Encapsulate |MemoryCacheEntry::m_resource| and refactor pruneDead/LiveResources

third_party/WebKit/Source/core/fetch/MemoryCache.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later version.
@@ skipping 57 matching lines @@
     visitor->trace(m_nextInLiveResourcesList);
     visitor->trace(m_previousInAllResourcesList);
     visitor->trace(m_nextInAllResourcesList);
 }
 
 void MemoryCacheEntry::dispose()
 {
     m_resource.clear();
 }
 
+Resource* MemoryCacheEntry::resource()
+{
+    return m_resource.get();
+}
+
 DEFINE_TRACE(MemoryCacheLRUList)
 {
     visitor->trace(m_head);
     visitor->trace(m_tail);
 }
 
 inline MemoryCache::MemoryCache()
     : m_inPruneResources(false)
     , m_prunePending(false)
     , m_maxPruneDeferralDelay(cMaxPruneDeferralDelay)
@@ skipping 101 matching lines @@
     if (!resourceURL.isValid() || resourceURL.isNull())
         return nullptr;
     ASSERT(!cacheIdentifier.isNull());
     ResourceMap* resources = m_resourceMaps.get(cacheIdentifier);
     if (!resources)
         return nullptr;
     KURL url = removeFragmentIdentifierIfNeeded(resourceURL);
     MemoryCacheEntry* entry = resources->get(url);
     if (!entry)
         return nullptr;
-    Resource* resource = entry->m_resource.get();
+    Resource* resource = entry->resource();
     if (resource && !resource->lock())
         return nullptr;
     return resource;
 }
 
 HeapVector<Member<Resource>> MemoryCache::resourcesForURL(const KURL& resourceURL)
 {
     ASSERT(WTF::isMainThread());
     KURL url = removeFragmentIdentifierIfNeeded(resourceURL);
     HeapVector<Member<Resource>> results;
     for (const auto& resourceMapIter : m_resourceMaps) {
         if (MemoryCacheEntry* entry = resourceMapIter.value->get(url))
-            results.append(entry->m_resource.get());
+            results.append(entry->resource());
     }
     return results;
 }
 
 size_t MemoryCache::deadCapacity() const
 {
     // Dead resource capacity is whatever space is not occupied by live resources, bounded by an independent minimum and maximum.
     size_t capacity = m_capacity - std::min(m_liveSize, m_capacity); // Start with available capacity.
     capacity = std::max(capacity, m_minDeadCapacity); // Make sure it's above the minimum.
     capacity = std::min(capacity, m_maxDeadCapacity); // Make sure it's below the maximum.
@@ skipping 22 matching lines @@
     // and least recently accessed of the objects.
 
     // The list might not be sorted by the m_lastDecodedFrameTimeStamp. The impact
     // of this weaker invariant is minor as the below if statement to check the
     // elapsedTime will evaluate to false as the current time will be a lot
     // greater than the current->m_lastDecodedFrameTimeStamp.
     // For more details see: https://bugs.webkit.org/show_bug.cgi?id=30209
 
     MemoryCacheEntry* current = m_liveDecodedResources.m_tail;
     while (current) {
+        Resource* resource = current->resource();
         MemoryCacheEntry* previous = current->m_previousInLiveResourcesList;
-        ASSERT(current->m_resource->hasClientsOrObservers());
-        if (current->m_resource->isLoaded() && current->m_resource->decodedSize()) {
+        ASSERT(resource->hasClientsOrObservers());
+
+        if (resource->isLoaded() && resource->decodedSize()) {
             // Check to see if the remaining resources are too new to prune.
             double elapsedTime = m_pruneFrameTimeStamp - current->m_lastDecodedAccessTime;
             if (strategy == AutomaticPrune && elapsedTime < m_delayBeforeLiveDecodedPrune)
                 return;
 
             // Destroy our decoded data if possible. This will remove us
             // from m_liveDecodedResources, and possibly move us to a
             // different LRU list in m_allResources.
-            current->m_resource->prune();
+            resource->prune();
 
             if (targetSize && m_liveSize <= targetSize)
                 return;
         }
         current = previous;
     }
 }
 
 void MemoryCache::pruneDeadResources(PruneStrategy strategy)
 {
     size_t capacity = deadCapacity();
     if (strategy == MaximalPrune)
         capacity = 0;
     if (!m_deadSize || (capacity && m_deadSize <= capacity))
         return;
 
     size_t targetSize = static_cast<size_t>(capacity * cTargetPrunePercentage); // Cut by a percentage to avoid immediately pruning again.
 
     int size = m_allResources.size();
     if (targetSize && m_deadSize <= targetSize)
         return;
 
     bool canShrinkLRULists = true;
     for (int i = size - 1; i >= 0; i--) {
         // Remove from the tail, since this is the least frequently accessed of the objects.
         MemoryCacheEntry* current = m_allResources[i].m_tail;
-        if (current) {
-            ASSERT(current->m_resource);
-            ASSERT(contains(current->m_resource.get()));
-        }
 
         // First flush all the decoded data in this queue.
         while (current) {
+            Resource* resource = current->resource();
             MemoryCacheEntry* previous = current->m_previousInAllResourcesList;
-            if (previous) {
-                ASSERT(previous->m_resource);
-                ASSERT(contains(previous->m_resource.get()));
+
+            // Decoded data may reference other resources. Skip |current| if
+            // |current| somehow got kicked out of cache during
+            // destroyDecodedData().
+            if (!resource || !contains(resource)) {
+                current = previous;
+                continue;
             }
-            if (!current->m_resource->hasClientsOrObservers() && !current->m_resource->isPreloaded() && current->m_resource->isLoaded()) {
+
+            if (!resource->hasClientsOrObservers() && !resource->isPreloaded() && resource->isLoaded()) {
                 // Destroy our decoded data. This will remove us from
                 // m_liveDecodedResources, and possibly move us to a different
                 // LRU list in m_allResources.
-                current->m_resource->prune();
+                resource->prune();
 
                 if (targetSize && m_deadSize <= targetSize)
                     return;
             }
-            // Decoded data may reference other resources. Stop iterating if 'previous' somehow got
-            // kicked out of cache during destroyDecodedData().
-            if (!previous || !previous->m_resource || !contains(previous->m_resource.get()))
-                break;
             current = previous;
         }
 
         // Now evict objects from this queue.
         current = m_allResources[i].m_tail;
-        if (current) {
-            ASSERT(current->m_resource);
-            ASSERT(contains(current->m_resource.get()));
-        }
         while (current) {
+            Resource* resource = current->resource();
             MemoryCacheEntry* previous = current->m_previousInAllResourcesList;
-            if (previous) {
-                ASSERT(previous->m_resource);
-                ASSERT(contains(previous->m_resource.get()));
+            if (!resource || !contains(resource)) {
+                current = previous;
+                continue;
             }
-            if (!current->m_resource->hasClientsOrObservers() && !current->m_resource->isPreloaded()) {
+            if (!resource->hasClientsOrObservers() && !resource->isPreloaded()) {
                 evict(current);
                 if (targetSize && m_deadSize <= targetSize)
                     return;
             }
-            if (!previous || !previous->m_resource || !contains(previous->m_resource.get()))
-                break;
             current = previous;
         }
 
         // Shrink the vector back down so we don't waste time inspecting
         // empty LRU lists on future prunes.
         if (m_allResources[i].m_head)
             canShrinkLRULists = false;
         else if (canShrinkLRULists)
             m_allResources.resize(i);
     }
 }
 
 void MemoryCache::setCapacities(size_t minDeadBytes, size_t maxDeadBytes, size_t totalBytes)
 {
     ASSERT(minDeadBytes <= maxDeadBytes);
     ASSERT(maxDeadBytes <= totalBytes);
     m_minDeadCapacity = minDeadBytes;
     m_maxDeadCapacity = maxDeadBytes;
     m_maxDeferredPruneDeadCapacity = cDeferredPruneDeadCapacityFactor * maxDeadBytes;
     m_capacity = totalBytes;
     prune();
 }
 
 void MemoryCache::evict(MemoryCacheEntry* entry)
 {
     ASSERT(WTF::isMainThread());
 
-    Resource* resource = entry->m_resource.get();
+    Resource* resource = entry->resource();
     WTF_LOG(ResourceLoading, "Evicting resource %p for '%s' from cache", resource, resource->url().getString().latin1().data());
     // The resource may have already been removed by someone other than our caller,
     // who needed a fresh copy for a reload. See <http://bugs.webkit.org/show_bug.cgi?id=12479#c6>.
     update(resource, resource->size(), 0, false);
     removeFromLiveDecodedResourcesList(entry);
 
     ResourceMap* resources = m_resourceMaps.get(resource->cacheIdentifier());
     ASSERT(resources);
     KURL url = removeFragmentIdentifierIfNeeded(resource->url());
     ResourceMap::iterator it = resources->find(url);
     ASSERT(it != resources->end());
 
     MemoryCacheEntry* entryPtr = it->value;
     resources->remove(it);
     if (entryPtr)
         entryPtr->dispose();
 }
 
 MemoryCacheEntry* MemoryCache::getEntryForResource(const Resource* resource) const
 {
     if (resource->url().isNull() || resource->url().isEmpty())
         return nullptr;
     ResourceMap* resources = m_resourceMaps.get(resource->cacheIdentifier());
     if (!resources)
         return nullptr;
     KURL url = removeFragmentIdentifierIfNeeded(resource->url());
     MemoryCacheEntry* entry = resources->get(url);
-    if (!entry || entry->m_resource != resource)
+    if (!entry || entry->resource() != resource)
         return nullptr;
     return entry;
 }
 
 MemoryCacheLRUList* MemoryCache::lruListFor(unsigned accessCount, size_t size)
 {
     ASSERT(accessCount > 0);
     unsigned queueIndex = WTF::fastLog2(size / accessCount);
     if (m_allResources.size() <= queueIndex)
         m_allResources.grow(queueIndex + 1);
@@ skipping 191 matching lines @@
     encodedSize += o->encodedSize();
     encodedSizeDuplicatedInDataURLs += o->url().protocolIsData() ? o->encodedSize() : 0;
     purgeableSize += purgeable ? pageSize : 0;
 }
 
 MemoryCache::Statistics MemoryCache::getStatistics()
 {
     Statistics stats;
     for (const auto& resourceMapIter : m_resourceMaps) {
         for (const auto& resourceIter : *resourceMapIter.value) {
-            Resource* resource = resourceIter.value->m_resource.get();
+            Resource* resource = resourceIter.value->resource();
             switch (resource->getType()) {
             case Resource::Image:
                 stats.images.addResource(resource);
                 break;
             case Resource::CSSStyleSheet:
                 stats.cssStyleSheets.addResource(resource);
                 break;
             case Resource::Script:
                 stats.scripts.addResource(resource);
                 break;
@@ skipping 109 matching lines @@
 
 void MemoryCache::updateFramePaintTimestamp()
 {
     m_lastFramePaintTimeStamp = currentTime();
 }
 
 void MemoryCache::onMemoryDump(WebMemoryDumpLevelOfDetail levelOfDetail, WebProcessMemoryDump* memoryDump)
 {
     for (const auto& resourceMapIter : m_resourceMaps) {
         for (const auto& resourceIter : *resourceMapIter.value) {
-            Resource* resource = resourceIter.value->m_resource.get();
+            Resource* resource = resourceIter.value->resource();
             resource->onMemoryDump(levelOfDetail, memoryDump);
         }
     }
 }
 
 bool MemoryCache::isInSameLRUListForTest(const Resource* x, const Resource* y)
 {
     MemoryCacheEntry* ex = getEntryForResource(x);
     MemoryCacheEntry* ey = getEntryForResource(y);
     ASSERT(ex);
@@ skipping 27 matching lines @@
 
 void MemoryCache::dumpLRULists(bool includeLive) const
 {
     printf("LRU-SP lists in eviction order (Kilobytes decoded, Kilobytes encoded, Access count, Referenced, isPurgeable):\n");
 
     int size = m_allResources.size();
     for (int i = size - 1; i >= 0; i--) {
         printf("\n\nList %d: ", i);
         MemoryCacheEntry* current = m_allResources[i].m_tail;
         while (current) {
-            Resource* currentResource = current->m_resource;
+            Resource* currentResource = current->resource();
             if (includeLive || !currentResource->hasClientsOrObservers())
                 printf("(%.1fK, %.1fK, %uA, %dR, %d); ", currentResource->decodedSize() / 1024.0f, (currentResource->encodedSize() + currentResource->overheadSize()) / 1024.0f, current->m_accessCount, currentResource->hasClientsOrObservers(), currentResource->isPurgeable());
 
             current = current->m_previousInAllResourcesList;
         }
     }
 }
 
 #endif // MEMORY_CACHE_STATS
 
 } // namespace blink