Use ashmem for CursorWindows.

Bug: 5332296

The memory dealer introduces additional delays for reclaiming
the memory owned by CursorWindows because the Binder object must
be finalized.  Using ashmem instead gives CursorWindow more
direct control over the lifetime of the shared memory region.

The provider now allocates the CursorWindows and returns them
to clients with a read-only protection bit set on the ashmem
region.

Improved the encapsulation of CursorWindow.  Callers shouldn't
need to care about details like how string fields are allocated.

Removed the compile-time configuration of string and numeric
storage modes to remove some dead weight.

Change-Id: I07c2bc2a9c573d7e435dcaecd269d25ea9807acd

Author: Jeff Brown

core/java/android/content/ContentProviderNative.java

@@ -108,21 +108,22 @@ public boolean onTransact(int code, Parcel data, Parcel reply, int flags)
                     String sortOrder = data.readString();
                     IContentObserver observer = IContentObserver.Stub.asInterface(
                             data.readStrongBinder());
-                    CursorWindow window = CursorWindow.CREATOR.createFromParcel(data);
 
                     Cursor cursor = query(url, projection, selection, selectionArgs, sortOrder);
                     if (cursor != null) {
                         CursorToBulkCursorAdaptor adaptor = new CursorToBulkCursorAdaptor(
-                                cursor, observer, getProviderName(), window);
+                                cursor, observer, getProviderName());
                         final IBinder binder = adaptor.asBinder();
                         final int count = adaptor.count();
                         final int index = BulkCursorToCursorAdaptor.findRowIdColumnIndex(
                                 adaptor.getColumnNames());
+                        final boolean wantsAllOnMoveCalls = adaptor.getWantsAllOnMoveCalls();
 
                         reply.writeNoException();
                         reply.writeStrongBinder(binder);
                         reply.writeInt(count);
                         reply.writeInt(index);
+                        reply.writeInt(wantsAllOnMoveCalls ? 1 : 0);
                     } else {
                         reply.writeNoException();
                         reply.writeStrongBinder(null);
@@ -324,67 +325,58 @@ public IBinder asBinder()
 
     public Cursor query(Uri url, String[] projection, String selection,
             String[] selectionArgs, String sortOrder) throws RemoteException {
-        CursorWindow window = new CursorWindow(false /* window will be used remotely */);
+        BulkCursorToCursorAdaptor adaptor = new BulkCursorToCursorAdaptor();
+        Parcel data = Parcel.obtain();
+        Parcel reply = Parcel.obtain();
         try {
-            BulkCursorToCursorAdaptor adaptor = new BulkCursorToCursorAdaptor();
-            Parcel data = Parcel.obtain();
-            Parcel reply = Parcel.obtain();
-            try {
-                data.writeInterfaceToken(IContentProvider.descriptor);
-
-                url.writeToParcel(data, 0);
-                int length = 0;
-                if (projection != null) {
-                    length = projection.length;
-                }
-                data.writeInt(length);
-                for (int i = 0; i < length; i++) {
-                    data.writeString(projection[i]);
-                }
-                data.writeString(selection);
-                if (selectionArgs != null) {
-                    length = selectionArgs.length;
-                } else {
-                    length = 0;
-                }
-                data.writeInt(length);
-                for (int i = 0; i < length; i++) {
-                    data.writeString(selectionArgs[i]);
-                }
-                data.writeString(sortOrder);
-                data.writeStrongBinder(adaptor.getObserver().asBinder());
-                window.writeToParcel(data, 0);
-
-                mRemote.transact(IContentProvider.QUERY_TRANSACTION, data, reply, 0);
-
-                DatabaseUtils.readExceptionFromParcel(reply);
-
-                IBulkCursor bulkCursor = BulkCursorNative.asInterface(reply.readStrongBinder());
-                if (bulkCursor != null) {
-                    int rowCount = reply.readInt();
-                    int idColumnPosition = reply.readInt();
-                    adaptor.initialize(bulkCursor, rowCount, idColumnPosition);
-                } else {
-                    adaptor.close();
-                    adaptor = null;
-                }
-                return adaptor;
-            } catch (RemoteException ex) {
-                adaptor.close();
-                throw ex;
-            } catch (RuntimeException ex) {
+            data.writeInterfaceToken(IContentProvider.descriptor);
+
+            url.writeToParcel(data, 0);
+            int length = 0;
+            if (projection != null) {
+                length = projection.length;
+            }
+            data.writeInt(length);
+            for (int i = 0; i < length; i++) {
+                data.writeString(projection[i]);
+            }
+            data.writeString(selection);
+            if (selectionArgs != null) {
+                length = selectionArgs.length;
+            } else {
+                length = 0;
+            }
+            data.writeInt(length);
+            for (int i = 0; i < length; i++) {
+                data.writeString(selectionArgs[i]);
+            }
+            data.writeString(sortOrder);
+            data.writeStrongBinder(adaptor.getObserver().asBinder());
+
+            mRemote.transact(IContentProvider.QUERY_TRANSACTION, data, reply, 0);
+
+            DatabaseUtils.readExceptionFromParcel(reply);
+
+            IBulkCursor bulkCursor = BulkCursorNative.asInterface(reply.readStrongBinder());
+            if (bulkCursor != null) {
+                int rowCount = reply.readInt();
+                int idColumnPosition = reply.readInt();
+                boolean wantsAllOnMoveCalls = reply.readInt() != 0;
+                adaptor.initialize(bulkCursor, rowCount, idColumnPosition, wantsAllOnMoveCalls);
+            } else {
                 adaptor.close();
-                throw ex;
-            } finally {
-                data.recycle();
-                reply.recycle();
+                adaptor = null;
             }
+            return adaptor;
+        } catch (RemoteException ex) {
+            adaptor.close();
+            throw ex;
+        } catch (RuntimeException ex) {
+            adaptor.close();
+            throw ex;
         } finally {
-            // We close the window now because the cursor adaptor does not
-            // take ownership of the window until the first call to onMove.
-            // The adaptor will obtain a fresh reference to the window when
-            // it is filled.
-            window.close();
+            data.recycle();
+            reply.recycle();
         }
     }
 

core/java/android/database/AbstractWindowedCursor.java

@@ -189,12 +189,14 @@ protected void closeWindow() {
     /**
      * If there is a window, clear it.
      * Otherwise, creates a local window.
+     *
+     * @param name The window name.
      * @hide
      */
-    protected void clearOrCreateLocalWindow() {
+    protected void clearOrCreateLocalWindow(String name) {
         if (mWindow == null) {
             // If there isn't a window set already it will only be accessed locally
-            mWindow = new CursorWindow(true /* the window is local only */);
+            mWindow = new CursorWindow(name, true /* the window is local only */);
         } else {
             mWindow.clear();
         }

core/java/android/database/BulkCursorNative.java

@@ -109,9 +109,8 @@ public boolean onTransact(int code, Parcel data, Parcel reply, int flags)
                 case REQUERY_TRANSACTION: {
                     data.enforceInterface(IBulkCursor.descriptor);
                     IContentObserver observer =
-                        IContentObserver.Stub.asInterface(data.readStrongBinder());
-                    CursorWindow window = CursorWindow.CREATOR.createFromParcel(data);
-                    int count = requery(observer, window);
+                            IContentObserver.Stub.asInterface(data.readStrongBinder());
+                    int count = requery(observer);
                     reply.writeNoException();
                     reply.writeInt(count);
                     reply.writeBundle(getExtras());
@@ -294,13 +293,12 @@ public void close() throws RemoteException
         }
     }
 
-    public int requery(IContentObserver observer, CursorWindow window) throws RemoteException {
+    public int requery(IContentObserver observer) throws RemoteException {
         Parcel data = Parcel.obtain();
         Parcel reply = Parcel.obtain();
         try {
             data.writeInterfaceToken(IBulkCursor.descriptor);
             data.writeStrongInterface(observer);
-            window.writeToParcel(data, 0);
 
             boolean result = mRemote.transact(REQUERY_TRANSACTION, data, reply, 0);
             DatabaseUtils.readExceptionFromParcel(reply);

core/java/android/database/BulkCursorToCursorAdaptor.java

@@ -38,11 +38,13 @@ public final class BulkCursorToCursorAdaptor extends AbstractWindowedCursor {
      * Initializes the adaptor.
      * Must be called before first use.
      */
-    public void initialize(IBulkCursor bulkCursor, int count, int idIndex) {
+    public void initialize(IBulkCursor bulkCursor, int count, int idIndex,
+            boolean wantsAllOnMoveCalls) {
         mBulkCursor = bulkCursor;
         mColumns = null;  // lazily retrieved
         mCount = count;
         mRowIdColumnIndex = idIndex;
+        mWantsAllOnMoveCalls = wantsAllOnMoveCalls;
     }
 
     /**
@@ -86,15 +88,12 @@ public boolean onMove(int oldPosition, int newPosition) {
 
         try {
             // Make sure we have the proper window
-            if (mWindow != null) {
-                if (newPosition < mWindow.getStartPosition() ||
-                        newPosition >= (mWindow.getStartPosition() + mWindow.getNumRows())) {
-                    setWindow(mBulkCursor.getWindow(newPosition));
-                } else if (mWantsAllOnMoveCalls) {
-                    mBulkCursor.onMove(newPosition);
-                }
-            } else {
+            if (mWindow == null
+                    || newPosition < mWindow.getStartPosition()
+                    || newPosition >= mWindow.getStartPosition() + mWindow.getNumRows()) {
                 setWindow(mBulkCursor.getWindow(newPosition));
+            } else if (mWantsAllOnMoveCalls) {
+                mBulkCursor.onMove(newPosition);
             }
         } catch (RemoteException ex) {
             // We tried to get a window and failed
@@ -145,25 +144,19 @@ public boolean requery() {
         throwIfCursorIsClosed();
 
         try {
-            CursorWindow newWindow = new CursorWindow(false /* create a remote window */);
-            try {
-                mCount = mBulkCursor.requery(getObserver(), newWindow);
-                if (mCount != -1) {
-                    mPos = -1;
-                    closeWindow();
-
-                    // super.requery() will call onChanged. Do it here instead of relying on the
-                    // observer from the far side so that observers can see a correct value for mCount
-                    // when responding to onChanged.
-                    super.requery();
-                    return true;
-                } else {
-                    deactivate();
-                    return false;
-                }
-            } finally {
-                // Don't take ownership of the window until the next call to onMove.
-                newWindow.close();
+            mCount = mBulkCursor.requery(getObserver());
+            if (mCount != -1) {
+                mPos = -1;
+                closeWindow();
+
+                // super.requery() will call onChanged. Do it here instead of relying on the
+                // observer from the far side so that observers can see a correct value for mCount
+                // when responding to onChanged.
+                super.requery();
+                return true;
+            } else {
+                deactivate();
+                return false;
             }
         } catch (Exception ex) {
             Log.e(TAG, "Unable to requery because the remote process exception " + ex.getMessage());