Implement issue # 3255887 could CursorLoader offer...

...to throttle contentobserver-based requeries

Why yes, I guess it could.

This also reworks AsyncTaskLoader to not generate multiple
concurrent tasks if it is getting change notifications before
the last background task is complete.

And removes some of the old APIs that had been deprecated but
need to be gone for final release.

And fixes a few little problems with applying the wrong theme
in system code.

Change-Id: Ic7a665b666d0fb9d348e5f23595532191065884f

1 files changed, 33 insertions, 18 deletions

diff --git a/core/java/android/content/Loader.java b/core/java/android/content/Loader.java
index ef81fe4e42d8..d63fe6915b8c 100644
--- a/core/java/android/content/Loader.java
+++ b/core/java/android/content/Loader.java
@@ -28,6 +28,13 @@ import java.io.PrintWriter;
  * they should monitor the source of their data and deliver new results when the contents
  * change.
  *
+ * <p><b>Note on threading:</b> Clients of loaders should as a rule perform
+ * any calls on to a Loader from the main thread of their process (that is,
+ * the thread the Activity callbacks and other things occur on).  Subclasses
+ * of Loader (such as {@link AsyncTaskLoader}) will often perform their work
+ * in a separate thread, but when delivering their results this too should
+ * be done on the main thread.</p>
+ *
  * <p>Subclasses generally must implement at least {@link #onStartLoading()},
  * {@link #onStopLoading()}, {@link #onForceLoad()}, and {@link #onReset()}.
  *
@@ -80,7 +87,7 @@ public class Loader<D> {
     /**
      * Sends the result of the load to the registered listener. Should only be called by subclasses.
      *
-     * Must be called from the UI thread.
+     * Must be called from the process's main thread.
      *
      * @param data the result of the load
      */
@@ -105,10 +112,11 @@ public class Loader<D> {
     }
 
     /**
-     * Registers a class that will receive callbacks when a load is complete. The callbacks will
-     * be called on the UI thread so it's safe to pass the results to widgets.
+     * Registers a class that will receive callbacks when a load is complete.
+     * The callback will be called on the process's main thread so it's safe to
+     * pass the results to widgets.
      *
-     * Must be called from the UI thread
+     * <p>Must be called from the process's main thread.
      */
     public void registerListener(int id, OnLoadCompleteListener<D> listener) {
         if (mListener != null) {
@@ -119,7 +127,9 @@ public class Loader<D> {
     }
 
     /**
-     * Must be called from the UI thread
+     * Remove a listener that was previously added with {@link #registerListener}.
+     *
+     * Must be called from the process's main thread.
      */
     public void unregisterListener(OnLoadCompleteListener<D> listener) {
         if (mListener == null) {
@@ -150,17 +160,19 @@ public class Loader<D> {
     }
 
     /**
-     * Starts an asynchronous load of the contacts list data. When the result is ready the callbacks
-     * will be called on the UI thread. If a previous load has been completed and is still valid
-     * the result may be passed to the callbacks immediately. The loader will monitor the source of
-     * the data set and may deliver future callbacks if the source changes. Calling
-     * {@link #stopLoading} will stop the delivery of callbacks.
+     * Starts an asynchronous load of the Loader's data. When the result
+     * is ready the callbacks will be called on the process's main thread.
+     * If a previous load has been completed and is still valid
+     * the result may be passed to the callbacks immediately.
+     * The loader will monitor the source of
+     * the data set and may deliver future callbacks if the source changes.
+     * Calling {@link #stopLoading} will stop the delivery of callbacks.
      *
      * <p>This updates the Loader's internal state so that
      * {@link #isStarted()} and {@link #isReset()} will return the correct
      * values, and then calls the implementation's {@link #onStartLoading()}.
      *
-     * <p>Must be called from the UI thread.
+     * <p>Must be called from the process's main thread.
      */
     public final void startLoading() {
         mStarted = true;
@@ -182,14 +194,15 @@ public class Loader<D> {
      * implementation's {@link #onForceLoad()}.  You generally should only call this
      * when the loader is started -- that is, {@link #isStarted()} returns true.
      *
-     * <p>Must be called from the UI thread.
+     * <p>Must be called from the process's main thread.
      */
-    public final void forceLoad() {
+    public void forceLoad() {
         onForceLoad();
     }
 
     /**
      * Subclasses must implement this to take care of requests to {@link #forceLoad()}.
+     * This will always be called from the process's main thread.
      */
     protected void onForceLoad() {
     }
@@ -206,9 +219,9 @@ public class Loader<D> {
      * {@link #isStarted()} will return the correct
      * value, and then calls the implementation's {@link #onStopLoading()}.
      *
-     * <p>Must be called from the UI thread.
+     * <p>Must be called from the process's main thread.
      */
-    public final void stopLoading() {
+    public void stopLoading() {
         mStarted = false;
         onStopLoading();
     }
@@ -217,6 +230,7 @@ public class Loader<D> {
      * Subclasses must implement this to take care of stopping their loader,
      * as per {@link #stopLoading()}.  This is not called by clients directly,
      * but as a result of a call to {@link #stopLoading()}.
+     * This will always be called from the process's main thread.
      */
     protected void onStopLoading() {
     }
@@ -231,9 +245,9 @@ public class Loader<D> {
      * {@link #isStarted()} and {@link #isReset()} will return the correct
      * values, and then calls the implementation's {@link #onReset()}.
      *
-     * <p>Must be called from the UI thread.
+     * <p>Must be called from the process's main thread.
      */
-    public final void reset() {
+    public void reset() {
         onReset();
         mReset = true;
         mStarted = false;
@@ -244,6 +258,7 @@ public class Loader<D> {
      * Subclasses must implement this to take care of resetting their loader,
      * as per {@link #reset()}.  This is not called by clients directly,
      * but as a result of a call to {@link #reset()}.
+     * This will always be called from the process's main thread.
      */
     protected void onReset() {
     }
@@ -265,7 +280,7 @@ public class Loader<D> {
      * if so, it simply calls {@link #forceLoad()}; otherwise, it sets a flag
      * so that {@link #takeContentChanged()} returns true.
      *
-     * <p>Must be called from the UI thread.
+     * <p>Must be called from the process's main thread.
      */
     public void onContentChanged() {
         if (mStarted) {