/* -*- 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 "QuotaObject.h"

#include "mozilla/TypeTraits.h"
#include "QuotaManager.h"
#include "Utilities.h"

USING_QUOTA_NAMESPACE

namespace {

template <typename T, bool = mozilla::IsUnsigned<T>::value>
struct IntChecker
{
  static void
  Assert(T aInt)
  {
    static_assert(mozilla::IsIntegral<T>::value, "Not an integer!");
    MOZ_ASSERT(aInt >= 0);
  }
};

template <typename T>
struct IntChecker<T, true>
{
  static void
  Assert(T aInt)
  {
    static_assert(mozilla::IsIntegral<T>::value, "Not an integer!");
  }
};

template <typename T>
void
AssertNoOverflow(uint64_t aDest, T aArg)
{
  IntChecker<T>::Assert(aDest);
  IntChecker<T>::Assert(aArg);
  MOZ_ASSERT(UINT64_MAX - aDest >= uint64_t(aArg));
}

template <typename T, typename U>
void
AssertNoUnderflow(T aDest, U aArg)
{
  IntChecker<T>::Assert(aDest);
  IntChecker<T>::Assert(aArg);
  MOZ_ASSERT(uint64_t(aDest) >= uint64_t(aArg));
}

} // anonymous namespace

void
QuotaObject::AddRef()
{
  QuotaManager* quotaManager = QuotaManager::Get();
  if (!quotaManager) {
    NS_ERROR("Null quota manager, this shouldn't happen, possible leak!");

    ++mRefCnt;

    return;
  }

  MutexAutoLock lock(quotaManager->mQuotaMutex);

  ++mRefCnt;
}

void
QuotaObject::Release()
{
  QuotaManager* quotaManager = QuotaManager::Get();
  if (!quotaManager) {
    NS_ERROR("Null quota manager, this shouldn't happen, possible leak!");

    nsrefcnt count = --mRefCnt;
    if (count == 0) {
      mRefCnt = 1;
      delete this;
    }

    return;
  }

  {
    MutexAutoLock lock(quotaManager->mQuotaMutex);

    --mRefCnt;

    if (mRefCnt > 0) {
      return;
    }

    if (mOriginInfo) {
      mOriginInfo->mQuotaObjects.Remove(mPath);
    }
  }

  delete this;
}

bool
QuotaObject::MaybeUpdateSize(int64_t aSize, bool aTruncate)
{
  QuotaManager* quotaManager = QuotaManager::Get();
  MOZ_ASSERT(quotaManager);

  MutexAutoLock lock(quotaManager->mQuotaMutex);

  if (mSize == aSize) {
    return true;
  }

  if (!mOriginInfo) {
    mSize = aSize;
    return true;
  }

  GroupInfo* groupInfo = mOriginInfo->mGroupInfo;
  MOZ_ASSERT(groupInfo);

  if (mSize > aSize) {
    if (aTruncate) {
      const int64_t delta = mSize - aSize;

      AssertNoUnderflow(quotaManager->mTemporaryStorageUsage, delta);
      quotaManager->mTemporaryStorageUsage -= delta;

      AssertNoUnderflow(groupInfo->mUsage, delta);
      groupInfo->mUsage -= delta;

      AssertNoUnderflow(mOriginInfo->mUsage, delta);
      mOriginInfo->mUsage -= delta;

      mSize = aSize;
    }
    return true;
  }

  MOZ_ASSERT(mSize < aSize);

  nsRefPtr<GroupInfo> complementaryGroupInfo =
    groupInfo->mGroupInfoPair->LockedGetGroupInfo(
      ComplementaryPersistenceType(groupInfo->mPersistenceType));

  uint64_t delta = aSize - mSize;

  AssertNoOverflow(mOriginInfo->mUsage, delta);
  uint64_t newUsage = mOriginInfo->mUsage + delta;

  // Temporary storage has no limit for origin usage (there's a group and the
  // global limit though).

  AssertNoOverflow(groupInfo->mUsage, delta);
  uint64_t newGroupUsage = groupInfo->mUsage + delta;

  uint64_t groupUsage = groupInfo->mUsage;
  if (complementaryGroupInfo) {
    AssertNoOverflow(groupUsage, complementaryGroupInfo->mUsage);
    groupUsage += complementaryGroupInfo->mUsage;
  }

  // Temporary storage has a hard limit for group usage (20 % of the global
  // limit).
  AssertNoOverflow(groupUsage, delta);
  if (groupUsage + delta > quotaManager->GetGroupLimit()) {
    return false;
  }

  AssertNoOverflow(quotaManager->mTemporaryStorageUsage, delta);
  uint64_t newTemporaryStorageUsage = quotaManager->mTemporaryStorageUsage +
                                      delta;

  if (newTemporaryStorageUsage > quotaManager->mTemporaryStorageLimit) {
    // This will block the thread without holding the lock while waitting.

    nsAutoTArray<OriginInfo*, 10> originInfos;
    uint64_t sizeToBeFreed =
      quotaManager->LockedCollectOriginsForEviction(delta, originInfos);

    if (!sizeToBeFreed) {
      return false;
    }

    NS_ASSERTION(sizeToBeFreed >= delta, "Huh?");

    {
      MutexAutoUnlock autoUnlock(quotaManager->mQuotaMutex);

      for (uint32_t i = 0; i < originInfos.Length(); i++) {
        OriginInfo* originInfo = originInfos[i];

        quotaManager->DeleteFilesForOrigin(
                                       originInfo->mGroupInfo->mPersistenceType,
                                       originInfo->mOrigin);
      }
    }

    // Relocked.

    NS_ASSERTION(mOriginInfo, "How come?!");

    nsTArray<OriginParams> origins;
    for (uint32_t i = 0; i < originInfos.Length(); i++) {
      OriginInfo* originInfo = originInfos[i];

      NS_ASSERTION(originInfo != mOriginInfo, "Deleted itself!");

      PersistenceType persistenceType =
        originInfo->mGroupInfo->mPersistenceType;
      nsCString group = originInfo->mGroupInfo->mGroup;
      nsCString origin = originInfo->mOrigin;
      bool isApp = originInfo->mIsApp;
      quotaManager->LockedRemoveQuotaForOrigin(persistenceType, group, origin);

#ifdef DEBUG
      originInfos[i] = nullptr;
#endif

      origins.AppendElement(OriginParams(persistenceType, origin, isApp));
    }

    // We unlocked and relocked several times so we need to recompute all the
    // essential variables and recheck the group limit.

    AssertNoUnderflow(aSize, mSize);
    delta = aSize - mSize;

    AssertNoOverflow(mOriginInfo->mUsage, delta);
    newUsage = mOriginInfo->mUsage + delta;

    AssertNoOverflow(groupInfo->mUsage, delta);
    newGroupUsage = groupInfo->mUsage + delta;

    groupUsage = groupInfo->mUsage;
    if (complementaryGroupInfo) {
      AssertNoOverflow(groupUsage, complementaryGroupInfo->mUsage);
      groupUsage += complementaryGroupInfo->mUsage;
    }

    AssertNoOverflow(groupUsage, delta);
    if (groupUsage + delta > quotaManager->GetGroupLimit()) {
      // Unfortunately some other thread increased the group usage in the
      // meantime and we are not below the group limit anymore.

      // However, the origin eviction must be finalized in this case too.
      MutexAutoUnlock autoUnlock(quotaManager->mQuotaMutex);

      quotaManager->FinalizeOriginEviction(origins);

      return false;
    }

    AssertNoOverflow(quotaManager->mTemporaryStorageUsage, delta);
    newTemporaryStorageUsage = quotaManager->mTemporaryStorageUsage + delta;

    NS_ASSERTION(newTemporaryStorageUsage <=
                 quotaManager->mTemporaryStorageLimit, "How come?!");

    // Ok, we successfully freed enough space and the operation can continue
    // without throwing the quota error.
    mOriginInfo->mUsage = newUsage;
    groupInfo->mUsage = newGroupUsage;
    quotaManager->mTemporaryStorageUsage = newTemporaryStorageUsage;;

    // Some other thread could increase the size in the meantime, but no more
    // than this one.
    MOZ_ASSERT(mSize < aSize);
    mSize = aSize;

    // Finally, release IO thread only objects and allow next synchronized
    // ops for the evicted origins.
    MutexAutoUnlock autoUnlock(quotaManager->mQuotaMutex);

    quotaManager->FinalizeOriginEviction(origins);

    return true;
  }

  mOriginInfo->mUsage = newUsage;
  groupInfo->mUsage = newGroupUsage;
  quotaManager->mTemporaryStorageUsage = newTemporaryStorageUsage;

  mSize = aSize;

  return true;
}

void
OriginInfo::LockedDecreaseUsage(int64_t aSize)
{
  AssertCurrentThreadOwnsQuotaMutex();

  AssertNoUnderflow(mUsage, aSize);
  mUsage -= aSize;

  AssertNoUnderflow(mGroupInfo->mUsage, aSize);
  mGroupInfo->mUsage -= aSize;

  QuotaManager* quotaManager = QuotaManager::Get();
  MOZ_ASSERT(quotaManager);

  AssertNoUnderflow(quotaManager->mTemporaryStorageUsage, aSize);
  quotaManager->mTemporaryStorageUsage -= aSize;
}

already_AddRefed<OriginInfo>
GroupInfo::LockedGetOriginInfo(const nsACString& aOrigin)
{
  AssertCurrentThreadOwnsQuotaMutex();

  for (uint32_t index = 0; index < mOriginInfos.Length(); index++) {
    nsRefPtr<OriginInfo>& originInfo = mOriginInfos[index];

    if (originInfo->mOrigin == aOrigin) {
      nsRefPtr<OriginInfo> result = originInfo;
      return result.forget();
    }
  }

  return nullptr;
}

void
GroupInfo::LockedAddOriginInfo(OriginInfo* aOriginInfo)
{
  AssertCurrentThreadOwnsQuotaMutex();

  NS_ASSERTION(!mOriginInfos.Contains(aOriginInfo),
               "Replacing an existing entry!");
  mOriginInfos.AppendElement(aOriginInfo);

  AssertNoOverflow(mUsage, aOriginInfo->mUsage);
  mUsage += aOriginInfo->mUsage;

  QuotaManager* quotaManager = QuotaManager::Get();
  MOZ_ASSERT(quotaManager);

  AssertNoOverflow(quotaManager->mTemporaryStorageUsage, aOriginInfo->mUsage);
  quotaManager->mTemporaryStorageUsage += aOriginInfo->mUsage;
}

void
GroupInfo::LockedRemoveOriginInfo(const nsACString& aOrigin)
{
  AssertCurrentThreadOwnsQuotaMutex();

  for (uint32_t index = 0; index < mOriginInfos.Length(); index++) {
    if (mOriginInfos[index]->mOrigin == aOrigin) {
      AssertNoUnderflow(mUsage, mOriginInfos[index]->mUsage);
      mUsage -= mOriginInfos[index]->mUsage;

      QuotaManager* quotaManager = QuotaManager::Get();
      MOZ_ASSERT(quotaManager);

      AssertNoUnderflow(quotaManager->mTemporaryStorageUsage,
                        mOriginInfos[index]->mUsage);
      quotaManager->mTemporaryStorageUsage -= mOriginInfos[index]->mUsage;

      mOriginInfos.RemoveElementAt(index);

      return;
    }
  }
}

void
GroupInfo::LockedRemoveOriginInfos()
{
  AssertCurrentThreadOwnsQuotaMutex();

  QuotaManager* quotaManager = QuotaManager::Get();
  MOZ_ASSERT(quotaManager);

  for (uint32_t index = mOriginInfos.Length(); index > 0; index--) {
    OriginInfo* originInfo = mOriginInfos[index - 1];

    AssertNoUnderflow(mUsage, originInfo->mUsage);
    mUsage -= originInfo->mUsage;

    AssertNoUnderflow(quotaManager->mTemporaryStorageUsage, originInfo->mUsage);
    quotaManager->mTemporaryStorageUsage -= originInfo->mUsage;

    mOriginInfos.RemoveElementAt(index - 1);
  }
}

nsRefPtr<GroupInfo>&
GroupInfoPair::GetGroupInfoForPersistenceType(PersistenceType aPersistenceType)
{
  switch (aPersistenceType) {
    case PERSISTENCE_TYPE_TEMPORARY:
      return mTemporaryStorageGroupInfo;
    case PERSISTENCE_TYPE_DEFAULT:
      return mDefaultStorageGroupInfo;

    case PERSISTENCE_TYPE_PERSISTENT:
    case PERSISTENCE_TYPE_INVALID:
    default:
      MOZ_CRASH("Bad persistence type value!");
  }
}