The Tor Browser: mobile/android/base/favicons/LoadFaviconTask.java@6474c204b198 (annotated)

mobile/android/base/favicons/LoadFaviconTask.java@6474c204b198 (annotated)

mobile/android/base/favicons/LoadFaviconTask.java

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 package org.mozilla.gecko.favicons;
 import android.content.ContentResolver;
 import android.graphics.Bitmap;
 import android.net.http.AndroidHttpClient;
 import android.os.Handler;
 import android.text.TextUtils;
 import android.util.Log;
 import org.apache.http.Header;
 import org.apache.http.HttpEntity;
 import org.apache.http.HttpResponse;
 import org.apache.http.client.methods.HttpGet;
 import org.mozilla.gecko.GeckoAppShell;
 import org.mozilla.gecko.db.BrowserDB;
 import org.mozilla.gecko.favicons.decoders.FaviconDecoder;
 import org.mozilla.gecko.favicons.decoders.LoadFaviconResult;
 import org.mozilla.gecko.util.GeckoJarReader;
 import org.mozilla.gecko.util.ThreadUtils;
 import org.mozilla.gecko.util.UiAsyncTask;
 import static org.mozilla.gecko.favicons.Favicons.context;
 import java.io.IOException;
 import java.io.InputStream;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.concurrent.atomic.AtomicInteger;
 /**
  * Class representing the asynchronous task to load a Favicon which is not currently in the in-memory
  * cache.
  * The implementation initially tries to get the Favicon from the database. Upon failure, the icon
  * is loaded from the internet.
  */
 public class LoadFaviconTask extends UiAsyncTask<Void, Void, Bitmap> {
     private static final String LOGTAG = "LoadFaviconTask";
     // Access to this map needs to be synchronized prevent multiple jobs loading the same favicon
     // from executing concurrently.
     private static final HashMap<String, LoadFaviconTask> loadsInFlight = new HashMap<String, LoadFaviconTask>();
     public static final int FLAG_PERSIST = 1;
     public static final int FLAG_SCALE = 2;
     private static final int MAX_REDIRECTS_TO_FOLLOW = 5;
     // The default size of the buffer to use for downloading Favicons in the event no size is given
     // by the server.
     private static final int DEFAULT_FAVICON_BUFFER_SIZE = 25000;
     private static AtomicInteger nextFaviconLoadId = new AtomicInteger(0);
     private int id;
     private String pageUrl;
     private String faviconURL;
     private OnFaviconLoadedListener listener;
     private int flags;
     private final boolean onlyFromLocal;
     // Assuming square favicons, judging by width only is acceptable.
     protected int targetWidth;
     private LinkedList<LoadFaviconTask> chainees;
     private boolean isChaining;
     static AndroidHttpClient httpClient = AndroidHttpClient.newInstance(GeckoAppShell.getGeckoInterface().getDefaultUAString());
     public LoadFaviconTask(Handler backgroundThreadHandler,
                            String pageUrl, String faviconUrl, int flags,
                            OnFaviconLoadedListener listener) {
         this(backgroundThreadHandler, pageUrl, faviconUrl, flags, listener, -1, false);
     }
     public LoadFaviconTask(Handler backgroundThreadHandler,
                            String pageUrl, String faviconUrl, int flags,
                            OnFaviconLoadedListener listener, int targetWidth, boolean onlyFromLocal) {
         super(backgroundThreadHandler);
         id = nextFaviconLoadId.incrementAndGet();
         this.pageUrl = pageUrl;
         this.faviconURL = faviconUrl;
         this.listener = listener;
         this.flags = flags;
         this.targetWidth = targetWidth;
         this.onlyFromLocal = onlyFromLocal;
     }
     // Runs in background thread
     private LoadFaviconResult loadFaviconFromDb() {
         ContentResolver resolver = context.getContentResolver();
         return BrowserDB.getFaviconForFaviconUrl(resolver, faviconURL);
     }
     // Runs in background thread
     private void saveFaviconToDb(final byte[] encodedFavicon) {
         if (encodedFavicon == null) {
             return;
         }
         if ((flags & FLAG_PERSIST) == 0) {
             return;
         }
         ContentResolver resolver = context.getContentResolver();
         BrowserDB.updateFaviconForUrl(resolver, pageUrl, encodedFavicon, faviconURL);
     }
     /**
      * Helper method for trying the download request to grab a Favicon.
      * @param faviconURI URL of Favicon to try and download
      * @return The HttpResponse containing the downloaded Favicon if successful, null otherwise.
      */
     private HttpResponse tryDownload(URI faviconURI) throws URISyntaxException, IOException {
         HashSet<String> visitedLinkSet = new HashSet<String>();
         visitedLinkSet.add(faviconURI.toString());
         return tryDownloadRecurse(faviconURI, visitedLinkSet);
     }
     private HttpResponse tryDownloadRecurse(URI faviconURI, HashSet<String> visited) throws URISyntaxException, IOException {
         if (visited.size() == MAX_REDIRECTS_TO_FOLLOW) {
             return null;
         }
         HttpGet request = new HttpGet(faviconURI);
         HttpResponse response = httpClient.execute(request);
         if (response == null) {
             return null;
         }
         if (response.getStatusLine() != null) {
             // Was the response a failure?
             int status = response.getStatusLine().getStatusCode();
             // Handle HTTP status codes requesting a redirect.
             if (status >= 300 && status < 400) {
                 Header header = response.getFirstHeader("Location");
                 // Handle mad webservers.
                 if (header == null) {
                     return null;
                 }
                 String newURI = header.getValue();
                 if (newURI == null || newURI.equals(faviconURI.toString())) {
                     return null;
                 }
                 if (visited.contains(newURI)) {
                     // Already been redirected here - abort.
                     return null;
                 }
                 visited.add(newURI);
                 return tryDownloadRecurse(new URI(newURI), visited);
             }
             if (status >= 400) {
                 return null;
             }
         }
         return response;
     }
     /**
      * Retrieve the specified favicon from the JAR, returning null if it's not
      * a JAR URI.
      */
     private static Bitmap fetchJARFavicon(String uri) {
         if (uri == null) {
             return null;
         }
         if (uri.startsWith("jar:jar:")) {
             Log.d(LOGTAG, "Fetching favicon from JAR.");
             try {
                 return GeckoJarReader.getBitmap(context.getResources(), uri);
             } catch (Exception e) {
                 // Just about anything could happen here.
                 Log.w(LOGTAG, "Error fetching favicon from JAR.", e);
                 return null;
             }
         }
         return null;
     }
     // Runs in background thread.
     // Does not attempt to fetch from JARs.
     private LoadFaviconResult downloadFavicon(URI targetFaviconURI) {
         if (targetFaviconURI == null) {
             return null;
         }
         // Only get favicons for HTTP/HTTPS.
         String scheme = targetFaviconURI.getScheme();
         if (!"http".equals(scheme) && !"https".equals(scheme)) {
             return null;
         }
         LoadFaviconResult result = null;
         try {
             result = downloadAndDecodeImage(targetFaviconURI);
         } catch (Exception e) {
             Log.e(LOGTAG, "Error reading favicon", e);
         }
         return result;
     }
     /**
      * Download the Favicon from the given URL and pass it to the decoder function.
      *
      * @param targetFaviconURL URL of the favicon to download.
      * @return A LoadFaviconResult containing the bitmap(s) extracted from the downloaded file, or
      *         null if no or corrupt data ware received.
      * @throws IOException If attempts to fully read the stream result in such an exception, such as
      *                     in the event of a transient connection failure.
      * @throws URISyntaxException If the underlying call to tryDownload retries and raises such an
      *                            exception trying a fallback URL.
      */
     private LoadFaviconResult downloadAndDecodeImage(URI targetFaviconURL) throws IOException, URISyntaxException {
         // Try the URL we were given.
         HttpResponse response = tryDownload(targetFaviconURL);
         if (response == null) {
             return null;
         }
         HttpEntity entity = response.getEntity();
         if (entity == null) {
             return null;
         }
         // This may not be provided, but if it is, it's useful.
         final long entityReportedLength = entity.getContentLength();
         int bufferSize;
         if (entityReportedLength > 0) {
             // The size was reported and sane, so let's use that.
             // Integer overflow should not be a problem for Favicon sizes...
             bufferSize = (int) entityReportedLength + 1;
         } else {
             // No declared size, so guess and reallocate later if it turns out to be too small.
             bufferSize = DEFAULT_FAVICON_BUFFER_SIZE;
         }
         // Allocate a buffer to hold the raw favicon data downloaded.
         byte[] buffer = new byte[bufferSize];
         // The offset of the start of the buffer's free space.
         int bPointer = 0;
         // The quantity of bytes the last call to read yielded.
         int lastRead = 0;
         InputStream contentStream = entity.getContent();
         try {
             // Fully read the entity into the buffer - decoding of streams is not supported
             // (and questionably pointful - what would one do with a half-decoded Favicon?)
             while (lastRead != -1) {
                 // Read as many bytes as are currently available into the buffer.
                 lastRead = contentStream.read(buffer, bPointer, buffer.length - bPointer);
                 bPointer += lastRead;
                 // If buffer has overflowed, double its size and carry on.
                 if (bPointer == buffer.length) {
                     bufferSize *= 2;
                     byte[] newBuffer = new byte[bufferSize];
                     // Copy the contents of the old buffer into the new buffer.
                     System.arraycopy(buffer, 0, newBuffer, 0, buffer.length);
                     buffer = newBuffer;
                 }
             }
         } finally {
             contentStream.close();
         }
         // Having downloaded the image, decode it.
         return FaviconDecoder.decodeFavicon(buffer, 0, bPointer + 1);
     }
     @Override
     protected Bitmap doInBackground(Void... unused) {
         if (isCancelled()) {
             return null;
         }
         String storedFaviconUrl;
         boolean isUsingDefaultURL = false;
         // Handle the case of malformed favicon URL.
         // If favicon is empty, fall back to the stored one.
         if (TextUtils.isEmpty(faviconURL)) {
             // Try to get the favicon URL from the memory cache.
             storedFaviconUrl = Favicons.getFaviconURLForPageURLFromCache(pageUrl);
             // If that failed, try to get the URL from the database.
             if (storedFaviconUrl == null) {
                 storedFaviconUrl = Favicons.getFaviconURLForPageURL(pageUrl);
                 if (storedFaviconUrl != null) {
                     // If that succeeded, cache the URL loaded from the database in memory.
                     Favicons.putFaviconURLForPageURLInCache(pageUrl, storedFaviconUrl);
                 }
             }
             // If we found a faviconURL - use it.
             if (storedFaviconUrl != null) {
                 faviconURL = storedFaviconUrl;
             } else {
                 // If we don't have a stored one, fall back to the default.
                 faviconURL = Favicons.guessDefaultFaviconURL(pageUrl);
                 if (TextUtils.isEmpty(faviconURL)) {
                     return null;
                 }
                 isUsingDefaultURL = true;
             }
         }
         // Check if favicon has failed - if so, give up. We need this check because, sometimes, we
         // didn't know the real Favicon URL until we asked the database.
         if (Favicons.isFailedFavicon(faviconURL)) {
             return null;
         }
         if (isCancelled()) {
             return null;
         }
         Bitmap image;
         // Determine if there is already an ongoing task to fetch the Favicon we desire.
         // If there is, just join the queue and wait for it to finish. If not, we carry on.
         synchronized(loadsInFlight) {
             // Another load of the current Favicon is already underway
             LoadFaviconTask existingTask = loadsInFlight.get(faviconURL);
             if (existingTask != null && !existingTask.isCancelled()) {
                 existingTask.chainTasks(this);
                 isChaining = true;
                 // If we are chaining, we want to keep the first task started to do this job as the one
                 // in the hashmap so subsequent tasks will add themselves to its chaining list.
                 return null;
             }
             // We do not want to update the hashmap if the task has chained - other tasks need to
             // chain onto the same parent task.
             loadsInFlight.put(faviconURL, this);
         }
         if (isCancelled()) {
             return null;
         }
         // If there are no valid bitmaps decoded, the returned LoadFaviconResult is null.
         LoadFaviconResult loadedBitmaps = loadFaviconFromDb();
         if (loadedBitmaps != null) {
             return pushToCacheAndGetResult(loadedBitmaps);
         }
         if (onlyFromLocal || isCancelled()) {
             return null;
         }
         // Let's see if it's in a JAR.
         image = fetchJARFavicon(faviconURL);
         if (imageIsValid(image)) {
             // We don't want to put this into the DB.
             Favicons.putFaviconInMemCache(faviconURL, image);
             return image;
         }
         try {
             loadedBitmaps = downloadFavicon(new URI(faviconURL));
         } catch (URISyntaxException e) {
             Log.e(LOGTAG, "The provided favicon URL is not valid");
             return null;
         } catch (Exception e) {
             Log.e(LOGTAG, "Couldn't download favicon.", e);
         }
         if (loadedBitmaps != null) {
             // Fetching bytes to store can fail. saveFaviconToDb will
             // do the right thing, but we still choose to cache the
             // downloaded icon in memory.
             saveFaviconToDb(loadedBitmaps.getBytesForDatabaseStorage());
             return pushToCacheAndGetResult(loadedBitmaps);
         }
         if (isUsingDefaultURL) {
             Favicons.putFaviconInFailedCache(faviconURL);
             return null;
         }
         if (isCancelled()) {
             return null;
         }
         // If we're not already trying the default URL, try it now.
         final String guessed = Favicons.guessDefaultFaviconURL(pageUrl);
         if (guessed == null) {
             Favicons.putFaviconInFailedCache(faviconURL);
             return null;
         }
         image = fetchJARFavicon(guessed);
         if (imageIsValid(image)) {
             // We don't want to put this into the DB.
             Favicons.putFaviconInMemCache(faviconURL, image);
             return image;
         }
         try {
             loadedBitmaps = downloadFavicon(new URI(guessed));
         } catch (Exception e) {
             // Not interesting. It was an educated guess, anyway.
             return null;
         }
         if (loadedBitmaps != null) {
             saveFaviconToDb(loadedBitmaps.getBytesForDatabaseStorage());
             return pushToCacheAndGetResult(loadedBitmaps);
         }
         return null;
     }
     /**
      * Helper method to put the result of a favicon load into the memory cache and then query the
      * cache for the particular bitmap we want for this request.
      * This call is certain to succeed, provided there was enough memory to decode this favicon.
      *
      * @param loadedBitmaps LoadFaviconResult to store.
      * @return The optimal favicon available to satisfy this LoadFaviconTask's request, or null if
      *         we are under extreme memory pressure and find ourselves dropping the cache immediately.
      */
     private Bitmap pushToCacheAndGetResult(LoadFaviconResult loadedBitmaps) {
         Favicons.putFaviconsInMemCache(faviconURL, loadedBitmaps.getBitmaps());
         Bitmap result = Favicons.getSizedFaviconFromCache(faviconURL, targetWidth);
         return result;
     }
     private static boolean imageIsValid(final Bitmap image) {
         return image != null &&
                image.getWidth() > 0 &&
                image.getHeight() > 0;
     }
     @Override
     protected void onPostExecute(Bitmap image) {
         if (isChaining) {
             return;
         }
         // Process the result, scale for the listener, etc.
         processResult(image);
         synchronized (loadsInFlight) {
             // Prevent any other tasks from chaining on this one.
             loadsInFlight.remove(faviconURL);
         }
         // Since any update to chainees is done while holding the loadsInFlight lock, once we reach
         // this point no further updates to that list can possibly take place (As far as other tasks
         // are concerned, there is no longer a task to chain from. The above block will have waited
         // for any tasks that were adding themselves to the list before reaching this point.)
         // As such, I believe we're safe to do the following without holding the lock.
         // This is nice - we do not want to take the lock unless we have to anyway, and chaining rarely
         // actually happens outside of the strange situations unit tests create.
         // Share the result with all chained tasks.
         if (chainees != null) {
             for (LoadFaviconTask t : chainees) {
                 // In the case that we just decoded multiple favicons, either we're passing the right
                 // image now, or the call into the cache in processResult will fetch the right one.
                 t.processResult(image);
             }
         }
     }
     private void processResult(Bitmap image) {
         Favicons.removeLoadTask(id);
         Bitmap scaled = image;
         // Notify listeners, scaling if required.
         if (targetWidth != -1 && image != null &&  image.getWidth() != targetWidth) {
             scaled = Favicons.getSizedFaviconFromCache(faviconURL, targetWidth);
         }
         Favicons.dispatchResult(pageUrl, faviconURL, scaled, listener);
     }
     @Override
     protected void onCancelled() {
         Favicons.removeLoadTask(id);
         synchronized(loadsInFlight) {
             // Only remove from the hashmap if the task there is the one that's being canceled.
             // Cancellation of a task that would have chained is not interesting to the hashmap.
             final LoadFaviconTask primary = loadsInFlight.get(faviconURL);
             if (primary == this) {
                 loadsInFlight.remove(faviconURL);
                 return;
             }
             if (primary == null) {
                 // This shouldn't happen.
                 return;
             }
             if (primary.chainees != null) {
               primary.chainees.remove(this);
             }
         }
         // Note that we don't call the listener callback if the
         // favicon load is cancelled.
     }
     /**
      * When the result of this job is ready, also notify the chainee of the result.
      * Used for aggregating concurrent requests for the same Favicon into a single actual request.
      * (Don't want to download a hundred instances of Google's Favicon at once, for example).
      * The loadsInFlight lock must be held when calling this function.
      *
      * @param aChainee LoadFaviconTask
      */
     private void chainTasks(LoadFaviconTask aChainee) {
         if (chainees == null) {
             chainees = new LinkedList<LoadFaviconTask>();
         }
         chainees.add(aChainee);
     }
     int getId() {
         return id;
     }
     static void closeHTTPClient() {
         // This work must be done on a background thread because it shuts down
         // the connection pool, which typically involves closing a connection --
         // which counts as network activity.
         if (ThreadUtils.isOnBackgroundThread()) {
             if (httpClient != null) {
                 httpClient.close();
             }
             return;
         }
         ThreadUtils.postToBackgroundThread(new Runnable() {
             @Override
             public void run() {
                 LoadFaviconTask.closeHTTPClient();
             }
         });
     }
 }

The Tor Browser / annotate

mobile/android/base/favicons/LoadFaviconTask.java@6474c204b198 (annotated)

mobile/android/base/favicons/LoadFaviconTask.java