Notify resource caches when pixelref genID goes stale

tests/SkResourceCacheTest.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "Test.h"
 #include "SkBitmapCache.h"
 #include "SkCanvas.h"
@@ skipping 138 matching lines @@
 
     SkBitmap src;
     src.allocN32Pixels(5, 5);
     src.setImmutable();
 
     const SkMipMap* mipmap = SkMipMapCache::FindAndRef(src, cache);
     REPORTER_ASSERT(reporter, NULL == mipmap);
 
     mipmap = SkMipMapCache::AddAndRef(src, cache);
     REPORTER_ASSERT(reporter, mipmap);
+
+    {
+        const SkMipMap* mm = SkMipMapCache::FindAndRef(src, cache);
+        REPORTER_ASSERT(reporter, mm);
+        REPORTER_ASSERT(reporter, mm == mipmap);
+        mm->unref();
+    }
+
     check_data(reporter, mipmap, 2, kInCache, kLocked);
 
     mipmap->unref();
     // tricky, since technically after this I'm no longer an owner, but since the cache is
     // local, I know it won't get purged behind my back
     check_data(reporter, mipmap, 1, kInCache, kNotLocked);
 
     // find us again
     mipmap = SkMipMapCache::FindAndRef(src, cache);
     check_data(reporter, mipmap, 2, kInCache, kLocked);
 
     cache->purgeAll();
     check_data(reporter, mipmap, 1, kNotInCache, kLocked);
 
     mipmap->unref();
 }
 
+// In a multi-threaded run, we can't reliably assert that something is in the global cache
+// even if we just added it, since another thread might have caused a purge, hence we guard
+// those checks with this flag (to be defined only when run locally in 1 thread).
+//
+// Basically, only define this locally if you're testing single-threaded.
+//#define ONLY_WORKS_RELIABLY_SINGLE_THREADED_SINCE_CACHE_MAY_HAVE_BEEN_PURGED
+
+static void test_mipmap_notify(skiatest::Reporter* reporter, SkResourceCache* cache) {
+    const int N = 3;
+    SkBitmap src[N];
+    for (int i = 0; i < N; ++i) {
+        src[i].allocN32Pixels(5, 5);
+        src[i].setImmutable();
+        SkMipMapCache::AddAndRef(src[i], cache)->unref();
+    }
+
+    for (int i = 0; i < N; ++i) {
+        const SkMipMap* mipmap = SkMipMapCache::FindAndRef(src[i], cache);
+#ifdef ONLY_WORKS_RELIABLY_SINGLE_THREADED_SINCE_CACHE_MAY_HAVE_BEEN_PURGED
+        REPORTER_ASSERT(reporter, mipmap);
+#endif
+        SkSafeUnref(mipmap);
+
+        src[i].reset(); // delete the underlying pixelref, which *should* remove us from the cache
+
+        mipmap = SkMipMapCache::FindAndRef(src[i], cache);
+        REPORTER_ASSERT(reporter, !mipmap);
+    }
+}
+
+static void test_bitmap_notify(skiatest::Reporter* reporter, SkResourceCache* cache) {
+    const SkIRect subset = SkIRect::MakeWH(5, 5);
+    const int N = 3;
+    SkBitmap src[N], dst[N];
+    for (int i = 0; i < N; ++i) {
+        src[i].allocN32Pixels(5, 5);
+        src[i].setImmutable();
+        dst[i].allocN32Pixels(5, 5);
+        dst[i].setImmutable();
+        SkBitmapCache::Add(src[i].getGenerationID(), subset, dst[i], cache);
+    }
+
+    for (int i = 0; i < N; ++i) {
+        const uint32_t genID = src[i].getGenerationID();
+        SkBitmap result;
+        bool found = SkBitmapCache::Find(genID, subset, &result, cache);
+#ifdef ONLY_WORKS_RELIABLY_SINGLE_THREADED_SINCE_CACHE_MAY_HAVE_BEEN_PURGED
+        REPORTER_ASSERT(reporter, found);
+#endif
+
+        src[i].reset(); // delete the underlying pixelref, which *should* remove us from the cache
+
+        found = SkBitmapCache::Find(genID, subset, &result, cache);
+        REPORTER_ASSERT(reporter, !found);
+    }
+}
+
 DEF_TEST(BitmapCache_discarded_bitmap, reporter) {
     SkResourceCache::DiscardableFactory factory = SkResourceCache::GetDiscardableFactory();
     SkBitmap::Allocator* allocator = SkBitmapCache::GetAllocator();
     
     SkAutoTDelete<SkResourceCache> cache;
     if (factory) {
         cache.reset(SkNEW_ARGS(SkResourceCache, (factory)));
     } else {
         const size_t byteLimit = 100 * 1024;
         cache.reset(SkNEW_ARGS(SkResourceCache, (byteLimit)));
@@ skipping 26 matching lines @@
 
     make_bitmap(&cachedBitmap, SkImageInfo::MakeN32Premul(5, 5), allocator);
     cachedBitmap.setImmutable();
     cachedBitmap.unlockPixels();
 
     // We can add the bitmap back to the cache and find it again.
     REPORTER_ASSERT(reporter, SkBitmapCache::Add(cachedBitmap.getGenerationID(), rect, cachedBitmap, cache));
     REPORTER_ASSERT(reporter, SkBitmapCache::Find(cachedBitmap.getGenerationID(), rect, &bm, cache));
 
     test_mipmapcache(reporter, cache);
+    test_bitmap_notify(reporter, cache);
+    test_mipmap_notify(reporter, cache);
 }