void MemoryCache::pruneLiveResourcesToSize(unsigned targetSize)
{
if (m_inPruneResources)
return;
TemporaryChange<bool> reentrancyProtector(m_inPruneResources, true);
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 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
CachedResource* current = m_liveDecodedResources.m_tail;
while (current) {
CachedResource* 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 < cMinDelayBeforeLiveDecodedPrune)
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::pruneDeadResourcesToSize(unsigned targetSize)
{
if (m_inPruneResources)
return;
TemporaryChange<bool> reentrancyProtector(m_inPruneResources, true);
int size = m_allResources.size();
// See if we have any purged resources we can evict.
for (int i = 0; i < size; i++) {
CachedResource* current = m_allResources[i].m_tail;
while (current) {
CachedResource* 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.
CachedResource* 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().
CachedResourceHandle<CachedResource> 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) {
CachedResourceHandle<CachedResource> previous = current->m_prevInAllResourcesList;
ASSERT(!previous || previous->inCache());
if (!current->hasClients() && !current->isPreloaded() && !current->isCacheValidator()) {
if (!makeResourcePurgeable(current))
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);
}
}
