only notify bitmaps that have been added to the cache

src/core/SkResourceCache.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkChecksum.h"
 #include "SkMessageBus.h"
 #include "SkMipMap.h"
@@ skipping 287 matching lines @@
         if (!forcePurge && fTotalBytesUsed < byteLimit && fCount < countLimit) {
             break;
         }
 
         Rec* prev = rec->fPrev;
         this->remove(rec);
         rec = prev;
     }
 }
 
+//#define SK_TRACK_PURGE_SHAREDID_HITRATE
+
+#ifdef SK_TRACK_PURGE_SHAREDID_HITRATE
+static int gPurgeCallCounter;
+static int gPurgeHitCounter;
+#endif
+
 void SkResourceCache::purgeSharedID(uint64_t sharedID) {
     if (0 == sharedID) {
         return;
     }
 
+#ifdef SK_TRACK_PURGE_SHAREDID_HITRATE
+    gPurgeCallCounter += 1;
+    bool found = false;
+#endif
     // go backwards, just like purgeAsNeeded, just to make the code similar.
     // could iterate either direction and still be correct.
     Rec* rec = fTail;
     while (rec) {
         Rec* prev = rec->fPrev;
         if (rec->getKey().getSharedID() == sharedID) {
 //            SkDebugf("purgeSharedID id=%llx rec=%p\n", sharedID, rec);
             this->remove(rec);
+#ifdef SK_TRACK_PURGE_SHAREDID_HITRATE
+            found = true;
+#endif
         }
         rec = prev;
     }
+
+#ifdef SK_TRACK_PURGE_SHAREDID_HITRATE
+    if (found) {
+        gPurgeHitCounter += 1;
+    }
+
+    SkDebugf("PurgeShared calls=%d hits=%d rate=%g\n", gPurgeCallCounter, gPurgeHitCounter,
+             gPurgeHitCounter * 100.0 / gPurgeCallCounter);
+#endif
 }
 
 size_t SkResourceCache::setTotalByteLimit(size_t newLimit) {
     size_t prevLimit = fTotalByteLimit;
     fTotalByteLimit = newLimit;
     if (newLimit < prevLimit) {
         this->purgeAsNeeded();
     }
     return prevLimit;
 }
@@ skipping 279 matching lines @@
 }
 
 size_t SkGraphics::SetResourceCacheSingleAllocationByteLimit(size_t newLimit) {
     return SkResourceCache::SetSingleAllocationByteLimit(newLimit);
 }
 
 void SkGraphics::PurgeResourceCache() {
     return SkResourceCache::PurgeAll();
 }