/*
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* Copyright (C) 2006 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.database;
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import android.net.Uri;
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import android.os.*;
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/**
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* Wraps a BulkCursor around an existing Cursor making it remotable.
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* <p>
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* If the wrapped cursor returns non-null from {@link CrossProcessCursor#getWindow}
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* then it is assumed to own the window. Otherwise, the adaptor provides a
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* window to be filled and ensures it gets closed as needed during deactivation
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* and requeries.
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* </p>
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*
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* {@hide}
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*/
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public final class CursorToBulkCursorAdaptor extends BulkCursorNative
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implements IBinder.DeathRecipient {
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private static final String TAG = "Cursor";
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private final Object mLock = new Object();
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private final String mProviderName;
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private ContentObserverProxy mObserver;
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/**
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* The cursor that is being adapted.
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* This field is set to null when the cursor is closed.
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*/
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private CrossProcessCursor mCursor;
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/**
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* The cursor window that was filled by the cross process cursor in the
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* case where the cursor does not support getWindow.
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* This field is only ever non-null when the window has actually be filled.
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*/
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private CursorWindow mFilledWindow;
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private static final class ContentObserverProxy extends ContentObserver {
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protected IContentObserver mRemote;
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public ContentObserverProxy(IContentObserver remoteObserver, DeathRecipient recipient) {
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super(null);
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mRemote = remoteObserver;
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try {
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remoteObserver.asBinder().linkToDeath(recipient, 0);
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} catch (RemoteException e) {
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// Do nothing, the far side is dead
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}
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}
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public boolean unlinkToDeath(DeathRecipient recipient) {
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return mRemote.asBinder().unlinkToDeath(recipient, 0);
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}
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@Override
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public boolean deliverSelfNotifications() {
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// The far side handles the self notifications.
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return false;
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}
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@Override
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public void onChange(boolean selfChange, Uri uri) {
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try {
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mRemote.onChange(selfChange, uri, android.os.Process.myUid());
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} catch (RemoteException ex) {
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// Do nothing, the far side is dead
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}
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}
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}
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public CursorToBulkCursorAdaptor(Cursor cursor, IContentObserver observer,
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String providerName) {
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if (cursor instanceof CrossProcessCursor) {
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mCursor = (CrossProcessCursor)cursor;
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} else {
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mCursor = new CrossProcessCursorWrapper(cursor);
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}
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mProviderName = providerName;
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synchronized (mLock) {
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createAndRegisterObserverProxyLocked(observer);
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}
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}
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private void closeFilledWindowLocked() {
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if (mFilledWindow != null) {
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mFilledWindow.close();
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mFilledWindow = null;
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}
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}
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private void disposeLocked() {
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if (mCursor != null) {
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unregisterObserverProxyLocked();
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mCursor.close();
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mCursor = null;
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}
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closeFilledWindowLocked();
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}
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private void throwIfCursorIsClosed() {
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if (mCursor == null) {
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throw new StaleDataException("Attempted to access a cursor after it has been closed.");
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}
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}
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@Override
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public void binderDied() {
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synchronized (mLock) {
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disposeLocked();
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}
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}
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/**
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* Returns an object that contains sufficient metadata to reconstruct
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* the cursor remotely. May throw if an error occurs when executing the query
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* and obtaining the row count.
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*/
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public BulkCursorDescriptor getBulkCursorDescriptor() {
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synchronized (mLock) {
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throwIfCursorIsClosed();
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BulkCursorDescriptor d = new BulkCursorDescriptor();
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d.cursor = this;
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d.columnNames = mCursor.getColumnNames();
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d.wantsAllOnMoveCalls = mCursor.getWantsAllOnMoveCalls();
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d.count = mCursor.getCount();
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d.window = mCursor.getWindow();
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if (d.window != null) {
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// Acquire a reference to the window because its reference count will be
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// decremented when it is returned as part of the binder call reply parcel.
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d.window.acquireReference();
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}
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return d;
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}
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}
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@Override
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public CursorWindow getWindow(int position) {
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synchronized (mLock) {
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throwIfCursorIsClosed();
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if (!mCursor.moveToPosition(position)) {
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closeFilledWindowLocked();
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return null;
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}
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CursorWindow window = mCursor.getWindow();
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if (window != null) {
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closeFilledWindowLocked();
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} else {
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window = mFilledWindow;
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if (window == null) {
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mFilledWindow = new CursorWindow(mProviderName);
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window = mFilledWindow;
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} else if (position < window.getStartPosition()
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|| position >= window.getStartPosition() + window.getNumRows()) {
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window.clear();
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}
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mCursor.fillWindow(position, window);
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}
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if (window != null) {
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// Acquire a reference to the window because its reference count will be
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// decremented when it is returned as part of the binder call reply parcel.
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window.acquireReference();
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}
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return window;
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}
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}
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@Override
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public void onMove(int position) {
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synchronized (mLock) {
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throwIfCursorIsClosed();
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mCursor.onMove(mCursor.getPosition(), position);
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}
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}
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@Override
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public void deactivate() {
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synchronized (mLock) {
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if (mCursor != null) {
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unregisterObserverProxyLocked();
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mCursor.deactivate();
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}
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closeFilledWindowLocked();
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}
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}
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@Override
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public void close() {
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synchronized (mLock) {
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disposeLocked();
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}
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}
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@Override
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public int requery(IContentObserver observer) {
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synchronized (mLock) {
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throwIfCursorIsClosed();
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closeFilledWindowLocked();
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try {
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if (!mCursor.requery()) {
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return -1;
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}
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} catch (IllegalStateException e) {
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IllegalStateException leakProgram = new IllegalStateException(
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mProviderName + " Requery misuse db, mCursor isClosed:" +
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mCursor.isClosed(), e);
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throw leakProgram;
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}
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unregisterObserverProxyLocked();
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createAndRegisterObserverProxyLocked(observer);
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return mCursor.getCount();
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}
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}
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/**
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* Create a ContentObserver from the observer and register it as an observer on the
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* underlying cursor.
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* @param observer the IContentObserver that wants to monitor the cursor
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* @throws IllegalStateException if an observer is already registered
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*/
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private void createAndRegisterObserverProxyLocked(IContentObserver observer) {
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if (mObserver != null) {
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throw new IllegalStateException("an observer is already registered");
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}
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mObserver = new ContentObserverProxy(observer, this);
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mCursor.registerContentObserver(mObserver);
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}
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/** Unregister the observer if it is already registered. */
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private void unregisterObserverProxyLocked() {
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if (mObserver != null) {
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mCursor.unregisterContentObserver(mObserver);
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mObserver.unlinkToDeath(this);
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mObserver = null;
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}
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}
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@Override
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public Bundle getExtras() {
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synchronized (mLock) {
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throwIfCursorIsClosed();
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return mCursor.getExtras();
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}
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}
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@Override
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public Bundle respond(Bundle extras) {
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synchronized (mLock) {
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throwIfCursorIsClosed();
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return mCursor.respond(extras);
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}
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}
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}
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