// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "third_party/blink/renderer/controller/blink_leak_detector.h"

#include "mojo/public/cpp/bindings/strong_binding.h"
#include "third_party/blink/public/platform/platform.h"
#include "third_party/blink/renderer/bindings/core/v8/v8_binding_for_core.h"
#include "third_party/blink/renderer/bindings/core/v8/v8_gc_controller.h"
#include "third_party/blink/renderer/core/core_initializer.h"
#include "third_party/blink/renderer/core/css/css_default_style_sheets.h"
#include "third_party/blink/renderer/core/dom/document.h"
#include "third_party/blink/renderer/core/editing/spellcheck/spell_checker.h"
#include "third_party/blink/renderer/core/frame/local_frame.h"
#include "third_party/blink/renderer/core/frame/web_local_frame_impl.h"
#include "third_party/blink/renderer/core/page/page.h"
#include "third_party/blink/renderer/core/workers/dedicated_worker_messaging_proxy.h"
#include "third_party/blink/renderer/core/workers/worker_thread.h"
#include "third_party/blink/renderer/platform/bindings/v8_per_isolate_data.h"
#include "third_party/blink/renderer/platform/instance_counters.h"
#include "third_party/blink/renderer/platform/loader/fetch/memory_cache.h"
#include "third_party/blink/renderer/platform/loader/fetch/resource_fetcher.h"

namespace blink {

BlinkLeakDetector::BlinkLeakDetector()
    : delayed_gc_timer_(Thread::Current()->GetTaskRunner(),
                        this,
                        &BlinkLeakDetector::TimerFiredGC) {}

BlinkLeakDetector::~BlinkLeakDetector() = default;

// static
void BlinkLeakDetector::Create(mojom::blink::LeakDetectorRequest request) {
  mojo::MakeStrongBinding(std::make_unique<BlinkLeakDetector>(),
                          std::move(request));
}

void BlinkLeakDetector::PerformLeakDetection(
    PerformLeakDetectionCallback callback) {
  callback_ = std::move(callback);

  v8::Isolate* isolate = v8::Isolate::GetCurrent();
  v8::HandleScope handle_scope(isolate);

  // For example, calling isValidEmailAddress in EmailInputType.cpp with a
  // non-empty string creates a static ScriptRegexp value which holds a
  // V8PerContextData indirectly. This affects the number of V8PerContextData.
  // To ensure that context data is created, call ensureScriptRegexpContext
  // here.
  V8PerIsolateData::From(isolate)->EnsureScriptRegexpContext();

  WorkerThread::TerminateAllWorkersForTesting();
  GetMemoryCache()->EvictResources();

  // If the spellchecker is allowed to continue issuing requests while the
  // leak detector runs, leaks may flakily be reported as the requests keep
  // their associated element (and document) alive.
  //
  // Stop the spellchecker to prevent this.
  // Currently PrepareForLeakDetection takes frame to get the spellchecker,
  // but in the future when leak detection runs with multiple frames,
  // this code must be refactored so that it iterates thru all the frames.
  for (Page* page : Page::OrdinaryPages()) {
    for (Frame* frame = page->MainFrame(); frame;
         frame = frame->Tree().TraverseNext()) {
      if (!frame->IsLocalFrame())
        continue;
      ToLocalFrame(frame)->GetSpellChecker().PrepareForLeakDetection();
    }
  }

  // FIXME: HTML5 Notification should be closed because notification affects
  // the result of number of DOM objects.
  V8PerIsolateData::From(isolate)->ClearScriptRegexpContext();

  // Clear lazily loaded style sheets.
  CSSDefaultStyleSheets::Instance().PrepareForLeakDetection();

  // Stop keepalive loaders that may persist after page navigation.
  for (auto resource_fetcher : ResourceFetcher::MainThreadFetchers())
    resource_fetcher->PrepareForLeakDetection();

  // Task queue may contain delayed object destruction tasks.
  // This method is called from navigation hook inside FrameLoader,
  // so previous document is still held by the loader until the next event loop.
  // Complete all pending tasks before proceeding to gc.
  number_of_gc_needed_ = 3;
  delayed_gc_timer_.StartOneShot(TimeDelta(), FROM_HERE);
}

void BlinkLeakDetector::TimerFiredGC(TimerBase*) {
  // Multiple rounds of GC are necessary as collectors may have postponed
  // clean-up tasks to the next event loop. E.g. the third GC is necessary for
  // cleaning up Document after the worker object has been reclaimed.

  V8GCController::CollectAllGarbageForTesting(
      V8PerIsolateData::MainThreadIsolate(),
      v8::EmbedderHeapTracer::EmbedderStackState::kEmpty);
  CoreInitializer::GetInstance().CollectAllGarbageForAnimationAndPaintWorklet();
  // Note: Oilpan precise GC is scheduled at the end of the event loop.

  // Inspect counters on the next event loop.
  if (--number_of_gc_needed_ > 0) {
    delayed_gc_timer_.StartOneShot(TimeDelta(), FROM_HERE);
  } else if (number_of_gc_needed_ > -1 &&
             DedicatedWorkerMessagingProxy::ProxyCount()) {
    // It is possible that all posted tasks for finalizing in-process proxy
    // objects will not have run before the final round of GCs started. If so,
    // do yet another pass, letting these tasks run and then afterwards perform
    // a GC to tidy up.
    //
    // TODO(sof): use proxyCount() to always decide if another GC needs to be
    // scheduled.  Some debug bots running browser unit tests disagree
    // (crbug.com/616714)
    delayed_gc_timer_.StartOneShot(TimeDelta(), FROM_HERE);
  } else {
    ReportResult();
  }
}

void BlinkLeakDetector::ReportResult() {
  mojom::blink::LeakDetectionResultPtr result =
      mojom::blink::LeakDetectionResult::New();
  result->number_of_live_audio_nodes =
      InstanceCounters::CounterValue(InstanceCounters::kAudioHandlerCounter);
  result->number_of_live_documents =
      InstanceCounters::CounterValue(InstanceCounters::kDocumentCounter);
  result->number_of_live_nodes =
      InstanceCounters::CounterValue(InstanceCounters::kNodeCounter);
  result->number_of_live_layout_objects =
      InstanceCounters::CounterValue(InstanceCounters::kLayoutObjectCounter);
  result->number_of_live_resources =
      InstanceCounters::CounterValue(InstanceCounters::kResourceCounter);
  result->number_of_live_pausable_objects =
      InstanceCounters::CounterValue(InstanceCounters::kPausableObjectCounter);
  result->number_of_live_script_promises =
      InstanceCounters::CounterValue(InstanceCounters::kScriptPromiseCounter);
  result->number_of_live_frames =
      InstanceCounters::CounterValue(InstanceCounters::kFrameCounter);
  result->number_of_live_v8_per_context_data = InstanceCounters::CounterValue(
      InstanceCounters::kV8PerContextDataCounter);
  result->number_of_worker_global_scopes = InstanceCounters::CounterValue(
      InstanceCounters::kWorkerGlobalScopeCounter);
  result->number_of_live_ua_css_resources =
      InstanceCounters::CounterValue(InstanceCounters::kUACSSResourceCounter);
  result->number_of_live_resource_fetchers =
      InstanceCounters::CounterValue(InstanceCounters::kResourceFetcherCounter);

#ifndef NDEBUG
  showLiveDocumentInstances();
#endif

  std::move(callback_).Run(std::move(result));
}

}  // namespace blink