When storing a cache, download images concurrently

Up to 5 downloads can happen simultaneously. Also, those downloads are
executed concurrently to static map requests if any.

4 files changed, 85 insertions, 29 deletions

diff --git a/main/src/cgeo/geocaching/Geocache.java b/main/src/cgeo/geocaching/Geocache.java
index 30ab55f..42b8f0a 100644
--- a/main/src/cgeo/geocaching/Geocache.java
+++ b/main/src/cgeo/geocaching/Geocache.java
@@ -1643,6 +1643,8 @@ public class Geocache implements ICache, IWaypoint {
 
             StaticMapsProvider.downloadMaps(cache);
 
+            imgGetter.waitForBackgroundLoading(handler);
+
             if (handler != null) {
                 handler.sendMessage(Message.obtain());
             }
diff --git a/main/src/cgeo/geocaching/network/HtmlImage.java b/main/src/cgeo/geocaching/network/HtmlImage.java
index 1f50bd7..774dbf6 100644
--- a/main/src/cgeo/geocaching/network/HtmlImage.java
+++ b/main/src/cgeo/geocaching/network/HtmlImage.java
@@ -6,6 +6,7 @@ import cgeo.geocaching.compatibility.Compatibility;
 import cgeo.geocaching.connector.ConnectorFactory;
 import cgeo.geocaching.files.LocalStorage;
 import cgeo.geocaching.list.StoredList;
+import cgeo.geocaching.utils.CancellableHandler;
 import cgeo.geocaching.utils.FileUtils;
 import cgeo.geocaching.utils.ImageUtils;
 import cgeo.geocaching.utils.Log;
@@ -15,6 +16,16 @@ import ch.boye.httpclientandroidlib.androidextra.Base64;
 import org.apache.commons.io.IOUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.eclipse.jdt.annotation.Nullable;
+import rx.Observable;
+import rx.Observable.OnSubscribeFunc;
+import rx.Observer;
+import rx.Scheduler;
+import rx.Subscription;
+import rx.concurrency.Schedulers;
+import rx.subjects.PublishSubject;
+import rx.subscriptions.CompositeSubscription;
+import rx.subscriptions.Subscriptions;
+import rx.util.functions.Func1;
 
 import android.content.res.Resources;
 import android.graphics.Bitmap;
@@ -32,6 +43,11 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.util.Date;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
 
 public class HtmlImage implements Html.ImageGetter {
 
@@ -65,6 +81,14 @@ public class HtmlImage implements Html.ImageGetter {
     final private int maxHeight;
     final private Resources resources;
 
+    // Background loading
+    final private PublishSubject<Observable<String>> loading = PublishSubject.create();
+    final Observable<String> waitForEnd = Observable.merge(loading).publish().refCount();
+    final CompositeSubscription subscription = new CompositeSubscription(waitForEnd.subscribe());
+    final private Scheduler downloadScheduler = Schedulers.executor(new ThreadPoolExecutor(5, 5, 5, TimeUnit.SECONDS,
+            new LinkedBlockingQueue<Runnable>()));
+    final private Set<String> downloading = new HashSet<String>();
+
     public HtmlImage(final String geocode, final boolean returnErrorImage, final int listId, final boolean onlySave) {
         this.geocode = geocode;
         this.returnErrorImage = returnErrorImage;
@@ -84,6 +108,46 @@ public class HtmlImage implements Html.ImageGetter {
     @Nullable
     @Override
     public BitmapDrawable getDrawable(final String url) {
+        if (!onlySave) {
+            return loadDrawable(url);
+        } else {
+            synchronized(downloading) {
+                if (!downloading.contains(url)) {
+                    loading.onNext(fetchDrawable(url).map(new Func1<BitmapDrawable, String>() {
+                        @Override
+                        public String call(final BitmapDrawable bitmapDrawable) {
+                            return url;
+                        }
+                    }));
+                    downloading.add(url);
+                }
+                return null;
+            }
+        }
+    }
+
+    public Observable<BitmapDrawable> fetchDrawable(final String url) {
+        return Observable.create(new OnSubscribeFunc<BitmapDrawable>() {
+            @Override
+            public Subscription onSubscribe(final Observer<? super BitmapDrawable> observer) {
+                if (!subscription.isUnsubscribed()) {
+                    observer.onNext(loadDrawable(url));
+                }
+                observer.onCompleted();
+                return Subscriptions.empty();
+            }
+        }).subscribeOn(downloadScheduler);
+    }
+
+    public void waitForBackgroundLoading(@Nullable final CancellableHandler handler) {
+        if (handler != null) {
+            handler.unsubscribeIfCancelled(subscription);
+        }
+        loading.onCompleted();
+        waitForEnd.toBlockingObservable().lastOrDefault(null);
+    }
+
+    private BitmapDrawable loadDrawable(final String url) {
         // Reject empty and counter images URL
         if (StringUtils.isBlank(url) || isCounter(url)) {
             return getTransparent1x1Image(resources);
diff --git a/main/src/cgeo/geocaching/ui/ImagesList.java b/main/src/cgeo/geocaching/ui/ImagesList.java
index fb2ac15..f564583 100644
--- a/main/src/cgeo/geocaching/ui/ImagesList.java
+++ b/main/src/cgeo/geocaching/ui/ImagesList.java
@@ -9,16 +9,8 @@ import cgeo.geocaching.utils.Log;
 
 import org.apache.commons.io.IOUtils;
 import org.apache.commons.lang3.StringUtils;
-
-import rx.Observable;
-import rx.Observable.OnSubscribeFunc;
-import rx.Observer;
-import rx.Scheduler;
-import rx.Subscription;
 import rx.android.concurrency.AndroidSchedulers;
-import rx.concurrency.Schedulers;
 import rx.subscriptions.CompositeSubscription;
-import rx.subscriptions.Subscriptions;
 import rx.util.functions.Action1;
 
 import android.app.Activity;
@@ -46,9 +38,6 @@ import java.io.FileOutputStream;
 import java.util.Collection;
 import java.util.LinkedList;
 import java.util.List;
-import java.util.concurrent.LinkedBlockingQueue;
-import java.util.concurrent.ThreadPoolExecutor;
-import java.util.concurrent.TimeUnit;
 
 public class ImagesList {
 
@@ -82,9 +71,6 @@ public class ImagesList {
     private final String geocode;
     private LinearLayout imagesView;
 
-    private Scheduler downloadScheduler = Schedulers.executor(new ThreadPoolExecutor(5, 5, 5, TimeUnit.SECONDS,
-            new LinkedBlockingQueue<Runnable>()));
-
     public ImagesList(final Activity activity, final String geocode) {
         this.activity = activity;
         this.geocode = geocode;
@@ -92,9 +78,10 @@ public class ImagesList {
     }
 
     public void loadImages(final View parentView, final List<Image> images, final boolean offline) {
-
         imagesView = (LinearLayout) parentView.findViewById(R.id.spoiler_list);
 
+        final HtmlImage imgGetter = new HtmlImage(geocode, true, offline ? StoredList.STANDARD_LIST_ID : StoredList.TEMPORARY_LIST_ID, false);
+
         for (final Image img : images) {
             final LinearLayout rowView = (LinearLayout) inflater.inflate(R.layout.cache_image_item, null);
             assert(rowView != null);
@@ -110,8 +97,7 @@ public class ImagesList {
                 descView.setVisibility(View.VISIBLE);
             }
 
-            subscriptions.add(loadImage(img, offline)
-                    .subscribeOn(downloadScheduler)
+            subscriptions.add(imgGetter.fetchDrawable(img.getUrl())
                     .observeOn(AndroidSchedulers.mainThread()).subscribe(new Action1<BitmapDrawable>() {
                         @Override
                         public void call(final BitmapDrawable image) {
@@ -123,18 +109,6 @@ public class ImagesList {
         }
     }
 
-    private Observable<BitmapDrawable> loadImage(final Image img, final boolean offline) {
-        return Observable.create(new OnSubscribeFunc<BitmapDrawable>() {
-            @Override
-            public Subscription onSubscribe(final Observer<? super BitmapDrawable> observer) {
-                final HtmlImage imgGetter = new HtmlImage(geocode, true, offline ? StoredList.STANDARD_LIST_ID : StoredList.TEMPORARY_LIST_ID, false);
-                observer.onNext(imgGetter.getDrawable(img.getUrl()));
-                observer.onCompleted();
-                return Subscriptions.empty();
-            }
-        });
-    }
-
     private void display(final BitmapDrawable image, final Image img, final LinearLayout view) {
         if (image != null) {
             bitmaps.add(image.getBitmap());
diff --git a/main/src/cgeo/geocaching/utils/CancellableHandler.java b/main/src/cgeo/geocaching/utils/CancellableHandler.java
index cb4b9db..01fb568 100644
--- a/main/src/cgeo/geocaching/utils/CancellableHandler.java
+++ b/main/src/cgeo/geocaching/utils/CancellableHandler.java
@@ -2,6 +2,9 @@ package cgeo.geocaching.utils;
 
 import cgeo.geocaching.CgeoApplication;
 
+import rx.Subscription;
+import rx.subscriptions.CompositeSubscription;
+
 import android.os.Handler;
 import android.os.Message;
 
@@ -13,6 +16,7 @@ public abstract class CancellableHandler extends Handler {
 
     protected static final int UPDATE_LOAD_PROGRESS_DETAIL = 42186;
     private volatile boolean cancelled = false;
+    private static CompositeSubscription subscriptions = new CompositeSubscription();
 
     private static class CancelHolder {
         final Object payload;
@@ -30,6 +34,7 @@ public abstract class CancellableHandler extends Handler {
 
         if (message.obj instanceof CancelHolder) {
             cancelled = true;
+            subscriptions.unsubscribe();
             handleCancel(((CancelHolder) message.obj).payload);
         } else {
             handleRegularMessage(message);
@@ -37,6 +42,17 @@ public abstract class CancellableHandler extends Handler {
     }
 
     /**
+     * Add a subscription to the list of subscriptions to be subscribed at cancellation time.
+     */
+    final public void unsubscribeIfCancelled(final Subscription subscription) {
+        subscriptions.add(subscription);
+        if (cancelled) {
+            // Protect against race conditions
+            subscriptions.unsubscribe();
+        }
+    }
+
+    /**
      * Handle a non-cancel message.<br>
      * Subclasses must implement this to handle messages.
      *