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

8 files changed, 153 insertions, 152 deletions

diff --git a/core/java/android/content/ContentProviderNative.java b/core/java/android/content/ContentProviderNative.java
index 064755e..b089bf2 100644
--- a/core/java/android/content/ContentProviderNative.java
+++ b/core/java/android/content/ContentProviderNative.java
@@ -108,21 +108,22 @@ abstract public class ContentProviderNative extends Binder implements IContentPr
                     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 @@ final class ContentProviderProxy implements IContentProvider
 
     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();
         }
     }
 
diff --git a/core/java/android/database/AbstractWindowedCursor.java b/core/java/android/database/AbstractWindowedCursor.java
index 5836265..d0aedd2 100644
--- a/core/java/android/database/AbstractWindowedCursor.java
+++ b/core/java/android/database/AbstractWindowedCursor.java
@@ -189,12 +189,14 @@ public abstract class AbstractWindowedCursor extends AbstractCursor {
     /**
      * 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();
         }
diff --git a/core/java/android/database/BulkCursorNative.java b/core/java/android/database/BulkCursorNative.java
index 4fada8c..20a9c67 100644
--- a/core/java/android/database/BulkCursorNative.java
+++ b/core/java/android/database/BulkCursorNative.java
@@ -109,9 +109,8 @@ public abstract class BulkCursorNative extends Binder implements IBulkCursor
                 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 @@ final class BulkCursorProxy implements IBulkCursor {
         }
     }
     
-    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);
diff --git a/core/java/android/database/BulkCursorToCursorAdaptor.java b/core/java/android/database/BulkCursorToCursorAdaptor.java
index cbdd07fb..885046b 100644
--- a/core/java/android/database/BulkCursorToCursorAdaptor.java
+++ b/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 final class BulkCursorToCursorAdaptor extends AbstractWindowedCursor {
 
         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 final class BulkCursorToCursorAdaptor extends AbstractWindowedCursor {
         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());
diff --git a/core/java/android/database/CursorToBulkCursorAdaptor.java b/core/java/android/database/CursorToBulkCursorAdaptor.java
index a65b3b3..dd2c9b7 100644
--- a/core/java/android/database/CursorToBulkCursorAdaptor.java
+++ b/core/java/android/database/CursorToBulkCursorAdaptor.java
@@ -53,6 +53,7 @@ public final class CursorToBulkCursorAdaptor extends BulkCursorNative
      * for managing the lifetime of their window.
      */
     private CursorWindow mWindowForNonWindowedCursor;
+    private boolean mWindowForNonWindowedCursorWasFilled;
 
     private static final class ContentObserverProxy extends ContentObserver {
         protected IContentObserver mRemote;
@@ -87,26 +88,11 @@ public final class CursorToBulkCursorAdaptor extends BulkCursorNative
         }
     }
 
-    public CursorToBulkCursorAdaptor(Cursor cursor, IContentObserver observer, String providerName,
-            CursorWindow window) {
+    public CursorToBulkCursorAdaptor(Cursor cursor, IContentObserver observer,
+            String providerName) {
         try {
             mCursor = (CrossProcessCursor) cursor;
-            if (mCursor instanceof AbstractWindowedCursor) {
-                AbstractWindowedCursor windowedCursor = (AbstractWindowedCursor) cursor;
-                if (windowedCursor.hasWindow()) {
-                    if (Log.isLoggable(TAG, Log.VERBOSE) || false) {
-                        Log.v(TAG, "Cross process cursor has a local window before setWindow in "
-                                + providerName, new RuntimeException());
-                    }
-                }
-                windowedCursor.setWindow(window); // cursor takes ownership of window
-            } else {
-                mWindowForNonWindowedCursor = window; // we own the window
-                mCursor.fillWindow(0, window);
-            }
         } catch (ClassCastException e) {
-            // TODO Implement this case.
-            window.close();
             throw new UnsupportedOperationException(
                     "Only CrossProcessCursor cursors are supported across process for now", e);
         }
@@ -117,17 +103,22 @@ public final class CursorToBulkCursorAdaptor extends BulkCursorNative
         }
     }
 
-    private void closeCursorAndWindowLocked() {
+    private void closeWindowForNonWindowedCursorLocked() {
+        if (mWindowForNonWindowedCursor != null) {
+            mWindowForNonWindowedCursor.close();
+            mWindowForNonWindowedCursor = null;
+            mWindowForNonWindowedCursorWasFilled = false;
+        }
+    }
+
+    private void disposeLocked() {
         if (mCursor != null) {
             unregisterObserverProxyLocked();
             mCursor.close();
             mCursor = null;
         }
 
-        if (mWindowForNonWindowedCursor != null) {
-            mWindowForNonWindowedCursor.close();
-            mWindowForNonWindowedCursor = null;
-        }
+        closeWindowForNonWindowedCursorLocked();
     }
 
     private void throwIfCursorIsClosed() {
@@ -139,7 +130,7 @@ public final class CursorToBulkCursorAdaptor extends BulkCursorNative
     @Override
     public void binderDied() {
         synchronized (mLock) {
-            closeCursorAndWindowLocked();
+            disposeLocked();
         }
     }
 
@@ -148,17 +139,30 @@ public final class CursorToBulkCursorAdaptor extends BulkCursorNative
         synchronized (mLock) {
             throwIfCursorIsClosed();
 
-            mCursor.moveToPosition(startPos);
-
-            final CursorWindow window;
+            CursorWindow window;
             if (mCursor instanceof AbstractWindowedCursor) {
-                window = ((AbstractWindowedCursor)mCursor).getWindow();
+                AbstractWindowedCursor windowedCursor = (AbstractWindowedCursor)mCursor;
+                window = windowedCursor.getWindow();
+                if (window == null) {
+                    window = new CursorWindow(mProviderName, false /*localOnly*/);
+                    windowedCursor.setWindow(window);
+                }
+
+                mCursor.moveToPosition(startPos);
             } else {
                 window = mWindowForNonWindowedCursor;
-                if (window != null
-                        && (startPos < window.getStartPosition() ||
-                                startPos >= (window.getStartPosition() + window.getNumRows()))) {
+                if (window == null) {
+                    window = new CursorWindow(mProviderName, false /*localOnly*/);
+                    mWindowForNonWindowedCursor = window;
+                }
+
+                mCursor.moveToPosition(startPos);
+
+                if (!mWindowForNonWindowedCursorWasFilled
+                        || startPos < window.getStartPosition()
+                        || startPos >= window.getStartPosition() + window.getNumRows()) {
                     mCursor.fillWindow(startPos, window);
+                    mWindowForNonWindowedCursorWasFilled = true;
                 }
             }
 
@@ -206,29 +210,24 @@ public final class CursorToBulkCursorAdaptor extends BulkCursorNative
                 unregisterObserverProxyLocked();
                 mCursor.deactivate();
             }
+
+            closeWindowForNonWindowedCursorLocked();
         }
     }
 
     @Override
     public void close() {
         synchronized (mLock) {
-            closeCursorAndWindowLocked();
+            disposeLocked();
         }
     }
 
     @Override
-    public int requery(IContentObserver observer, CursorWindow window) {
+    public int requery(IContentObserver observer) {
         synchronized (mLock) {
             throwIfCursorIsClosed();
 
-            if (mCursor instanceof AbstractWindowedCursor) {
-                ((AbstractWindowedCursor) mCursor).setWindow(window);
-            } else {
-                if (mWindowForNonWindowedCursor != null) {
-                    mWindowForNonWindowedCursor.close();
-                }
-                mWindowForNonWindowedCursor = window;
-            }
+            closeWindowForNonWindowedCursorLocked();
 
             try {
                 if (!mCursor.requery()) {
@@ -241,12 +240,6 @@ public final class CursorToBulkCursorAdaptor extends BulkCursorNative
                 throw leakProgram;
             }
 
-            if (!(mCursor instanceof AbstractWindowedCursor)) {
-                if (window != null) {
-                    mCursor.fillWindow(0, window);
-                }
-            }
-
             unregisterObserverProxyLocked();
             createAndRegisterObserverProxyLocked(observer);
             return mCursor.getCount();
diff --git a/core/java/android/database/CursorWindow.java b/core/java/android/database/CursorWindow.java
index 5a91b80..a18a721 100644
--- a/core/java/android/database/CursorWindow.java
+++ b/core/java/android/database/CursorWindow.java
@@ -22,7 +22,6 @@ import android.content.res.Resources;
 import android.database.sqlite.SQLiteClosable;
 import android.database.sqlite.SQLiteException;
 import android.os.Binder;
-import android.os.IBinder;
 import android.os.Parcel;
 import android.os.Parcelable;
 import android.os.Process;
@@ -31,6 +30,13 @@ import android.util.SparseIntArray;
 
 /**
  * A buffer containing multiple cursor rows.
+ * <p>
+ * A {@link CursorWindow} is read-write when created and used locally.  When sent
+ * to a remote process (by writing it to a {@link Parcel}), the remote process
+ * receives a read-only view of the cursor window.  Typically the cursor window
+ * will be allocated by the producer, filled with data, and then sent to the
+ * consumer for reading.
+ * </p>
  */
 public class CursorWindow extends SQLiteClosable implements Parcelable {
     private static final String STATS_TAG = "CursorWindowStats";
@@ -52,10 +58,11 @@ public class CursorWindow extends SQLiteClosable implements Parcelable {
 
     private final CloseGuard mCloseGuard = CloseGuard.get();
 
-    private static native int nativeInitializeEmpty(int cursorWindowSize, boolean localOnly);
-    private static native int nativeInitializeFromBinder(IBinder nativeBinder);
+    private static native int nativeCreate(String name,
+            int cursorWindowSize, boolean localOnly);
+    private static native int nativeCreateFromParcel(Parcel parcel);
     private static native void nativeDispose(int windowPtr);
-    private static native IBinder nativeGetBinder(int windowPtr);
+    private static native void nativeWriteToParcel(int windowPtr, Parcel parcel);
 
     private static native void nativeClear(int windowPtr);
 
@@ -79,18 +86,21 @@ public class CursorWindow extends SQLiteClosable implements Parcelable {
     private static native boolean nativePutNull(int windowPtr, int row, int column);
 
     /**
-     * Creates a new empty cursor window.
+     * Creates a new empty cursor window and gives it a name.
      * <p>
      * The cursor initially has no rows or columns.  Call {@link #setNumColumns(int)} to
      * set the number of columns before adding any rows to the cursor.
      * </p>
      *
+     * @param name The name of the cursor window, or null if none.
      * @param localWindow True if this window will be used in this process only,
      * false if it might be sent to another processes.
+     *
+     * @hide
      */
-    public CursorWindow(boolean localWindow) {
+    public CursorWindow(String name, boolean localWindow) {
         mStartPos = 0;
-        mWindowPtr = nativeInitializeEmpty(sCursorWindowSize, localWindow);
+        mWindowPtr = nativeCreate(name, sCursorWindowSize, localWindow);
         if (mWindowPtr == 0) {
             throw new CursorWindowAllocationException("Cursor window allocation of " +
                     (sCursorWindowSize / 1024) + " kb failed. " + printStats());
@@ -99,10 +109,23 @@ public class CursorWindow extends SQLiteClosable implements Parcelable {
         recordNewWindow(Binder.getCallingPid(), mWindowPtr);
     }
 
+    /**
+     * Creates a new empty cursor window.
+     * <p>
+     * The cursor initially has no rows or columns.  Call {@link #setNumColumns(int)} to
+     * set the number of columns before adding any rows to the cursor.
+     * </p>
+     *
+     * @param localWindow True if this window will be used in this process only,
+     * false if it might be sent to another processes.
+     */
+    public CursorWindow(boolean localWindow) {
+        this(null, localWindow);
+    }
+
     private CursorWindow(Parcel source) {
-        IBinder binder = source.readStrongBinder();
         mStartPos = source.readInt();
-        mWindowPtr = nativeInitializeFromBinder(binder);
+        mWindowPtr = nativeCreateFromParcel(source);
         if (mWindowPtr == 0) {
             throw new CursorWindowAllocationException("Cursor window could not be "
                     + "created from binder.");
@@ -687,8 +710,8 @@ public class CursorWindow extends SQLiteClosable implements Parcelable {
     }
 
     public void writeToParcel(Parcel dest, int flags) {
-        dest.writeStrongBinder(nativeGetBinder(mWindowPtr));
         dest.writeInt(mStartPos);
+        nativeWriteToParcel(mWindowPtr, dest);
 
         if ((flags & Parcelable.PARCELABLE_WRITE_RETURN_VALUE) != 0) {
             releaseReference();
diff --git a/core/java/android/database/IBulkCursor.java b/core/java/android/database/IBulkCursor.java
index 244c88f..7c96797 100644
--- a/core/java/android/database/IBulkCursor.java
+++ b/core/java/android/database/IBulkCursor.java
@@ -56,7 +56,7 @@ public interface IBulkCursor extends IInterface  {
 
     public void close() throws RemoteException;
 
-    public int requery(IContentObserver observer, CursorWindow window) throws RemoteException;
+    public int requery(IContentObserver observer) throws RemoteException;
 
     boolean getWantsAllOnMoveCalls() throws RemoteException;
 
diff --git a/core/java/android/database/sqlite/SQLiteCursor.java b/core/java/android/database/sqlite/SQLiteCursor.java
index 9d7e152..a1c36e2 100644
--- a/core/java/android/database/sqlite/SQLiteCursor.java
+++ b/core/java/android/database/sqlite/SQLiteCursor.java
@@ -155,7 +155,7 @@ public class SQLiteCursor extends AbstractWindowedCursor {
     }
 
     private void fillWindow(int startPos) {
-        clearOrCreateLocalWindow();
+        clearOrCreateLocalWindow(getDatabase().getPath());
         mWindow.setStartPosition(startPos);
         int count = getQuery().fillWindow(mWindow);
         if (startPos == 0) { // fillWindow returns count(*) only for startPos = 0