Source/WebCore/dom/ScriptRunner.cpp

/*
 * Copyright (C) 2010 Google, Inc. All rights reserved.
 * Copyright (C) 2011-2025 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:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 APPLE INC. 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 "ScriptRunner.h"

#include "Document.h"
#include "Element.h"
#include "PendingScript.h"
#include "ScriptElement.h"
#include <wtf/TZoneMallocInlines.h>

namespace WebCore {

WTF_MAKE_TZONE_ALLOCATED_IMPL(ScriptRunner);

ScriptRunner::ScriptRunner(Document& document)
    : m_document(document)
    , m_timer(*this, &ScriptRunner::timerFired)
{
}

ScriptRunner::~ScriptRunner()
{
    Ref document = m_document.get();
    for (auto& pendingScript : m_scriptsToExecuteSoon) {
        UNUSED_PARAM(pendingScript);
        document->decrementLoadEventDelayCount();
    }
    for (auto& pendingScript : m_scriptsToExecuteInOrder) {
        if (pendingScript->watchingForLoad())
            pendingScript->clearClient();
        document->decrementLoadEventDelayCount();
    }
    for (auto& pendingScript : m_pendingAsyncScripts) {
        if (pendingScript->watchingForLoad())
            pendingScript->clearClient();
        document->decrementLoadEventDelayCount();
    }
}

void ScriptRunner::ref() const
{
    m_document->ref();
}

void ScriptRunner::deref() const
{
    m_document->deref();
}

void ScriptRunner::queueScriptForExecution(ScriptElement& scriptElement, LoadableScript& loadableScript, ExecutionType executionType)
{
    ASSERT(scriptElement.element().isConnected());

    m_document->incrementLoadEventDelayCount();

    Ref pendingScript = PendingScript::create(scriptElement, loadableScript);
    switch (executionType) {
    case ASYNC_EXECUTION:
        m_pendingAsyncScripts.add(pendingScript.copyRef());
        break;
    case IN_ORDER_EXECUTION:
        m_scriptsToExecuteInOrder.append(pendingScript.copyRef());
        break;
    }
    pendingScript->setClient(*this);
}

void ScriptRunner::suspend()
{
    m_timer.stop();
}

void ScriptRunner::resume()
{
    if (hasPendingScripts() && !m_document->hasActiveParserYieldToken())
        m_timer.startOneShot(0_s);
}

void ScriptRunner::documentFinishedParsing()
{
    if (!m_scriptsToExecuteSoon.isEmpty() && !m_timer.isActive())
        resume();
}

void ScriptRunner::notifyFinished(PendingScript& pendingScript)
{
    if (pendingScript.element().willExecuteInOrder())
        ASSERT(!m_scriptsToExecuteInOrder.isEmpty());
    else
        m_scriptsToExecuteSoon.append(m_pendingAsyncScripts.take(pendingScript).releaseNonNull());
    pendingScript.clearClient();

    if (!m_document->hasActiveParserYieldToken())
        m_timer.startOneShot(0_s);
}

void ScriptRunner::timerFired()
{
    Ref document = m_document.get();

    Vector<Ref<PendingScript>> scripts;

    if (document->shouldDeferAsynchronousScriptsUntilParsingFinishes()) {
        // Scripts not added by the parser are executed asynchronously and yet do not have the 'async' attribute set.
        // We only want to delay scripts that were explicitly marked as 'async' by the developer.
        m_scriptsToExecuteSoon.removeAllMatching([&](auto& pendingScript) {
            if (pendingScript->element().hasAsyncAttribute())
                return false;
            scripts.append(WTF::move(pendingScript));
            return true;
        });
    } else
        scripts.swap(m_scriptsToExecuteSoon);

    while (!m_scriptsToExecuteInOrder.isEmpty() && Ref { m_scriptsToExecuteInOrder.first() }->isLoaded())
        scripts.append(m_scriptsToExecuteInOrder.takeFirst());

    for (Ref script : scripts) {
        ASSERT(script->needsLoading());
        script->element().executePendingScript(script);
        document->decrementLoadEventDelayCount();
    }
}

void ScriptRunner::clearPendingScripts()
{
    m_scriptsToExecuteInOrder.clear();
    m_scriptsToExecuteSoon.clear();
    m_pendingAsyncScripts.clear();
}

} // namespace WebCore