Home | History | Annotate | Download | only in sqlite 
      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 
     17 package android.database.sqlite;
     18 
     19 import android.content.res.Resources;
     20 import android.os.StatFs;
     21 import 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  */
     37 public 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