void MemoryCache::pruneLiveResources() { unsigned capacity = liveCapacity(); if (!m_liveSize || (capacity && m_liveSize <= capacity)) return; unsigned targetSize = static_cast<unsigned>(capacity * cTargetPrunePercentage); // Cut by a percentage to avoid immediately pruning again. double currentTime = FrameView::currentPaintTimeStamp(); if (!currentTime) // In case prune is called directly, outside of a Frame paint. currentTime = WTF::currentTime(); // Destroy any decoded data in live objects that we can. // Start from the tail, since this is the lowest priority // and least recently accessed of the objects. // The list might not be sorted by the m_lastDecodedAccessTime. The impact // of this weaker invariant is minor as the below if statement to check the // elapsedTime will evaluate to false as the currentTime will be a lot // greater than the current->m_lastDecodedAccessTime. // For more details see: https://bugs.webkit.org/show_bug.cgi?id=30209 // Start pruning from the lowest priority list. for (int priority = Resource::CacheLiveResourcePriorityLow; priority <= Resource::CacheLiveResourcePriorityHigh; ++priority) { Resource* current = m_liveDecodedResources[priority].m_tail; while (current) { Resource* prev = current->m_prevInLiveResourcesList; ASSERT(current->hasClients()); if (current->isLoaded() && current->decodedSize()) { // Check to see if the remaining resources are too new to prune. double elapsedTime = currentTime - current->m_lastDecodedAccessTime; if (elapsedTime < m_delayBeforeLiveDecodedPrune) return; // Destroy our decoded data. This will remove us from // m_liveDecodedResources, and possibly move us to a different LRU // list in m_allResources. current->destroyDecodedData(); if (targetSize && m_liveSize <= targetSize) return; } current = prev; } } }
void MemoryCache::pruneDeadResources() { unsigned capacity = deadCapacity(); if (!m_deadSize || (capacity && m_deadSize <= capacity)) return; unsigned targetSize = static_cast<unsigned>(capacity * cTargetPrunePercentage); // Cut by a percentage to avoid immediately pruning again. int size = m_allResources.size(); // See if we have any purged resources we can evict. for (int i = 0; i < size; i++) { Resource* current = m_allResources[i].m_tail; while (current) { Resource* prev = current->m_prevInAllResourcesList; if (current->wasPurged()) { ASSERT(!current->hasClients()); ASSERT(!current->isPreloaded()); evict(current); } current = prev; } } 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. Resource* current = m_allResources[i].m_tail; // First flush all the decoded data in this queue. while (current) { // Protect 'previous' so it can't get deleted during destroyDecodedData(). ResourcePtr<Resource> previous = current->m_prevInAllResourcesList; ASSERT(!previous || previous->inCache()); if (!current->hasClients() && !current->isPreloaded() && current->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->destroyDecodedData(); 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->inCache()) break; current = previous.get(); } // Now evict objects from this queue. current = m_allResources[i].m_tail; while (current) { ResourcePtr<Resource> previous = current->m_prevInAllResourcesList; ASSERT(!previous || previous->inCache()); if (!current->hasClients() && !current->isPreloaded() && !current->isCacheValidator()) { evict(current); if (targetSize && m_deadSize <= targetSize) return; } if (previous && !previous->inCache()) break; current = previous.get(); } // 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); } }