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Commit 80d8343a authored by Lee Shombert's avatar Lee Shombert
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Make SQLiteOpenHelper thread safe 

Concurrent SQLiteOpenHelper instances is a common anti-pattern that
leads to SQLiteDatabase exceptions.  The specific problem occurs when
a database upgrade is triggered automatically inside the open helper.

This creates a lock for every database file managed by a
SQLiteOpenHelper.  The lock guards the code that opens a database and
optionally upgrades it.  This does not protect against code that might
access the database outside of a SQLiteOpenHelper.

Flag: android.database.sqlite.concurrent_open_helper
Bug: 335904370
Test: atest
 * CtsDatabaseTestCases
 * FrameworksCoreTests:android.database
Change-Id: I4d79375c44ca3170495fce6cd9d682cf21e62e2f
parent e302462c

core/java/android/database/sqlite/SQLiteOpenHelper.java

+85 −55
Original line number Diff line number Diff line
@@ -25,10 +25,15 @@ import android.database.DatabaseErrorHandler; 
import android.database.SQLException;

import android.database.sqlite.SQLiteDatabase.CursorFactory;

import android.os.FileUtils;

import android.util.ArrayMap;

import android.util.Log;



import com.android.internal.annotations.GuardedBy;



import java.io.File;

import java.io.IOException;

import java.util.Objects;

import java.util.concurrent.ConcurrentHashMap;



/**

 * A helper class to manage database creation and version management.
@@ -54,6 +59,13 @@ import java.util.Objects; 
public abstract class SQLiteOpenHelper implements AutoCloseable {

    private static final String TAG = SQLiteOpenHelper.class.getSimpleName();



    // Every database file has a lock, saved in this map.  The lock is held while the database is

    // opened.

    private static final ConcurrentHashMap<String, Object> sDbLock = new ConcurrentHashMap<>();



    // The lock that this open helper instance must hold when the database is opened.

    private final Object mLock;



    private final Context mContext;

    @UnsupportedAppUsage

    private final String mName;
@@ -168,6 +180,21 @@ public abstract class SQLiteOpenHelper implements AutoCloseable { 
        mNewVersion = version;

        mMinimumSupportedVersion = Math.max(0, minimumSupportedVersion);

        setOpenParamsBuilder(openParamsBuilder);



        Object lock = null;

        if (mName == null || !Flags.concurrentOpenHelper()) {

            lock = new Object();

        } else {

            try {

                final String path = mContext.getDatabasePath(mName).getCanonicalPath();

                lock = sDbLock.computeIfAbsent(path, (String k) -> new Object());

            } catch (IOException e) {

                Log.d(TAG, "failed to construct db path for " + mName);

                // Ensure the lock is not null.

                lock = new Object();

            }

        }

        mLock = lock;

    }



    /**
@@ -358,6 +385,7 @@ public abstract class SQLiteOpenHelper implements AutoCloseable { 


        SQLiteDatabase db = mDatabase;

        try {

            synchronized (mLock) {

                mIsInitializing = true;



                if (db != null) {
@@ -378,7 +406,8 @@ public abstract class SQLiteOpenHelper implements AutoCloseable { 
                            throw ex;

                        }

                        Log.e(TAG, "Couldn't open database for writing (will try read-only):", ex);

                    params = params.toBuilder().addOpenFlags(SQLiteDatabase.OPEN_READONLY).build();

                        params = params.toBuilder()

                                 .addOpenFlags(SQLiteDatabase.OPEN_READONLY).build();

                        db = SQLiteDatabase.openDatabase(filePath, params);

                    }

                }
@@ -388,8 +417,8 @@ public abstract class SQLiteOpenHelper implements AutoCloseable { 
                final int version = db.getVersion();

                if (version != mNewVersion) {

                    if (db.isReadOnly()) {

                    throw new SQLiteException("Can't upgrade read-only database from version " +

                            db.getVersion() + " to " + mNewVersion + ": " + mName);

                        throw new SQLiteException("Can't upgrade read-only database from version "

                                + db.getVersion() + " to " + mNewVersion + ": " + mName);

                    }



                    if (version > 0 && version < mMinimumSupportedVersion) {
@@ -426,6 +455,7 @@ public abstract class SQLiteOpenHelper implements AutoCloseable { 
                onOpen(db);

                mDatabase = db;

                return db;

            }

        } finally {

            mIsInitializing = false;

            if (db != null && db != mDatabase) {

core/java/android/database/sqlite/flags.aconfig

+9 −0
Original line number Diff line number Diff line
@@ -17,3 +17,12 @@ flag { 
     description: "SQLite APIs held back for Android 15"

     bug: "279043253"

}



flag {

     name: "concurrent_open_helper"

     is_exported: true

     namespace: "system_performance"

     is_fixed_read_only: false

     description: "Make SQLiteOpenHelper thread-safe"

     bug: "335904370"

}