Exemplo n.º 1
0
void PaintController::checkUnderInvalidation(DisplayItemList::iterator& newIt, DisplayItemList::iterator& currentIt)
{
    ASSERT(RuntimeEnabledFeatures::slimmingPaintUnderInvalidationCheckingEnabled());
    ASSERT(newIt->isCached());

    // When under-invalidation-checking is enabled, the forced painting is following the cached display item.
    DisplayItem::Type nextItemType = DisplayItem::nonCachedType(newIt->type());
    ++newIt;
    ASSERT(newIt->type() == nextItemType);

    if (newIt->isDrawing()) {
        checkCachedDisplayItemIsUnchanged("", *newIt, *currentIt);
        return;
    }

    ASSERT(newIt->type() == DisplayItem::Subsequence);

#ifndef NDEBUG
    CString messagePrefix = String::format("(In CachedSubsequence of %s)", newIt->clientDebugString().utf8().data()).utf8();
#else
    CString messagePrefix = "(In CachedSubsequence)";
#endif

    DisplayItem::Id endSubsequenceId(newIt->client(), DisplayItem::EndSubsequence, 0);
    while (true) {
        ASSERT(newIt != m_newDisplayItemList.end());
        if (newIt->isCached())
            checkUnderInvalidation(newIt, currentIt);
        else
            checkCachedDisplayItemIsUnchanged(messagePrefix.data(), *newIt, *currentIt);

        if (endSubsequenceId.matches(*newIt))
            break;

        ++newIt;
        ++currentIt;
    }
}
// Update the existing display items by removing invalidated entries, updating
// repainted ones, and appending new items.
// - For CachedDisplayItem, copy the corresponding cached DrawingDisplayItem;
// - For SubtreeCachedDisplayItem, copy the cached display items between the
//   corresponding BeginSubtreeDisplayItem and EndSubtreeDisplayItem (incl.);
// - Otherwise, copy the new display item.
//
// The algorithm is O(|m_currentDisplayItems| + |m_newDisplayItems|).
// Coefficients are related to the ratio of out-of-order [Subtree]CachedDisplayItems
// and the average number of (Drawing|BeginSubtree)DisplayItems per client.
//
// TODO(pdr): Implement the DisplayListDiff algorithm for SlimmingPaintV2.
void DisplayItemList::commitNewDisplayItems(DisplayListDiff*)
{
    TRACE_EVENT2("blink,benchmark", "DisplayItemList::commitNewDisplayItems", "current_display_list_size", (int)m_currentDisplayItems.size(),
        "num_non_cached_new_items", (int)m_newDisplayItems.size() - m_numCachedItems);

    // These data structures are used during painting only.
    ASSERT(m_scopeStack.isEmpty());
    m_scopeStack.clear();
    m_nextScope = 1;
    ASSERT(!skippingCache());
#if ENABLE(ASSERT)
    m_newDisplayItemIndicesByClient.clear();
#endif

    if (m_currentDisplayItems.isEmpty()) {
#if ENABLE(ASSERT)
        for (const auto& item : m_newDisplayItems)
            ASSERT(!item.isCached());
#endif
        m_currentDisplayItems.swap(m_newDisplayItems);
        m_validlyCachedClientsDirty = true;
        m_numCachedItems = 0;
        return;
    }

    updateValidlyCachedClientsIfNeeded();

    // Stores indices to valid DrawingDisplayItems in m_currentDisplayItems that have not been matched
    // by CachedDisplayItems during synchronized matching. The indexed items will be matched
    // by later out-of-order CachedDisplayItems in m_newDisplayItems. This ensures that when
    // out-of-order CachedDisplayItems occur, we only traverse at most once over m_currentDisplayItems
    // looking for potential matches. Thus we can ensure that the algorithm runs in linear time.
    OutOfOrderIndexContext outOfOrderIndexContext(m_currentDisplayItems.begin());

#if ENABLE(ASSERT)
    if (RuntimeEnabledFeatures::slimmingPaintUnderInvalidationCheckingEnabled()) {
        // Under-invalidation checking requires a full index of m_currentDisplayItems.
        size_t i = 0;
        for (const auto& item : m_currentDisplayItems) {
            addItemToIndexIfNeeded(item, i, outOfOrderIndexContext.displayItemIndicesByClient);
            ++i;
        }
    }
#endif // ENABLE(ASSERT)

    // TODO(jbroman): Consider revisiting this heuristic.
    DisplayItems updatedList(
        kMaximumDisplayItemSize,
        std::max(m_currentDisplayItems.usedCapacityInBytes(), m_newDisplayItems.usedCapacityInBytes()));
    DisplayItems::iterator currentIt = m_currentDisplayItems.begin();
    DisplayItems::iterator currentEnd = m_currentDisplayItems.end();
    for (DisplayItems::iterator newIt = m_newDisplayItems.begin(); newIt != m_newDisplayItems.end(); ++newIt) {
        const DisplayItem& newDisplayItem = *newIt;
        const DisplayItem::Id newDisplayItemId = newDisplayItem.nonCachedId();
        bool newDisplayItemHasCachedType = newDisplayItem.type() != newDisplayItemId.type;

        bool isSynchronized = currentIt != currentEnd && newDisplayItemId.matches(*currentIt);

        if (newDisplayItemHasCachedType) {
            ASSERT(!RuntimeEnabledFeatures::slimmingPaintUnderInvalidationCheckingEnabled());
            ASSERT(newDisplayItem.isCached());
            ASSERT(clientCacheIsValid(newDisplayItem.client()));
            if (!isSynchronized) {
                DisplayItems::iterator foundIt = findOutOfOrderCachedItem(currentIt, newDisplayItemId, outOfOrderIndexContext);

                if (foundIt == currentEnd) {
#ifndef NDEBUG
                    showDebugData();
                    WTFLogAlways("%s not found in m_currentDisplayItems\n", newDisplayItem.asDebugString().utf8().data());
#endif
                    ASSERT_NOT_REACHED();

                    // If foundIt == currentEnd, it means that we did not find the cached display item. This should be impossible, but may occur
                    // if there is a bug in the system, such as under-invalidation, incorrect cache checking or duplicate display ids. In this case,
                    // attempt to recover rather than crashing or bailing on display of the rest of the display list.
                    continue;
                }

                ASSERT(foundIt != currentIt); // because we are in 'if (!isSynchronized)'
                currentIt = foundIt;
            }

            if (newDisplayItem.isCachedDrawing()) {
                updatedList.appendByMoving(*currentIt, currentIt->derivedSize());
                ++currentIt;
            } else {
                ASSERT(newDisplayItem.isCachedSubtree());
                copyCachedSubtree(currentIt, updatedList);
                ASSERT(updatedList.last().isEndSubtree());
            }
        } else {
#if ENABLE(ASSERT)
            if (RuntimeEnabledFeatures::slimmingPaintUnderInvalidationCheckingEnabled())
                checkCachedDisplayItemIsUnchanged(newDisplayItem, outOfOrderIndexContext.displayItemIndicesByClient);
            else
                ASSERT(!newDisplayItem.isDrawing() || newDisplayItem.skippedCache() || !clientCacheIsValid(newDisplayItem.client()));
#endif // ENABLE(ASSERT)
            updatedList.appendByMoving(*newIt, newIt->derivedSize());

            if (isSynchronized)
                ++currentIt;
        }
    }

#if ENABLE(ASSERT)
    if (RuntimeEnabledFeatures::slimmingPaintUnderInvalidationCheckingEnabled())
        checkNoRemainingCachedDisplayItems();
#endif // ENABLE(ASSERT)

    m_newDisplayItems.clear();
    m_validlyCachedClientsDirty = true;
    m_currentDisplayItems.swap(updatedList);
    m_numCachedItems = 0;
}