core/java/android/database/sqlite/SQLiteDatabase.java

/*
 * Copyright (C) 2006 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 android.database.sqlite;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.DatabaseUtils;
import android.database.SQLException;
import android.os.Debug;
import android.os.SystemClock;
import android.os.SystemProperties;
import android.text.TextUtils;
import android.util.Config;
import android.util.EventLog;
import android.util.Log;

import java.io.File;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
import java.util.WeakHashMap;
import java.util.concurrent.locks.ReentrantLock;

/**
 * Exposes methods to manage a SQLite database.
 * <p>SQLiteDatabase has methods to create, delete, execute SQL commands, and
 * perform other common database management tasks.
 * <p>See the Notepad sample application in the SDK for an example of creating
 * and managing a database.
 * <p> Database names must be unique within an application, not across all
 * applications.
 *
 * <h3>Localized Collation - ORDER BY</h3>
 * <p>In addition to SQLite's default <code>BINARY</code> collator, Android supplies
 * two more, <code>LOCALIZED</code>, which changes with the system's current locale
 * if you wire it up correctly (XXX a link needed!), and <code>UNICODE</code>, which
 * is the Unicode Collation Algorithm and not tailored to the current locale.
 */
public class SQLiteDatabase extends SQLiteClosable {
    private static final String TAG = "Database";
    private static final int DB_OPERATION_EVENT = 52000;

    /**
     * Algorithms used in ON CONFLICT clause
     * http://www.sqlite.org/lang_conflict.html
     * @hide
     */
    public enum ConflictAlgorithm {
        /**
         *  When a constraint violation occurs, an immediate ROLLBACK occurs,
         * thus ending the current transaction, and the command aborts with a
         * return code of SQLITE_CONSTRAINT. If no transaction is active
         * (other than the implied transaction that is created on every command)
         *  then this algorithm works the same as ABORT.
         */
        ROLLBACK("ROLLBACK"),

        /**
         * When a constraint violation occurs,no ROLLBACK is executed
         * so changes from prior commands within the same transaction
         * are preserved. This is the default behavior.
         */
        ABORT("ABORT"),

        /**
         * When a constraint violation occurs, the command aborts with a return
         * code SQLITE_CONSTRAINT. But any changes to the database that
         * the command made prior to encountering the constraint violation
         * are preserved and are not backed out.
         */
        FAIL("FAIL"),

        /**
         * When a constraint violation occurs, the one row that contains
         * the constraint violation is not inserted or changed.
         * But the command continues executing normally. Other rows before and
         * after the row that contained the constraint violation continue to be
         * inserted or updated normally. No error is returned.
         */
        IGNORE("IGNORE"),

        /**
         * When a UNIQUE constraint violation occurs, the pre-existing rows that
         * are causing the constraint violation are removed prior to inserting
         * or updating the current row. Thus the insert or update always occurs.
         * The command continues executing normally. No error is returned.
         * If a NOT NULL constraint violation occurs, the NULL value is replaced
         * by the default value for that column. If the column has no default
         * value, then the ABORT algorithm is used. If a CHECK constraint
         * violation occurs then the IGNORE algorithm is used. When this conflict
         * resolution strategy deletes rows in order to satisfy a constraint,
         * it does not invoke delete triggers on those rows.
         *  This behavior might change in a future release.
         */
        REPLACE("REPLACE");

        private final String mValue;
        ConflictAlgorithm(String value) {
            mValue = value;
        }
        public String value() {
            return mValue;
        }
    }

    /**
     * Maximum Length Of A LIKE Or GLOB Pattern
     * The pattern matching algorithm used in the default LIKE and GLOB implementation
     * of SQLite can exhibit O(N^2) performance (where N is the number of characters in
     * the pattern) for certain pathological cases. To avoid denial-of-service attacks
     * the length of the LIKE or GLOB pattern is limited to SQLITE_MAX_LIKE_PATTERN_LENGTH bytes.
     * The default value of this limit is 50000. A modern workstation can evaluate
     * even a pathological LIKE or GLOB pattern of 50000 bytes relatively quickly.
     * The denial of service problem only comes into play when the pattern length gets
     * into millions of bytes. Nevertheless, since most useful LIKE or GLOB patterns
     * are at most a few dozen bytes in length, paranoid application developers may
     * want to reduce this parameter to something in the range of a few hundred
     * if they know that external users are able to generate arbitrary patterns.
     */
    public static final int SQLITE_MAX_LIKE_PATTERN_LENGTH = 50000;

    /**
     * Flag for {@link #openDatabase} to open the database for reading and writing.
     * If the disk is full, this may fail even before you actually write anything.
     *
     * {@more} Note that the value of this flag is 0, so it is the default.
     */
    public static final int OPEN_READWRITE = 0x00000000;          // update native code if changing

    /**
     * Flag for {@link #openDatabase} to open the database for reading only.
     * This is the only reliable way to open a database if the disk may be full.
     */
    public static final int OPEN_READONLY = 0x00000001;           // update native code if changing

    private static final int OPEN_READ_MASK = 0x00000001;         // update native code if changing

    /**
     * Flag for {@link #openDatabase} to open the database without support for localized collators.
     *
     * {@more} This causes the collator <code>LOCALIZED</code> not to be created.
     * You must be consistent when using this flag to use the setting the database was
     * created with.  If this is set, {@link #setLocale} will do nothing.
     */
    public static final int NO_LOCALIZED_COLLATORS = 0x00000010;  // update native code if changing

    /**
     * Flag for {@link #openDatabase} to create the database file if it does not already exist.
     */
    public static final int CREATE_IF_NECESSARY = 0x10000000;     // update native code if changing

    /**
     * Indicates whether the most-recently started transaction has been marked as successful.
     */
    private boolean mInnerTransactionIsSuccessful;

    /**
     * Valid during the life of a transaction, and indicates whether the entire transaction (the
     * outer one and all of the inner ones) so far has been successful.
     */
    private boolean mTransactionIsSuccessful;

    /**
     * Valid during the life of a transaction.
     */
    private SQLiteTransactionListener mTransactionListener;

    /** Synchronize on this when accessing the database */
    private final ReentrantLock mLock = new ReentrantLock(true);

    private long mLockAcquiredWallTime = 0L;
    private long mLockAcquiredThreadTime = 0L;

    // limit the frequency of complaints about each database to one within 20 sec
    // unless run command adb shell setprop log.tag.Database VERBOSE
    private static final int LOCK_WARNING_WINDOW_IN_MS = 20000;
    /** If the lock is held this long then a warning will be printed when it is released. */
    private static final int LOCK_ACQUIRED_WARNING_TIME_IN_MS = 300;
    private static final int LOCK_ACQUIRED_WARNING_THREAD_TIME_IN_MS = 100;
    private static final int LOCK_ACQUIRED_WARNING_TIME_IN_MS_ALWAYS_PRINT = 2000;

    private static final int SLEEP_AFTER_YIELD_QUANTUM = 1000;

    private long mLastLockMessageTime = 0L;

    /** Used by native code, do not rename */
    /* package */ int mNativeHandle = 0;

    /** Used to make temp table names unique */
    /* package */ int mTempTableSequence = 0;

    /** The path for the database file */
    private String mPath;

    /** The flags passed to open/create */
    private int mFlags;

    /** The optional factory to use when creating new Cursors */
    private CursorFactory mFactory;

    private WeakHashMap<SQLiteClosable, Object> mPrograms;

    private final RuntimeException mLeakedException;

    // package visible, since callers will access directly to minimize overhead in the case
    // that logging is not enabled.
    /* package */ final boolean mLogStats;

    // System property that enables logging of slow queries. Specify the threshold in ms.
    private static final String LOG_SLOW_QUERIES_PROPERTY = "db.log.slow_query_threshold";
    private final int mSlowQueryThreshold;

    /**
     * @param closable
     */
    void addSQLiteClosable(SQLiteClosable closable) {
        lock();
        try {
            mPrograms.put(closable, null);
        } finally {
            unlock();
        }
    }

    void removeSQLiteClosable(SQLiteClosable closable) {
        lock();
        try {
            mPrograms.remove(closable);
        } finally {
            unlock();
        }
    }

    @Override
    protected void onAllReferencesReleased() {
        if (isOpen()) {
            dbclose();
        }
    }

    /**
     * Attempts to release memory that SQLite holds but does not require to
     * operate properly. Typically this memory will come from the page cache.
     *
     * @return the number of bytes actually released
     */
    static public native int releaseMemory();

    /**
     * Control whether or not the SQLiteDatabase is made thread-safe by using locks
     * around critical sections. This is pretty expensive, so if you know that your
     * DB will only be used by a single thread then you should set this to false.
     * The default is true.
     * @param lockingEnabled set to true to enable locks, false otherwise
     */
    public void setLockingEnabled(boolean lockingEnabled) {
        mLockingEnabled = lockingEnabled;
    }

    /**
     * If set then the SQLiteDatabase is made thread-safe by using locks
     * around critical sections
     */
    private boolean mLockingEnabled = true;

    /* package */ void onCorruption() {
        try {
            // Close the database (if we can), which will cause subsequent operations to fail.
            close();
        } finally {
            Log.e(TAG, "Removing corrupt database: " + mPath);
            // Delete the corrupt file.  Don't re-create it now -- that would just confuse people
            // -- but the next time someone tries to open it, they can set it up from scratch.
            new File(mPath).delete();
        }
    }

    /**
     * Locks the database for exclusive access. The database lock must be held when
     * touch the native sqlite3* object since it is single threaded and uses
     * a polling lock contention algorithm. The lock is recursive, and may be acquired
     * multiple times by the same thread. This is a no-op if mLockingEnabled is false.
     *
     * @see #unlock()
     */
    /* package */ void lock() {
        if (!mLockingEnabled) return;
        mLock.lock();
        if (SQLiteDebug.DEBUG_LOCK_TIME_TRACKING) {
            if (mLock.getHoldCount() == 1) {
                // Use elapsed real-time since the CPU may sleep when waiting for IO
                mLockAcquiredWallTime = SystemClock.elapsedRealtime();
                mLockAcquiredThreadTime = Debug.threadCpuTimeNanos();
            }
        }
    }

    /**
     * Locks the database for exclusive access. The database lock must be held when
     * touch the native sqlite3* object since it is single threaded and uses
     * a polling lock contention algorithm. The lock is recursive, and may be acquired
     * multiple times by the same thread.
     *
     * @see #unlockForced()
     */
    private void lockForced() {
        mLock.lock();
        if (SQLiteDebug.DEBUG_LOCK_TIME_TRACKING) {
            if (mLock.getHoldCount() == 1) {
                // Use elapsed real-time since the CPU may sleep when waiting for IO
                mLockAcquiredWallTime = SystemClock.elapsedRealtime();
                mLockAcquiredThreadTime = Debug.threadCpuTimeNanos();
            }
        }
    }

    /**
     * Releases the database lock. This is a no-op if mLockingEnabled is false.
     *
     * @see #unlock()
     */
    /* package */ void unlock() {
        if (!mLockingEnabled) return;
        if (SQLiteDebug.DEBUG_LOCK_TIME_TRACKING) {
            if (mLock.getHoldCount() == 1) {
                checkLockHoldTime();
            }
        }
        mLock.unlock();
    }

    /**
     * Releases the database lock.
     *
     * @see #unlockForced()
     */
    private void unlockForced() {
        if (SQLiteDebug.DEBUG_LOCK_TIME_TRACKING) {
            if (mLock.getHoldCount() == 1) {
                checkLockHoldTime();
            }
        }
        mLock.unlock();
    }

    private void checkLockHoldTime() {
        // Use elapsed real-time since the CPU may sleep when waiting for IO
        long elapsedTime = SystemClock.elapsedRealtime();
        long lockedTime = elapsedTime - mLockAcquiredWallTime;
        if (lockedTime < LOCK_ACQUIRED_WARNING_TIME_IN_MS_ALWAYS_PRINT &&
                !Log.isLoggable(TAG, Log.VERBOSE) &&
                (elapsedTime - mLastLockMessageTime) < LOCK_WARNING_WINDOW_IN_MS) {
            return;
        }
        if (lockedTime > LOCK_ACQUIRED_WARNING_TIME_IN_MS) {
            int threadTime = (int)
                    ((Debug.threadCpuTimeNanos() - mLockAcquiredThreadTime) / 1000000);
            if (threadTime > LOCK_ACQUIRED_WARNING_THREAD_TIME_IN_MS ||
                    lockedTime > LOCK_ACQUIRED_WARNING_TIME_IN_MS_ALWAYS_PRINT) {
                mLastLockMessageTime = elapsedTime;
                String msg = "lock held on " + mPath + " for " + lockedTime + "ms. Thread time was "
                        + threadTime + "ms";
                if (SQLiteDebug.DEBUG_LOCK_TIME_TRACKING_STACK_TRACE) {
                    Log.d(TAG, msg, new Exception());
                } else {
                    Log.d(TAG, msg);
                }
            }
        }
    }

    /**
     * Begins a transaction. Transactions can be nested. When the outer transaction is ended all of
     * the work done in that transaction and all of the nested transactions will be committed or
     * rolled back. The changes will be rolled back if any transaction is ended without being
     * marked as clean (by calling setTransactionSuccessful). Otherwise they will be committed.
     *
     * <p>Here is the standard idiom for transactions:
     *
     * <pre>
     *   db.beginTransaction();
     *   try {
     *     ...
     *     db.setTransactionSuccessful();
     *   } finally {
     *     db.endTransaction();
     *   }
     * </pre>
     */
    public void beginTransaction() {
        beginTransactionWithListener(null /* transactionStatusCallback */);
    }

    /**
     * Begins a transaction. Transactions can be nested. When the outer transaction is ended all of
     * the work done in that transaction and all of the nested transactions will be committed or
     * rolled back. The changes will be rolled back if any transaction is ended without being
     * marked as clean (by calling setTransactionSuccessful). Otherwise they will be committed.
     *
     * <p>Here is the standard idiom for transactions:
     *
     * <pre>
     *   db.beginTransactionWithListener(listener);
     *   try {
     *     ...
     *     db.setTransactionSuccessful();
     *   } finally {
     *     db.endTransaction();
     *   }
     * </pre>
     * @param transactionListener listener that should be notified when the transaction begins,
     * commits, or is rolled back, either explicitly or by a call to
     * {@link #yieldIfContendedSafely}.
     */
    public void beginTransactionWithListener(SQLiteTransactionListener transactionListener) {
        lockForced();
        boolean ok = false;
        try {
            // If this thread already had the lock then get out
            if (mLock.getHoldCount() > 1) {
                if (mInnerTransactionIsSuccessful) {
                    String msg = "Cannot call beginTransaction between "
                            + "calling setTransactionSuccessful and endTransaction";
                    IllegalStateException e = new IllegalStateException(msg);
                    Log.e(TAG, "beginTransaction() failed", e);
                    throw e;
                }
                ok = true;
                return;
            }

            // This thread didn't already have the lock, so begin a database
            // transaction now.
            execSQL("BEGIN EXCLUSIVE;");
            mTransactionListener = transactionListener;
            mTransactionIsSuccessful = true;
            mInnerTransactionIsSuccessful = false;
            if (transactionListener != null) {
                try {
                    transactionListener.onBegin();
                } catch (RuntimeException e) {
                    execSQL("ROLLBACK;");
                    throw e;
                }
            }
            ok = true;
        } finally {
            if (!ok) {
                // beginTransaction is called before the try block so we must release the lock in
                // the case of failure.
                unlockForced();
            }
        }
    }

    /**
     * End a transaction. See beginTransaction for notes about how to use this and when transactions
     * are committed and rolled back.
     */
    public void endTransaction() {
        if (!mLock.isHeldByCurrentThread()) {
            throw new IllegalStateException("no transaction pending");
        }
        try {
            if (mInnerTransactionIsSuccessful) {
                mInnerTransactionIsSuccessful = false;
            } else {
                mTransactionIsSuccessful = false;
            }
            if (mLock.getHoldCount() != 1) {
                return;
            }
            RuntimeException savedException = null;
            if (mTransactionListener != null) {
                try {
                    if (mTransactionIsSuccessful) {
                        mTransactionListener.onCommit();
                    } else {
                        mTransactionListener.onRollback();
                    }
                } catch (RuntimeException e) {
                    savedException = e;
                    mTransactionIsSuccessful = false;
                }
            }
            if (mTransactionIsSuccessful) {
                execSQL("COMMIT;");
            } else {
                try {
                    execSQL("ROLLBACK;");
                    if (savedException != null) {
                        throw savedException;
                    }
                } catch (SQLException e) {
                    if (Config.LOGD) {
                        Log.d(TAG, "exception during rollback, maybe the DB previously "
                                + "performed an auto-rollback");
                    }
                }
            }
        } finally {
            mTransactionListener = null;
            unlockForced();
            if (Config.LOGV) {
                Log.v(TAG, "unlocked " + Thread.currentThread()
                        + ", holdCount is " + mLock.getHoldCount());
            }
        }
    }

    /**
     * Marks the current transaction as successful. Do not do any more database work between
     * calling this and calling endTransaction. Do as little non-database work as possible in that
     * situation too. If any errors are encountered between this and endTransaction the transaction
     * will still be committed.
     *
     * @throws IllegalStateException if the current thread is not in a transaction or the
     * transaction is already marked as successful.
     */
    public void setTransactionSuccessful() {
        if (!mLock.isHeldByCurrentThread()) {
            throw new IllegalStateException("no transaction pending");
        }
        if (mInnerTransactionIsSuccessful) {
            throw new IllegalStateException(
                    "setTransactionSuccessful may only be called once per call to beginTransaction");
        }
        mInnerTransactionIsSuccessful = true;
    }

    /**
     * return true if there is a transaction pending
     */
    public boolean inTransaction() {
        return mLock.getHoldCount() > 0;
    }

    /**
     * Checks if the database lock is held by this thread.
     *
     * @return true, if this thread is holding the database lock.
     */
    public boolean isDbLockedByCurrentThread() {
        return mLock.isHeldByCurrentThread();
    }

    /**
     * Checks if the database is locked by another thread. This is
     * just an estimate, since this status can change at any time,
     * including after the call is made but before the result has
     * been acted upon.
     *
     * @return true, if the database is locked by another thread
     */
    public boolean isDbLockedByOtherThreads() {
        return !mLock.isHeldByCurrentThread() && mLock.isLocked();
    }

    /**
     * Temporarily end the transaction to let other threads run. The transaction is assumed to be
     * successful so far. Do not call setTransactionSuccessful before calling this. When this
     * returns a new transaction will have been created but not marked as successful.
     * @return true if the transaction was yielded
     * @deprecated if the db is locked more than once (becuase of nested transactions) then the lock
     *   will not be yielded. Use yieldIfContendedSafely instead.
     */
    @Deprecated
    public boolean yieldIfContended() {
        return yieldIfContendedHelper(false /* do not check yielding */,
                -1 /* sleepAfterYieldDelay */);
    }

    /**
     * Temporarily end the transaction to let other threads run. The transaction is assumed to be
     * successful so far. Do not call setTransactionSuccessful before calling this. When this
     * returns a new transaction will have been created but not marked as successful. This assumes
     * that there are no nested transactions (beginTransaction has only been called once) and will
     * throw an exception if that is not the case.
     * @return true if the transaction was yielded
     */
    public boolean yieldIfContendedSafely() {
        return yieldIfContendedHelper(true /* check yielding */, -1 /* sleepAfterYieldDelay*/);
    }

    /**
     * Temporarily end the transaction to let other threads run. The transaction is assumed to be
     * successful so far. Do not call setTransactionSuccessful before calling this. When this
     * returns a new transaction will have been created but not marked as successful. This assumes
     * that there are no nested transactions (beginTransaction has only been called once) and will
     * throw an exception if that is not the case.
     * @param sleepAfterYieldDelay if > 0, sleep this long before starting a new transaction if
     *   the lock was actually yielded. This will allow other background threads to make some
     *   more progress than they would if we started the transaction immediately.
     * @return true if the transaction was yielded
     */
    public boolean yieldIfContendedSafely(long sleepAfterYieldDelay) {
        return yieldIfContendedHelper(true /* check yielding */, sleepAfterYieldDelay);
    }

    private boolean yieldIfContendedHelper(boolean checkFullyYielded, long sleepAfterYieldDelay) {
        if (mLock.getQueueLength() == 0) {
            // Reset the lock acquire time since we know that the thread was willing to yield
            // the lock at this time.
            mLockAcquiredWallTime = SystemClock.elapsedRealtime();
            mLockAcquiredThreadTime = Debug.threadCpuTimeNanos();
            return false;
        }
        setTransactionSuccessful();
        SQLiteTransactionListener transactionListener = mTransactionListener;
        endTransaction();
        if (checkFullyYielded) {
            if (this.isDbLockedByCurrentThread()) {
                throw new IllegalStateException(
                        "Db locked more than once. yielfIfContended cannot yield");
            }
        }
        if (sleepAfterYieldDelay > 0) {
            // Sleep for up to sleepAfterYieldDelay milliseconds, waking up periodically to
            // check if anyone is using the database.  If the database is not contended,
            // retake the lock and return.
            long remainingDelay = sleepAfterYieldDelay;
            while (remainingDelay > 0) {
                try {
                    Thread.sleep(remainingDelay < SLEEP_AFTER_YIELD_QUANTUM ?
                            remainingDelay : SLEEP_AFTER_YIELD_QUANTUM);
                } catch (InterruptedException e) {
                    Thread.interrupted();
                }
                remainingDelay -= SLEEP_AFTER_YIELD_QUANTUM;
                if (mLock.getQueueLength() == 0) {
                    break;
                }
            }
        }
        beginTransactionWithListener(transactionListener);
        return true;
    }

    /** Maps table names to info about what to which _sync_time column to set
     * to NULL on an update. This is used to support syncing. */
    private final Map<String, SyncUpdateInfo> mSyncUpdateInfo =
            new HashMap<String, SyncUpdateInfo>();

    public Map<String, String> getSyncedTables() {
        synchronized(mSyncUpdateInfo) {
            HashMap<String, String> tables = new HashMap<String, String>();
            for (String table : mSyncUpdateInfo.keySet()) {
                SyncUpdateInfo info = mSyncUpdateInfo.get(table);
                if (info.deletedTable != null) {
                    tables.put(table, info.deletedTable);
                }
            }
            return tables;
        }
    }

    /**
     * Internal class used to keep track what needs to be marked as changed
     * when an update occurs. This is used for syncing, so the sync engine
     * knows what data has been updated locally.
     */
    static private class SyncUpdateInfo {
        /**
         * Creates the SyncUpdateInfo class.
         *
         * @param masterTable The table to set _sync_time to NULL in
         * @param deletedTable The deleted table that corresponds to the
         *          master table
         * @param foreignKey The key that refers to the primary key in table
         */
        SyncUpdateInfo(String masterTable, String deletedTable,
                String foreignKey) {
            this.masterTable = masterTable;
            this.deletedTable = deletedTable;
            this.foreignKey = foreignKey;
        }

        /** The table containing the _sync_time column */
        String masterTable;

        /** The deleted table that corresponds to the master table */
        String deletedTable;

        /** The key in the local table the row in table. It may be _id, if table
         * is the local table. */
        String foreignKey;
    }

    /**
     * Used to allow returning sub-classes of {@link Cursor} when calling query.
     */
    public interface CursorFactory {
        /**
         * See
         * {@link SQLiteCursor#SQLiteCursor(SQLiteDatabase, SQLiteCursorDriver,
         * String, SQLiteQuery)}.
         */
        public Cursor newCursor(SQLiteDatabase db,
                SQLiteCursorDriver masterQuery, String editTable,
                SQLiteQuery query);
    }

    /**
     * Open the database according to the flags {@link #OPEN_READWRITE}
     * {@link #OPEN_READONLY} {@link #CREATE_IF_NECESSARY} and/or {@link #NO_LOCALIZED_COLLATORS}.
     *
     * <p>Sets the locale of the database to the  the system's current locale.
     * Call {@link #setLocale} if you would like something else.</p>
     *
     * @param path to database file to open and/or create
     * @param factory an optional factory class that is called to instantiate a
     *            cursor when query is called, or null for default
     * @param flags to control database access mode
     * @return the newly opened database
     * @throws SQLiteException if the database cannot be opened
     */
    public static SQLiteDatabase openDatabase(String path, CursorFactory factory, int flags) {
        SQLiteDatabase db = null;
        try {
            // Open the database.
            return new SQLiteDatabase(path, factory, flags);
        } catch (SQLiteDatabaseCorruptException e) {
            // Try to recover from this, if we can.
            // TODO: should we do this for other open failures?
            Log.e(TAG, "Deleting and re-creating corrupt database " + path, e);
            new File(path).delete();
            return new SQLiteDatabase(path, factory, flags);
        }
    }

    /**
     * Equivalent to openDatabase(file.getPath(), factory, CREATE_IF_NECESSARY).
     */
    public static SQLiteDatabase openOrCreateDatabase(File file, CursorFactory factory) {
        return openOrCreateDatabase(file.getPath(), factory);
    }

    /**
     * Equivalent to openDatabase(path, factory, CREATE_IF_NECESSARY).
     */
    public static SQLiteDatabase openOrCreateDatabase(String path, CursorFactory factory) {
        return openDatabase(path, factory, CREATE_IF_NECESSARY);
    }

    /**
     * Create a memory backed SQLite database.  Its contents will be destroyed
     * when the database is closed.
     *
     * <p>Sets the locale of the database to the  the system's current locale.
     * Call {@link #setLocale} if you would like something else.</p>
     *
     * @param factory an optional factory class that is called to instantiate a
     *            cursor when query is called
     * @return a SQLiteDatabase object, or null if the database can't be created
     */
    public static SQLiteDatabase create(CursorFactory factory) {
        // This is a magic string with special meaning for SQLite.
        return openDatabase(":memory:", factory, CREATE_IF_NECESSARY);
    }

    /**
     * Close the database.
     */
    public void close() {
        lock();
        try {
            closeClosable();
            releaseReference();
        } finally {
            unlock();
        }
    }

    private void closeClosable() {
        Iterator<Map.Entry<SQLiteClosable, Object>> iter = mPrograms.entrySet().iterator();
        while (iter.hasNext()) {
            Map.Entry<SQLiteClosable, Object> entry = iter.next();
            SQLiteClosable program = entry.getKey();
            if (program != null) {
                program.onAllReferencesReleasedFromContainer();
            }
        }
    }

    /**
     * Native call to close the database.
     */
    private native void dbclose();

    /**
     * Gets the database version.
     *
     * @return the database version
     */
    public int getVersion() {
        SQLiteStatement prog = null;
        lock();
        try {
            prog = new SQLiteStatement(this, "PRAGMA user_version;");
            long version = prog.simpleQueryForLong();
            return (int) version;
        } finally {
            if (prog != null) prog.close();
            unlock();
        }
    }

    /**
     * Sets the database version.
     *
     * @param version the new database version
     */
    public void setVersion(int version) {
        execSQL("PRAGMA user_version = " + version);
    }

    /**
     * Returns the maximum size the database may grow to.
     *
     * @return the new maximum database size
     */
    public long getMaximumSize() {
        SQLiteStatement prog = null;
        lock();
        try {
            prog = new SQLiteStatement(this,
                    "PRAGMA max_page_count;");
            long pageCount = prog.simpleQueryForLong();
            return pageCount * getPageSize();
        } finally {
            if (prog != null) prog.close();
            unlock();
        }
    }

    /**
     * Sets the maximum size the database will grow to. The maximum size cannot
     * be set below the current size.
     *
     * @param numBytes the maximum database size, in bytes
     * @return the new maximum database size
     */
    public long setMaximumSize(long numBytes) {
        SQLiteStatement prog = null;
        lock();
        try {
            long pageSize = getPageSize();
            long numPages = numBytes / pageSize;
            // If numBytes isn't a multiple of pageSize, bump up a page
            if ((numBytes % pageSize) != 0) {
                numPages++;
            }
            prog = new SQLiteStatement(this,
                    "PRAGMA max_page_count = " + numPages);
            long newPageCount = prog.simpleQueryForLong();
            return newPageCount * pageSize;
        } finally {
            if (prog != null) prog.close();
            unlock();
        }
    }

    /**
     * Returns the current database page size, in bytes.
     *
     * @return the database page size, in bytes
     */
    public long getPageSize() {
        SQLiteStatement prog = null;
        lock();
        try {
            prog = new SQLiteStatement(this,
                    "PRAGMA page_size;");
            long size = prog.simpleQueryForLong();
            return size;
        } finally {
            if (prog != null) prog.close();
            unlock();
        }
    }

    /**
     * Sets the database page size. The page size must be a power of two. This
     * method does not work if any data has been written to the database file,
     * and must be called right after the database has been created.
     *
     * @param numBytes the database page size, in bytes
     */
    public void setPageSize(long numBytes) {
        execSQL("PRAGMA page_size = " + numBytes);
    }

    /**
     * Mark this table as syncable. When an update occurs in this table the
     * _sync_dirty field will be set to ensure proper syncing operation.
     *
     * @param table the table to mark as syncable
     * @param deletedTable The deleted table that corresponds to the
     *          syncable table
     */
    public void markTableSyncable(String table, String deletedTable) {
        markTableSyncable(table, "_id", table, deletedTable);
    }

    /**
     * Mark this table as syncable, with the _sync_dirty residing in another
     * table. When an update occurs in this table the _sync_dirty field of the
     * row in updateTable with the _id in foreignKey will be set to
     * ensure proper syncing operation.
     *
     * @param table an update on this table will trigger a sync time removal
     * @param foreignKey this is the column in table whose value is an _id in
     *          updateTable
     * @param updateTable this is the table that will have its _sync_dirty
     */
    public void markTableSyncable(String table, String foreignKey,
            String updateTable) {
        markTableSyncable(table, foreignKey, updateTable, null);
    }

    /**
     * Mark this table as syncable, with the _sync_dirty residing in another
     * table. When an update occurs in this table the _sync_dirty field of the
     * row in updateTable with the _id in foreignKey will be set to
     * ensure proper syncing operation.
     *
     * @param table an update on this table will trigger a sync time removal
     * @param foreignKey this is the column in table whose value is an _id in
     *          updateTable
     * @param updateTable this is the table that will have its _sync_dirty
     * @param deletedTable The deleted table that corresponds to the
     *          updateTable
     */
    private void markTableSyncable(String table, String foreignKey,
            String updateTable, String deletedTable) {
        lock();
        try {
            native_execSQL("SELECT _sync_dirty FROM " + updateTable
                    + " LIMIT 0");
            native_execSQL("SELECT " + foreignKey + " FROM " + table
                    + " LIMIT 0");
        } finally {
            unlock();
        }

        SyncUpdateInfo info = new SyncUpdateInfo(updateTable, deletedTable,
                foreignKey);
        synchronized (mSyncUpdateInfo) {
            mSyncUpdateInfo.put(table, info);
        }
    }

    /**
     * Call for each row that is updated in a cursor.
     *
     * @param table the table the row is in
     * @param rowId the row ID of the updated row
     */
    /* package */ void rowUpdated(String table, long rowId) {
        SyncUpdateInfo info;
        synchronized (mSyncUpdateInfo) {
            info = mSyncUpdateInfo.get(table);
        }
        if (info != null) {
            execSQL("UPDATE " + info.masterTable
                    + " SET _sync_dirty=1 WHERE _id=(SELECT " + info.foreignKey
                    + " FROM " + table + " WHERE _id=" + rowId + ")");
        }
    }

    /**
     * Finds the name of the first table, which is editable.
     *
     * @param tables a list of tables
     * @return the first table listed
     */
    public static String findEditTable(String tables) {
        if (!TextUtils.isEmpty(tables)) {
            // find the first word terminated by either a space or a comma
            int spacepos = tables.indexOf(' ');
            int commapos = tables.indexOf(',');

            if (spacepos > 0 && (spacepos < commapos || commapos < 0)) {
                return tables.substring(0, spacepos);
            } else if (commapos > 0 && (commapos < spacepos || spacepos < 0) ) {
                return tables.substring(0, commapos);
            }
            return tables;
        } else {
            throw new IllegalStateException("Invalid tables");
        }
    }

    /**
     * Compiles an SQL statement into a reusable pre-compiled statement object.
     * The parameters are identical to {@link #execSQL(String)}. You may put ?s in the
     * statement and fill in those values with {@link SQLiteProgram#bindString}
     * and {@link SQLiteProgram#bindLong} each time you want to run the
     * statement. Statements may not return result sets larger than 1x1.
     *
     * @param sql The raw SQL statement, may contain ? for unknown values to be
     *            bound later.
     * @return a pre-compiled statement object.
     */
    public SQLiteStatement compileStatement(String sql) throws SQLException {
        lock();
        try {
            return new SQLiteStatement(this, sql);
        } finally {
            unlock();
        }
    }

    /**
     * Query the given URL, returning a {@link Cursor} over the result set.
     *
     * @param distinct true if you want each row to be unique, false otherwise.
     * @param table The table name to compile the query against.
     * @param columns A list of which columns to return. Passing null will
     *            return all columns, which is discouraged to prevent reading
     *            data from storage that isn't going to be used.
     * @param selection A filter declaring which rows to return, formatted as an
     *            SQL WHERE clause (excluding the WHERE itself). Passing null
     *            will return all rows for the given table.
     * @param selectionArgs You may include ?s in selection, which will be
     *         replaced by the values from selectionArgs, in order that they
     *         appear in the selection. The values will be bound as Strings.
     * @param groupBy A filter declaring how to group rows, formatted as an SQL
     *            GROUP BY clause (excluding the GROUP BY itself). Passing null
     *            will cause the rows to not be grouped.
     * @param having A filter declare which row groups to include in the cursor,
     *            if row grouping is being used, formatted as an SQL HAVING
     *            clause (excluding the HAVING itself). Passing null will cause
     *            all row groups to be included, and is required when row
     *            grouping is not being used.
     * @param orderBy How to order the rows, formatted as an SQL ORDER BY clause
     *            (excluding the ORDER BY itself). Passing null will use the
     *            default sort order, which may be unordered.
     * @param limit Limits the number of rows returned by the query,
     *            formatted as LIMIT clause. Passing null denotes no LIMIT clause.
     * @return A Cursor object, which is positioned before the first entry
     * @see Cursor
     */
    public Cursor query(boolean distinct, String table, String[] columns,
            String selection, String[] selectionArgs, String groupBy,
            String having, String orderBy, String limit) {
        return queryWithFactory(null, distinct, table, columns, selection, selectionArgs,
                groupBy, having, orderBy, limit);
    }

    /**
     * Query the given URL, returning a {@link Cursor} over the result set.
     *
     * @param cursorFactory the cursor factory to use, or null for the default factory
     * @param distinct true if you want each row to be unique, false otherwise.
     * @param table The table name to compile the query against.
     * @param columns A list of which columns to return. Passing null will
     *            return all columns, which is discouraged to prevent reading
     *            data from storage that isn't going to be used.
     * @param selection A filter declaring which rows to return, formatted as an
     *            SQL WHERE clause (excluding the WHERE itself). Passing null
     *            will return all rows for the given table.
     * @param selectionArgs You may include ?s in selection, which will be
     *         replaced by the values from selectionArgs, in order that they
     *         appear in the selection. The values will be bound as Strings.
     * @param groupBy A filter declaring how to group rows, formatted as an SQL
     *            GROUP BY clause (excluding the GROUP BY itself). Passing null
     *            will cause the rows to not be grouped.
     * @param having A filter declare which row groups to include in the cursor,
     *            if row grouping is being used, formatted as an SQL HAVING
     *            clause (excluding the HAVING itself). Passing null will cause
     *            all row groups to be included, and is required when row
     *            grouping is not being used.
     * @param orderBy How to order the rows, formatted as an SQL ORDER BY clause
     *            (excluding the ORDER BY itself). Passing null will use the
     *            default sort order, which may be unordered.
     * @param limit Limits the number of rows returned by the query,
     *            formatted as LIMIT clause. Passing null denotes no LIMIT clause.
     * @return A Cursor object, which is positioned before the first entry
     * @see Cursor
     */
    public Cursor queryWithFactory(CursorFactory cursorFactory,
            boolean distinct, String table, String[] columns,
            String selection, String[] selectionArgs, String groupBy,
            String having, String orderBy, String limit) {
        String sql = SQLiteQueryBuilder.buildQueryString(
                distinct, table, columns, selection, groupBy, having, orderBy, limit);

        return rawQueryWithFactory(
                cursorFactory, sql, selectionArgs, findEditTable(table));
    }

    /**
     * Query the given table, returning a {@link Cursor} over the result set.
     *
     * @param table The table name to compile the query against.
     * @param columns A list of which columns to return. Passing null will
     *            return all columns, which is discouraged to prevent reading
     *            data from storage that isn't going to be used.
     * @param selection A filter declaring which rows to return, formatted as an
     *            SQL WHERE clause (excluding the WHERE itself). Passing null
     *            will return all rows for the given table.
     * @param selectionArgs You may include ?s in selection, which will be
     *         replaced by the values from selectionArgs, in order that they
     *         appear in the selection. The values will be bound as Strings.
     * @param groupBy A filter declaring how to group rows, formatted as an SQL
     *            GROUP BY clause (excluding the GROUP BY itself). Passing null
     *            will cause the rows to not be grouped.
     * @param having A filter declare which row groups to include in the cursor,
     *            if row grouping is being used, formatted as an SQL HAVING
     *            clause (excluding the HAVING itself). Passing null will cause
     *            all row groups to be included, and is required when row
     *            grouping is not being used.
     * @param orderBy How to order the rows, formatted as an SQL ORDER BY clause
     *            (excluding the ORDER BY itself). Passing null will use the
     *            default sort order, which may be unordered.
     * @return A {@link Cursor} object, which is positioned before the first entry
     * @see Cursor
     */
    public Cursor query(String table, String[] columns, String selection,
            String[] selectionArgs, String groupBy, String having,
            String orderBy) {

        return query(false, table, columns, selection, selectionArgs, groupBy,
                having, orderBy, null /* limit */);
    }

    /**
     * Query the given table, returning a {@link Cursor} over the result set.
     *
     * @param table The table name to compile the query against.
     * @param columns A list of which columns to return. Passing null will
     *            return all columns, which is discouraged to prevent reading
     *            data from storage that isn't going to be used.
     * @param selection A filter declaring which rows to return, formatted as an
     *            SQL WHERE clause (excluding the WHERE itself). Passing null
     *            will return all rows for the given table.
     * @param selectionArgs You may include ?s in selection, which will be
     *         replaced by the values from selectionArgs, in order that they
     *         appear in the selection. The values will be bound as Strings.
     * @param groupBy A filter declaring how to group rows, formatted as an SQL
     *            GROUP BY clause (excluding the GROUP BY itself). Passing null
     *            will cause the rows to not be grouped.
     * @param having A filter declare which row groups to include in the cursor,
     *            if row grouping is being used, formatted as an SQL HAVING
     *            clause (excluding the HAVING itself). Passing null will cause
     *            all row groups to be included, and is required when row
     *            grouping is not being used.
     * @param orderBy How to order the rows, formatted as an SQL ORDER BY clause
     *            (excluding the ORDER BY itself). Passing null will use the
     *            default sort order, which may be unordered.
     * @param limit Limits the number of rows returned by the query,
     *            formatted as LIMIT clause. Passing null denotes no LIMIT clause.
     * @return A {@link Cursor} object, which is positioned before the first entry
     * @see Cursor
     */
    public Cursor query(String table, String[] columns, String selection,
            String[] selectionArgs, String groupBy, String having,
            String orderBy, String limit) {

        return query(false, table, columns, selection, selectionArgs, groupBy,
                having, orderBy, limit);
    }

    /**
     * Runs the provided SQL and returns a {@link Cursor} over the result set.
     *
     * @param sql the SQL query. The SQL string must not be ; terminated
     * @param selectionArgs You may include ?s in where clause in the query,
     *     which will be replaced by the values from selectionArgs. The
     *     values will be bound as Strings.
     * @return A {@link Cursor} object, which is positioned before the first entry
     */
    public Cursor rawQuery(String sql, String[] selectionArgs) {
        return rawQueryWithFactory(null, sql, selectionArgs, null);
    }

    /**
     * Runs the provided SQL and returns a cursor over the result set.
     *
     * @param cursorFactory the cursor factory to use, or null for the default factory
     * @param sql the SQL query. The SQL string must not be ; terminated
     * @param selectionArgs You may include ?s in where clause in the query,
     *     which will be replaced by the values from selectionArgs. The
     *     values will be bound as Strings.
     * @param editTable the name of the first table, which is editable
     * @return A {@link Cursor} object, which is positioned before the first entry
     */
    public Cursor rawQueryWithFactory(
            CursorFactory cursorFactory, String sql, String[] selectionArgs,
            String editTable) {
        long timeStart = 0;

        if (Config.LOGV || mSlowQueryThreshold != -1) {
            timeStart = System.currentTimeMillis();
        }

        SQLiteCursorDriver driver = new SQLiteDirectCursorDriver(this, sql, editTable);

        Cursor cursor = null;
        try {
            cursor = driver.query(
                    cursorFactory != null ? cursorFactory : mFactory,
                    selectionArgs);
        } finally {
            if (Config.LOGV || mSlowQueryThreshold != -1) {

                // Force query execution
                if (cursor != null) {
                    cursor.moveToFirst();
                    cursor.moveToPosition(-1);
                }

                long duration = System.currentTimeMillis() - timeStart;

                if (Config.LOGV || duration >= mSlowQueryThreshold) {
                    Log.v(SQLiteCursor.TAG,
                          "query (" + duration + " ms): " + driver.toString() + ", args are "
                                  + (selectionArgs != null
                                  ? TextUtils.join(",", selectionArgs)
                                  : "<null>"));
                }
            }
        }
        return cursor;
    }

    /**
     * Runs the provided SQL and returns a cursor over the result set.
     * The cursor will read an initial set of rows and the return to the caller.
     * It will continue to read in batches and send data changed notifications
     * when the later batches are ready.
     * @param sql the SQL query. The SQL string must not be ; terminated
     * @param selectionArgs You may include ?s in where clause in the query,
     *     which will be replaced by the values from selectionArgs. The
     *     values will be bound as Strings.
     * @param initialRead set the initial count of items to read from the cursor
     * @param maxRead set the count of items to read on each iteration after the first
     * @return A {@link Cursor} object, which is positioned before the first entry
     *
     * This work is incomplete and not fully tested or reviewed, so currently
     * hidden.
     * @hide
     */
    public Cursor rawQuery(String sql, String[] selectionArgs,
            int initialRead, int maxRead) {
        SQLiteCursor c = (SQLiteCursor)rawQueryWithFactory(
                null, sql, selectionArgs, null);
        c.setLoadStyle(initialRead, maxRead);
        return c;
    }

    /**
     * Convenience method for inserting a row into the database.
     *
     * @param table the table to insert the row into
     * @param nullColumnHack SQL doesn't allow inserting a completely empty row,
     *            so if initialValues is empty this column will explicitly be
     *            assigned a NULL value
     * @param values this map contains the initial column values for the
     *            row. The keys should be the column names and the values the
     *            column values
     * @return the row ID of the newly inserted row, or -1 if an error occurred
     */
    public long insert(String table, String nullColumnHack, ContentValues values) {
        try {
            return insertWithOnConflict(table, nullColumnHack, values, null);
        } catch (SQLException e) {
            Log.e(TAG, "Error inserting " + values, e);
            return -1;
        }
    }

    /**
     * Convenience method for inserting a row into the database.
     *
     * @param table the table to insert the row into
     * @param nullColumnHack SQL doesn't allow inserting a completely empty row,
     *            so if initialValues is empty this column will explicitly be
     *            assigned a NULL value
     * @param values this map contains the initial column values for the
     *            row. The keys should be the column names and the values the
     *            column values
     * @throws SQLException
     * @return the row ID of the newly inserted row, or -1 if an error occurred
     */
    public long insertOrThrow(String table, String nullColumnHack, ContentValues values)
            throws SQLException {
        return insertWithOnConflict(table, nullColumnHack, values, null);
    }

    /**
     * Convenience method for replacing a row in the database.
     *
     * @param table the table in which to replace the row
     * @param nullColumnHack SQL doesn't allow inserting a completely empty row,
     *            so if initialValues is empty this row will explicitly be
     *            assigned a NULL value
     * @param initialValues this map contains the initial column values for
     *   the row. The key
     * @return the row ID of the newly inserted row, or -1 if an error occurred
     */
    public long replace(String table, String nullColumnHack, ContentValues initialValues) {
        try {
            return insertWithOnConflict(table, nullColumnHack, initialValues,
                    ConflictAlgorithm.REPLACE);
        } catch (SQLException e) {
            Log.e(TAG, "Error inserting " + initialValues, e);
            return -1;
        }
    }

    /**
     * Convenience method for replacing a row in the database.
     *
     * @param table the table in which to replace the row
     * @param nullColumnHack SQL doesn't allow inserting a completely empty row,
     *            so if initialValues is empty this row will explicitly be
     *            assigned a NULL value
     * @param initialValues this map contains the initial column values for
     *   the row. The key
     * @throws SQLException
     * @return the row ID of the newly inserted row, or -1 if an error occurred
     */
    public long replaceOrThrow(String table, String nullColumnHack,
            ContentValues initialValues) throws SQLException {
        return insertWithOnConflict(table, nullColumnHack, initialValues,
                ConflictAlgorithm.REPLACE);
    }

    /**
     * General method for inserting a row into the database.
     *
     * @param table the table to insert the row into
     * @param nullColumnHack SQL doesn't allow inserting a completely empty row,
     *            so if initialValues is empty this column will explicitly be
     *            assigned a NULL value
     * @param initialValues this map contains the initial column values for the
     *            row. The keys should be the column names and the values the
     *            column values
     * @param algorithm  {@link ConflictAlgorithm} for insert conflict resolver
     * @return the row ID of the newly inserted row, or -1 if an error occurred
     * @hide
     */
    public long insertWithOnConflict(String table, String nullColumnHack,
            ContentValues initialValues, ConflictAlgorithm algorithm) {
        if (!isOpen()) {
            throw new IllegalStateException("database not open");
        }

        // Measurements show most sql lengths <= 152
        StringBuilder sql = new StringBuilder(152);
        sql.append("INSERT");
        if (algorithm != null) {
            sql.append(" OR ");
            sql.append(algorithm.value());
        }
        sql.append(" INTO ");
        sql.append(table);
        // Measurements show most values lengths < 40
        StringBuilder values = new StringBuilder(40);

        Set<Map.Entry<String, Object>> entrySet = null;
        if (initialValues != null && initialValues.size() > 0) {
            entrySet = initialValues.valueSet();
            Iterator<Map.Entry<String, Object>> entriesIter = entrySet.iterator();
            sql.append('(');

            boolean needSeparator = false;
            while (entriesIter.hasNext()) {
                if (needSeparator) {
                    sql.append(", ");
                    values.append(", ");
                }
                needSeparator = true;
                Map.Entry<String, Object> entry = entriesIter.next();
                sql.append(entry.getKey());
                values.append('?');
            }

            sql.append(')');
        } else {
            sql.append("(" + nullColumnHack + ") ");
            values.append("NULL");
        }

        sql.append(" VALUES(");
        sql.append(values);
        sql.append(");");

        lock();
        SQLiteStatement statement = null;
        try {
            statement = compileStatement(sql.toString());

            // Bind the values
            if (entrySet != null) {
                int size = entrySet.size();
                Iterator<Map.Entry<String, Object>> entriesIter = entrySet.iterator();
                for (int i = 0; i < size; i++) {
                    Map.Entry<String, Object> entry = entriesIter.next();
                    DatabaseUtils.bindObjectToProgram(statement, i + 1, entry.getValue());
                }
            }

            // Run the program and then cleanup
            statement.execute();

            long insertedRowId = lastInsertRow();
            if (insertedRowId == -1) {
                Log.e(TAG, "Error inserting " + initialValues + " using " + sql);
            } else {
                if (Config.LOGD && Log.isLoggable(TAG, Log.VERBOSE)) {
                    Log.v(TAG, "Inserting row " + insertedRowId + " from "
                            + initialValues + " using " + sql);
                }
            }
            return insertedRowId;
        } catch (SQLiteDatabaseCorruptException e) {
            onCorruption();
            throw e;
        } finally {
            if (statement != null) {
                statement.close();
            }
            unlock();
        }
    }

    /**
     * Convenience method for deleting rows in the database.
     *
     * @param table the table to delete from
     * @param whereClause the optional WHERE clause to apply when deleting.
     *            Passing null will delete all rows.
     * @return the number of rows affected if a whereClause is passed in, 0
     *         otherwise. To remove all rows and get a count pass "1" as the
     *         whereClause.
     */
    public int delete(String table, String whereClause, String[] whereArgs) {
        if (!isOpen()) {
            throw new IllegalStateException("database not open");
        }
        lock();
        SQLiteStatement statement = null;
        try {
            statement = compileStatement("DELETE FROM " + table
                    + (!TextUtils.isEmpty(whereClause)
                    ? " WHERE " + whereClause : ""));
            if (whereArgs != null) {
                int numArgs = whereArgs.length;
                for (int i = 0; i < numArgs; i++) {
                    DatabaseUtils.bindObjectToProgram(statement, i + 1, whereArgs[i]);
                }
            }
            statement.execute();
            statement.close();
            return lastChangeCount();
        } catch (SQLiteDatabaseCorruptException e) {
            onCorruption();
            throw e;
        } finally {
            if (statement != null) {
                statement.close();
            }
            unlock();
        }
    }

    /**
     * Convenience method for updating rows in the database.
     *
     * @param table the table to update in
     * @param values a map from column names to new column values. null is a
     *            valid value that will be translated to NULL.
     * @param whereClause the optional WHERE clause to apply when updating.
     *            Passing null will update all rows.
     * @return the number of rows affected
     */
    public int update(String table, ContentValues values, String whereClause, String[] whereArgs) {
        return updateWithOnConflict(table, values, whereClause, whereArgs, null);
    }

    /**
     * Convenience method for updating rows in the database.
     *
     * @param table the table to update in
     * @param values a map from column names to new column values. null is a
     *            valid value that will be translated to NULL.
     * @param whereClause the optional WHERE clause to apply when updating.
     *            Passing null will update all rows.
     * @param algorithm  {@link ConflictAlgorithm} for update conflict resolver
     * @return the number of rows affected
     * @hide
     */
    public int updateWithOnConflict(String table, ContentValues values,
            String whereClause, String[] whereArgs, ConflictAlgorithm algorithm) {
        if (!isOpen()) {
            throw new IllegalStateException("database not open");
        }

        if (values == null || values.size() == 0) {
            throw new IllegalArgumentException("Empty values");
        }

        StringBuilder sql = new StringBuilder(120);
        sql.append("UPDATE ");
        if (algorithm != null) {
            sql.append("OR ");
            sql.append(algorithm.value());
            sql.append(" ");
        }

        sql.append(table);
        sql.append(" SET ");

        Set<Map.Entry<String, Object>> entrySet = values.valueSet();
        Iterator<Map.Entry<String, Object>> entriesIter = entrySet.iterator();

        while (entriesIter.hasNext()) {
            Map.Entry<String, Object> entry = entriesIter.next();
            sql.append(entry.getKey());
            sql.append("=?");
            if (entriesIter.hasNext()) {
                sql.append(", ");
            }
        }

        if (!TextUtils.isEmpty(whereClause)) {
            sql.append(" WHERE ");
            sql.append(whereClause);
        }

        lock();
        SQLiteStatement statement = null;
        try {
            statement = compileStatement(sql.toString());

            // Bind the values
            int size = entrySet.size();
            entriesIter = entrySet.iterator();
            int bindArg = 1;
            for (int i = 0; i < size; i++) {
                Map.Entry<String, Object> entry = entriesIter.next();
                DatabaseUtils.bindObjectToProgram(statement, bindArg, entry.getValue());
                bindArg++;
            }

            if (whereArgs != null) {
                size = whereArgs.length;
                for (int i = 0; i < size; i++) {
                    statement.bindString(bindArg, whereArgs[i]);
                    bindArg++;
                }
            }

            // Run the program and then cleanup
            statement.execute();
            statement.close();
            int numChangedRows = lastChangeCount();
            if (Config.LOGD && Log.isLoggable(TAG, Log.VERBOSE)) {
                Log.v(TAG, "Updated " + numChangedRows + " using " + values + " and " + sql);
            }
            return numChangedRows;
        } catch (SQLiteDatabaseCorruptException e) {
            onCorruption();
            throw e;
        } catch (SQLException e) {
            Log.e(TAG, "Error updating " + values + " using " + sql);
            throw e;
        } finally {
            if (statement != null) {
                statement.close();
            }
            unlock();
        }
    }

    /**
     * Execute a single SQL statement that is not a query. For example, CREATE
     * TABLE, DELETE, INSERT, etc. Multiple statements separated by ;s are not
     * supported. it takes a write lock
     *
     * @throws SQLException If the SQL string is invalid for some reason
     */
    public void execSQL(String sql) throws SQLException {
        boolean logStats = mLogStats;
        long timeStart = logStats ? SystemClock.elapsedRealtime() : 0;
        lock();
        try {
            native_execSQL(sql);
        } catch (SQLiteDatabaseCorruptException e) {
            onCorruption();
            throw e;
        } finally {
            unlock();
        }
        if (logStats) {
            logTimeStat(false /* not a read */, timeStart, SystemClock.elapsedRealtime());
        }
    }

    /**
     * Execute a single SQL statement that is not a query. For example, CREATE
     * TABLE, DELETE, INSERT, etc. Multiple statements separated by ;s are not
     * supported. it takes a write lock,
     *
     * @param sql
     * @param bindArgs only byte[], String, Long and Double are supported in bindArgs.
     * @throws SQLException If the SQL string is invalid for some reason
     */
    public void execSQL(String sql, Object[] bindArgs) throws SQLException {
        if (bindArgs == null) {
            throw new IllegalArgumentException("Empty bindArgs");
        }

        boolean logStats = mLogStats;
        long timeStart = logStats ? SystemClock.elapsedRealtime() : 0;
        lock();
        SQLiteStatement statement = null;
        try {
            statement = compileStatement(sql);
            if (bindArgs != null) {
                int numArgs = bindArgs.length;
                for (int i = 0; i < numArgs; i++) {
                    DatabaseUtils.bindObjectToProgram(statement, i + 1, bindArgs[i]);
                }
            }
            statement.execute();
        } catch (SQLiteDatabaseCorruptException e) {
            onCorruption();
            throw e;
        } finally {
            if (statement != null) {
                statement.close();
            }
            unlock();
        }
        if (logStats) {
            logTimeStat(false /* not a read */, timeStart, SystemClock.elapsedRealtime());
        }
    }

    @Override
    protected void finalize() {
        if (isOpen()) {
            if (mPrograms.isEmpty()) {
                Log.e(TAG, "Leak found", mLeakedException);
            } else {
                IllegalStateException leakProgram = new IllegalStateException(
                        "mPrograms size " + mPrograms.size(), mLeakedException);
                Log.e(TAG, "Leak found", leakProgram);
            }
            closeClosable();
            onAllReferencesReleased();
        }
    }

    /**
     * Private constructor. See {@link #create} and {@link #openDatabase}.
     *
     * @param path The full path to the database
     * @param factory The factory to use when creating cursors, may be NULL.
     * @param flags 0 or {@link #NO_LOCALIZED_COLLATORS}.  If the database file already
     *              exists, mFlags will be updated appropriately.
     */
    private SQLiteDatabase(String path, CursorFactory factory, int flags) {
        if (path == null) {
            throw new IllegalArgumentException("path should not be null");
        }
        mFlags = flags;
        mPath = path;
        mLogStats = "1".equals(android.os.SystemProperties.get("db.logstats"));
        mSlowQueryThreshold = SystemProperties.getInt(LOG_SLOW_QUERIES_PROPERTY, -1);

        mLeakedException = new IllegalStateException(path +
            " SQLiteDatabase created and never closed");
        mFactory = factory;
        dbopen(mPath, mFlags);
        mPrograms = new WeakHashMap<SQLiteClosable,Object>();
        try {
            setLocale(Locale.getDefault());
        } catch (RuntimeException e) {
            Log.e(TAG, "Failed to setLocale() when constructing, closing the database", e);
            dbclose();
            throw e;
        }
    }

    /**
     * return whether the DB is opened as read only.
     * @return true if DB is opened as read only
     */
    public boolean isReadOnly() {
        return (mFlags & OPEN_READ_MASK) == OPEN_READONLY;
    }

    /**
     * @return true if the DB is currently open (has not been closed)
     */
    public boolean isOpen() {
        return mNativeHandle != 0;
    }

    public boolean needUpgrade(int newVersion) {
        return newVersion > getVersion();
    }

    /**
     * Getter for the path to the database file.
     *
     * @return the path to our database file.
     */
    public final String getPath() {
        return mPath;
    }

    /* package */ void logTimeStat(boolean read, long begin, long end) {
        EventLog.writeEvent(DB_OPERATION_EVENT, mPath, read ? 0 : 1, end - begin);
    }

    /**
     * Sets the locale for this database.  Does nothing if this database has
     * the NO_LOCALIZED_COLLATORS flag set or was opened read only.
     * @throws SQLException if the locale could not be set.  The most common reason
     * for this is that there is no collator available for the locale you requested.
     * In this case the database remains unchanged.
     */
    public void setLocale(Locale locale) {
        lock();
        try {
            native_setLocale(locale.toString(), mFlags);
        } finally {
            unlock();
        }
    }

    /**
     * Native call to open the database.
     *
     * @param path The full path to the database
     */
    private native void dbopen(String path, int flags);

    /**
     * Native call to execute a raw SQL statement. {@link #lock} must be held
     * when calling this method.
     *
     * @param sql The raw SQL string
     * @throws SQLException
     */
    /* package */ native void native_execSQL(String sql) throws SQLException;

    /**
     * Native call to set the locale.  {@link #lock} must be held when calling
     * this method.
     * @throws SQLException
     */
    /* package */ native void native_setLocale(String loc, int flags);

    /**
     * Returns the row ID of the last row inserted into the database.
     *
     * @return the row ID of the last row inserted into the database.
     */
    /* package */ native long lastInsertRow();

    /**
     * Returns the number of changes made in the last statement executed.
     *
     * @return the number of changes made in the last statement executed.
     */
    /* package */ native int lastChangeCount();
}