1 files changed, 72 insertions, 15 deletions

diff --git a/src/com/android/gallery3d/data/MediaSet.java b/src/com/android/gallery3d/data/MediaSet.java
index 9bc148f89..cc8a4a71a 100644
--- a/src/com/android/gallery3d/data/MediaSet.java
+++ b/src/com/android/gallery3d/data/MediaSet.java
@@ -18,6 +18,8 @@ package com.android.gallery3d.data;
 
 import com.android.gallery3d.common.Utils;
 import com.android.gallery3d.util.Future;
+import com.android.gallery3d.util.ThreadPool.CancelListener;
+import com.android.gallery3d.util.ThreadPool.JobContext;
 
 import java.util.ArrayList;
 import java.util.WeakHashMap;
@@ -54,6 +56,9 @@ public abstract class MediaSet extends MediaObject {
         void onSyncDone(MediaSet mediaSet, int resultCode);
     }
 
+    private Object mLoadLock = new Object();
+    private boolean mIsLoading;
+
     public MediaSet(Path path, long version) {
         super(path, version);
     }
@@ -99,14 +104,6 @@ public abstract class MediaSet extends MediaObject {
         return false;
     }
 
-    /**
-     * Method {@link #reload()} may process the loading task in background, this method tells
-     * its client whether the loading is still in process or not.
-     */
-    public boolean isLoading() {
-        return false;
-    }
-
     public int getTotalMediaItemCount() {
         int total = getMediaItemCount();
         for (int i = 0, n = getSubMediaSetCount(); i < n; i++) {
@@ -176,15 +173,76 @@ public abstract class MediaSet extends MediaObject {
         }
     }
 
-    // Reload the content. Return the current data version. reload() should be called
-    // in the same thread as getMediaItem(int, int) and getSubMediaSet(int).
-    public abstract long reload();
+    // TODO: Remove this once createJobContextCompat is no longer needed
+    // Note that canceling a load is not strictly supported as it can leave
+    // MediaSets with bad internal state. Fortunately they are never canceled
+    // anywhere, so the isCancelled() exists purely for completeness sake
+    private static class LoadJobContextCompat implements JobContext {
+
+        @Override
+        public boolean isCancelled() {
+            return Thread.interrupted();
+        }
+
+        @Override
+        public void setCancelListener(CancelListener listener) {
+        }
+
+        @Override
+        public boolean setMode(int mode) {
+            return false;
+        }
+    }
+
+    @Deprecated
+    protected final JobContext createJobContextCompat() {
+        return new LoadJobContextCompat();
+    }
+
+    /**
+     * Synchronously load if the MediaSet is dirty. Note that this must be called
+     * on the same thread as getMediaItem(int, int) and getSubMediaSet(int)
+     * @return DataVersion
+     */
+    public final long loadIfDirty() {
+        try {
+            boolean doLoad = false;
+            synchronized (mLoadLock) {
+                if (mIsLoading) {
+                    mLoadLock.wait();
+                }
+                doLoad = isDirtyLocked();
+                if (doLoad) {
+                    mIsLoading = true;
+                }
+            }
+            if (doLoad) {
+                load();
+                synchronized (mLoadLock) {
+                    mDataVersion = nextVersionNumber();
+                    mIsLoading = false;
+                    mLoadLock.notifyAll();
+                }
+            }
+        } catch (InterruptedException ex) {
+        }
+        return getDataVersion();
+    }
+
+    /**
+     * Called inside of synchronized(mLoadLock). It is guaranteed this will only
+     * be called once before a call to load() if this returns true. It is
+     * acceptable to clear any internal dirty flags in this function as a result.
+     * @return true if the set wants a load() call, false otherwise
+     */
+    protected abstract boolean isDirtyLocked();
 
     /**
-     * Synchronously load if the MediaSet is dirty
-     * @return True if new data was loaded, false otherwise
+     * Synchronously load the MediaSet. Only called if {@link #isDirtyLocked()}
+     * returned true
+     * @throws InterruptedException if the load was interrupted
      */
-    public boolean loadIfDirty() { throw new IllegalStateException("not implemented"); }
+    protected abstract void load() throws InterruptedException;
 
     @Override
     public MediaDetails getDetails() {
@@ -283,7 +341,6 @@ public abstract class MediaSet extends MediaObject {
     }
 
     private class MultiSetSyncFuture implements Future<Integer>, SyncListener {
-        @SuppressWarnings("hiding")
         private static final String TAG = "Gallery.MultiSetSync";
 
         private final SyncListener mListener;