The Tor Browser: mobile/android/base/favicons/cache/FaviconCacheElement.java@b8a032363ba2

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

     1 /* This Source Code Form is subject to the terms of the Mozilla Public

     2  * License, v. 2.0. If a copy of the MPL was not distributed with this

     3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     5 package org.mozilla.gecko.favicons.cache;

     7 import android.graphics.Bitmap;

     9 /**

    10  * Objects stored in the Favicon cache - allow for the bitmap to be tagged to indicate if it has

    11  * been scaled. Unscaled bitmaps are not included in the scaled-bitmap cache's size calculation.

    12  */

    13 public class FaviconCacheElement implements Comparable<FaviconCacheElement> {

    14     // Was this Favicon computed via scaling another primary Favicon, or is this a primary Favicon?

    15     final boolean isPrimary;

    17     // The Favicon bitmap.

    18     Bitmap faviconPayload;

    20     // If set, faviconPayload is absent. Since the underlying ICO may contain multiple primary

    21     // payloads, primary payloads are never truly deleted from the cache, but instead have their

    22     // payload deleted and this flag set on their FaviconCacheElement. That way, the cache always

    23     // has a record of the existence of a primary payload, even if it is no longer in the cache.

    24     // This means that when a request comes in that will be best served using a primary that is in

    25     // the database but no longer cached, we know that it exists and can go get it (Useful when ICO

    26     // support is added).

    27     volatile boolean invalidated;

    29     final int imageSize;

    31     // Used for LRU pruning.

    32     final FaviconsForURL backpointer;

    34     public FaviconCacheElement(Bitmap payload, boolean primary, int size, FaviconsForURL backpointer) {

    35         this.faviconPayload = payload;

    36         this.isPrimary = primary;

    37         this.imageSize = size;

    38         this.backpointer = backpointer;

    39     }

    41     public FaviconCacheElement(Bitmap faviconPayload, boolean isPrimary, FaviconsForURL backpointer) {

    42         this.faviconPayload = faviconPayload;

    43         this.isPrimary = isPrimary;

    44         this.backpointer = backpointer;

    46         if (faviconPayload != null) {

    47             imageSize = faviconPayload.getWidth();

    48         } else {

    49             imageSize = 0;

    50         }

    51     }

    53     public int sizeOf() {

    54         if (invalidated) {

    55             return 0;

    56         }

    57         return faviconPayload.getRowBytes() * faviconPayload.getHeight();

    58     }

    60     /**

    61      * Establish an ordering on FaviconCacheElements based on size and validity. An element is

    62      * considered "greater than" another if it is valid and the other is not, or if it contains a

    63      * larger payload.

    64      *

    65      * @param another The FaviconCacheElement to compare to this one.

    66      * @return -1 if this element is less than the given one, 1 if the other one is larger than this

    67      *         and 0 if both are of equal value.

    68      */

    69     @Override

    70     public int compareTo(FaviconCacheElement another) {

    71         if (invalidated && !another.invalidated) {

    72             return -1;

    73         }

    75         if (!invalidated && another.invalidated) {

    76             return 1;

    77         }

    79         if (invalidated) {

    80             return 0;

    81         }

    83         final int w1 = imageSize;

    84         final int w2 = another.imageSize;

    85         if (w1 > w2) {

    86             return 1;

    87         } else if (w2 > w1) {

    88             return -1;

    89         }

    90         return 0;

    91     }

    93     /**

    94      * Called when this element is evicted from the cache.

    95      *

    96      * If primary, drop the payload and set invalid. If secondary, just unlink from parent node.

    97      */

    98     public void onEvictedFromCache() {

    99         if (isPrimary) {

   100             // So we keep a record of which primaries exist in the database for this URL, we

   101             // don't actually delete the entry for primaries. Instead, we delete their payload

   102             // and flag them as invalid. This way, we can later figure out that what a request

   103             // really want is one of the primaries that have been dropped from the cache, and we

   104             // can go get it.

   105             invalidated = true;

   106             faviconPayload = null;

   107         } else {

   108             // Secondaries don't matter - just delete them.

   109             if (backpointer == null) {

   110                 return;

   111             }

   112             backpointer.favicons.remove(this);

   113         }

   114     }

   115 }

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