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/*
* Copyright (C) 2011 Google Inc. All rights reserved.
* Copyright (C) 2018 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "MutationObserver.h"
#include "Document.h"
#include "EventLoop.h"
#include "GCReachableRef.h"
#include "HTMLSlotElement.h"
#include "InspectorInstrumentation.h"
#include "Microtasks.h"
#include "MutationCallback.h"
#include "MutationObserverRegistration.h"
#include "MutationRecord.h"
#include <algorithm>
#include <wtf/IsoMallocInlines.h>
#include <wtf/MainThread.h>
#include <wtf/NeverDestroyed.h>
namespace WebCore {
WTF_MAKE_ISO_ALLOCATED_IMPL(MutationObserver);
static unsigned s_observerPriority = 0;
Ref<MutationObserver> MutationObserver::create(Ref<MutationCallback>&& callback)
{
ASSERT(isMainThread());
return adoptRef(*new MutationObserver(WTFMove(callback)));
}
MutationObserver::MutationObserver(Ref<MutationCallback>&& callback)
: m_callback(WTFMove(callback))
, m_priority(s_observerPriority++)
{
}
MutationObserver::~MutationObserver()
{
ASSERT(m_registrations.isEmpty());
}
bool MutationObserver::validateOptions(MutationObserverOptions options)
{
return (options & (Attributes | CharacterData | ChildList))
&& ((options & Attributes) || !(options & AttributeOldValue))
&& ((options & Attributes) || !(options & AttributeFilter))
&& ((options & CharacterData) || !(options & CharacterDataOldValue));
}
ExceptionOr<void> MutationObserver::observe(Node& node, const Init& init)
{
MutationObserverOptions options = 0;
if (init.childList)
options |= ChildList;
if (init.subtree)
options |= Subtree;
if (init.attributeOldValue.valueOr(false))
options |= AttributeOldValue;
if (init.characterDataOldValue.valueOr(false))
options |= CharacterDataOldValue;
HashSet<AtomString> attributeFilter;
if (init.attributeFilter) {
for (auto& value : init.attributeFilter.value())
attributeFilter.add(value);
options |= AttributeFilter;
}
if (init.attributes ? init.attributes.value() : (options & (AttributeFilter | AttributeOldValue)))
options |= Attributes;
if (init.characterData ? init.characterData.value() : (options & CharacterDataOldValue))
options |= CharacterData;
if (!validateOptions(options))
return Exception { TypeError };
node.registerMutationObserver(*this, options, attributeFilter);
return { };
}
auto MutationObserver::takeRecords() -> TakenRecords
{
return { WTFMove(m_records), WTFMove(m_pendingTargets) };
}
void MutationObserver::disconnect()
{
m_pendingTargets.clear();
m_records.clear();
HashSet<MutationObserverRegistration*> registrations(m_registrations);
for (auto* registration : registrations)
registration->node().unregisterMutationObserver(*registration);
}
void MutationObserver::observationStarted(MutationObserverRegistration& registration)
{
ASSERT(!m_registrations.contains(&registration));
m_registrations.add(&registration);
}
void MutationObserver::observationEnded(MutationObserverRegistration& registration)
{
ASSERT(m_registrations.contains(&registration));
m_registrations.remove(&registration);
}
typedef HashSet<RefPtr<MutationObserver>> MutationObserverSet;
static MutationObserverSet& activeMutationObservers()
{
static NeverDestroyed<MutationObserverSet> activeObservers;
return activeObservers;
}
static MutationObserverSet& suspendedMutationObservers()
{
static NeverDestroyed<MutationObserverSet> suspendedObservers;
return suspendedObservers;
}
// https://dom.spec.whatwg.org/#signal-slot-list
static Vector<GCReachableRef<HTMLSlotElement>>& signalSlotList()
{
static NeverDestroyed<Vector<GCReachableRef<HTMLSlotElement>>> list;
return list;
}
// This state must be per event loop.
static bool mutationObserverCompoundMicrotaskQueuedFlag = false;
void MutationObserver::queueMutationObserverCompoundMicrotask(Document& document)
{
if (mutationObserverCompoundMicrotaskQueuedFlag)
return;
mutationObserverCompoundMicrotaskQueuedFlag = true;
document.eventLoop().queueMicrotask([] {
notifyMutationObservers();
});
}
void MutationObserver::enqueueMutationRecord(Ref<MutationRecord>&& mutation)
{
ASSERT(isMainThread());
ASSERT(mutation->target());
auto document = makeRef(mutation->target()->document());
m_pendingTargets.add(*mutation->target());
m_records.append(WTFMove(mutation));
activeMutationObservers().add(this);
queueMutationObserverCompoundMicrotask(document.get());
}
void MutationObserver::enqueueSlotChangeEvent(HTMLSlotElement& slot)
{
ASSERT(isMainThread());
ASSERT(signalSlotList().findMatching([&slot](auto& entry) { return entry.ptr() == &slot; }) == notFound);
signalSlotList().append(slot);
queueMutationObserverCompoundMicrotask(slot.document());
}
void MutationObserver::setHasTransientRegistration(Document& document)
{
ASSERT(isMainThread());
activeMutationObservers().add(this);
queueMutationObserverCompoundMicrotask(document);
}
HashSet<Node*> MutationObserver::observedNodes() const
{
HashSet<Node*> observedNodes;
for (auto* registration : m_registrations)
registration->addRegistrationNodesToSet(observedNodes);
return observedNodes;
}
bool MutationObserver::canDeliver()
{
return m_callback->canInvokeCallback();
}
void MutationObserver::deliver()
{
ASSERT(canDeliver());
// Calling takeTransientRegistrations() can modify m_registrations, so it's necessary
// to make a copy of the transient registrations before operating on them.
Vector<MutationObserverRegistration*, 1> transientRegistrations;
Vector<std::unique_ptr<HashSet<GCReachableRef<Node>>>, 1> nodesToKeepAlive;
HashSet<GCReachableRef<Node>> pendingTargets;
pendingTargets.swap(m_pendingTargets);
for (auto* registration : m_registrations) {
if (registration->hasTransientRegistrations())
transientRegistrations.append(registration);
}
for (auto& registration : transientRegistrations)
nodesToKeepAlive.append(registration->takeTransientRegistrations());
if (m_records.isEmpty()) {
ASSERT(m_pendingTargets.isEmpty());
return;
}
Vector<Ref<MutationRecord>> records;
records.swap(m_records);
// FIXME: Keep mutation observer callback as long as its observed nodes are alive. See https://webkit.org/b/179224.
if (m_callback->hasCallback()) {
auto* context = m_callback->scriptExecutionContext();
if (!context)
return;
InspectorInstrumentation::willFireObserverCallback(*context, "MutationObserver"_s);
m_callback->handleEvent(*this, records, *this);
InspectorInstrumentation::didFireObserverCallback(*context);
}
}
void MutationObserver::notifyMutationObservers()
{
// https://dom.spec.whatwg.org/#notify-mutation-observers
// 1. Unset mutation observer compound microtask queued flag.
mutationObserverCompoundMicrotaskQueuedFlag = false;
ASSERT(isMainThread());
static bool deliveryInProgress = false;
if (deliveryInProgress)
return;
deliveryInProgress = true;
if (!suspendedMutationObservers().isEmpty()) {
for (auto& observer : copyToVector(suspendedMutationObservers())) {
if (!observer->canDeliver())
continue;
suspendedMutationObservers().remove(observer);
activeMutationObservers().add(observer);
}
}
while (!activeMutationObservers().isEmpty() || !signalSlotList().isEmpty()) {
// 2. Let notify list be a copy of unit of related similar-origin browsing contexts' list of MutationObserver objects.
auto notifyList = copyToVector(activeMutationObservers());
activeMutationObservers().clear();
std::sort(notifyList.begin(), notifyList.end(), [](auto& lhs, auto& rhs) {
return lhs->m_priority < rhs->m_priority;
});
// 3. Let signalList be a copy of unit of related similar-origin browsing contexts' signal slot list.
// 4. Empty unit of related similar-origin browsing contexts' signal slot list.
Vector<GCReachableRef<HTMLSlotElement>> slotList;
if (!signalSlotList().isEmpty()) {
slotList.swap(signalSlotList());
for (auto& slot : slotList)
slot->didRemoveFromSignalSlotList();
}
// 5. For each MutationObserver object mo in notify list, execute a compound microtask subtask
for (auto& observer : notifyList) {
if (observer->canDeliver())
observer->deliver();
else
suspendedMutationObservers().add(observer);
}
// 6. For each slot slot in signalList, in order, fire an event named slotchange, with its bubbles attribute set to true, at slot.
for (auto& slot : slotList)
slot->dispatchSlotChangeEvent();
}
deliveryInProgress = false;
}
} // namespace WebCore