SQLiteContentProvider.java revision 8402962ef58546d3cfd48fbb211b5e36df0f118e 
1/*
2 * Copyright (C) 2009 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.browser.provider;
18
19import android.content.ContentProvider;
20import android.content.ContentProviderOperation;
21import android.content.ContentProviderResult;
22import android.content.ContentValues;
23import android.content.Context;
24import android.content.OperationApplicationException;
25import android.database.sqlite.SQLiteDatabase;
26import android.database.sqlite.SQLiteOpenHelper;
27import android.database.sqlite.SQLiteTransactionListener;
28import android.net.Uri;
29
30import java.util.ArrayList;
31
32/**
33 * General purpose {@link ContentProvider} base class that uses SQLiteDatabase for storage.
34 */
35public abstract class SQLiteContentProvider extends ContentProvider
36        implements SQLiteTransactionListener {
37
38    private static final String TAG = "SQLiteContentProvider";
39
40    private SQLiteOpenHelper mOpenHelper;
41    private volatile boolean mNotifyChange;
42    protected SQLiteDatabase mDb;
43
44    private final ThreadLocal<Boolean> mApplyingBatch = new ThreadLocal<Boolean>();
45    private static final int SLEEP_AFTER_YIELD_DELAY = 4000;
46
47    /**
48     * Maximum number of operations allowed in a batch between yield points.
49     */
50    private static final int MAX_OPERATIONS_PER_YIELD_POINT = 500;
51
52    @Override
53    public boolean onCreate() {
54        Context context = getContext();
55        mOpenHelper = getDatabaseHelper(context);
56        return true;
57    }
58
59    /**
60     * Returns a {@link SQLiteOpenHelper} that can open the database.
61     */
62    public abstract SQLiteOpenHelper getDatabaseHelper(Context context);
63
64    /**
65     * The equivalent of the {@link #insert} method, but invoked within a transaction.
66     */
67    public abstract Uri insertInTransaction(Uri uri, ContentValues values,
68            boolean callerIsSyncAdapter);
69
70    /**
71     * The equivalent of the {@link #update} method, but invoked within a transaction.
72     */
73    public abstract int updateInTransaction(Uri uri, ContentValues values, String selection,
74            String[] selectionArgs, boolean callerIsSyncAdapter);
75
76    /**
77     * The equivalent of the {@link #delete} method, but invoked within a transaction.
78     */
79    public abstract int deleteInTransaction(Uri uri, String selection, String[] selectionArgs,
80            boolean callerIsSyncAdapter);
81
82    /**
83     * Called when the provider needs to notify the system of a change.
84     * @param callerIsSyncAdapter true if the caller that caused the change was a sync adapter.
85     */
86    public abstract void notifyChange(boolean callerIsSyncAdapter);
87
88    public boolean isCallerSyncAdapter(Uri uri) {
89        return false;
90    }
91
92    public SQLiteOpenHelper getDatabaseHelper() {
93        return mOpenHelper;
94    }
95
96    private boolean applyingBatch() {
97        return mApplyingBatch.get() != null && mApplyingBatch.get();
98    }
99
100    @Override
101    public Uri insert(Uri uri, ContentValues values) {
102        Uri result = null;
103        boolean callerIsSyncAdapter = isCallerSyncAdapter(uri);
104        boolean applyingBatch = applyingBatch();
105        if (!applyingBatch) {
106            mDb = mOpenHelper.getWritableDatabase();
107            mDb.beginTransactionWithListener(this);
108            try {
109                result = insertInTransaction(uri, values, callerIsSyncAdapter);
110                if (result != null) {
111                    mNotifyChange = true;
112                }
113                mDb.setTransactionSuccessful();
114            } finally {
115                mDb.endTransaction();
116            }
117
118            onEndTransaction(callerIsSyncAdapter);
119        } else {
120            result = insertInTransaction(uri, values, callerIsSyncAdapter);
121            if (result != null) {
122                mNotifyChange = true;
123            }
124        }
125        return result;
126    }
127
128    @Override
129    public int bulkInsert(Uri uri, ContentValues[] values) {
130        int numValues = values.length;
131        boolean callerIsSyncAdapter = isCallerSyncAdapter(uri);
132        mDb = mOpenHelper.getWritableDatabase();
133        mDb.beginTransactionWithListener(this);
134        try {
135            for (int i = 0; i < numValues; i++) {
136                Uri result = insertInTransaction(uri, values[i], callerIsSyncAdapter);
137                if (result != null) {
138                    mNotifyChange = true;
139                }
140                mDb.yieldIfContendedSafely();
141            }
142            mDb.setTransactionSuccessful();
143        } finally {
144            mDb.endTransaction();
145        }
146
147        onEndTransaction(callerIsSyncAdapter);
148        return numValues;
149    }
150
151    @Override
152    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
153        int count = 0;
154        boolean callerIsSyncAdapter = isCallerSyncAdapter(uri);
155        boolean applyingBatch = applyingBatch();
156        if (!applyingBatch) {
157            mDb = mOpenHelper.getWritableDatabase();
158            mDb.beginTransactionWithListener(this);
159            try {
160                count = updateInTransaction(uri, values, selection, selectionArgs,
161                        callerIsSyncAdapter);
162                if (count > 0) {
163                    mNotifyChange = true;
164                }
165                mDb.setTransactionSuccessful();
166            } finally {
167                mDb.endTransaction();
168            }
169
170            onEndTransaction(callerIsSyncAdapter);
171        } else {
172            count = updateInTransaction(uri, values, selection, selectionArgs, callerIsSyncAdapter);
173            if (count > 0) {
174                mNotifyChange = true;
175            }
176        }
177
178        return count;
179    }
180
181    @Override
182    public int delete(Uri uri, String selection, String[] selectionArgs) {
183        int count = 0;
184        boolean callerIsSyncAdapter = isCallerSyncAdapter(uri);
185        boolean applyingBatch = applyingBatch();
186        if (!applyingBatch) {
187            mDb = mOpenHelper.getWritableDatabase();
188            mDb.beginTransactionWithListener(this);
189            try {
190                count = deleteInTransaction(uri, selection, selectionArgs, callerIsSyncAdapter);
191                if (count > 0) {
192                    mNotifyChange = true;
193                }
194                mDb.setTransactionSuccessful();
195            } finally {
196                mDb.endTransaction();
197            }
198
199            onEndTransaction(callerIsSyncAdapter);
200        } else {
201            count = deleteInTransaction(uri, selection, selectionArgs, callerIsSyncAdapter);
202            if (count > 0) {
203                mNotifyChange = true;
204            }
205        }
206        return count;
207    }
208
209    @Override
210    public ContentProviderResult[] applyBatch(ArrayList<ContentProviderOperation> operations)
211            throws OperationApplicationException {
212        int ypCount = 0;
213        int opCount = 0;
214        boolean callerIsSyncAdapter = false;
215        mDb = mOpenHelper.getWritableDatabase();
216        mDb.beginTransactionWithListener(this);
217        try {
218            mApplyingBatch.set(true);
219            final int numOperations = operations.size();
220            final ContentProviderResult[] results = new ContentProviderResult[numOperations];
221            for (int i = 0; i < numOperations; i++) {
222                if (++opCount >= MAX_OPERATIONS_PER_YIELD_POINT) {
223                    throw new OperationApplicationException(
224                            "Too many content provider operations between yield points. "
225                                    + "The maximum number of operations per yield point is "
226                                    + MAX_OPERATIONS_PER_YIELD_POINT, ypCount);
227                }
228                final ContentProviderOperation operation = operations.get(i);
229                if (!callerIsSyncAdapter && isCallerSyncAdapter(operation.getUri())) {
230                    callerIsSyncAdapter = true;
231                }
232                if (i > 0 && operation.isYieldAllowed()) {
233                    opCount = 0;
234                    if (mDb.yieldIfContendedSafely(SLEEP_AFTER_YIELD_DELAY)) {
235                        ypCount++;
236                    }
237                }
238                results[i] = operation.apply(this, results, i);
239            }
240            mDb.setTransactionSuccessful();
241            return results;
242        } finally {
243            mApplyingBatch.set(false);
244            mDb.endTransaction();
245            onEndTransaction(callerIsSyncAdapter);
246        }
247    }
248
249    @Override
250    public void onBegin() {
251        onBeginTransaction();
252    }
253
254    @Override
255    public void onCommit() {
256        beforeTransactionCommit();
257    }
258
259    @Override
260    public void onRollback() {
261        // not used
262    }
263
264    protected void onBeginTransaction() {
265    }
266
267    protected void beforeTransactionCommit() {
268    }
269
270    protected void onEndTransaction(boolean callerIsSyncAdapter) {
271        if (mNotifyChange) {
272            mNotifyChange = false;
273            notifyChange(callerIsSyncAdapter);
274        }
275    }
276}
277