notify resource caches when pixelref genID goes stale

src/core/SkResourceCache.cpp

Index: src/core/SkResourceCache.cpp
diff --git a/src/core/SkResourceCache.cpp b/src/core/SkResourceCache.cpp
index 4ed889a0aba3095900d934187f812f170217cca8..62263605dea187c95ca3864f31c9a776f2b2b7fb 100644
--- a/src/core/SkResourceCache.cpp
+++ b/src/core/SkResourceCache.cpp
@@ -61,6 +61,8 @@ void SkResourceCache::init() {
     // One of these should be explicit set by the caller after we return.
     fTotalByteLimit = 0;
     fDiscardableFactory = NULL;
+
+    fInsidePurgeAllCounter = 0;
 }
 
 #include "SkDiscardableMemory.h"
@@ -199,7 +201,7 @@ SkResourceCache::~SkResourceCache() {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-bool SkResourceCache::find(const Key& key, VisitorProc visitor, void* context) {
+bool SkResourceCache::find(const Key& key, FindVisitor visitor, void* context) {
     Rec* rec = fHash->find(key);
     if (rec) {
         if (visitor(*rec, context)) {
@@ -294,6 +296,34 @@ void SkResourceCache::purgeAsNeeded(bool forcePurge) {
     }
 }
 
+void SkResourceCache::purge(const void* nameSpace, PurgeVisitor proc, void* context) {
+    if (this->insidePurgeAll()) {
+        return;
+    }
+
+    // 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().getNamespace() == nameSpace) {
+            switch (proc(*rec, context)) {
+                case kRetainAndContinue_PurgeVisitorResult:
+                    break;
+                case kPurgeAndContinue_PurgeVisitorResult:
+                    this->remove(rec);
+                    break;
+                case kRetainAndStop_PurgeVisitorResult:
+                    return;
+                case kPurgeAndStop_PurgeVisitorResult:
+                    this->remove(rec);
+                    return;
+            }
+        }
+        rec = prev;
+    }
+}
+
 size_t SkResourceCache::setTotalByteLimit(size_t newLimit) {
     size_t prevLimit = fTotalByteLimit;
     fTotalByteLimit = newLimit;
@@ -532,12 +562,17 @@ size_t SkResourceCache::GetEffectiveSingleAllocationByteLimit() {
     return get_cache()->getEffectiveSingleAllocationByteLimit();
 }
 
+void SkResourceCache::Purge(const void* nameSpace, PurgeVisitor proc, void* context) {
+    SkAutoMutexAcquire am(gMutex);
+    return get_cache()->purge(nameSpace, proc, context);
+}
+
 void SkResourceCache::PurgeAll() {
     SkAutoMutexAcquire am(gMutex);
     return get_cache()->purgeAll();
 }
 
-bool SkResourceCache::Find(const Key& key, VisitorProc visitor, void* context) {
+bool SkResourceCache::Find(const Key& key, FindVisitor visitor, void* context) {
     SkAutoMutexAcquire am(gMutex);
     return get_cache()->find(key, visitor, context);
 }