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/*
* Copyright (C) 2010 Google, 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 "third_party/blink/renderer/core/html/parser/html_parser_scheduler.h"
#include "third_party/blink/public/platform/platform.h"
#include "third_party/blink/renderer/core/dom/document.h"
#include "third_party/blink/renderer/core/frame/local_frame_view.h"
#include "third_party/blink/renderer/core/html/parser/html_document_parser.h"
#include "third_party/blink/renderer/platform/scheduler/public/thread.h"
#include "third_party/blink/renderer/platform/scheduler/public/thread_scheduler.h"
#include "third_party/blink/renderer/platform/wtf/time.h"
namespace blink {
PumpSession::PumpSession(unsigned& nesting_level)
: NestingLevelIncrementer(nesting_level) {}
PumpSession::~PumpSession() = default;
SpeculationsPumpSession::SpeculationsPumpSession(unsigned& nesting_level)
: NestingLevelIncrementer(nesting_level),
start_time_(CurrentTime()),
processed_element_tokens_(0) {}
SpeculationsPumpSession::~SpeculationsPumpSession() = default;
inline double SpeculationsPumpSession::ElapsedTime() const {
return CurrentTime() - start_time_;
}
void SpeculationsPumpSession::AddedElementTokens(size_t count) {
processed_element_tokens_ += count;
}
HTMLParserScheduler::HTMLParserScheduler(
HTMLDocumentParser* parser,
scoped_refptr<base::SingleThreadTaskRunner> loading_task_runner)
: parser_(parser),
loading_task_runner_(std::move(loading_task_runner)),
is_paused_with_active_timer_(false) {}
HTMLParserScheduler::~HTMLParserScheduler() = default;
void HTMLParserScheduler::Trace(Visitor* visitor) {
visitor->Trace(parser_);
}
bool HTMLParserScheduler::IsScheduledForUnpause() const {
return is_paused_with_active_timer_ ||
cancellable_continue_parse_task_handle_.IsActive();
}
void HTMLParserScheduler::ScheduleForUnpause() {
DCHECK(!is_paused_with_active_timer_);
cancellable_continue_parse_task_handle_ =
PostCancellableTask(*loading_task_runner_, FROM_HERE,
WTF::Bind(&HTMLParserScheduler::ContinueParsing,
WrapWeakPersistent(this)));
}
void HTMLParserScheduler::Pause() {
DCHECK(!is_paused_with_active_timer_);
if (!cancellable_continue_parse_task_handle_.IsActive())
return;
is_paused_with_active_timer_ = true;
cancellable_continue_parse_task_handle_.Cancel();
}
void HTMLParserScheduler::Unpause() {
DCHECK(!cancellable_continue_parse_task_handle_.IsActive());
if (!is_paused_with_active_timer_)
return;
is_paused_with_active_timer_ = false;
ScheduleForUnpause();
}
void HTMLParserScheduler::Detach() {
cancellable_continue_parse_task_handle_.Cancel();
is_paused_with_active_timer_ = false;
}
inline bool HTMLParserScheduler::ShouldYield(
const SpeculationsPumpSession& session,
bool starting_script) const {
if (ThreadScheduler::Current()->ShouldYieldForHighPriorityWork())
return true;
const double kParserTimeLimit = 0.5;
if (session.ElapsedTime() > kParserTimeLimit)
return true;
// Yield if a lot of DOM work has been done in this session and a script tag
// is about to be parsed. This significantly improves render performance for
// documents that place their scripts at the bottom of the page. Yielding too
// often significantly slows down the parsing so a balance needs to be struck
// to only yield when enough changes have happened to make it worthwhile.
// Emperical testing shows that anything > ~40 and < ~200 gives all of the
// benefit without impacting parser performance, only adding a few yields per
// page but at just the right times.
const size_t kSufficientWork = 50;
if (starting_script && session.ProcessedElementTokens() > kSufficientWork)
return true;
return false;
}
bool HTMLParserScheduler::YieldIfNeeded(const SpeculationsPumpSession& session,
bool starting_script) {
if (ShouldYield(session, starting_script)) {
ScheduleForUnpause();
return true;
}
return false;
}
void HTMLParserScheduler::ForceUnpauseAfterYield() {
DCHECK(!cancellable_continue_parse_task_handle_.IsActive());
is_paused_with_active_timer_ = true;
}
void HTMLParserScheduler::ContinueParsing() {
parser_->ResumeParsingAfterYield();
}
} // namespace blink