void Resource::addClient(ResourceClient* client)
{
ASSERT(!isPurgeable());
if (m_preloadResult == PreloadNotReferenced) {
if (isLoaded())
m_preloadResult = PreloadReferencedWhileComplete;
else if (m_requestedFromNetworkingLayer)
m_preloadResult = PreloadReferencedWhileLoading;
else
m_preloadResult = PreloadReferenced;
}
if (!hasClients())
memoryCache()->makeLive(this);
if (!m_revalidatingRequest.isNull()) {
m_clients.add(client);
return;
}
// If we have existing data to send to the new client and the resource type supprts it, send it asynchronously.
if (!m_response.isNull() && !shouldSendCachedDataSynchronouslyForType(type()) && !m_needsSynchronousCacheHit) {
m_clientsAwaitingCallback.add(client);
ResourceCallback::callbackHandler()->schedule(this);
return;
}
m_clients.add(client);
didAddClient(client);
return;
}
void Resource::finishPendingClients()
{
// We're going to notify clients one by one. It is simple if the client does nothing.
// However there are a couple other things that can happen.
//
// 1. Clients can be added during the loop. Make sure they are not processed.
// 2. Clients can be removed during the loop. Make sure they are always available to be
// removed. Also don't call removed clients or add them back.
// Handle case (1) by saving a list of clients to notify. A separate list also ensure
// a client is either in m_clients or m_clientsAwaitingCallback.
Vector<ResourceClient*> clientsToNotify;
copyToVector(m_clientsAwaitingCallback, clientsToNotify);
for (const auto& client : clientsToNotify) {
// Handle case (2) to skip removed clients.
if (!m_clientsAwaitingCallback.remove(client))
continue;
m_clients.add(client);
didAddClient(client);
}
// It is still possible for the above loop to finish a new client synchronously.
// If there's no client waiting we should deschedule.
bool scheduled = ResourceCallback::callbackHandler()->isScheduled(this);
if (scheduled && m_clientsAwaitingCallback.isEmpty())
ResourceCallback::callbackHandler()->cancel(this);
// Prevent the case when there are clients waiting but no callback scheduled.
ASSERT(m_clientsAwaitingCallback.isEmpty() || scheduled);
}
void CachedResource::addClient(CachedResourceClient* client)
{
if (addClientToSet(client))
didAddClient(client);
}