Quelle  ActorsParent.cpp   Sprache: C

/* -*- 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 "ActorsParent.h"

#include <inttypes.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <algorithm>
#include <cstdint>
#include <functional>
#include <iterator>
#include <new>
#include <numeric>
#include <tuple>
#include <type_traits>
#include <utility>
#include "ActorsParentCommon.h"
#include "CrashAnnotations.h"
#include "DatabaseFileInfo.h"
#include "DatabaseFileManager.h"
#include "DatabaseFileManagerImpl.h"
#include "DBSchema.h"
#include "ErrorList.h"
#include "IDBCursorType.h"
#include "IDBObjectStore.h"
#include "IDBTransaction.h"
#include "IndexedDBCommon.h"
#include "IndexedDatabaseInlines.h"
#include "IndexedDatabaseManager.h"
#include "IndexedDBCipherKeyManager.h"
#include "KeyPath.h"
#include "MainThreadUtils.h"
#include "ProfilerHelpers.h"
#include "ReportInternalError.h"
#include "SafeRefPtr.h"
#include "SchemaUpgrades.h"
#include "chrome/common/ipc_channel.h"
#include "ipc/IPCMessageUtils.h"
#include "js/RootingAPI.h"
#include "js/StructuredClone.h"
#include "js/Value.h"
#include "jsapi.h"
#include "mozIStorageAsyncConnection.h"
#include "mozIStorageConnection.h"
#include "mozIStorageFunction.h"
#include "mozIStorageProgressHandler.h"
#include "mozIStorageService.h"
#include "mozIStorageStatement.h"
#include "mozIStorageValueArray.h"
#include "mozStorageCID.h"
#include "mozStorageHelper.h"
#include "mozilla/Algorithm.h"
#include "mozilla/ArrayAlgorithm.h"
#include "mozilla/ArrayIterator.h"
#include "mozilla/Assertions.h"
#include "mozilla/Atomics.h"
#include "mozilla/Attributes.h"
#include "mozilla/Casting.h"
#include "mozilla/CondVar.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/EndianUtils.h"
#include "mozilla/ErrorNames.h"
#include "mozilla/ErrorResult.h"
#include "mozilla/InitializedOnce.h"
#include "mozilla/Logging.h"
#include "mozilla/MacroForEach.h"
#include "mozilla/Maybe.h"
#include "mozilla/Monitor.h"
#include "mozilla/Mutex.h"
#include "mozilla/NotNull.h"
#include "mozilla/Preferences.h"
#include "mozilla/ProfilerLabels.h"
#include "mozilla/RefCountType.h"
#include "mozilla/RefCounted.h"
#include "mozilla/RemoteLazyInputStreamParent.h"
#include "mozilla/RemoteLazyInputStreamStorage.h"
#include "mozilla/Result.h"
#include "mozilla/ResultExtensions.h"
#include "mozilla/SchedulerGroup.h"
#include "mozilla/SnappyCompressOutputStream.h"
#include "mozilla/SpinEventLoopUntil.h"
#include "mozilla/StaticPtr.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/Unused.h"
#include "mozilla/Variant.h"
#include "mozilla/dom/BlobImpl.h"
#include "mozilla/dom/ContentParent.h"
#include "mozilla/dom/FileBlobImpl.h"
#include "mozilla/dom/FlippedOnce.h"
#include "mozilla/dom/IDBCursorBinding.h"
#include "mozilla/dom/IDBFactory.h"
#include "mozilla/dom/IPCBlob.h"
#include "mozilla/dom/IPCBlobUtils.h"
#include "mozilla/dom/IndexedDatabase.h"
#include "mozilla/dom/Nullable.h"
#include "mozilla/dom/PContentParent.h"
#include "mozilla/dom/ScriptSettings.h"
#include "mozilla/dom/indexedDB/IDBResult.h"
#include "mozilla/dom/indexedDB/Key.h"
#include "mozilla/dom/indexedDB/PBackgroundIDBCursor.h"
#include "mozilla/dom/indexedDB/PBackgroundIDBCursorParent.h"
#include "mozilla/dom/indexedDB/PBackgroundIDBDatabase.h"
#include "mozilla/dom/indexedDB/PBackgroundIDBDatabaseFileParent.h"
#include "mozilla/dom/indexedDB/PBackgroundIDBDatabaseParent.h"
#include "mozilla/dom/indexedDB/PBackgroundIDBFactory.h"
#include "mozilla/dom/indexedDB/PBackgroundIDBFactoryParent.h"
#include "mozilla/dom/indexedDB/PBackgroundIDBFactoryRequestParent.h"
#include "mozilla/dom/indexedDB/PBackgroundIDBRequest.h"
#include "mozilla/dom/indexedDB/PBackgroundIDBRequestParent.h"
#include "mozilla/dom/indexedDB/PBackgroundIDBSharedTypes.h"
#include "mozilla/dom/indexedDB/PBackgroundIDBTransactionParent.h"
#include "mozilla/dom/indexedDB/PBackgroundIDBVersionChangeTransactionParent.h"
#include "mozilla/dom/indexedDB/PBackgroundIndexedDBUtilsParent.h"
#include "mozilla/dom/ipc/IdType.h"
#include "mozilla/dom/quota/Assertions.h"
#include "mozilla/dom/quota/CachingDatabaseConnection.h"
#include "mozilla/dom/quota/CheckedUnsafePtr.h"
#include "mozilla/dom/quota/Client.h"
#include "mozilla/dom/quota/ClientDirectoryLock.h"
#include "mozilla/dom/quota/ClientImpl.h"
#include "mozilla/dom/quota/DebugOnlyMacro.h"
#include "mozilla/dom/quota/DirectoryLock.h"
#include "mozilla/dom/quota/DirectoryLockInlines.h"
#include "mozilla/dom/quota/DecryptingInputStream_impl.h"
#include "mozilla/dom/quota/EncryptingOutputStream_impl.h"
#include "mozilla/dom/quota/ErrorHandling.h"
#include "mozilla/dom/quota/FileStreams.h"
#include "mozilla/dom/quota/OriginScope.h"
#include "mozilla/dom/quota/PersistenceScope.h"
#include "mozilla/dom/quota/PersistenceType.h"
#include "mozilla/dom/quota/PrincipalUtils.h"
#include "mozilla/dom/quota/QuotaCommon.h"
#include "mozilla/dom/quota/QuotaManager.h"
#include "mozilla/dom/quota/QuotaObject.h"
#include "mozilla/dom/quota/ResultExtensions.h"
#include "mozilla/dom/quota/ThreadUtils.h"
#include "mozilla/dom/quota/UniversalDirectoryLock.h"
#include "mozilla/dom/quota/UsageInfo.h"
#include "mozilla/fallible.h"
#include "mozilla/ipc/BackgroundParent.h"
#include "mozilla/ipc/BackgroundUtils.h"
#include "mozilla/ipc/InputStreamParams.h"
#include "mozilla/ipc/PBackgroundParent.h"
#include "mozilla/ipc/PBackgroundSharedTypes.h"
#include "mozilla/ipc/ProtocolUtils.h"
#include "mozilla/mozalloc.h"
#include "mozilla/storage/Variant.h"
#include "NotifyUtils.h"
#include "nsBaseHashtable.h"
#include "nsCOMPtr.h"
#include "nsClassHashtable.h"
#include "nsContentUtils.h"
#include "nsTHashMap.h"
#include "nsDebug.h"
#include "nsError.h"
#include "nsEscape.h"
#include "nsHashKeys.h"
#include "nsIAsyncInputStream.h"
#include "nsID.h"
#include "nsIDUtils.h"
#include "nsIDirectoryEnumerator.h"
#include "nsIEventTarget.h"
#include "nsIFile.h"
#include "nsIFileProtocolHandler.h"
#include "nsIFileStreams.h"
#include "nsIFileURL.h"
#include "nsIInputStream.h"
#include "nsIOutputStream.h"
#include "nsIProtocolHandler.h"
#include "nsIRunnable.h"
#include "nsISupports.h"
#include "nsISupportsPriority.h"
#include "nsISupportsUtils.h"
#include "nsIThread.h"
#include "nsIThreadInternal.h"
#include "nsITimer.h"
#include "nsIURIMutator.h"
#include "nsIVariant.h"
#include "nsLiteralString.h"
#include "nsNetCID.h"
#include "nsPrintfCString.h"
#include "nsProxyRelease.h"
#include "nsServiceManagerUtils.h"
#include "nsStreamUtils.h"
#include "nsString.h"
#include "nsStringFlags.h"
#include "nsStringFwd.h"
#include "nsTArray.h"
#include "nsTHashSet.h"
#include "nsTHashtable.h"
#include "nsTLiteralString.h"
#include "nsTStringRepr.h"
#include "nsThreadPool.h"
#include "nsThreadUtils.h"
#include "nscore.h"
#include "prinrval.h"
#include "prio.h"
#include "prsystem.h"
#include "prthread.h"
#include "prtime.h"
#include "prtypes.h"
#include "snappy/snappy.h"

struct JSContext;
class JSObject;
template <class T>
class nsPtrHashKey;

#define IDB_DEBUG_LOG(_args) \
  MOZ_LOG(IndexedDatabaseManager::GetLoggingModule(), LogLevel::Debug, _args)

#if defined(MOZ_WIDGET_ANDROID)
#  define IDB_MOBILE
#endif

// Helper macros to reduce assertion verbosity
// AUUF == ASSERT_UNREACHABLE_UNLESS_FUZZING
#ifdef DEBUG
#  ifdef FUZZING
#    define NS_AUUF_OR_WARN(...) NS_WARNING(__VA_ARGS__)
#  else
#    define NS_AUUF_OR_WARN(...) MOZ_ASSERT(false, __VA_ARGS__)
#  endif
#  define NS_AUUF_OR_WARN_IF(cond) \
    [](bool aCond) {               \
      if (MOZ_UNLIKELY(aCond)) {   \
        NS_AUUF_OR_WARN(#cond);    \
      }                            \
      return aCond;                \
    }((cond))
#else
#  define NS_AUUF_OR_WARN(...) \
    do {                       \
    } while (false)
#  define NS_AUUF_OR_WARN_IF(cond) static_cast<bool>(cond)
#endif

namespace mozilla {

namespace dom::indexedDB {

using namespace mozilla::dom::quota;
using namespace mozilla::ipc;
using mozilla::dom::quota::Client;

namespace {

class ConnectionPool;
class Database;
struct DatabaseActorInfo;
class DatabaseFile;
class DatabaseLoggingInfo;
class DatabaseMaintenance;
class Factory;
class Maintenance;
class OpenDatabaseOp;
class TransactionBase;
class TransactionDatabaseOperationBase;
class VersionChangeTransaction;
template <bool StatementHasIndexKeyBindings>
struct ValuePopulateResponseHelper;

/*******************************************************************************
 * Constants
 ******************************************************************************/

const int32_t kStorageProgressGranularity = 1000;

// Changing the value here will override the page size of new databases only.
// A journal mode change and VACUUM are needed to change existing databases, so
// the best way to do that is to use the schema version upgrade mechanism.
const uint32_t kSQLitePageSizeOverride =
#ifdef IDB_MOBILE
    2048;
#else
    4096;
#endif

static_assert(kSQLitePageSizeOverride == /* mozStorage default */ 0 ||
                  (kSQLitePageSizeOverride % 2 == 0 &&
                   kSQLitePageSizeOverride >= 512 &&
                   kSQLitePageSizeOverride <= 65536),
              "Must be 0 (disabled) or a power of 2 between 512 and 65536!");

// Set to -1 to use SQLite's default, 0 to disable, or some positive number to
// enforce a custom limit.
const int32_t kMaxWALPages = 5000;  // 20MB on desktop, 10MB on mobile.

// Set to some multiple of the page size to grow the database in larger chunks.
const uint32_t kSQLiteGrowthIncrement = kSQLitePageSizeOverride * 2;

static_assert(kSQLiteGrowthIncrement >= 0 &&
                  kSQLiteGrowthIncrement % kSQLitePageSizeOverride == 0 &&
                  kSQLiteGrowthIncrement < uint32_t(INT32_MAX),
              "Must be 0 (disabled) or a positive multiple of the page size!");

// The maximum number of threads that can be used for database activity at a
// single time. Please keep in sync with the constants in
// test_connection_idle_maintenance*.js tests
const uint32_t kMaxConnectionThreadCount = 20;

static_assert(kMaxConnectionThreadCount, "Must have at least one thread!");

// The maximum number of threads to keep when idle. Until we switch to the STS
// pool, we can reduce the number of idle threads kept around thanks to the
// grace timeout.
const uint32_t kMaxIdleConnectionThreadCount = 1;

static_assert(kMaxConnectionThreadCount >= kMaxIdleConnectionThreadCount,
              "Idle thread limit must be less than total thread limit!");

// The length of time that wanted idle threads will stay alive before being shut
// down.
const uint32_t kConnectionThreadMaxIdleMS = 30 * 1000;  // 30 seconds

// The length of time that excess idle threads will stay alive before being shut
// down.
const uint32_t kConnectionThreadGraceIdleMS = 500;  // 0.5 seconds

// The length of time that database connections will be held open after all
// transactions have completed before doing idle maintenance. Please keep in
// sync with the timeouts in test_connection_idle_maintenance*.js tests
const uint32_t kConnectionIdleMaintenanceMS = 2 * 1000;  // 2 seconds

// The length of time that database connections will be held open after all
// transactions and maintenance have completed.
const uint32_t kConnectionIdleCloseMS = 10 * 1000;  // 10 seconds

#define SAVEPOINT_CLAUSE "SAVEPOINT sp;"_ns

// For efficiency reasons, kEncryptedStreamBlockSize must be a multiple of large
// 4k disk sectors.
static_assert(kEncryptedStreamBlockSize % 4096 == 0);
// Similarly, the file copy buffer size must be a multiple of the encrypted
// block size.
static_assert(kFileCopyBufferSize % kEncryptedStreamBlockSize == 0);

constexpr auto kFileManagerDirectoryNameSuffix = u".files"_ns;
constexpr auto kSQLiteSuffix = u".sqlite"_ns;
constexpr auto kSQLiteJournalSuffix = u".sqlite-journal"_ns;
constexpr auto kSQLiteSHMSuffix = u".sqlite-shm"_ns;
constexpr auto kSQLiteWALSuffix = u".sqlite-wal"_ns;

// The following constants define all names of binding parameters in statements,
// where they are bound by name. This should include all parameter names which
// are bound by name. Binding may be done by index when the statement definition
// and binding are done in the same local scope, and no other reasons prevent
// using the indexes (e.g. multiple statement variants with differing number or
// order of parameters). Neither the styles of specifying parameter names
// (literally vs. via these constants) nor the binding styles (by index vs. by
// name) should not be mixed for the same statement. The decision must be made
// for each statement based on the proximity of statement and binding calls.
constexpr auto kStmtParamNameCurrentKey = "current_key"_ns;
constexpr auto kStmtParamNameRangeBound = "range_bound"_ns;
constexpr auto kStmtParamNameObjectStorePosition = "object_store_position"_ns;
constexpr auto kStmtParamNameLowerKey = "lower_key"_ns;
constexpr auto kStmtParamNameUpperKey = "upper_key"_ns;
constexpr auto kStmtParamNameKey = "key"_ns;
constexpr auto kStmtParamNameObjectStoreId = "object_store_id"_ns;
constexpr auto kStmtParamNameIndexId = "index_id"_ns;
// TODO: Maybe the uses of kStmtParamNameId should be replaced by more
// specific constants such as kStmtParamNameObjectStoreId.
constexpr auto kStmtParamNameId = "id"_ns;
constexpr auto kStmtParamNameValue = "value"_ns;
constexpr auto kStmtParamNameObjectDataKey = "object_data_key"_ns;
constexpr auto kStmtParamNameIndexDataValues = "index_data_values"_ns;
constexpr auto kStmtParamNameData = "data"_ns;
constexpr auto kStmtParamNameFileIds = "file_ids"_ns;
constexpr auto kStmtParamNameValueLocale = "value_locale"_ns;
constexpr auto kStmtParamNameLimit = "limit"_ns;

// The following constants define some names of columns in tables, which are
// referred to in remote locations, e.g. in calls to
// GetBindingClauseForKeyRange.
constexpr auto kColumnNameKey = "key"_ns;
constexpr auto kColumnNameValue = "value"_ns;
constexpr auto kColumnNameAliasSortKey = "sort_column"_ns;

// SQL fragments used at multiple locations.
constexpr auto kOpenLimit = " LIMIT "_ns;

// The deletion marker file is created before RemoveDatabaseFilesAndDirectory
// begins deleting a database. It is removed as the last step of deletion. If a
// deletion marker file is found when initializing the origin, the deletion
// routine is run again to ensure that the database and all of its related files
// are removed. The primary goal of this mechanism is to avoid situations where
// a database has been partially deleted, leading to inconsistent state for the
// origin.
constexpr auto kIdbDeletionMarkerFilePrefix = u"idb-deleting-"_ns;

const uint32_t kDeleteTimeoutMs = 1000;

#ifdef DEBUG

const int32_t kDEBUGThreadPriority = nsISupportsPriority::PRIORITY_NORMAL;
const uint32_t kDEBUGThreadSleepMS = 0;

// Set to a non-zero number to enable debugging of transaction event targets.
// It will cause sleeping after every transaction runnable!
//
// This can be useful for discovering race conditions related to switching to
// another thread. Such races are usually avoided by using MozPromise or
// RunAfterProcessingCurrentEvent. Chaos mode doesn't always help with
// uncovering these issues, and only a precisely targeted sleep call can
// simulate the problem.
const uint32_t kDEBUGTransactionThreadSleepMS = 0;

// Make sure that we notice if we ever accidentally check in a non-zero value.
#  ifdef MOZILLA_OFFICIAL
static_assert(kDEBUGTransactionThreadSleepMS == 0);
#  endif

#endif

/*******************************************************************************
 * Metadata classes
 ******************************************************************************/

// Can be instantiated either on the QuotaManager IO thread or on a
// versionchange transaction thread. These threads can never race so this is
// totally safe.
struct FullIndexMetadata {
  IndexMetadata mCommonMetadata = {0,     nsString(), KeyPath(0), nsCString(),
                                   false, false,      false};

  FlippedOnce<false> mDeleted;

  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(FullIndexMetadata)

 private:
  ~FullIndexMetadata() = default;
};

using IndexTable = nsTHashMap<nsUint64HashKey, SafeRefPtr<FullIndexMetadata>>;

// Can be instantiated either on the QuotaManager IO thread or on a
// versionchange transaction thread. These threads can never race so this is
// totally safe.
struct FullObjectStoreMetadata {
  ObjectStoreMetadata mCommonMetadata;
  IndexTable mIndexes;

  // The auto increment ids are touched on both the background thread and the
  // transaction I/O thread, and they must be kept in sync, so we need a mutex
  // to protect them.
  struct AutoIncrementIds {
    int64_t next;
    int64_t committed;
  };
  DataMutex<AutoIncrementIds> mAutoIncrementIds;

  FlippedOnce<false> mDeleted;

  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(FullObjectStoreMetadata);

  bool HasLiveIndexes() const;

  FullObjectStoreMetadata(ObjectStoreMetadata aCommonMetadata,
                          const AutoIncrementIds& aAutoIncrementIds)
      : mCommonMetadata{std::move(aCommonMetadata)},
        mAutoIncrementIds{AutoIncrementIds{aAutoIncrementIds},
                          "FullObjectStoreMetadata"} {}

 private:
  ~FullObjectStoreMetadata() = default;
};

using ObjectStoreTable =
    nsTHashMap<nsUint64HashKey, SafeRefPtr<FullObjectStoreMetadata>>;

static_assert(
    std::is_same_v<IndexOrObjectStoreId,
                   std::remove_cv_t<std::remove_reference_t<
                       decltype(std::declval<const ObjectStoreGetParams&>()
                                    .objectStoreId())>>>);
static_assert(
    std::is_same_v<
        IndexOrObjectStoreId,
        std::remove_cv_t<std::remove_reference_t<
            decltype(std::declval<const IndexGetParams&>().objectStoreId())>>>);

struct FullDatabaseMetadata final : AtomicSafeRefCounted<FullDatabaseMetadata> {
  DatabaseMetadata mCommonMetadata;
  nsCString mDatabaseId;
  nsString mFilePath;
  ObjectStoreTable mObjectStores;

  IndexOrObjectStoreId mNextObjectStoreId = 0;
  IndexOrObjectStoreId mNextIndexId = 0;

 public:
  explicit FullDatabaseMetadata(const DatabaseMetadata& aCommonMetadata)
      : mCommonMetadata(aCommonMetadata) {
    AssertIsOnBackgroundThread();
  }

  [[nodiscard]] SafeRefPtr<FullDatabaseMetadata> Duplicate() const;

  MOZ_DECLARE_REFCOUNTED_TYPENAME(FullDatabaseMetadata)
};

template <class Enumerable>
auto MatchMetadataNameOrId(const Enumerable& aEnumerable,
                           IndexOrObjectStoreId aId,
                           Maybe<const nsAString&> aName = Nothing()) {
  AssertIsOnBackgroundThread();
  MOZ_ASSERT(aId);

  const auto it = std::find_if(
      aEnumerable.cbegin(), aEnumerable.cend(),
      [aId, aName](const auto& entry) {
        MOZ_ASSERT(entry.GetKey() != 0);

        const auto& value = entry.GetData();
        MOZ_ASSERT(value);

        return !value->mDeleted &&
               (aId == value->mCommonMetadata.id() ||
                (aName && *aName == value->mCommonMetadata.name()));
      });

  return ToMaybeRef(it != aEnumerable.cend() ? it->GetData().unsafeGetRawPtr()
                                             : nullptr);
}

/*******************************************************************************
 * SQLite functions
 ******************************************************************************/

// WARNING: the hash function used for the database name must not change.
// That's why this function exists separately from mozilla::HashString(), even
// though it is (at the time of writing) equivalent. See bug 780408 and bug
// 940315 for details.
uint32_t HashName(const nsAString& aName) {
  struct Helper {
    static uint32_t RotateBitsLeft32(uint32_t aValue, uint8_t aBits) {
      MOZ_ASSERT(aBits < 32);
      return (aValue << aBits) | (aValue >> (32 - aBits));
    }
  };

  static const uint32_t kGoldenRatioU32 = 0x9e3779b9u;

  return std::accumulate(aName.BeginReading(), aName.EndReading(), uint32_t(0),
                         [](uint32_t hash, char16_t ch) {
                           return kGoldenRatioU32 *
                                  (Helper::RotateBitsLeft32(hash, 5) ^ ch);
                         });
}

nsresult ClampResultCode(nsresult aResultCode) {
  if (NS_SUCCEEDED(aResultCode) ||
      NS_ERROR_GET_MODULE(aResultCode) == NS_ERROR_MODULE_DOM_INDEXEDDB) {
    return aResultCode;
  }

  switch (aResultCode) {
    case NS_ERROR_FILE_NO_DEVICE_SPACE:
      return NS_ERROR_DOM_INDEXEDDB_QUOTA_ERR;
    case NS_ERROR_STORAGE_CONSTRAINT:
      return NS_ERROR_DOM_INDEXEDDB_CONSTRAINT_ERR;
    default:
#ifdef DEBUG
      nsPrintfCString message("Converting non-IndexedDB error code (0x%" PRIX32
                              ") to "
                              "NS_ERROR_DOM_INDEXEDDB_UNKNOWN_ERR",
                              static_cast<uint32_t>(aResultCode));
      NS_WARNING(message.get());
#else
        ;
#endif
  }

  IDB_REPORT_INTERNAL_ERR();
  return NS_ERROR_DOM_INDEXEDDB_UNKNOWN_ERR;
}

Result<nsCOMPtr<nsIFileURL>, nsresult> GetDatabaseFileURL(
    nsIFile& aDatabaseFile, const int64_t aDirectoryLockId,
    const Maybe<CipherKey>& aMaybeKey) {
  MOZ_ASSERT(aDirectoryLockId >= -1);

  QM_TRY_INSPECT(
      const auto& protocolHandler,
      MOZ_TO_RESULT_GET_TYPED(nsCOMPtr<nsIProtocolHandler>,
                              MOZ_SELECT_OVERLOAD(do_GetService),
                              NS_NETWORK_PROTOCOL_CONTRACTID_PREFIX "file"));

  QM_TRY_INSPECT(const auto& fileHandler,
                 MOZ_TO_RESULT_GET_TYPED(nsCOMPtr<nsIFileProtocolHandler>,
                                         MOZ_SELECT_OVERLOAD(do_QueryInterface),
                                         protocolHandler));

  QM_TRY_INSPECT(const auto& mutator, MOZ_TO_RESULT_INVOKE_MEMBER_TYPED(
                                          nsCOMPtr<nsIURIMutator>, fileHandler,
                                          NewFileURIMutator, &aDatabaseFile));

  // aDirectoryLockId should only be -1 when we are called
  // - from DatabaseFileManager::InitDirectory when the temporary storage
  //    hasn't been initialized yet. At that time, the in-memory objects (e.g.
  //    OriginInfo) are only being created so it doesn't make sense to tunnel
  //    quota information to QuotaVFS to get corresponding QuotaObject instances
  //    for SQLite files.
  // - from DeleteDatabaseOp::LoadPreviousVersion, since this might require
  //   temporarily exceeding the quota limit before the database can be
  //   deleted.
  const nsCString directoryLockIdClause =
      "&directoryLockId="_ns + IntToCString(aDirectoryLockId);

  const auto keyClause = [&aMaybeKey] {
    nsAutoCString keyClause;
    if (aMaybeKey) {
      keyClause.AssignLiteral("&key=");
      for (uint8_t byte : IndexedDBCipherStrategy::SerializeKey(*aMaybeKey)) {
        keyClause.AppendPrintf("%02x", byte);
      }
    }
    return keyClause;
  }();

  QM_TRY_UNWRAP(auto result, ([&mutator, &directoryLockIdClause, &keyClause] {
                  nsCOMPtr<nsIFileURL> result;
                  nsresult rv = NS_MutateURI(mutator)
                                    .SetQuery("cache=private"_ns +
                                              directoryLockIdClause + keyClause)
                                    .Finalize(result);
                  return NS_SUCCEEDED(rv)
                             ? Result<nsCOMPtr<nsIFileURL>, nsresult>{result}
                             : Err(rv);
                }()));

  return result;
}

nsLiteralCString GetDefaultSynchronousMode() {
  return IndexedDatabaseManager::FullSynchronous() ? "FULL"_ns : "NORMAL"_ns;
}

nsresult SetDefaultPragmas(mozIStorageConnection& aConnection) {
  MOZ_ASSERT(!NS_IsMainThread());

  static constexpr auto kBuiltInPragmas =
      // We use foreign keys in DEBUG builds only because there is a performance
      // cost to using them.
      "PRAGMA foreign_keys = "
#ifdef DEBUG
      "ON"
#else
      "OFF"
#endif
      ";"

      // The "INSERT OR REPLACE" statement doesn't fire the update trigger,
      // instead it fires only the insert trigger. This confuses the update
      // refcount function. This behavior changes with enabled recursive
      // triggers, so the statement fires the delete trigger first and then the
      // insert trigger.
      "PRAGMA recursive_triggers = ON;"

      // We aggressively truncate the database file when idle so don't bother
      // overwriting the WAL with 0 during active periods.
      "PRAGMA secure_delete = OFF;"_ns;

  QM_TRY(MOZ_TO_RESULT(aConnection.ExecuteSimpleSQL(kBuiltInPragmas)));

  QM_TRY(MOZ_TO_RESULT(aConnection.ExecuteSimpleSQL(nsAutoCString{
      "PRAGMA synchronous = "_ns + GetDefaultSynchronousMode() + ";"_ns})));

#ifndef IDB_MOBILE
  if (kSQLiteGrowthIncrement) {
    // This is just an optimization so ignore the failure if the disk is
    // currently too full.
    QM_TRY(QM_OR_ELSE_WARN_IF(
        // Expression.
        MOZ_TO_RESULT(
            aConnection.SetGrowthIncrement(kSQLiteGrowthIncrement, ""_ns)),
        // Predicate.
        IsSpecificError<NS_ERROR_FILE_TOO_BIG>,
        // Fallback.
        ErrToDefaultOk<>));
  }
#endif  // IDB_MOBILE

  return NS_OK;
}

nsresult SetJournalMode(mozIStorageConnection& aConnection) {
  MOZ_ASSERT(!NS_IsMainThread());

  // Try enabling WAL mode. This can fail in various circumstances so we have to
  // check the results here.
  constexpr auto journalModeQueryStart = "PRAGMA journal_mode = "_ns;
  constexpr auto journalModeWAL = "wal"_ns;

  QM_TRY_INSPECT(const auto& stmt,
                 CreateAndExecuteSingleStepStatement(
                     aConnection, journalModeQueryStart + journalModeWAL));

  QM_TRY_INSPECT(
      const auto& journalMode,
      MOZ_TO_RESULT_INVOKE_MEMBER_TYPED(nsCString, *stmt, GetUTF8String, 0));

  if (journalMode.Equals(journalModeWAL)) {
    // WAL mode successfully enabled. Maybe set limits on its size here.
    if (kMaxWALPages >= 0) {
      QM_TRY(MOZ_TO_RESULT(aConnection.ExecuteSimpleSQL(
          "PRAGMA wal_autocheckpoint = "_ns + IntToCString(kMaxWALPages))));
    }
  } else {
    NS_WARNING("Failed to set WAL mode, falling back to normal journal mode.");
#ifdef IDB_MOBILE
    QM_TRY(MOZ_TO_RESULT(
        aConnection.ExecuteSimpleSQL(journalModeQueryStart + "truncate"_ns)));
#endif
  }

  return NS_OK;
}

Result<MovingNotNull<nsCOMPtr<mozIStorageConnection>>, nsresult> OpenDatabase(
    mozIStorageService& aStorageService, nsIFileURL& aFileURL,
    const uint32_t aTelemetryId = 0) {
  const nsAutoCString telemetryFilename =
      aTelemetryId ? "indexedDB-"_ns + IntToCString(aTelemetryId) +
                         NS_ConvertUTF16toUTF8(kSQLiteSuffix)
                   : nsAutoCString();

  QM_TRY_UNWRAP(auto connection,
                MOZ_TO_RESULT_INVOKE_MEMBER_TYPED(
                    nsCOMPtr<mozIStorageConnection>, aStorageService,
                    OpenDatabaseWithFileURL, &aFileURL, telemetryFilename,
                    mozIStorageService::CONNECTION_INTERRUPTIBLE));

  return WrapMovingNotNull(std::move(connection));
}

Result<MovingNotNull<nsCOMPtr<mozIStorageConnection>>, nsresult>
OpenDatabaseAndHandleBusy(mozIStorageService& aStorageService,
                          nsIFileURL& aFileURL,
                          const uint32_t aTelemetryId = 0) {
  MOZ_ASSERT(!NS_IsMainThread());
  MOZ_ASSERT(!IsOnBackgroundThread());

  using ConnectionType = Maybe<MovingNotNull<nsCOMPtr<mozIStorageConnection>>>;

  QM_TRY_UNWRAP(auto connection,
                QM_OR_ELSE_WARN_IF(
                    // Expression
                    OpenDatabase(aStorageService, aFileURL, aTelemetryId)
                        .map([](auto connection) -> ConnectionType {
                          return Some(std::move(connection));
                        }),
                    // Predicate.
                    IsSpecificError<NS_ERROR_STORAGE_BUSY>,
                    // Fallback.
                    ErrToDefaultOk<ConnectionType>));

  if (connection.isNothing()) {
#ifdef DEBUG
    {
      nsCString path;
      MOZ_ALWAYS_SUCCEEDS(aFileURL.GetFileName(path));

      nsPrintfCString message(
          "Received NS_ERROR_STORAGE_BUSY when attempting to open database "
          "'%s', retrying for up to 10 seconds",
          path.get());
      NS_WARNING(message.get());
    }
#endif

    // Another thread must be checkpointing the WAL. Wait up to 10 seconds for
    // that to complete.
    const TimeStamp start = TimeStamp::NowLoRes();

    do {
      PR_Sleep(PR_MillisecondsToInterval(100));

      QM_TRY_UNWRAP(connection,
                    QM_OR_ELSE_WARN_IF(
                        // Expression.
                        OpenDatabase(aStorageService, aFileURL, aTelemetryId)
                            .map([](auto connection) -> ConnectionType {
                              return Some(std::move(connection));
                            }),
                        // Predicate.
                        ([&start](nsresult aValue) {
                          return aValue == NS_ERROR_STORAGE_BUSY &&
                                 TimeStamp::NowLoRes() - start <=
                                     TimeDuration::FromSeconds(10);
                        }),
                        // Fallback.
                        ErrToDefaultOk<ConnectionType>));
    } while (connection.isNothing());
  }

  return connection.extract();
}

// Returns true if a given nsIFile exists and is a directory. Returns false if
// it doesn't exist. Returns an error if it exists, but is not a directory, or
// any other error occurs.
Result<bool, nsresult> ExistsAsDirectory(nsIFile& aDirectory) {
  QM_TRY_INSPECT(const bool& exists,
                 MOZ_TO_RESULT_INVOKE_MEMBER(aDirectory, Exists));

  if (exists) {
    QM_TRY_INSPECT(const bool& isDirectory,
                   MOZ_TO_RESULT_INVOKE_MEMBER(aDirectory, IsDirectory));

    QM_TRY(OkIf(isDirectory), Err(NS_ERROR_FAILURE));
  }

  return exists;
}

constexpr nsresult mapNoDeviceSpaceError(nsresult aRv) {
  if (aRv == NS_ERROR_FILE_NO_DEVICE_SPACE) {
    // mozstorage translates SQLITE_FULL to
    // NS_ERROR_FILE_NO_DEVICE_SPACE, which we know better as
    // NS_ERROR_DOM_INDEXEDDB_QUOTA_ERR.
    return NS_ERROR_DOM_INDEXEDDB_QUOTA_ERR;
  }
  return aRv;
}

Result<MovingNotNull<nsCOMPtr<mozIStorageConnection>>, nsresult>
CreateStorageConnection(nsIFile& aDBFile, nsIFile& aFMDirectory,
                        const nsAString& aName, const nsACString& aOrigin,
                        const int64_t aDirectoryLockId,
                        const uint32_t aTelemetryId,
                        const Maybe<CipherKey>& aMaybeKey) {
  AssertIsOnIOThread();
  MOZ_ASSERT(aDirectoryLockId >= -1);

  AUTO_PROFILER_LABEL("CreateStorageConnection", DOM);

  QM_TRY_INSPECT(const auto& dbFileUrl,
                 GetDatabaseFileURL(aDBFile, aDirectoryLockId, aMaybeKey));

  QM_TRY_INSPECT(const auto& storageService,
                 MOZ_TO_RESULT_GET_TYPED(nsCOMPtr<mozIStorageService>,
                                         MOZ_SELECT_OVERLOAD(do_GetService),
                                         MOZ_STORAGE_SERVICE_CONTRACTID));

  QM_TRY_UNWRAP(
      auto connection,
      QM_OR_ELSE_WARN_IF(
          // Expression.
          OpenDatabaseAndHandleBusy(*storageService, *dbFileUrl, aTelemetryId)
              .map([](auto connection) -> nsCOMPtr<mozIStorageConnection> {
                return std::move(connection).unwrapBasePtr();
              }),
          // Predicate.
          ([&aName](nsresult aValue) {
            // If we're just opening the database during origin initialization,
            // then we don't want to erase any files. The failure here will fail
            // origin initialization too.
            return IsDatabaseCorruptionError(aValue) && !aName.IsVoid();
          }),
          // Fallback.
          ErrToDefaultOk<nsCOMPtr<mozIStorageConnection>>));

  if (!connection) {
    // XXX Shouldn't we also update quota usage?

    // Nuke the database file.
    QM_TRY(MOZ_TO_RESULT(aDBFile.Remove(false)));
    QM_TRY_INSPECT(const bool& existsAsDirectory,
                   ExistsAsDirectory(aFMDirectory));

    if (existsAsDirectory) {
      QM_TRY(MOZ_TO_RESULT(aFMDirectory.Remove(true)));
    }

    QM_TRY_UNWRAP(connection, OpenDatabaseAndHandleBusy(
                                  *storageService, *dbFileUrl, aTelemetryId));
  }

  QM_TRY(MOZ_TO_RESULT(SetDefaultPragmas(*connection)));
  QM_TRY(MOZ_TO_RESULT(connection->EnableModule("filesystem"_ns)));

  // Check to make sure that the database schema is correct.
  QM_TRY_INSPECT(const int32_t& schemaVersion,
                 MOZ_TO_RESULT_INVOKE_MEMBER(connection, GetSchemaVersion));

  // Unknown schema will fail origin initialization too.
  QM_TRY(OkIf(schemaVersion || !aName.IsVoid()),
         Err(NS_ERROR_DOM_INDEXEDDB_UNKNOWN_ERR), [](const auto&) {
           IDB_WARNING("Unable to open IndexedDB database, schema is not set!");
         });

  QM_TRY(
      OkIf(schemaVersion <= kSQLiteSchemaVersion),
      Err(NS_ERROR_DOM_INDEXEDDB_UNKNOWN_ERR), [](const auto&) {
        IDB_WARNING("Unable to open IndexedDB database, schema is too high!");
      });

  bool journalModeSet = false;

  if (schemaVersion != kSQLiteSchemaVersion) {
    const bool newDatabase = !schemaVersion;

    if (newDatabase) {
      // Set the page size first.
      const auto sqlitePageSizeOverride =
          aMaybeKey ? 8192 : kSQLitePageSizeOverride;
      if (sqlitePageSizeOverride) {
        QM_TRY(MOZ_TO_RESULT(connection->ExecuteSimpleSQL(nsPrintfCString(
            "PRAGMA page_size = %" PRIu32 ";", sqlitePageSizeOverride))));
      }

      // We have to set the auto_vacuum mode before opening a transaction.
      QM_TRY((MOZ_TO_RESULT_INVOKE_MEMBER(
                  connection, ExecuteSimpleSQL,
#ifdef IDB_MOBILE
                  // Turn on full auto_vacuum mode to reclaim disk space on
                  // mobile devices (at the cost of some COMMIT speed).
                  "PRAGMA auto_vacuum = FULL;"_ns
#else
                  // Turn on incremental auto_vacuum mode on desktop builds.
                  "PRAGMA auto_vacuum = INCREMENTAL;"_ns
#endif
                  )
                  .mapErr(mapNoDeviceSpaceError)));

      QM_TRY(MOZ_TO_RESULT(SetJournalMode(*connection)));

      journalModeSet = true;
    } else {
#ifdef DEBUG
      // Disable foreign key support while upgrading. This has to be done before
      // starting a transaction.
      MOZ_ALWAYS_SUCCEEDS(
          connection->ExecuteSimpleSQL("PRAGMA foreign_keys = OFF;"_ns));
#endif
    }

    bool vacuumNeeded = false;

    mozStorageTransaction transaction(
        connection.get(), false, mozIStorageConnection::TRANSACTION_IMMEDIATE);

    QM_TRY(MOZ_TO_RESULT(transaction.Start()));

    if (newDatabase) {
      QM_TRY(MOZ_TO_RESULT(CreateTables(*connection)));

#ifdef DEBUG
      {
        QM_TRY_INSPECT(
            const int32_t& schemaVersion,
            MOZ_TO_RESULT_INVOKE_MEMBER(connection, GetSchemaVersion),
            QM_ASSERT_UNREACHABLE);
        MOZ_ASSERT(schemaVersion == kSQLiteSchemaVersion);
      }
#endif

      // The parameter names are not used, parameters are bound by index only
      // locally in the same function.
      QM_TRY_INSPECT(
          const auto& stmt,
          MOZ_TO_RESULT_INVOKE_MEMBER_TYPED(
              nsCOMPtr<mozIStorageStatement>, connection, CreateStatement,
              "INSERT INTO database (name, origin) "
              "VALUES (:name, :origin)"_ns));

      QM_TRY(MOZ_TO_RESULT(stmt->BindStringByIndex(0, aName)));
      QM_TRY(MOZ_TO_RESULT(stmt->BindUTF8StringByIndex(1, aOrigin)));
      QM_TRY(MOZ_TO_RESULT(stmt->Execute()));
    } else {
      QM_TRY_UNWRAP(vacuumNeeded, MaybeUpgradeSchema(*connection, schemaVersion,
                                                     aFMDirectory, aOrigin));
    }

    QM_TRY(MOZ_TO_RESULT_INVOKE_MEMBER(transaction, Commit)
               .mapErr(mapNoDeviceSpaceError));

#ifdef DEBUG
    if (!newDatabase) {
      // Re-enable foreign key support after doing a foreign key check.
      QM_TRY_INSPECT(const bool& foreignKeyError,
                     CreateAndExecuteSingleStepStatement<
                         SingleStepResult::ReturnNullIfNoResult>(
                         *connection, "PRAGMA foreign_key_check;"_ns),
                     QM_ASSERT_UNREACHABLE);

      MOZ_ASSERT(!foreignKeyError, "Database has inconsisistent foreign keys!");

      MOZ_ALWAYS_SUCCEEDS(
          connection->ExecuteSimpleSQL("PRAGMA foreign_keys = OFF;"_ns));
    }
#endif

    if (kSQLitePageSizeOverride && !newDatabase) {
      QM_TRY_INSPECT(const auto& stmt,
                     CreateAndExecuteSingleStepStatement(
                         *connection, "PRAGMA page_size;"_ns));

      QM_TRY_INSPECT(const int32_t& pageSize,
                     MOZ_TO_RESULT_INVOKE_MEMBER(*stmt, GetInt32, 0));
      MOZ_ASSERT(pageSize >= 512 && pageSize <= 65536);

      if (kSQLitePageSizeOverride != uint32_t(pageSize)) {
        // We must not be in WAL journal mode to change the page size.
        QM_TRY(MOZ_TO_RESULT(
            connection->ExecuteSimpleSQL("PRAGMA journal_mode = DELETE;"_ns)));

        QM_TRY_INSPECT(const auto& stmt,
                       CreateAndExecuteSingleStepStatement(
                           *connection, "PRAGMA journal_mode;"_ns));

        QM_TRY_INSPECT(const auto& journalMode,
                       MOZ_TO_RESULT_INVOKE_MEMBER_TYPED(nsCString, *stmt,
                                                         GetUTF8String, 0));

        if (journalMode.EqualsLiteral("delete")) {
          // Successfully set to rollback journal mode so changing the page size
          // is possible with a VACUUM.
          QM_TRY(MOZ_TO_RESULT(connection->ExecuteSimpleSQL(nsPrintfCString(
              "PRAGMA page_size = %" PRIu32 ";", kSQLitePageSizeOverride))));

          // We will need to VACUUM in order to change the page size.
          vacuumNeeded = true;
        } else {
          NS_WARNING(
              "Failed to set journal_mode for database, unable to "
              "change the page size!");
        }
      }
    }

    if (vacuumNeeded) {
      QM_TRY(MOZ_TO_RESULT(connection->ExecuteSimpleSQL("VACUUM;"_ns)));
    }

    if (newDatabase || vacuumNeeded) {
      if (journalModeSet) {
        // Make sure we checkpoint to get an accurate file size.
        QM_TRY(MOZ_TO_RESULT(
            connection->ExecuteSimpleSQL("PRAGMA wal_checkpoint(FULL);"_ns)));
      }

      QM_TRY_INSPECT(const int64_t& fileSize,
                     MOZ_TO_RESULT_INVOKE_MEMBER(aDBFile, GetFileSize));
      MOZ_ASSERT(fileSize > 0);

      PRTime vacuumTime = PR_Now();
      MOZ_ASSERT(vacuumTime);

      // The parameter names are not used, parameters are bound by index only
      // locally in the same function.
      QM_TRY_INSPECT(
          const auto& vacuumTimeStmt,
          MOZ_TO_RESULT_INVOKE_MEMBER_TYPED(nsCOMPtr<mozIStorageStatement>,
                                            connection, CreateStatement,
                                            "UPDATE database "
                                            "SET last_vacuum_time = :time"
                                            ", last_vacuum_size = :size;"_ns));

      QM_TRY(MOZ_TO_RESULT(vacuumTimeStmt->BindInt64ByIndex(0, vacuumTime)));
      QM_TRY(MOZ_TO_RESULT(vacuumTimeStmt->BindInt64ByIndex(1, fileSize)));
      QM_TRY(MOZ_TO_RESULT(vacuumTimeStmt->Execute()));
    }
  }

  if (!journalModeSet) {
    QM_TRY(MOZ_TO_RESULT(SetJournalMode(*connection)));
  }

  return WrapMovingNotNullUnchecked(std::move(connection));
}

nsCOMPtr<nsIFile> GetFileForPath(const nsAString& aPath) {
  MOZ_ASSERT(!aPath.IsEmpty());

  QM_TRY_RETURN(QM_NewLocalFile(aPath), nullptr);
}

Result<MovingNotNull<nsCOMPtr<mozIStorageConnection>>, nsresult>
GetStorageConnection(nsIFile& aDatabaseFile, const int64_t aDirectoryLockId,
                     const uint32_t aTelemetryId,
                     const Maybe<CipherKey>& aMaybeKey) {
  MOZ_ASSERT(!NS_IsMainThread());
  MOZ_ASSERT(!IsOnBackgroundThread());
  MOZ_ASSERT(aDirectoryLockId >= 0);

  AUTO_PROFILER_LABEL("GetStorageConnection", DOM);

  QM_TRY_INSPECT(const bool& exists,
                 MOZ_TO_RESULT_INVOKE_MEMBER(aDatabaseFile, Exists));

  QM_TRY(OkIf(exists), Err(NS_ERROR_DOM_INDEXEDDB_UNKNOWN_ERR),
         IDB_REPORT_INTERNAL_ERR_LAMBDA);

  QM_TRY_INSPECT(
      const auto& dbFileUrl,
      GetDatabaseFileURL(aDatabaseFile, aDirectoryLockId, aMaybeKey));

  QM_TRY_INSPECT(const auto& storageService,
                 MOZ_TO_RESULT_GET_TYPED(nsCOMPtr<mozIStorageService>,
                                         MOZ_SELECT_OVERLOAD(do_GetService),
                                         MOZ_STORAGE_SERVICE_CONTRACTID));

  QM_TRY_UNWRAP(
      nsCOMPtr<mozIStorageConnection> connection,
      OpenDatabaseAndHandleBusy(*storageService, *dbFileUrl, aTelemetryId));

  QM_TRY(MOZ_TO_RESULT(SetDefaultPragmas(*connection)));

  QM_TRY(MOZ_TO_RESULT(SetJournalMode(*connection)));

  return WrapMovingNotNullUnchecked(std::move(connection));
}

Result<MovingNotNull<nsCOMPtr<mozIStorageConnection>>, nsresult>
GetStorageConnection(const nsAString& aDatabaseFilePath,
                     const int64_t aDirectoryLockId,
                     const uint32_t aTelemetryId,
                     const Maybe<CipherKey>& aMaybeKey) {
  MOZ_ASSERT(!NS_IsMainThread());
  MOZ_ASSERT(!IsOnBackgroundThread());
  MOZ_ASSERT(!aDatabaseFilePath.IsEmpty());
  MOZ_ASSERT(StringEndsWith(aDatabaseFilePath, kSQLiteSuffix));
  MOZ_ASSERT(aDirectoryLockId >= 0);

  nsCOMPtr<nsIFile> dbFile = GetFileForPath(aDatabaseFilePath);

  QM_TRY(OkIf(dbFile), Err(NS_ERROR_DOM_INDEXEDDB_UNKNOWN_ERR),
         IDB_REPORT_INTERNAL_ERR_LAMBDA);

  return GetStorageConnection(*dbFile, aDirectoryLockId, aTelemetryId,
                              aMaybeKey);
}

/*******************************************************************************
 * ConnectionPool declarations
 ******************************************************************************/

class DatabaseConnection final : public CachingDatabaseConnection {
  friend class ConnectionPool;

  enum class CheckpointMode { Full, Restart, Truncate };

 public:
  class AutoSavepoint;
  class UpdateRefcountFunction;

 private:
  InitializedOnce<const NotNull<SafeRefPtr<DatabaseFileManager>>> mFileManager;
  RefPtr<UpdateRefcountFunction> mUpdateRefcountFunction;
  RefPtr<QuotaObject> mQuotaObject;
  RefPtr<QuotaObject> mJournalQuotaObject;
  IDBTransaction::Durability mLastDurability;
  bool mInReadTransaction;
  bool mInWriteTransaction;

#ifdef DEBUG
  uint32_t mDEBUGSavepointCount;
#endif

 public:
  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(DatabaseConnection)

  UpdateRefcountFunction* GetUpdateRefcountFunction() const {
    AssertIsOnConnectionThread();

    return mUpdateRefcountFunction;
  }

  nsresult BeginWriteTransaction(const IDBTransaction::Durability aDurability);

  nsresult CommitWriteTransaction();

  void RollbackWriteTransaction();

  void FinishWriteTransaction();

  nsresult StartSavepoint();

  nsresult ReleaseSavepoint();

  nsresult RollbackSavepoint();

  nsresult Checkpoint() {
    AssertIsOnConnectionThread();

    return CheckpointInternal(CheckpointMode::Full);
  }

  void DoIdleProcessing(bool aNeedsCheckpoint,
                        const Atomic<bool>& aInterrupted);

  void Close();

  nsresult DisableQuotaChecks();

  void EnableQuotaChecks();

 private:
  DatabaseConnection(
      MovingNotNull<nsCOMPtr<mozIStorageConnection>> aStorageConnection,
      MovingNotNull<SafeRefPtr<DatabaseFileManager>> aFileManager);

  ~DatabaseConnection();

  nsresult Init();

  nsresult CheckpointInternal(CheckpointMode aMode);

  Result<uint32_t, nsresult> GetFreelistCount(
      CachedStatement& aCachedStatement);

  /**
   * On success, returns whether some pages were freed.
   */
  Result<bool, nsresult> ReclaimFreePagesWhileIdle(
      CachedStatement& aFreelistStatement, CachedStatement& aRollbackStatement,
      uint32_t aFreelistCount, bool aNeedsCheckpoint,
      const Atomic<bool>& aInterrupted);

  Result<int64_t, nsresult> GetFileSize(const nsAString& aPath);
};

class MOZ_STACK_CLASS DatabaseConnection::AutoSavepoint final {
  DatabaseConnection* mConnection;
#ifdef DEBUG
  const TransactionBase* mDEBUGTransaction;
#endif

 public:
  AutoSavepoint();
  ~AutoSavepoint();

  nsresult Start(const TransactionBase& aTransaction);

  nsresult Commit();
};

class DatabaseConnection::UpdateRefcountFunction final
    : public mozIStorageFunction {
  class FileInfoEntry;

  enum class UpdateType { Increment, Decrement };

  DatabaseConnection* const mConnection;
  DatabaseFileManager& mFileManager;
  nsClassHashtable<nsUint64HashKey, FileInfoEntry> mFileInfoEntries;
  nsTHashMap<nsUint64HashKey, NotNull<FileInfoEntry*>> mSavepointEntriesIndex;

  nsTArray<int64_t> mJournalsToCreateBeforeCommit;
  nsTArray<int64_t> mJournalsToRemoveAfterCommit;
  nsTArray<int64_t> mJournalsToRemoveAfterAbort;

  bool mInSavepoint;

 public:
  NS_DECL_ISUPPORTS_ONEVENTTARGET
  NS_DECL_MOZISTORAGEFUNCTION

  UpdateRefcountFunction(DatabaseConnection* aConnection,
                         DatabaseFileManager& aFileManager);

  nsresult WillCommit();

  void DidCommit();

  void DidAbort();

  void StartSavepoint();

  void ReleaseSavepoint();

  void RollbackSavepoint();

  void Reset();

 private:
  ~UpdateRefcountFunction() = default;

  nsresult ProcessValue(mozIStorageValueArray* aValues, int32_t aIndex,
                        UpdateType aUpdateType);

  nsresult CreateJournals();

  nsresult RemoveJournals(const nsTArray<int64_t>& aJournals);
};

class DatabaseConnection::UpdateRefcountFunction::FileInfoEntry final {
  SafeRefPtr<DatabaseFileInfo> mFileInfo;
  int32_t mDelta;
  int32_t mSavepointDelta;

 public:
  explicit FileInfoEntry(SafeRefPtr<DatabaseFileInfo> aFileInfo)
      : mFileInfo(std::move(aFileInfo)), mDelta(0), mSavepointDelta(0) {
    MOZ_COUNT_CTOR(DatabaseConnection::UpdateRefcountFunction::FileInfoEntry);
  }

  void IncDeltas(bool aUpdateSavepointDelta) {
    ++mDelta;
    if (aUpdateSavepointDelta) {
      ++mSavepointDelta;
    }
  }
  void DecDeltas(bool aUpdateSavepointDelta) {
    --mDelta;
    if (aUpdateSavepointDelta) {
      --mSavepointDelta;
    }
  }
  void DecBySavepointDelta() { mDelta -= mSavepointDelta; }
  SafeRefPtr<DatabaseFileInfo> ReleaseFileInfo() {
    return std::move(mFileInfo);
  }
  void MaybeUpdateDBRefs() {
    if (mDelta) {
      mFileInfo->UpdateDBRefs(mDelta);
    }
  }

  int32_t Delta() const { return mDelta; }
  int32_t SavepointDelta() const { return mSavepointDelta; }

  ~FileInfoEntry() {
    MOZ_COUNT_DTOR(DatabaseConnection::UpdateRefcountFunction::FileInfoEntry);
  }
};

class ConnectionPool final {
 public:
  class FinishCallback;

 private:
  class ConnectionRunnable;
  class CloseConnectionRunnable;
  struct DatabaseInfo;
  struct DatabaseCompleteCallback;
  class FinishCallbackWrapper;
  class IdleConnectionRunnable;

#ifdef DEBUG
  class TransactionRunnable;
#endif
  class TransactionInfo;
  struct TransactionInfoPair;

  struct IdleResource {
    TimeStamp mIdleTime;

    IdleResource(const IdleResource& aOther) = delete;
    IdleResource(IdleResource&& aOther) noexcept
        : IdleResource(aOther.mIdleTime) {}
    IdleResource& operator=(const IdleResource& aOther) = delete;
    IdleResource& operator=(IdleResource&& aOther) = delete;

   protected:
    explicit IdleResource(const TimeStamp& aIdleTime);

    ~IdleResource();
  };

  struct IdleDatabaseInfo final : public IdleResource {
    InitializedOnce<const NotNull<DatabaseInfo*>> mDatabaseInfo;

   public:
    explicit IdleDatabaseInfo(DatabaseInfo& aDatabaseInfo);

    IdleDatabaseInfo(const IdleDatabaseInfo& aOther) = delete;
    IdleDatabaseInfo(IdleDatabaseInfo&& aOther) noexcept
        : IdleResource(std::move(aOther)),
          mDatabaseInfo{std::move(aOther.mDatabaseInfo)} {
      MOZ_ASSERT(mDatabaseInfo);

      MOZ_COUNT_CTOR(ConnectionPool::IdleDatabaseInfo);
    }
    IdleDatabaseInfo& operator=(const IdleDatabaseInfo& aOther) = delete;
    IdleDatabaseInfo& operator=(IdleDatabaseInfo&& aOther) = delete;

    ~IdleDatabaseInfo();

    bool operator==(const IdleDatabaseInfo& aOther) const {
      return *mDatabaseInfo == *aOther.mDatabaseInfo;
    }

    bool operator==(const DatabaseInfo* aDatabaseInfo) const {
      return *mDatabaseInfo == aDatabaseInfo;
    }

    bool operator<(const IdleDatabaseInfo& aOther) const {
      return mIdleTime < aOther.mIdleTime;
    }
  };

  struct PerformingIdleMaintenanceDatabaseInfo {
    const NotNull<DatabaseInfo*> mDatabaseInfo;
    RefPtr<IdleConnectionRunnable> mIdleConnectionRunnable;

    PerformingIdleMaintenanceDatabaseInfo(
        DatabaseInfo& aDatabaseInfo,
        RefPtr<IdleConnectionRunnable> aIdleConnectionRunnable);

    PerformingIdleMaintenanceDatabaseInfo(
        const PerformingIdleMaintenanceDatabaseInfo& aOther) = delete;
    PerformingIdleMaintenanceDatabaseInfo(
        PerformingIdleMaintenanceDatabaseInfo&& aOther) noexcept
        : mDatabaseInfo{aOther.mDatabaseInfo},
          mIdleConnectionRunnable{std::move(aOther.mIdleConnectionRunnable)} {
      MOZ_COUNT_CTOR(ConnectionPool::PerformingIdleMaintenanceDatabaseInfo);
    }
    PerformingIdleMaintenanceDatabaseInfo& operator=(
        const PerformingIdleMaintenanceDatabaseInfo& aOther) = delete;
    PerformingIdleMaintenanceDatabaseInfo& operator=(
        PerformingIdleMaintenanceDatabaseInfo&& aOther) = delete;

    ~PerformingIdleMaintenanceDatabaseInfo();

    bool operator==(const DatabaseInfo* aDatabaseInfo) const {
      return mDatabaseInfo == aDatabaseInfo;
    }
  };

  // This mutex guards mDatabases, see below.
  Mutex mDatabasesMutex MOZ_UNANNOTATED;

  nsCOMPtr<nsIThreadPool> mIOTarget;
  nsTArray<IdleDatabaseInfo> mIdleDatabases;
  nsTArray<PerformingIdleMaintenanceDatabaseInfo>
      mDatabasesPerformingIdleMaintenance;
  nsCOMPtr<nsITimer> mIdleTimer;
  TimeStamp mTargetIdleTime;

  // Only modifed on the owning thread, but read on multiple threads. Therefore
  // all modifications and all reads off the owning thread must be protected by
  // mDatabasesMutex.
  nsClassHashtable<nsCStringHashKey, DatabaseInfo> mDatabases;

  nsClassHashtable<nsUint64HashKey, TransactionInfo> mTransactions;
  nsTArray<NotNull<TransactionInfo*>> mQueuedTransactions;

  nsTArray<UniquePtr<DatabaseCompleteCallback>> mCompleteCallbacks;

  uint64_t mNextTransactionId;
  FlippedOnce<false> mShutdownRequested;
  FlippedOnce<false> mShutdownComplete;

 public:
  ConnectionPool();

  void AssertIsOnOwningThread() const {
    NS_ASSERT_OWNINGTHREAD(ConnectionPool);
  }

  Result<RefPtr<DatabaseConnection>, nsresult> GetOrCreateConnection(
      const Database& aDatabase);

  uint64_t Start(const nsID& aBackgroundChildLoggingId,
                 const nsACString& aDatabaseId, int64_t aLoggingSerialNumber,
                 const nsTArray<nsString>& aObjectStoreNames,
                 bool aIsWriteTransaction,
                 TransactionDatabaseOperationBase* aTransactionOp);

  void Dispatch(uint64_t aTransactionId, nsIRunnable* aRunnable);

  void Finish(uint64_t aTransactionId, FinishCallback* aCallback);

  void CloseDatabaseWhenIdle(const nsACString& aDatabaseId) {
    Unused << CloseDatabaseWhenIdleInternal(aDatabaseId);
  }

  void WaitForDatabaseToComplete(const nsCString& aDatabaseId,
                                 nsIRunnable* aCallback);

  void Shutdown();

  NS_INLINE_DECL_REFCOUNTING(ConnectionPool)

 private:
  ~ConnectionPool();

  static void IdleTimerCallback(nsITimer* aTimer, void* aClosure);

  static uint32_t SerialNumber() { return ++sSerialNumber; }

  static uint32_t sSerialNumber;

  void Cleanup();

  void AdjustIdleTimer();

  void CancelIdleTimer();

  void CloseIdleDatabases();

  bool ScheduleTransaction(TransactionInfo& aTransactionInfo,
                           bool aFromQueuedTransactions);

  void NoteFinishedTransaction(uint64_t aTransactionId);

  void ScheduleQueuedTransactions();

  void NoteIdleDatabase(DatabaseInfo& aDatabaseInfo);

  void NoteClosedDatabase(DatabaseInfo& aDatabaseInfo);

  bool MaybeFireCallback(DatabaseCompleteCallback* aCallback);

  void PerformIdleDatabaseMaintenance(DatabaseInfo& aDatabaseInfo);

  void CloseDatabase(DatabaseInfo& aDatabaseInfo) const;

  bool CloseDatabaseWhenIdleInternal(const nsACString& aDatabaseId);
};

class ConnectionPool::ConnectionRunnable : public Runnable {
 protected:
  DatabaseInfo& mDatabaseInfo;
  nsCOMPtr<nsIEventTarget> mOwningEventTarget;

  explicit ConnectionRunnable(DatabaseInfo& aDatabaseInfo);

  ~ConnectionRunnable() override = default;
};

class ConnectionPool::IdleConnectionRunnable final : public ConnectionRunnable {
  const bool mNeedsCheckpoint;
  Atomic<bool> mInterrupted;

 public:
  IdleConnectionRunnable(DatabaseInfo& aDatabaseInfo, bool aNeedsCheckpoint)
      : ConnectionRunnable(aDatabaseInfo), mNeedsCheckpoint(aNeedsCheckpoint) {}

  NS_INLINE_DECL_REFCOUNTING_INHERITED(IdleConnectionRunnable,
                                       ConnectionRunnable)

  void Interrupt() { mInterrupted = true; }

 private:
  ~IdleConnectionRunnable() override = default;

  NS_DECL_NSIRUNNABLE
};

class ConnectionPool::CloseConnectionRunnable final
    : public ConnectionRunnable {
 public:
  explicit CloseConnectionRunnable(DatabaseInfo& aDatabaseInfo)
      : ConnectionRunnable(aDatabaseInfo) {}

  NS_INLINE_DECL_REFCOUNTING_INHERITED(CloseConnectionRunnable,
                                       ConnectionRunnable)

 private:
  ~CloseConnectionRunnable() override = default;

  NS_DECL_NSIRUNNABLE
};

struct ConnectionPool::DatabaseInfo final {
  friend class mozilla::DefaultDelete<DatabaseInfo>;

  RefPtr<ConnectionPool> mConnectionPool;
  const nsCString mDatabaseId;
  RefPtr<DatabaseConnection> mConnection;
  nsClassHashtable<nsStringHashKey, TransactionInfoPair> mBlockingTransactions;
  nsTArray<NotNull<TransactionInfo*>> mTransactionsScheduledDuringClose;
  nsTArray<NotNull<TransactionInfo*>> mScheduledWriteTransactions;
  Maybe<TransactionInfo&> mRunningWriteTransaction;
  RefPtr<TaskQueue> mEventTarget;
  uint32_t mReadTransactionCount;
  uint32_t mWriteTransactionCount;
  bool mNeedsCheckpoint;
  bool mIdle;
  FlippedOnce<false> mCloseOnIdle;
  bool mClosing;

#ifdef DEBUG
  nsISerialEventTarget* mDEBUGConnectionEventTarget;
#endif

  DatabaseInfo(ConnectionPool* aConnectionPool, const nsACString& aDatabaseId);

  void AssertIsOnConnectionThread() const {
    MOZ_ASSERT(mDEBUGConnectionEventTarget);
    MOZ_ASSERT(GetCurrentSerialEventTarget() == mDEBUGConnectionEventTarget);
  }

  uint64_t TotalTransactionCount() const {
    return mReadTransactionCount + mWriteTransactionCount;
  }

  nsresult Dispatch(already_AddRefed<nsIRunnable> aRunnable);

 private:
  ~DatabaseInfo();

  DatabaseInfo(const DatabaseInfo&) = delete;
  DatabaseInfo& operator=(const DatabaseInfo&) = delete;
};

struct ConnectionPool::DatabaseCompleteCallback final {
  friend class DefaultDelete<DatabaseCompleteCallback>;

  nsCString mDatabaseId;
  nsCOMPtr<nsIRunnable> mCallback;

  DatabaseCompleteCallback(const nsCString& aDatabaseIds,
                           nsIRunnable* aCallback);

 private:
  ~DatabaseCompleteCallback();
};

class NS_NO_VTABLE ConnectionPool::FinishCallback : public nsIRunnable {
 public:
  // Called on the owning thread before any additional transactions are
  // unblocked.
  virtual void TransactionFinishedBeforeUnblock() = 0;

  // Called on the owning thread after additional transactions may have been
  // unblocked.
  virtual void TransactionFinishedAfterUnblock() = 0;

 protected:
  FinishCallback() = default;

  virtual ~FinishCallback() = default;
};

class ConnectionPool::FinishCallbackWrapper final : public Runnable {
  RefPtr<ConnectionPool> mConnectionPool;
  RefPtr<FinishCallback> mCallback;
  nsCOMPtr<nsIEventTarget> mOwningEventTarget;
  uint64_t mTransactionId;
  bool mHasRunOnce;

 public:
  FinishCallbackWrapper(ConnectionPool* aConnectionPool,
                        uint64_t aTransactionId, FinishCallback* aCallback);

  NS_INLINE_DECL_REFCOUNTING_INHERITED(FinishCallbackWrapper, Runnable)

 private:
  ~FinishCallbackWrapper() override;

  NS_DECL_NSIRUNNABLE
};

#ifdef DEBUG

class ConnectionPool::TransactionRunnable final : public Runnable {
 public:
  explicit TransactionRunnable(nsCOMPtr<nsIRunnable> aRunnable);

 private:
  NS_DECL_NSIRUNNABLE

  nsCOMPtr<nsIRunnable> mRunnable;
};

#endif

class ConnectionPool::TransactionInfo final {
  friend class mozilla::DefaultDelete<TransactionInfo>;

  nsTHashSet<TransactionInfo*> mBlocking;
  nsTArray<NotNull<TransactionInfo*>> mBlockingOrdered;

 public:
  DatabaseInfo& mDatabaseInfo;
  const nsID mBackgroundChildLoggingId;
  const nsCString mDatabaseId;
  const uint64_t mTransactionId;
  const int64_t mLoggingSerialNumber;
  const nsTArray<nsString> mObjectStoreNames;
  nsTHashSet<TransactionInfo*> mBlockedOn;
  nsTArray<nsCOMPtr<nsIRunnable>> mQueuedRunnables;
  const bool mIsWriteTransaction;
  bool mRunning;

#ifdef DEBUG
  FlippedOnce<false> mFinished;
#endif

  TransactionInfo(DatabaseInfo& aDatabaseInfo,
                  const nsID& aBackgroundChildLoggingId,
                  const nsACString& aDatabaseId, uint64_t aTransactionId,
                  int64_t aLoggingSerialNumber,
                  const nsTArray<nsString>& aObjectStoreNames,
                  bool aIsWriteTransaction,
                  TransactionDatabaseOperationBase* aTransactionOp);

  void AddBlockingTransaction(TransactionInfo& aTransactionInfo);

  void RemoveBlockingTransactions();

 private:
  ~TransactionInfo();

  void MaybeUnblock(TransactionInfo& aTransactionInfo);
};

struct ConnectionPool::TransactionInfoPair final {
  // Multiple reading transactions can block future writes.
  nsTArray<NotNull<TransactionInfo*>> mLastBlockingWrites;
  // But only a single writing transaction can block future reads.
  Maybe<TransactionInfo&> mLastBlockingReads;

#if defined(DEBUG) || defined(NS_BUILD_REFCNT_LOGGING)
  TransactionInfoPair();
  ~TransactionInfoPair();
#endif
};

/*******************************************************************************
 * Actor class declarations
 ******************************************************************************/

template <IDBCursorType CursorType>
class CommonOpenOpHelper;
template <IDBCursorType CursorType>
class IndexOpenOpHelper;
template <IDBCursorType CursorType>
class ObjectStoreOpenOpHelper;
template <IDBCursorType CursorType>
class OpenOpHelper;

class DatabaseOperationBase : public Runnable,
                              public mozIStorageProgressHandler {
  template <IDBCursorType CursorType>
  friend class OpenOpHelper;

 protected:
  class AutoSetProgressHandler;

  using UniqueIndexTable = nsTHashMap<nsUint64HashKey, bool>;

  const nsCOMPtr<nsIEventTarget> mOwningEventTarget;
  const nsID mBackgroundChildLoggingId;
  const uint64_t mLoggingSerialNumber;

 private:
  nsresult mResultCode = NS_OK;
  Atomic<bool> mOperationMayProceed;
  FlippedOnce<false> mActorDestroyed;

 public:
  NS_DECL_ISUPPORTS_INHERITED

  bool IsOnOwningThread() const {
    MOZ_ASSERT(mOwningEventTarget);

    bool current;
    return NS_SUCCEEDED(mOwningEventTarget->IsOnCurrentThread(¤t)) &&
           current;
  }

  void AssertIsOnOwningThread() const {
    MOZ_ASSERT(IsOnBackgroundThread());
    MOZ_ASSERT(IsOnOwningThread());
  }

  void NoteActorDestroyed() {
    AssertIsOnOwningThread();

    mActorDestroyed.EnsureFlipped();
    mOperationMayProceed = false;
  }

  bool IsActorDestroyed() const {
    AssertIsOnOwningThread();

    return mActorDestroyed;
  }

  // May be called on any thread, but you should call IsActorDestroyed() if
  // you know you're on the background thread because it is slightly faster.
  bool OperationMayProceed() const { return mOperationMayProceed; }

  const nsID& BackgroundChildLoggingId() const {
    return mBackgroundChildLoggingId;
  }

  uint64_t LoggingSerialNumber() const { return mLoggingSerialNumber; }

  nsresult ResultCode() const { return mResultCode; }

  void SetFailureCode(nsresult aFailureCode) {
    MOZ_ASSERT(NS_SUCCEEDED(mResultCode));
    OverrideFailureCode(aFailureCode);
  }

  void SetFailureCodeIfUnset(nsresult aFailureCode) {
    if (NS_SUCCEEDED(mResultCode)) {
      OverrideFailureCode(aFailureCode);
    }
  }

  bool HasFailed() const { return NS_FAILED(mResultCode); }

 protected:
  DatabaseOperationBase(const nsID& aBackgroundChildLoggingId,
                        uint64_t aLoggingSerialNumber)
      : Runnable("dom::indexedDB::DatabaseOperationBase"),
        mOwningEventTarget(GetCurrentSerialEventTarget()),
        mBackgroundChildLoggingId(aBackgroundChildLoggingId),
        mLoggingSerialNumber(aLoggingSerialNumber),
        mOperationMayProceed(true) {
    AssertIsOnOwningThread();
  }

  ~DatabaseOperationBase() override { MOZ_ASSERT(mActorDestroyed); }

  void OverrideFailureCode(nsresult aFailureCode) {
    MOZ_ASSERT(NS_FAILED(aFailureCode));

    mResultCode = aFailureCode;
  }

  static nsAutoCString MaybeGetBindingClauseForKeyRange(
      const Maybe<SerializedKeyRange>& aOptionalKeyRange,
      const nsACString& aKeyColumnName);

  static nsAutoCString GetBindingClauseForKeyRange(
      const SerializedKeyRange& aKeyRange, const nsACString& aKeyColumnName);

  static uint64_t ReinterpretDoubleAsUInt64(double aDouble);

  static nsresult BindKeyRangeToStatement(const SerializedKeyRange& aKeyRange,
                                          mozIStorageStatement* aStatement);

  static nsresult BindKeyRangeToStatement(const SerializedKeyRange& aKeyRange,
                                          mozIStorageStatement* aStatement,
                                          const nsCString& aLocale);

  static Result<IndexDataValuesAutoArray, nsresult>
  IndexDataValuesFromUpdateInfos(const nsTArray<IndexUpdateInfo>& aUpdateInfos,
                                 const UniqueIndexTable& aUniqueIndexTable);

  static nsresult InsertIndexTableRows(
      DatabaseConnection* aConnection, IndexOrObjectStoreId aObjectStoreId,
      const Key& aObjectStoreKey, const nsTArray<IndexDataValue>& aIndexValues);

  static nsresult DeleteIndexDataTableRows(
      DatabaseConnection* aConnection, const Key& aObjectStoreKey,
      const nsTArray<IndexDataValue>& aIndexValues);

  static nsresult DeleteObjectStoreDataTableRowsWithIndexes(
      DatabaseConnection* aConnection, IndexOrObjectStoreId aObjectStoreId,
      const Maybe<SerializedKeyRange>& aKeyRange);

  static nsresult UpdateIndexValues(
      DatabaseConnection* aConnection, IndexOrObjectStoreId aObjectStoreId,
      const Key& aObjectStoreKey, const nsTArray<IndexDataValue>& aIndexValues);

  static Result<bool, nsresult> ObjectStoreHasIndexes(
      DatabaseConnection& aConnection, IndexOrObjectStoreId aObjectStoreId);

 private:
  template <typename KeyTransformation>
  static nsresult MaybeBindKeyToStatement(
      const Key& aKey, mozIStorageStatement* aStatement,
      const nsACString& aParameterName,
      const KeyTransformation& aKeyTransformation);

  template <typename KeyTransformation>
  static nsresult BindTransformedKeyRangeToStatement(
      const SerializedKeyRange& aKeyRange, mozIStorageStatement* aStatement,
      const KeyTransformation& aKeyTransformation);

  // Not to be overridden by subclasses.
  NS_DECL_MOZISTORAGEPROGRESSHANDLER
};

class MOZ_STACK_CLASS DatabaseOperationBase::AutoSetProgressHandler final {
  Maybe<mozIStorageConnection&> mConnection;
#ifdef DEBUG
  DatabaseOperationBase* mDEBUGDatabaseOp;
#endif

 public:
  AutoSetProgressHandler();

  ~AutoSetProgressHandler();

  nsresult Register(mozIStorageConnection& aConnection,
                    DatabaseOperationBase* aDatabaseOp);

  void Unregister();
};

class TransactionDatabaseOperationBase : public DatabaseOperationBase {
  enum class InternalState {
    Initial,
    DatabaseWork,
    SendingPreprocess,
    WaitingForContinue,
    SendingResults,
    Completed
  };

  InitializedOnce<const NotNull<SafeRefPtr<TransactionBase>>> mTransaction;
  // Unique request id within the context of the transaction, allocated by the
  // transaction in the content process starting from 0. Values less than 0 are
  // impossible and forbidden. Used to support the explicit commit() request.
  const int64_t mRequestId;
  InternalState mInternalState = InternalState::Initial;
  bool mWaitingForContinue = false;
  const bool mTransactionIsAborted;

 protected:
  const int64_t mTransactionLoggingSerialNumber;

#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
 protected:
  // A check only enables when the diagnostic assert turns on. It assumes the
  // mUpdateRefcountFunction is a nullptr because the previous
  // StartTransactionOp failed on the connection thread and the next write
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