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1/*
2 * Copyright (C) 2011 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 android.database.sqlite;
18
19import android.content.res.Resources;
20import android.os.StatFs;
21import android.os.SystemProperties;
22
23/**
24 * Provides access to SQLite functions that affect all database connection,
25 * such as memory management.
26 *
27 * The native code associated with SQLiteGlobal is also sets global configuration options
28 * using sqlite3_config() then calls sqlite3_initialize() to ensure that the SQLite
29 * library is properly initialized exactly once before any other framework or application
30 * code has a chance to run.
31 *
32 * Verbose SQLite logging is enabled if the "log.tag.SQLiteLog" property is set to "V".
33 * (per {@link SQLiteDebug#DEBUG_SQL_LOG}).
34 *
35 * @hide
36 */
37public final class SQLiteGlobal {
38    private static final String TAG = "SQLiteGlobal";
39
40    private static final Object sLock = new Object();
41    private static int sDefaultPageSize;
42
43    private static native int nativeReleaseMemory();
44
45    private SQLiteGlobal() {
46    }
47
48    /**
49     * Attempts to release memory by pruning the SQLite page cache and other
50     * internal data structures.
51     *
52     * @return The number of bytes that were freed.
53     */
54    public static int releaseMemory() {
55        return nativeReleaseMemory();
56    }
57
58    /**
59     * Gets the default page size to use when creating a database.
60     */
61    public static int getDefaultPageSize() {
62        synchronized (sLock) {
63            if (sDefaultPageSize == 0) {
64                sDefaultPageSize = new StatFs("/data").getBlockSize();
65            }
66            return SystemProperties.getInt("debug.sqlite.pagesize", sDefaultPageSize);
67        }
68    }
69
70    /**
71     * Gets the default journal mode when WAL is not in use.
72     */
73    public static String getDefaultJournalMode() {
74        return SystemProperties.get("debug.sqlite.journalmode",
75                Resources.getSystem().getString(
76                com.android.internal.R.string.db_default_journal_mode));
77    }
78
79    /**
80     * Gets the journal size limit in bytes.
81     */
82    public static int getJournalSizeLimit() {
83        return SystemProperties.getInt("debug.sqlite.journalsizelimit",
84                Resources.getSystem().getInteger(
85                com.android.internal.R.integer.db_journal_size_limit));
86    }
87
88    /**
89     * Gets the default database synchronization mode when WAL is not in use.
90     */
91    public static String getDefaultSyncMode() {
92        return SystemProperties.get("debug.sqlite.syncmode",
93                Resources.getSystem().getString(
94                com.android.internal.R.string.db_default_sync_mode));
95    }
96
97    /**
98     * Gets the database synchronization mode when in WAL mode.
99     */
100    public static String getWALSyncMode() {
101        return SystemProperties.get("debug.sqlite.wal.syncmode",
102                Resources.getSystem().getString(
103                com.android.internal.R.string.db_wal_sync_mode));
104    }
105
106    /**
107     * Gets the WAL auto-checkpoint integer in database pages.
108     */
109    public static int getWALAutoCheckpoint() {
110        int value = SystemProperties.getInt("debug.sqlite.wal.autocheckpoint",
111                Resources.getSystem().getInteger(
112                com.android.internal.R.integer.db_wal_autocheckpoint));
113        return Math.max(1, value);
114    }
115
116    /**
117     * Gets the connection pool size when in WAL mode.
118     */
119    public static int getWALConnectionPoolSize() {
120        int value = SystemProperties.getInt("debug.sqlite.wal.poolsize",
121                Resources.getSystem().getInteger(
122                com.android.internal.R.integer.db_connection_pool_size));
123        return Math.max(2, value);
124    }
125}
126