionary. This is used to
* answer unigram and bigram queries.
*/
private BinaryDictionary mBinaryDictionary;
/** The expandable fusion dictionary used to generate the binary dictionary. */
private FusionDictionary mFusionDictionary;
/** The dictionary type id. */
public final int mDicTypeId;
/**
* The name of this dictionary, used as the filename for storing the binary dictionary. Multiple
* dictionary instances with the same filename is supported, with access controlled by
* DictionaryController.
*/
private final String mFilename;
/** Controls access to the shared binary dictionary file across multiple instances. */
private final DictionaryController mSharedDictionaryController;
/** Controls access to the local binary dictionary for this instance. */
private final DictionaryController mLocalDictionaryController = new DictionaryController();
/**
* Abstract method for loading the unigrams and bigrams of a given dictionary in a background
* thread.
*/
protected abstract void loadDictionaryAsync();
/**
* Gets the shared dictionary controller for the given filename.
*/
private static synchronized DictionaryController getSharedDictionaryController(
String filename) {
DictionaryController controller = sSharedDictionaryControllers.get(filename);
if (controller == null) {
controller = new DictionaryController();
sSharedDictionaryControllers.put(filename, controller);
}
return controller;
}
/**
* Creates a new expandable binary dictionary.
*
* @param context The application context of the parent.
* @param filename The filename for this binary dictionary. Multiple dictionaries with the same
* filename is supported.
* @param dictType The type of this dictionary.
*/
public ExpandableBinaryDictionary(
final Context context, final String filename, final int dictType) {
mDicTypeId = dictType;
mFilename = filename;
mContext = context;
mBinaryDictionary = null;
mSharedDictionaryController = getSharedDictionaryController(filename);
clearFusionDictionary();
}
/**
* Closes and cleans up the binary dictionary.
*/
@Override
public void close() {
// Ensure that no other threads are accessing the local binary dictionary.
mLocalDictionaryController.lock();
try {
if (mBinaryDictionary != null) {
mBinaryDictionary.close();
mBinaryDictionary = null;
}
} finally {
mLocalDictionaryController.unlock();
}
}
/**
* Clears the fusion dictionary on the Java side. Note: Does not modify the binary dictionary on
* the native side.
*/
public void clearFusionDictionary() {
mFusionDictionary = new FusionDictionary(new Node(), new FusionDictionary.DictionaryOptions(
new HashMap<String, String>(), false, false));
}
/**
* Adds a word unigram to the fusion dictionary. Call updateBinaryDictionary when all changes
* are done to update the binary dictionary.
*/
// TODO: Create "cache dictionary" to cache fresh words for frequently updated dictionaries,
// considering performance regression.
protected void addWord(final String word, final int frequency) {
mFusionDictionary.add(word, frequency, null, null);
}
/**
* Sets a word bigram in the fusion dictionary. Call updateBinaryDictionary when all changes are
* done to update the binary dictionary.
*/
// TODO: Create "cache dictionary" to cache fresh bigrams for frequently updated dictionaries,
// considering performance regression.
protected void setBigram(final String prevWord, final String word, final int frequency) {
mFusionDictionary.setBigram(prevWord, word, frequency);
}
@Override
public void getWords(final WordComposer codes, final WordCallback callback,
final ProximityInfo proximityInfo) {
asyncReloadDictionaryIfRequired();
getWordsInner(codes, callback, proximityInfo);
}
protected final void getWordsInner(final WordComposer codes, final WordCallback callback,
final ProximityInfo proximityInfo) {
// Ensure that there are no concurrent calls to getWords. If there are, do nothing and
// return.
if (mLocalDictionaryController.tryLock()) {
try {
if (mBinaryDictionary != null) {
mBinaryDictionary.getWords(codes, callback, proximityInfo);
}
} finally {
mLocalDictionaryController.unlock();
}
}
}
@Override
public void getBigrams(final WordComposer codes, final CharSequence previousWord,
final WordCallback callback) {
asyncReloadDictionaryIfRequired();
getBigramsInner(codes, previousWord, callback);
}
protected void getBigramsInner(final WordComposer codes, final CharSequence previousWord,
final WordCallback callback) {
if (mLocalDictionaryController.tryLock()) {
try {
if (mBinaryDictionary != null) {
mBinaryDictionary.getBigrams(codes, previousWord, callback);
}
} finally {
mLocalDictionaryController.unlock();
}
}
}
@Override
public boolean isValidWord(final CharSequence word) {
asyncReloadDictionaryIfRequired();
return isValidWordInner(word);
}
protected boolean isValidWordInner(final CharSequence word) {
if (mLocalDictionaryController.tryLock()) {
try {
if (mBinaryDictionary != null) {
return mBinaryDictionary.isValidWord(word);
}
} finally {
mLocalDictionaryController.unlock();
}
}
return false;
}
/**
* Load the current binary dictionary from internal storage in a background thread. If no binary
* dictionary exists, this method will generate one.
*/
protected void loadDictionary() {
mLocalDictionaryController.mLastUpdateRequestTime = SystemClock.uptimeMillis();
asyncReloadDictionaryIfRequired();
}
/**
* Loads the current binary dictionary from internal storage. Assumes the dictionary file
* exists.
*/
protected void loadBinaryDictionary() {
if (DEBUG) {
Log.d(TAG, "Loading binary dictionary: request="
+ mSharedDictionaryController.mLastUpdateRequestTime + " update="
+ mSharedDictionaryController.mLastUpdateTime);
}
final File file = new File(mContext.getFilesDir(), mFilename);
final String filename = file.getAbsolutePath();
final long length = file.length();
// Build the new binary dictionary
final BinaryDictionary newBinaryDictionary =
new BinaryDictionary(mContext, filename, 0, length, true /* useFullEditDistance */,
null);
if (mBinaryDictionary != null) {
// Ensure all threads accessing the current dictionary have finished before swapping in
// the new one.
final BinaryDictionary oldBinaryDictionary = mBinaryDictionary;
mLocalDictionaryController.lock();
mBinaryDictionary = newBinaryDictionary;
mLocalDictionaryController.unlock();
oldBinaryDictionary.close();
} else {
mBinaryDictionary = newBinaryDictionary;
}
}
/**
* Generates and writes a new binary dictionary based on the contents of the fusion dictionary.
*/
private void generateBinaryDictionary() {
if (DEBUG) {
Log.d(TAG, "Generating binary dictionary: request="
+ mSharedDictionaryController.mLastUpdateRequestTime + " update="
+ mSharedDictionaryController.mLastUpdateTime);
}
loadDictionaryAsync();
final File file = new File(mContext.getFilesDir(), mFilename);
FileOutputStream out = null;
try {
out = new FileOutputStream(file);
BinaryDictInputOutput.writeDictionaryBinary(out, mFusionDictionary, 1);
out.flush();
out.close();
clearFusionDictionary();
} catch (IOException e) {
Log.e(TAG, "IO exception while writing file: " + e);
} catch (UnsupportedFormatException e) {
Log.e(TAG, "Unsupported format: " + e);
} finally {
if (out != null) {
try {
out.close();
} catch (IOException e) {
// ignore
}
}
}
}
/**
* Sets whether or not the dictionary is out of date and requires a reload.
*/
protected void setRequiresReload(final boolean reload) {
final long time = reload ? SystemClock.uptimeMillis() : 0;
mSharedDictionaryController.mLastUpdateRequestTime = time;
mLocalDictionaryController.mLastUpdateRequestTime = time;
if (DEBUG) {
Log.d(TAG, "Reload request: request=" + time + " update="
+ mSharedDictionaryController.mLastUpdateTime);
}
}
/**
* Reloads the dictionary if required. Reload will occur asynchronously in a separate thread.
*/
void asyncReloadDictionaryIfRequired() {
new AsyncReloadDictionaryTask().start();
}
/**
* Reloads the dictionary if required. Access is controlled on a per dictionary file basis and
* supports concurrent calls from multiple instances that share the same dictionary file.
*/
protected final void syncReloadDictionaryIfRequired() {
if (mBinaryDictionary != null && !mLocalDictionaryController.isOutOfDate()) {
return;
}
// Ensure that only one thread attempts to read or write to the shared binary dictionary
// file at the same time.
mSharedDictionaryController.lock();
try {
final long time = SystemClock.uptimeMillis();
if (mSharedDictionaryController.isOutOfDate() || !dictionaryFileExists()) {
// If the shared dictionary file does not exist or is out of date, the first
// instance that acquires the lock will generate a new one.
mSharedDictionaryController.mLastUpdateTime = time;
mLocalDictionaryController.mLastUpdateTime = time;
generateBinaryDictionary();
loadBinaryDictionary();
} else if (mLocalDictionaryController.isOutOfDate()) {
// Otherwise, if only the local dictionary for this instance is out of date, load
// the shared dictionary from file.
mLocalDictionaryController.mLastUpdateTime = time;
loadBinaryDictionary();
}
} finally {
mSharedDictionaryController.unlock();
}
}
private boolean dictionaryFileExists() {
final File file = new File(mContext.getFilesDir(), mFilename);
return file.exists();
}
/**
* Thread class for asynchronously reloading and rewriting the binary dictionary.
*/
private class AsyncReloadDictionaryTask extends Thread {
@Override
public void run() {
syncReloadDictionaryIfRequired();
}
}
/**
* Lock for controlling access to a given binary dictionary and for tracking whether the
* dictionary is out of date. Can be shared across multiple dictionary instances that access the
* same filename.
*/
private static class DictionaryController extends ReentrantLock {
private volatile long mLastUpdateTime = 0;
private volatile long mLastUpdateRequestTime = 0;
private boolean isOutOfDate() {
return (mLastUpdateRequestTime > mLastUpdateTime);
}
}
}