/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "TimelineConsumers.h"

#include "mozilla/ClearOnShutdown.h"
#include "jsapi.h"
#include "nsAppRunner.h" // for XRE_IsContentProcess, XRE_IsParentProcess
#include "nsDocShell.h"

namespace mozilla {

NS_IMPL_ISUPPORTS(TimelineConsumers, nsIObserver);

StaticMutex TimelineConsumers::sMutex;

// Manually manage this singleton's lifetime and destroy it before shutdown.
// This avoids the leakchecker detecting false-positive memory leaks when
// using automatic memory management (i.e. statically instantiating this
// singleton inside the `Get` method), which would automatically destroy it on
// application shutdown, but too late for the leakchecker. Sigh...
StaticRefPtr<TimelineConsumers> TimelineConsumers::sInstance;

// This flag makes sure the singleton never gets instantiated while a shutdown
// is in progress. This can actually happen, and `ClearOnShutdown` doesn't work
// in these cases.
bool TimelineConsumers::sInShutdown = false;

already_AddRefed<TimelineConsumers>
TimelineConsumers::Get()
{
  // Using this class is not supported yet for other processes other than
  // parent or content. To avoid accidental checks to methods like `IsEmpty`,
  // which would probably always be true in those cases, assert here.
  // Remember, there will be different singletons available to each process.
  MOZ_ASSERT(XRE_IsContentProcess() || XRE_IsParentProcess());

  // If we are shutting down, don't bother doing anything. Note: we can only
  // know whether or not we're in shutdown if we're instantiated.
  if (sInShutdown) {
    return nullptr;
  }

  // Note: We don't simply check `sInstance` for null-ness here, since otherwise
  // this can resurrect the TimelineConsumers pretty late during shutdown.
  // We won't know if we're in shutdown or not though, because the singleton
  // could have been destroyed or just never instantiated, so in the previous
  // conditional `sInShutdown` would be false.
  static bool firstTime = true;
  if (firstTime) {
    firstTime = false;

    StaticMutexAutoLock lock(sMutex);
    sInstance = new TimelineConsumers();

    // Make sure the initialization actually suceeds, otherwise don't allow
    // access by destroying the instance immediately.
    if (sInstance->Init()) {
      ClearOnShutdown(&sInstance);
    } else {
      sInstance->RemoveObservers();
      sInstance = nullptr;
    }
  }

  RefPtr<TimelineConsumers> copy = sInstance.get();
  return copy.forget();
}

bool
TimelineConsumers::Init()
{
  nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
  if (!obs) {
    return false;
  }
  if (NS_WARN_IF(NS_FAILED(
    obs->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false)))) {
    return false;
  }
  return true;
}

bool
TimelineConsumers::RemoveObservers()
{
  nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
  if (!obs) {
    return false;
  }
  if (NS_WARN_IF(NS_FAILED(
    obs->RemoveObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID)))) {
    return false;
  }
  return true;
}

nsresult
TimelineConsumers::Observe(nsISupports* aSubject,
                           const char* aTopic,
                           const char16_t* aData)
{
  if (!nsCRT::strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID)) {
    sInShutdown = true;
    RemoveObservers();
    return NS_OK;
  }

  MOZ_ASSERT(false, "TimelineConsumers got unexpected topic!");
  return NS_ERROR_UNEXPECTED;
}

TimelineConsumers::TimelineConsumers()
  : mActiveConsumers(0)
{
}

void
TimelineConsumers::AddConsumer(nsDocShell* aDocShell)
{
  MOZ_ASSERT(NS_IsMainThread());
  StaticMutexAutoLock lock(sMutex); // for `mActiveConsumers` and `mMarkersStores`.

  UniquePtr<ObservedDocShell>& observed = aDocShell->mObserved;
  MOZ_ASSERT(!observed);

  if (mActiveConsumers == 0) {
    JS::SetProfileTimelineRecordingEnabled(true);
  }
  mActiveConsumers++;

  ObservedDocShell* obsDocShell = new ObservedDocShell(aDocShell);
  MarkersStorage* storage = static_cast<MarkersStorage*>(obsDocShell);

  observed.reset(obsDocShell);
  mMarkersStores.insertFront(storage);
}

void
TimelineConsumers::RemoveConsumer(nsDocShell* aDocShell)
{
  MOZ_ASSERT(NS_IsMainThread());
  StaticMutexAutoLock lock(sMutex); // for `mActiveConsumers` and `mMarkersStores`.

  UniquePtr<ObservedDocShell>& observed = aDocShell->mObserved;
  MOZ_ASSERT(observed);

  mActiveConsumers--;
  if (mActiveConsumers == 0) {
    JS::SetProfileTimelineRecordingEnabled(false);
  }

  // Clear all markers from the `mTimelineMarkers` store.
  observed.get()->ClearMarkers();
  // Remove self from the `mMarkersStores` store.
  observed.get()->remove();
  // Prepare for becoming a consumer later.
  observed.reset(nullptr);
}

bool
TimelineConsumers::HasConsumer(nsIDocShell* aDocShell)
{
  MOZ_ASSERT(NS_IsMainThread());
  return aDocShell
       ? aDocShell->GetRecordProfileTimelineMarkers()
       : false;
}

bool
TimelineConsumers::IsEmpty()
{
  StaticMutexAutoLock lock(sMutex); // for `mActiveConsumers`.
  return mActiveConsumers == 0;
}

void
TimelineConsumers::AddMarkerForDocShell(nsDocShell* aDocShell,
                                        const char* aName,
                                        MarkerTracingType aTracingType,
                                        MarkerStackRequest aStackRequest)
{
  MOZ_ASSERT(NS_IsMainThread());
  if (HasConsumer(aDocShell)) {
    aDocShell->mObserved->AddMarker(MakeUnique<TimelineMarker>(aName, aTracingType, aStackRequest));
  }
}

void
TimelineConsumers::AddMarkerForDocShell(nsDocShell* aDocShell,
                                        const char* aName,
                                        const TimeStamp& aTime,
                                        MarkerTracingType aTracingType,
                                        MarkerStackRequest aStackRequest)
{
  MOZ_ASSERT(NS_IsMainThread());
  if (HasConsumer(aDocShell)) {
    aDocShell->mObserved->AddMarker(MakeUnique<TimelineMarker>(aName, aTime, aTracingType, aStackRequest));
  }
}

void
TimelineConsumers::AddMarkerForDocShell(nsDocShell* aDocShell,
                                        UniquePtr<AbstractTimelineMarker>&& aMarker)
{
  MOZ_ASSERT(NS_IsMainThread());
  if (HasConsumer(aDocShell)) {
    aDocShell->mObserved->AddMarker(std::move(aMarker));
  }
}

void
TimelineConsumers::AddMarkerForDocShell(nsIDocShell* aDocShell,
                                        const char* aName,
                                        MarkerTracingType aTracingType,
                                        MarkerStackRequest aStackRequest)
{
  MOZ_ASSERT(NS_IsMainThread());
  AddMarkerForDocShell(static_cast<nsDocShell*>(aDocShell), aName, aTracingType, aStackRequest);
}

void
TimelineConsumers::AddMarkerForDocShell(nsIDocShell* aDocShell,
                                        const char* aName,
                                        const TimeStamp& aTime,
                                        MarkerTracingType aTracingType,
                                        MarkerStackRequest aStackRequest)
{
  MOZ_ASSERT(NS_IsMainThread());
  AddMarkerForDocShell(static_cast<nsDocShell*>(aDocShell), aName, aTime, aTracingType, aStackRequest);
}

void
TimelineConsumers::AddMarkerForDocShell(nsIDocShell* aDocShell,
                                        UniquePtr<AbstractTimelineMarker>&& aMarker)
{
  MOZ_ASSERT(NS_IsMainThread());
  AddMarkerForDocShell(static_cast<nsDocShell*>(aDocShell), std::move(aMarker));
}

void
TimelineConsumers::AddMarkerForAllObservedDocShells(const char* aName,
                                                    MarkerTracingType aTracingType,
                                                    MarkerStackRequest aStackRequest /* = STACK */)
{
  bool isMainThread = NS_IsMainThread();
  StaticMutexAutoLock lock(sMutex); // for `mMarkersStores`.

  for (MarkersStorage* storage = mMarkersStores.getFirst();
       storage != nullptr;
       storage = storage->getNext()) {
    UniquePtr<AbstractTimelineMarker> marker =
      MakeUnique<TimelineMarker>(aName, aTracingType, aStackRequest);
    if (isMainThread) {
      storage->AddMarker(std::move(marker));
    } else {
      storage->AddOTMTMarker(std::move(marker));
    }
  }
}

void
TimelineConsumers::AddMarkerForAllObservedDocShells(const char* aName,
                                                    const TimeStamp& aTime,
                                                    MarkerTracingType aTracingType,
                                                    MarkerStackRequest aStackRequest /* = STACK */)
{
  bool isMainThread = NS_IsMainThread();
  StaticMutexAutoLock lock(sMutex); // for `mMarkersStores`.

  for (MarkersStorage* storage = mMarkersStores.getFirst();
       storage != nullptr;
       storage = storage->getNext()) {
    UniquePtr<AbstractTimelineMarker> marker =
      MakeUnique<TimelineMarker>(aName, aTime, aTracingType, aStackRequest);
    if (isMainThread) {
      storage->AddMarker(std::move(marker));
    } else {
      storage->AddOTMTMarker(std::move(marker));
    }
  }
}

void
TimelineConsumers::AddMarkerForAllObservedDocShells(UniquePtr<AbstractTimelineMarker>& aMarker)
{
  bool isMainThread = NS_IsMainThread();
  StaticMutexAutoLock lock(sMutex); // for `mMarkersStores`.

  for (MarkersStorage* storage = mMarkersStores.getFirst();
       storage != nullptr;
       storage = storage->getNext()) {
    UniquePtr<AbstractTimelineMarker> clone = aMarker->Clone();
    if (isMainThread) {
      storage->AddMarker(std::move(clone));
    } else {
      storage->AddOTMTMarker(std::move(clone));
    }
  }
}

void
TimelineConsumers::PopMarkers(nsDocShell* aDocShell,
                              JSContext* aCx,
                              nsTArray<dom::ProfileTimelineMarker>& aStore)
{
  MOZ_ASSERT(NS_IsMainThread());

  if (!aDocShell || !aDocShell->mObserved) {
    return;
  }

  aDocShell->mObserved->PopMarkers(aCx, aStore);
}

} // namespace mozilla
