| /* |
| * Copyright (C) 2017 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 androidx.room; |
| |
| import android.database.Cursor; |
| import android.database.sqlite.SQLiteException; |
| import android.util.Log; |
| |
| import androidx.annotation.NonNull; |
| import androidx.annotation.Nullable; |
| import androidx.annotation.RestrictTo; |
| import androidx.annotation.VisibleForTesting; |
| import androidx.annotation.WorkerThread; |
| import androidx.arch.core.internal.SafeIterableMap; |
| import androidx.collection.ArrayMap; |
| import androidx.collection.ArraySet; |
| import androidx.arch.core.executor.ArchTaskExecutor; |
| import androidx.sqlite.db.SupportSQLiteDatabase; |
| import androidx.sqlite.db.SupportSQLiteStatement; |
| |
| import java.lang.ref.WeakReference; |
| import java.util.Arrays; |
| import java.util.Collections; |
| import java.util.Locale; |
| import java.util.Map; |
| import java.util.Set; |
| import java.util.concurrent.atomic.AtomicBoolean; |
| import java.util.concurrent.locks.Lock; |
| |
| /** |
| * InvalidationTracker keeps a list of tables modified by queries and notifies its callbacks about |
| * these tables. |
| */ |
| // We create an in memory table with (version, table_id) where version is an auto-increment primary |
| // key and a table_id (hardcoded int from initialization). |
| // ObservedTableTracker tracks list of tables we should be watching (e.g. adding triggers for). |
| // Before each beginTransaction, RoomDatabase invokes InvalidationTracker to sync trigger states. |
| // After each endTransaction, RoomDatabase invokes InvalidationTracker to refresh invalidated |
| // tables. |
| // Each update on one of the observed tables triggers an insertion into this table, hence a |
| // new version. |
| // Unfortunately, we cannot override the previous row because sqlite uses the conflict resolution |
| // of the outer query (the thing that triggered us) so we do a cleanup as we sync instead of letting |
| // SQLite override the rows. |
| // https://sqlite.org/lang_createtrigger.html: An ON CONFLICT clause may be specified as part of an |
| // UPDATE or INSERT action within the body of the trigger. However if an ON CONFLICT clause is |
| // specified as part of the statement causing the trigger to fire, then conflict handling policy of |
| // the outer statement is used instead. |
| public class InvalidationTracker { |
| |
| private static final String[] TRIGGERS = new String[]{"UPDATE", "DELETE", "INSERT"}; |
| |
| private static final String UPDATE_TABLE_NAME = "room_table_modification_log"; |
| |
| private static final String VERSION_COLUMN_NAME = "version"; |
| |
| private static final String TABLE_ID_COLUMN_NAME = "table_id"; |
| |
| private static final String CREATE_VERSION_TABLE_SQL = "CREATE TEMP TABLE " + UPDATE_TABLE_NAME |
| + "(" + VERSION_COLUMN_NAME |
| + " INTEGER PRIMARY KEY AUTOINCREMENT, " |
| + TABLE_ID_COLUMN_NAME |
| + " INTEGER)"; |
| |
| @VisibleForTesting |
| static final String CLEANUP_SQL = "DELETE FROM " + UPDATE_TABLE_NAME |
| + " WHERE " + VERSION_COLUMN_NAME + " NOT IN( SELECT MAX(" |
| + VERSION_COLUMN_NAME + ") FROM " + UPDATE_TABLE_NAME |
| + " GROUP BY " + TABLE_ID_COLUMN_NAME + ")"; |
| |
| @VisibleForTesting |
| // We always clean before selecting so it is unlikely to have the same row twice and if we |
| // do, it is not a big deal, just more data in the cursor. |
| static final String SELECT_UPDATED_TABLES_SQL = "SELECT * FROM " + UPDATE_TABLE_NAME |
| + " WHERE " + VERSION_COLUMN_NAME |
| + " > ? ORDER BY " + VERSION_COLUMN_NAME + " ASC;"; |
| |
| @NonNull |
| @VisibleForTesting |
| ArrayMap<String, Integer> mTableIdLookup; |
| private String[] mTableNames; |
| |
| @NonNull |
| @VisibleForTesting |
| long[] mTableVersions; |
| |
| private Object[] mQueryArgs = new Object[1]; |
| |
| // max id in the last syc |
| private long mMaxVersion = 0; |
| |
| private final RoomDatabase mDatabase; |
| |
| AtomicBoolean mPendingRefresh = new AtomicBoolean(false); |
| |
| private volatile boolean mInitialized = false; |
| |
| private volatile SupportSQLiteStatement mCleanupStatement; |
| |
| private ObservedTableTracker mObservedTableTracker; |
| |
| // should be accessed with synchronization only. |
| @VisibleForTesting |
| final SafeIterableMap<Observer, ObserverWrapper> mObserverMap = new SafeIterableMap<>(); |
| |
| /** |
| * Used by the generated code. |
| * |
| * @hide |
| */ |
| @SuppressWarnings("WeakerAccess") |
| @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP) |
| public InvalidationTracker(RoomDatabase database, String... tableNames) { |
| mDatabase = database; |
| mObservedTableTracker = new ObservedTableTracker(tableNames.length); |
| mTableIdLookup = new ArrayMap<>(); |
| final int size = tableNames.length; |
| mTableNames = new String[size]; |
| for (int id = 0; id < size; id++) { |
| final String tableName = tableNames[id].toLowerCase(Locale.US); |
| mTableIdLookup.put(tableName, id); |
| mTableNames[id] = tableName; |
| } |
| mTableVersions = new long[tableNames.length]; |
| Arrays.fill(mTableVersions, 0); |
| } |
| |
| /** |
| * Internal method to initialize table tracking. |
| * <p> |
| * You should never call this method, it is called by the generated code. |
| */ |
| void internalInit(SupportSQLiteDatabase database) { |
| synchronized (this) { |
| if (mInitialized) { |
| Log.e(Room.LOG_TAG, "Invalidation tracker is initialized twice :/."); |
| return; |
| } |
| |
| database.beginTransaction(); |
| try { |
| database.execSQL("PRAGMA temp_store = MEMORY;"); |
| database.execSQL("PRAGMA recursive_triggers='ON';"); |
| database.execSQL(CREATE_VERSION_TABLE_SQL); |
| database.setTransactionSuccessful(); |
| } finally { |
| database.endTransaction(); |
| } |
| syncTriggers(database); |
| mCleanupStatement = database.compileStatement(CLEANUP_SQL); |
| mInitialized = true; |
| } |
| } |
| |
| private static void appendTriggerName(StringBuilder builder, String tableName, |
| String triggerType) { |
| builder.append("`") |
| .append("room_table_modification_trigger_") |
| .append(tableName) |
| .append("_") |
| .append(triggerType) |
| .append("`"); |
| } |
| |
| private void stopTrackingTable(SupportSQLiteDatabase writableDb, int tableId) { |
| final String tableName = mTableNames[tableId]; |
| StringBuilder stringBuilder = new StringBuilder(); |
| for (String trigger : TRIGGERS) { |
| stringBuilder.setLength(0); |
| stringBuilder.append("DROP TRIGGER IF EXISTS "); |
| appendTriggerName(stringBuilder, tableName, trigger); |
| writableDb.execSQL(stringBuilder.toString()); |
| } |
| } |
| |
| private void startTrackingTable(SupportSQLiteDatabase writableDb, int tableId) { |
| final String tableName = mTableNames[tableId]; |
| StringBuilder stringBuilder = new StringBuilder(); |
| for (String trigger : TRIGGERS) { |
| stringBuilder.setLength(0); |
| stringBuilder.append("CREATE TEMP TRIGGER IF NOT EXISTS "); |
| appendTriggerName(stringBuilder, tableName, trigger); |
| stringBuilder.append(" AFTER ") |
| .append(trigger) |
| .append(" ON `") |
| .append(tableName) |
| .append("` BEGIN INSERT OR REPLACE INTO ") |
| .append(UPDATE_TABLE_NAME) |
| .append(" VALUES(null, ") |
| .append(tableId) |
| .append("); END"); |
| writableDb.execSQL(stringBuilder.toString()); |
| } |
| } |
| |
| /** |
| * Adds the given observer to the observers list and it will be notified if any table it |
| * observes changes. |
| * <p> |
| * Database changes are pulled on another thread so in some race conditions, the observer might |
| * be invoked for changes that were done before it is added. |
| * <p> |
| * If the observer already exists, this is a no-op call. |
| * <p> |
| * If one of the tables in the Observer does not exist in the database, this method throws an |
| * {@link IllegalArgumentException}. |
| * |
| * @param observer The observer which listens the database for changes. |
| */ |
| @WorkerThread |
| public void addObserver(@NonNull Observer observer) { |
| final String[] tableNames = observer.mTables; |
| int[] tableIds = new int[tableNames.length]; |
| final int size = tableNames.length; |
| long[] versions = new long[tableNames.length]; |
| |
| // TODO sync versions ? |
| for (int i = 0; i < size; i++) { |
| Integer tableId = mTableIdLookup.get(tableNames[i].toLowerCase(Locale.US)); |
| if (tableId == null) { |
| throw new IllegalArgumentException("There is no table with name " + tableNames[i]); |
| } |
| tableIds[i] = tableId; |
| versions[i] = mMaxVersion; |
| } |
| ObserverWrapper wrapper = new ObserverWrapper(observer, tableIds, tableNames, versions); |
| ObserverWrapper currentObserver; |
| synchronized (mObserverMap) { |
| currentObserver = mObserverMap.putIfAbsent(observer, wrapper); |
| } |
| if (currentObserver == null && mObservedTableTracker.onAdded(tableIds)) { |
| syncTriggers(); |
| } |
| } |
| |
| /** |
| * Adds an observer but keeps a weak reference back to it. |
| * <p> |
| * Note that you cannot remove this observer once added. It will be automatically removed |
| * when the observer is GC'ed. |
| * |
| * @param observer The observer to which InvalidationTracker will keep a weak reference. |
| * @hide |
| */ |
| @SuppressWarnings("unused") |
| @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP) |
| public void addWeakObserver(Observer observer) { |
| addObserver(new WeakObserver(this, observer)); |
| } |
| |
| /** |
| * Removes the observer from the observers list. |
| * |
| * @param observer The observer to remove. |
| */ |
| @SuppressWarnings("WeakerAccess") |
| @WorkerThread |
| public void removeObserver(@NonNull final Observer observer) { |
| ObserverWrapper wrapper; |
| synchronized (mObserverMap) { |
| wrapper = mObserverMap.remove(observer); |
| } |
| if (wrapper != null && mObservedTableTracker.onRemoved(wrapper.mTableIds)) { |
| syncTriggers(); |
| } |
| } |
| |
| private boolean ensureInitialization() { |
| if (!mDatabase.isOpen()) { |
| return false; |
| } |
| if (!mInitialized) { |
| // trigger initialization |
| mDatabase.getOpenHelper().getWritableDatabase(); |
| } |
| if (!mInitialized) { |
| Log.e(Room.LOG_TAG, "database is not initialized even though it is open"); |
| return false; |
| } |
| return true; |
| } |
| |
| @VisibleForTesting |
| Runnable mRefreshRunnable = new Runnable() { |
| @Override |
| public void run() { |
| final Lock closeLock = mDatabase.getCloseLock(); |
| boolean hasUpdatedTable = false; |
| try { |
| closeLock.lock(); |
| |
| if (!ensureInitialization()) { |
| return; |
| } |
| |
| if (!mPendingRefresh.compareAndSet(true, false)) { |
| // no pending refresh |
| return; |
| } |
| |
| if (mDatabase.inTransaction()) { |
| // current thread is in a transaction. when it ends, it will invoke |
| // refreshRunnable again. mPendingRefresh is left as false on purpose |
| // so that the last transaction can flip it on again. |
| return; |
| } |
| |
| mCleanupStatement.executeUpdateDelete(); |
| mQueryArgs[0] = mMaxVersion; |
| if (mDatabase.mWriteAheadLoggingEnabled) { |
| // This transaction has to be on the underlying DB rather than the RoomDatabase |
| // in order to avoid a recursive loop after endTransaction. |
| SupportSQLiteDatabase db = mDatabase.getOpenHelper().getWritableDatabase(); |
| try { |
| db.beginTransaction(); |
| hasUpdatedTable = checkUpdatedTable(); |
| db.setTransactionSuccessful(); |
| } finally { |
| db.endTransaction(); |
| } |
| } else { |
| hasUpdatedTable = checkUpdatedTable(); |
| } |
| } catch (IllegalStateException | SQLiteException exception) { |
| // may happen if db is closed. just log. |
| Log.e(Room.LOG_TAG, "Cannot run invalidation tracker. Is the db closed?", |
| exception); |
| } finally { |
| closeLock.unlock(); |
| } |
| if (hasUpdatedTable) { |
| synchronized (mObserverMap) { |
| for (Map.Entry<Observer, ObserverWrapper> entry : mObserverMap) { |
| entry.getValue().checkForInvalidation(mTableVersions); |
| } |
| } |
| } |
| } |
| |
| private boolean checkUpdatedTable() { |
| boolean hasUpdatedTable = false; |
| Cursor cursor = mDatabase.query(SELECT_UPDATED_TABLES_SQL, mQueryArgs); |
| //noinspection TryFinallyCanBeTryWithResources |
| try { |
| while (cursor.moveToNext()) { |
| final long version = cursor.getLong(0); |
| final int tableId = cursor.getInt(1); |
| |
| mTableVersions[tableId] = version; |
| hasUpdatedTable = true; |
| // result is ordered so we can safely do this assignment |
| mMaxVersion = version; |
| } |
| } finally { |
| cursor.close(); |
| } |
| return hasUpdatedTable; |
| } |
| }; |
| |
| /** |
| * Enqueues a task to refresh the list of updated tables. |
| * <p> |
| * This method is automatically called when {@link RoomDatabase#endTransaction()} is called but |
| * if you have another connection to the database or directly use {@link |
| * SupportSQLiteDatabase}, you may need to call this manually. |
| */ |
| @SuppressWarnings("WeakerAccess") |
| public void refreshVersionsAsync() { |
| // TODO we should consider doing this sync instead of async. |
| if (mPendingRefresh.compareAndSet(false, true)) { |
| ArchTaskExecutor.getInstance().executeOnDiskIO(mRefreshRunnable); |
| } |
| } |
| |
| /** |
| * Check versions for tables, and run observers synchronously if tables have been updated. |
| * |
| * @hide |
| */ |
| @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP) |
| @WorkerThread |
| public void refreshVersionsSync() { |
| syncTriggers(); |
| mRefreshRunnable.run(); |
| } |
| |
| void syncTriggers(SupportSQLiteDatabase database) { |
| if (database.inTransaction()) { |
| // we won't run this inside another transaction. |
| return; |
| } |
| try { |
| // This method runs in a while loop because while changes are synced to db, another |
| // runnable may be skipped. If we cause it to skip, we need to do its work. |
| while (true) { |
| Lock closeLock = mDatabase.getCloseLock(); |
| closeLock.lock(); |
| try { |
| // there is a potential race condition where another mSyncTriggers runnable |
| // can start running right after we get the tables list to sync. |
| final int[] tablesToSync = mObservedTableTracker.getTablesToSync(); |
| if (tablesToSync == null) { |
| return; |
| } |
| final int limit = tablesToSync.length; |
| try { |
| database.beginTransaction(); |
| for (int tableId = 0; tableId < limit; tableId++) { |
| switch (tablesToSync[tableId]) { |
| case ObservedTableTracker.ADD: |
| startTrackingTable(database, tableId); |
| break; |
| case ObservedTableTracker.REMOVE: |
| stopTrackingTable(database, tableId); |
| break; |
| } |
| } |
| database.setTransactionSuccessful(); |
| } finally { |
| database.endTransaction(); |
| } |
| mObservedTableTracker.onSyncCompleted(); |
| } finally { |
| closeLock.unlock(); |
| } |
| } |
| } catch (IllegalStateException | SQLiteException exception) { |
| // may happen if db is closed. just log. |
| Log.e(Room.LOG_TAG, "Cannot run invalidation tracker. Is the db closed?", |
| exception); |
| } |
| } |
| |
| /** |
| * Called by RoomDatabase before each beginTransaction call. |
| * <p> |
| * It is important that pending trigger changes are applied to the database before any query |
| * runs. Otherwise, we may miss some changes. |
| * <p> |
| * This api should eventually be public. |
| */ |
| void syncTriggers() { |
| if (!mDatabase.isOpen()) { |
| return; |
| } |
| syncTriggers(mDatabase.getOpenHelper().getWritableDatabase()); |
| } |
| |
| /** |
| * Wraps an observer and keeps the table information. |
| * <p> |
| * Internally table ids are used which may change from database to database so the table |
| * related information is kept here rather than in the Observer. |
| */ |
| @SuppressWarnings("WeakerAccess") |
| static class ObserverWrapper { |
| final int[] mTableIds; |
| private final String[] mTableNames; |
| private final long[] mVersions; |
| final Observer mObserver; |
| private final Set<String> mSingleTableSet; |
| |
| ObserverWrapper(Observer observer, int[] tableIds, String[] tableNames, long[] versions) { |
| mObserver = observer; |
| mTableIds = tableIds; |
| mTableNames = tableNames; |
| mVersions = versions; |
| if (tableIds.length == 1) { |
| ArraySet<String> set = new ArraySet<>(); |
| set.add(mTableNames[0]); |
| mSingleTableSet = Collections.unmodifiableSet(set); |
| } else { |
| mSingleTableSet = null; |
| } |
| } |
| |
| void checkForInvalidation(long[] versions) { |
| Set<String> invalidatedTables = null; |
| final int size = mTableIds.length; |
| for (int index = 0; index < size; index++) { |
| final int tableId = mTableIds[index]; |
| final long newVersion = versions[tableId]; |
| final long currentVersion = mVersions[index]; |
| if (currentVersion < newVersion) { |
| mVersions[index] = newVersion; |
| if (size == 1) { |
| // Optimization for a single-table observer |
| invalidatedTables = mSingleTableSet; |
| } else { |
| if (invalidatedTables == null) { |
| invalidatedTables = new ArraySet<>(size); |
| } |
| invalidatedTables.add(mTableNames[index]); |
| } |
| } |
| } |
| if (invalidatedTables != null) { |
| mObserver.onInvalidated(invalidatedTables); |
| } |
| } |
| } |
| |
| /** |
| * An observer that can listen for changes in the database. |
| */ |
| public abstract static class Observer { |
| final String[] mTables; |
| |
| /** |
| * Observes the given list of tables. |
| * |
| * @param firstTable The table name |
| * @param rest More table names |
| */ |
| @SuppressWarnings("unused") |
| protected Observer(@NonNull String firstTable, String... rest) { |
| mTables = Arrays.copyOf(rest, rest.length + 1); |
| mTables[rest.length] = firstTable; |
| } |
| |
| /** |
| * Observes the given list of tables. |
| * |
| * @param tables The list of tables to observe for changes. |
| */ |
| public Observer(@NonNull String[] tables) { |
| // copy tables in case user modifies them afterwards |
| mTables = Arrays.copyOf(tables, tables.length); |
| } |
| |
| /** |
| * Called when one of the observed tables is invalidated in the database. |
| * |
| * @param tables A set of invalidated tables. This is useful when the observer targets |
| * multiple tables and want to know which table is invalidated. |
| */ |
| public abstract void onInvalidated(@NonNull Set<String> tables); |
| } |
| |
| |
| /** |
| * Keeps a list of tables we should observe. Invalidation tracker lazily syncs this list w/ |
| * triggers in the database. |
| * <p> |
| * This class is thread safe |
| */ |
| static class ObservedTableTracker { |
| static final int NO_OP = 0; // don't change trigger state for this table |
| static final int ADD = 1; // add triggers for this table |
| static final int REMOVE = 2; // remove triggers for this table |
| |
| // number of observers per table |
| final long[] mTableObservers; |
| // trigger state for each table at last sync |
| // this field is updated when syncAndGet is called. |
| final boolean[] mTriggerStates; |
| // when sync is called, this field is returned. It includes actions as ADD, REMOVE, NO_OP |
| final int[] mTriggerStateChanges; |
| |
| boolean mNeedsSync; |
| |
| /** |
| * After we return non-null value from getTablesToSync, we expect a onSyncCompleted before |
| * returning any non-null value from getTablesToSync. |
| * This allows us to workaround any multi-threaded state syncing issues. |
| */ |
| boolean mPendingSync; |
| |
| ObservedTableTracker(int tableCount) { |
| mTableObservers = new long[tableCount]; |
| mTriggerStates = new boolean[tableCount]; |
| mTriggerStateChanges = new int[tableCount]; |
| Arrays.fill(mTableObservers, 0); |
| Arrays.fill(mTriggerStates, false); |
| } |
| |
| /** |
| * @return true if # of triggers is affected. |
| */ |
| boolean onAdded(int... tableIds) { |
| boolean needTriggerSync = false; |
| synchronized (this) { |
| for (int tableId : tableIds) { |
| final long prevObserverCount = mTableObservers[tableId]; |
| mTableObservers[tableId] = prevObserverCount + 1; |
| if (prevObserverCount == 0) { |
| mNeedsSync = true; |
| needTriggerSync = true; |
| } |
| } |
| } |
| return needTriggerSync; |
| } |
| |
| /** |
| * @return true if # of triggers is affected. |
| */ |
| boolean onRemoved(int... tableIds) { |
| boolean needTriggerSync = false; |
| synchronized (this) { |
| for (int tableId : tableIds) { |
| final long prevObserverCount = mTableObservers[tableId]; |
| mTableObservers[tableId] = prevObserverCount - 1; |
| if (prevObserverCount == 1) { |
| mNeedsSync = true; |
| needTriggerSync = true; |
| } |
| } |
| } |
| return needTriggerSync; |
| } |
| |
| /** |
| * If this returns non-null, you must call onSyncCompleted. |
| * |
| * @return int[] An int array where the index for each tableId has the action for that |
| * table. |
| */ |
| @Nullable |
| int[] getTablesToSync() { |
| synchronized (this) { |
| if (!mNeedsSync || mPendingSync) { |
| return null; |
| } |
| final int tableCount = mTableObservers.length; |
| for (int i = 0; i < tableCount; i++) { |
| final boolean newState = mTableObservers[i] > 0; |
| if (newState != mTriggerStates[i]) { |
| mTriggerStateChanges[i] = newState ? ADD : REMOVE; |
| } else { |
| mTriggerStateChanges[i] = NO_OP; |
| } |
| mTriggerStates[i] = newState; |
| } |
| mPendingSync = true; |
| mNeedsSync = false; |
| return mTriggerStateChanges; |
| } |
| } |
| |
| /** |
| * if getTablesToSync returned non-null, the called should call onSyncCompleted once it |
| * is done. |
| */ |
| void onSyncCompleted() { |
| synchronized (this) { |
| mPendingSync = false; |
| } |
| } |
| } |
| |
| /** |
| * An Observer wrapper that keeps a weak reference to the given object. |
| * <p> |
| * This class with automatically unsubscribe when the wrapped observer goes out of memory. |
| */ |
| static class WeakObserver extends Observer { |
| final InvalidationTracker mTracker; |
| final WeakReference<Observer> mDelegateRef; |
| |
| WeakObserver(InvalidationTracker tracker, Observer delegate) { |
| super(delegate.mTables); |
| mTracker = tracker; |
| mDelegateRef = new WeakReference<>(delegate); |
| } |
| |
| @Override |
| public void onInvalidated(@NonNull Set<String> tables) { |
| final Observer observer = mDelegateRef.get(); |
| if (observer == null) { |
| mTracker.removeObserver(this); |
| } else { |
| observer.onInvalidated(tables); |
| } |
| } |
| } |
| } |
