Add m-esr52 at 52.6.0

1 files changed, 982 insertions, 0 deletions

diff --git a/storage/mozStorageService.cpp b/storage/mozStorageService.cpp
new file mode 100644
index 000000000..4f288ad42
--- /dev/null
+++ b/storage/mozStorageService.cpp
@@ -0,0 +1,982 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
+ * 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 "mozilla/Attributes.h"
+#include "mozilla/DebugOnly.h"
+
+#include "mozStorageService.h"
+#include "mozStorageConnection.h"
+#include "nsAutoPtr.h"
+#include "nsCollationCID.h"
+#include "nsEmbedCID.h"
+#include "nsThreadUtils.h"
+#include "mozStoragePrivateHelpers.h"
+#include "nsILocale.h"
+#include "nsILocaleService.h"
+#include "nsIXPConnect.h"
+#include "nsIObserverService.h"
+#include "nsIPropertyBag2.h"
+#include "mozilla/Services.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/LateWriteChecks.h"
+#include "mozIStorageCompletionCallback.h"
+#include "mozIStoragePendingStatement.h"
+
+#include "sqlite3.h"
+
+#ifdef SQLITE_OS_WIN
+// "windows.h" was included and it can #define lots of things we care about...
+#undef CompareString
+#endif
+
+#include "nsIPromptService.h"
+
+#ifdef MOZ_STORAGE_MEMORY
+#  include "mozmemory.h"
+#  ifdef MOZ_DMD
+#    include "DMD.h"
+#  endif
+#endif
+
+////////////////////////////////////////////////////////////////////////////////
+//// Defines
+
+#define PREF_TS_SYNCHRONOUS "toolkit.storage.synchronous"
+#define PREF_TS_SYNCHRONOUS_DEFAULT 1
+
+#define PREF_TS_PAGESIZE "toolkit.storage.pageSize"
+
+// This value must be kept in sync with the value of SQLITE_DEFAULT_PAGE_SIZE in
+// db/sqlite3/src/Makefile.in.
+#define PREF_TS_PAGESIZE_DEFAULT 32768
+
+namespace mozilla {
+namespace storage {
+
+////////////////////////////////////////////////////////////////////////////////
+//// Memory Reporting
+
+#ifdef MOZ_DMD
+static mozilla::Atomic<size_t> gSqliteMemoryUsed;
+#endif
+
+static int64_t
+StorageSQLiteDistinguishedAmount()
+{
+  return ::sqlite3_memory_used();
+}
+
+/**
+ * Passes a single SQLite memory statistic to a memory reporter callback.
+ *
+ * @param aHandleReport
+ *        The callback.
+ * @param aData
+ *        The data for the callback.
+ * @param aConn
+ *        The SQLite connection.
+ * @param aPathHead
+ *        Head of the path for the memory report.
+ * @param aKind
+ *        The memory report statistic kind, one of "stmt", "cache" or
+ *        "schema".
+ * @param aDesc
+ *        The memory report description.
+ * @param aOption
+ *        The SQLite constant for getting the measurement.
+ * @param aTotal
+ *        The accumulator for the measurement.
+ */
+static void
+ReportConn(nsIHandleReportCallback *aHandleReport,
+           nsISupports *aData,
+           Connection *aConn,
+           const nsACString &aPathHead,
+           const nsACString &aKind,
+           const nsACString &aDesc,
+           int32_t aOption,
+           size_t *aTotal)
+{
+  nsCString path(aPathHead);
+  path.Append(aKind);
+  path.AppendLiteral("-used");
+
+  int32_t val = aConn->getSqliteRuntimeStatus(aOption);
+  aHandleReport->Callback(EmptyCString(), path,
+                          nsIMemoryReporter::KIND_HEAP,
+                          nsIMemoryReporter::UNITS_BYTES,
+                          int64_t(val), aDesc, aData);
+  *aTotal += val;
+}
+
+// Warning: To get a Connection's measurements requires holding its lock.
+// There may be a delay getting the lock if another thread is accessing the
+// Connection.  This isn't very nice if CollectReports is called from the main
+// thread!  But at the time of writing this function is only called when
+// about:memory is loaded (not, for example, when telemetry pings occur) and
+// any delays in that case aren't so bad.
+NS_IMETHODIMP
+Service::CollectReports(nsIHandleReportCallback *aHandleReport,
+                        nsISupports *aData, bool aAnonymize)
+{
+  size_t totalConnSize = 0;
+  {
+    nsTArray<RefPtr<Connection> > connections;
+    getConnections(connections);
+
+    for (uint32_t i = 0; i < connections.Length(); i++) {
+      RefPtr<Connection> &conn = connections[i];
+
+      // Someone may have closed the Connection, in which case we skip it.
+      bool isReady;
+      (void)conn->GetConnectionReady(&isReady);
+      if (!isReady) {
+          continue;
+      }
+
+      nsCString pathHead("explicit/storage/sqlite/");
+      // This filename isn't privacy-sensitive, and so is never anonymized.
+      pathHead.Append(conn->getFilename());
+      pathHead.Append('/');
+
+      SQLiteMutexAutoLock lockedScope(conn->sharedDBMutex);
+
+      NS_NAMED_LITERAL_CSTRING(stmtDesc,
+        "Memory (approximate) used by all prepared statements used by "
+        "connections to this database.");
+      ReportConn(aHandleReport, aData, conn, pathHead,
+                 NS_LITERAL_CSTRING("stmt"), stmtDesc,
+                 SQLITE_DBSTATUS_STMT_USED, &totalConnSize);
+
+      NS_NAMED_LITERAL_CSTRING(cacheDesc,
+        "Memory (approximate) used by all pager caches used by connections "
+        "to this database.");
+      ReportConn(aHandleReport, aData, conn, pathHead,
+                 NS_LITERAL_CSTRING("cache"), cacheDesc,
+                 SQLITE_DBSTATUS_CACHE_USED_SHARED, &totalConnSize);
+
+      NS_NAMED_LITERAL_CSTRING(schemaDesc,
+        "Memory (approximate) used to store the schema for all databases "
+        "associated with connections to this database.");
+      ReportConn(aHandleReport, aData, conn, pathHead,
+                 NS_LITERAL_CSTRING("schema"), schemaDesc,
+                 SQLITE_DBSTATUS_SCHEMA_USED, &totalConnSize);
+    }
+
+#ifdef MOZ_DMD
+    if (::sqlite3_memory_used() != int64_t(gSqliteMemoryUsed)) {
+      NS_WARNING("memory consumption reported by SQLite doesn't match "
+                 "our measurements");
+    }
+#endif
+  }
+
+  int64_t other = ::sqlite3_memory_used() - totalConnSize;
+
+  MOZ_COLLECT_REPORT(
+    "explicit/storage/sqlite/other", KIND_HEAP, UNITS_BYTES, other,
+    "All unclassified sqlite memory.");
+
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+//// Service
+
+NS_IMPL_ISUPPORTS(
+  Service,
+  mozIStorageService,
+  nsIObserver,
+  nsIMemoryReporter
+)
+
+Service *Service::gService = nullptr;
+
+Service *
+Service::getSingleton()
+{
+  if (gService) {
+    NS_ADDREF(gService);
+    return gService;
+  }
+
+  // Ensure that we are using the same version of SQLite that we compiled with
+  // or newer.  Our configure check ensures we are using a new enough version
+  // at compile time.
+  if (SQLITE_VERSION_NUMBER > ::sqlite3_libversion_number()) {
+    nsCOMPtr<nsIPromptService> ps(do_GetService(NS_PROMPTSERVICE_CONTRACTID));
+    if (ps) {
+      nsAutoString title, message;
+      title.AppendLiteral("SQLite Version Error");
+      message.AppendLiteral("The application has been updated, but the SQLite "
+                            "library wasn't updated properly and the application "
+                            "cannot run. Please try to launch the application again. "
+                            "If that should still fail, please try reinstalling "
+                            "it, or visit https://support.mozilla.org/.");
+      (void)ps->Alert(nullptr, title.get(), message.get());
+    }
+    MOZ_CRASH("SQLite Version Error");
+  }
+
+  // The first reference to the storage service must be obtained on the
+  // main thread.
+  NS_ENSURE_TRUE(NS_IsMainThread(), nullptr);
+  gService = new Service();
+  if (gService) {
+    NS_ADDREF(gService);
+    if (NS_FAILED(gService->initialize()))
+      NS_RELEASE(gService);
+  }
+
+  return gService;
+}
+
+nsIXPConnect *Service::sXPConnect = nullptr;
+
+// static
+already_AddRefed<nsIXPConnect>
+Service::getXPConnect()
+{
+  NS_PRECONDITION(NS_IsMainThread(),
+                  "Must only get XPConnect on the main thread!");
+  NS_PRECONDITION(gService,
+                  "Can not get XPConnect without an instance of our service!");
+
+  // If we've been shutdown, sXPConnect will be null.  To prevent leaks, we do
+  // not cache the service after this point.
+  nsCOMPtr<nsIXPConnect> xpc(sXPConnect);
+  if (!xpc)
+    xpc = do_GetService(nsIXPConnect::GetCID());
+  NS_ASSERTION(xpc, "Could not get XPConnect!");
+  return xpc.forget();
+}
+
+int32_t Service::sSynchronousPref;
+
+// static
+int32_t
+Service::getSynchronousPref()
+{
+  return sSynchronousPref;
+}
+
+int32_t Service::sDefaultPageSize = PREF_TS_PAGESIZE_DEFAULT;
+
+Service::Service()
+: mMutex("Service::mMutex")
+, mSqliteVFS(nullptr)
+, mRegistrationMutex("Service::mRegistrationMutex")
+, mConnections()
+{
+}
+
+Service::~Service()
+{
+  mozilla::UnregisterWeakMemoryReporter(this);
+  mozilla::UnregisterStorageSQLiteDistinguishedAmount();
+
+  int rc = sqlite3_vfs_unregister(mSqliteVFS);
+  if (rc != SQLITE_OK)
+    NS_WARNING("Failed to unregister sqlite vfs wrapper.");
+
+  // Shutdown the sqlite3 API.  Warn if shutdown did not turn out okay, but
+  // there is nothing actionable we can do in that case.
+  rc = ::sqlite3_shutdown();
+  if (rc != SQLITE_OK)
+    NS_WARNING("sqlite3 did not shutdown cleanly.");
+
+  DebugOnly<bool> shutdownObserved = !sXPConnect;
+  NS_ASSERTION(shutdownObserved, "Shutdown was not observed!");
+
+  gService = nullptr;
+  delete mSqliteVFS;
+  mSqliteVFS = nullptr;
+}
+
+void
+Service::registerConnection(Connection *aConnection)
+{
+  mRegistrationMutex.AssertNotCurrentThreadOwns();
+  MutexAutoLock mutex(mRegistrationMutex);
+  (void)mConnections.AppendElement(aConnection);
+}
+
+void
+Service::unregisterConnection(Connection *aConnection)
+{
+  // If this is the last Connection it might be the only thing keeping Service
+  // alive.  So ensure that Service is destroyed only after the Connection is
+  // cleanly unregistered and destroyed.
+  RefPtr<Service> kungFuDeathGrip(this);
+  {
+    mRegistrationMutex.AssertNotCurrentThreadOwns();
+    MutexAutoLock mutex(mRegistrationMutex);
+
+    for (uint32_t i = 0 ; i < mConnections.Length(); ++i) {
+      if (mConnections[i] == aConnection) {
+        nsCOMPtr<nsIThread> thread = mConnections[i]->threadOpenedOn;
+
+        // Ensure the connection is released on its opening thread.  Note, we
+        // must use .forget().take() so that we can manually cast to an
+        // unambiguous nsISupports type.
+        NS_ProxyRelease(thread, mConnections[i].forget());
+
+        mConnections.RemoveElementAt(i);
+        return;
+      }
+    }
+
+    MOZ_ASSERT_UNREACHABLE("Attempt to unregister unknown storage connection!");
+  }
+}
+
+void
+Service::getConnections(/* inout */ nsTArray<RefPtr<Connection> >& aConnections)
+{
+  mRegistrationMutex.AssertNotCurrentThreadOwns();
+  MutexAutoLock mutex(mRegistrationMutex);
+  aConnections.Clear();
+  aConnections.AppendElements(mConnections);
+}
+
+void
+Service::minimizeMemory()
+{
+  nsTArray<RefPtr<Connection> > connections;
+  getConnections(connections);
+
+  for (uint32_t i = 0; i < connections.Length(); i++) {
+    RefPtr<Connection> conn = connections[i];
+    if (!conn->connectionReady())
+      continue;
+
+    NS_NAMED_LITERAL_CSTRING(shrinkPragma, "PRAGMA shrink_memory");
+    nsCOMPtr<mozIStorageConnection> syncConn = do_QueryInterface(
+      NS_ISUPPORTS_CAST(mozIStorageAsyncConnection*, conn));
+    bool onOpenedThread = false;
+
+    if (!syncConn) {
+      // This is a mozIStorageAsyncConnection, it can only be used on the main
+      // thread, so we can do a straight API call.
+      nsCOMPtr<mozIStoragePendingStatement> ps;
+      DebugOnly<nsresult> rv =
+        conn->ExecuteSimpleSQLAsync(shrinkPragma, nullptr, getter_AddRefs(ps));
+      MOZ_ASSERT(NS_SUCCEEDED(rv), "Should have purged sqlite caches");
+    } else if (NS_SUCCEEDED(conn->threadOpenedOn->IsOnCurrentThread(&onOpenedThread)) &&
+               onOpenedThread) {
+      // We are on the opener thread, so we can just proceed.
+      conn->ExecuteSimpleSQL(shrinkPragma);
+    } else {
+      // We are on the wrong thread, the query should be executed on the
+      // opener thread, so we must dispatch to it.
+      nsCOMPtr<nsIRunnable> event =
+        NewRunnableMethod<const nsCString>(
+          conn, &Connection::ExecuteSimpleSQL, shrinkPragma);
+      conn->threadOpenedOn->Dispatch(event, NS_DISPATCH_NORMAL);
+    }
+  }
+}
+
+void
+Service::shutdown()
+{
+  NS_IF_RELEASE(sXPConnect);
+}
+
+sqlite3_vfs *ConstructTelemetryVFS();
+
+#ifdef MOZ_STORAGE_MEMORY
+
+namespace {
+
+// By default, SQLite tracks the size of all its heap blocks by adding an extra
+// 8 bytes at the start of the block to hold the size.  Unfortunately, this
+// causes a lot of 2^N-sized allocations to be rounded up by jemalloc
+// allocator, wasting memory.  For example, a request for 1024 bytes has 8
+// bytes added, becoming a request for 1032 bytes, and jemalloc rounds this up
+// to 2048 bytes, wasting 1012 bytes.  (See bug 676189 for more details.)
+//
+// So we register jemalloc as the malloc implementation, which avoids this
+// 8-byte overhead, and thus a lot of waste.  This requires us to provide a
+// function, sqliteMemRoundup(), which computes the actual size that will be
+// allocated for a given request.  SQLite uses this function before all
+// allocations, and may be able to use any excess bytes caused by the rounding.
+//
+// Note: the wrappers for malloc, realloc and moz_malloc_usable_size are
+// necessary because the sqlite_mem_methods type signatures differ slightly
+// from the standard ones -- they use int instead of size_t.  But we don't need
+// a wrapper for free.
+
+#ifdef MOZ_DMD
+
+// sqlite does its own memory accounting, and we use its numbers in our memory
+// reporters.  But we don't want sqlite's heap blocks to show up in DMD's
+// output as unreported, so we mark them as reported when they're allocated and
+// mark them as unreported when they are freed.
+//
+// In other words, we are marking all sqlite heap blocks as reported even
+// though we're not reporting them ourselves.  Instead we're trusting that
+// sqlite is fully and correctly accounting for all of its heap blocks via its
+// own memory accounting.  Well, we don't have to trust it entirely, because
+// it's easy to keep track (while doing this DMD-specific marking) of exactly
+// how much memory SQLite is using.  And we can compare that against what
+// SQLite reports it is using.
+
+MOZ_DEFINE_MALLOC_SIZE_OF_ON_ALLOC(SqliteMallocSizeOfOnAlloc)
+MOZ_DEFINE_MALLOC_SIZE_OF_ON_FREE(SqliteMallocSizeOfOnFree)
+
+#endif
+
+static void *sqliteMemMalloc(int n)
+{
+  void* p = ::malloc(n);
+#ifdef MOZ_DMD
+  gSqliteMemoryUsed += SqliteMallocSizeOfOnAlloc(p);
+#endif
+  return p;
+}
+
+static void sqliteMemFree(void *p)
+{
+#ifdef MOZ_DMD
+  gSqliteMemoryUsed -= SqliteMallocSizeOfOnFree(p);
+#endif
+  ::free(p);
+}
+
+static void *sqliteMemRealloc(void *p, int n)
+{
+#ifdef MOZ_DMD
+  gSqliteMemoryUsed -= SqliteMallocSizeOfOnFree(p);
+  void *pnew = ::realloc(p, n);
+  if (pnew) {
+    gSqliteMemoryUsed += SqliteMallocSizeOfOnAlloc(pnew);
+  } else {
+    // realloc failed;  undo the SqliteMallocSizeOfOnFree from above
+    gSqliteMemoryUsed += SqliteMallocSizeOfOnAlloc(p);
+  }
+  return pnew;
+#else
+  return ::realloc(p, n);
+#endif
+}
+
+static int sqliteMemSize(void *p)
+{
+  return ::moz_malloc_usable_size(p);
+}
+
+static int sqliteMemRoundup(int n)
+{
+  n = malloc_good_size(n);
+
+  // jemalloc can return blocks of size 2 and 4, but SQLite requires that all
+  // allocations be 8-aligned.  So we round up sub-8 requests to 8.  This
+  // wastes a small amount of memory but is obviously safe.
+  return n <= 8 ? 8 : n;
+}
+
+static int sqliteMemInit(void *p)
+{
+  return 0;
+}
+
+static void sqliteMemShutdown(void *p)
+{
+}
+
+const sqlite3_mem_methods memMethods = {
+  &sqliteMemMalloc,
+  &sqliteMemFree,
+  &sqliteMemRealloc,
+  &sqliteMemSize,
+  &sqliteMemRoundup,
+  &sqliteMemInit,
+  &sqliteMemShutdown,
+  nullptr
+};
+
+} // namespace
+
+#endif  // MOZ_STORAGE_MEMORY
+
+static const char* sObserverTopics[] = {
+  "memory-pressure",
+  "xpcom-shutdown",
+  "xpcom-shutdown-threads"
+};
+
+nsresult
+Service::initialize()
+{
+  MOZ_ASSERT(NS_IsMainThread(), "Must be initialized on the main thread");
+
+  int rc;
+
+#ifdef MOZ_STORAGE_MEMORY
+  rc = ::sqlite3_config(SQLITE_CONFIG_MALLOC, &memMethods);
+  if (rc != SQLITE_OK)
+    return convertResultCode(rc);
+#endif
+
+  // TODO (bug 1191405): do not preallocate the connections caches until we
+  // have figured the impact on our consumers and memory.
+  sqlite3_config(SQLITE_CONFIG_PAGECACHE, NULL, 0, 0);
+
+  // Explicitly initialize sqlite3.  Although this is implicitly called by
+  // various sqlite3 functions (and the sqlite3_open calls in our case),
+  // the documentation suggests calling this directly.  So we do.
+  rc = ::sqlite3_initialize();
+  if (rc != SQLITE_OK)
+    return convertResultCode(rc);
+
+  mSqliteVFS = ConstructTelemetryVFS();
+  if (mSqliteVFS) {
+    rc = sqlite3_vfs_register(mSqliteVFS, 1);
+    if (rc != SQLITE_OK)
+      return convertResultCode(rc);
+  } else {
+    NS_WARNING("Failed to register telemetry VFS");
+  }
+
+  // Register for xpcom-shutdown so we can cleanup after ourselves.  The
+  // observer service can only be used on the main thread.
+  nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
+  NS_ENSURE_TRUE(os, NS_ERROR_FAILURE);
+
+  for (size_t i = 0; i < ArrayLength(sObserverTopics); ++i) {
+    nsresult rv = os->AddObserver(this, sObserverTopics[i], false);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  // We cache XPConnect for our language helpers.  XPConnect can only be
+  // used on the main thread.
+  (void)CallGetService(nsIXPConnect::GetCID(), &sXPConnect);
+
+  // We need to obtain the toolkit.storage.synchronous preferences on the main
+  // thread because the preference service can only be accessed there.  This
+  // is cached in the service for all future Open[Unshared]Database calls.
+  sSynchronousPref =
+    Preferences::GetInt(PREF_TS_SYNCHRONOUS, PREF_TS_SYNCHRONOUS_DEFAULT);
+
+  // We need to obtain the toolkit.storage.pageSize preferences on the main
+  // thread because the preference service can only be accessed there.  This
+  // is cached in the service for all future Open[Unshared]Database calls.
+  sDefaultPageSize =
+      Preferences::GetInt(PREF_TS_PAGESIZE, PREF_TS_PAGESIZE_DEFAULT);
+
+  mozilla::RegisterWeakMemoryReporter(this);
+  mozilla::RegisterStorageSQLiteDistinguishedAmount(StorageSQLiteDistinguishedAmount);
+
+  return NS_OK;
+}
+
+int
+Service::localeCompareStrings(const nsAString &aStr1,
+                              const nsAString &aStr2,
+                              int32_t aComparisonStrength)
+{
+  // The implementation of nsICollation.CompareString() is platform-dependent.
+  // On Linux it's not thread-safe.  It may not be on Windows and OS X either,
+  // but it's more difficult to tell.  We therefore synchronize this method.
+  MutexAutoLock mutex(mMutex);
+
+  nsICollation *coll = getLocaleCollation();
+  if (!coll) {
+    NS_ERROR("Storage service has no collation");
+    return 0;
+  }
+
+  int32_t res;
+  nsresult rv = coll->CompareString(aComparisonStrength, aStr1, aStr2, &res);
+  if (NS_FAILED(rv)) {
+    NS_ERROR("Collation compare string failed");
+    return 0;
+  }
+
+  return res;
+}
+
+nsICollation *
+Service::getLocaleCollation()
+{
+  mMutex.AssertCurrentThreadOwns();
+
+  if (mLocaleCollation)
+    return mLocaleCollation;
+
+  nsCOMPtr<nsILocaleService> svc(do_GetService(NS_LOCALESERVICE_CONTRACTID));
+  if (!svc) {
+    NS_WARNING("Could not get locale service");
+    return nullptr;
+  }
+
+  nsCOMPtr<nsILocale> appLocale;
+  nsresult rv = svc->GetApplicationLocale(getter_AddRefs(appLocale));
+  if (NS_FAILED(rv)) {
+    NS_WARNING("Could not get application locale");
+    return nullptr;
+  }
+
+  nsCOMPtr<nsICollationFactory> collFact =
+    do_CreateInstance(NS_COLLATIONFACTORY_CONTRACTID);
+  if (!collFact) {
+    NS_WARNING("Could not create collation factory");
+    return nullptr;
+  }
+
+  rv = collFact->CreateCollation(appLocale, getter_AddRefs(mLocaleCollation));
+  if (NS_FAILED(rv)) {
+    NS_WARNING("Could not create collation");
+    return nullptr;
+  }
+
+  return mLocaleCollation;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+//// mozIStorageService
+
+
+NS_IMETHODIMP
+Service::OpenSpecialDatabase(const char *aStorageKey,
+                             mozIStorageConnection **_connection)
+{
+  nsresult rv;
+
+  nsCOMPtr<nsIFile> storageFile;
+  if (::strcmp(aStorageKey, "memory") == 0) {
+    // just fall through with nullptr storageFile, this will cause the storage
+    // connection to use a memory DB.
+  }
+  else {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  RefPtr<Connection> msc = new Connection(this, SQLITE_OPEN_READWRITE, false);
+
+  rv = storageFile ? msc->initialize(storageFile) : msc->initialize();
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  msc.forget(_connection);
+  return NS_OK;
+
+}
+
+namespace {
+
+class AsyncInitDatabase final : public Runnable
+{
+public:
+  AsyncInitDatabase(Connection* aConnection,
+                    nsIFile* aStorageFile,
+                    int32_t aGrowthIncrement,
+                    mozIStorageCompletionCallback* aCallback)
+    : mConnection(aConnection)
+    , mStorageFile(aStorageFile)
+    , mGrowthIncrement(aGrowthIncrement)
+    , mCallback(aCallback)
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+  }
+
+  NS_IMETHOD Run() override
+  {
+    MOZ_ASSERT(!NS_IsMainThread());
+    nsresult rv = mStorageFile ? mConnection->initialize(mStorageFile)
+                               : mConnection->initialize();
+    if (NS_FAILED(rv)) {
+      nsCOMPtr<nsIRunnable> closeRunnable =
+        NewRunnableMethod<mozIStorageCompletionCallback*>(
+          mConnection.get(),
+          &Connection::AsyncClose,
+          nullptr);
+      MOZ_ASSERT(closeRunnable);
+      MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(closeRunnable));
+
+      return DispatchResult(rv, nullptr);
+    }
+
+    if (mGrowthIncrement >= 0) {
+      // Ignore errors. In the future, we might wish to log them.
+      (void)mConnection->SetGrowthIncrement(mGrowthIncrement, EmptyCString());
+    }
+
+    return DispatchResult(NS_OK, NS_ISUPPORTS_CAST(mozIStorageAsyncConnection*,
+                          mConnection));
+  }
+
+private:
+  nsresult DispatchResult(nsresult aStatus, nsISupports* aValue) {
+    RefPtr<CallbackComplete> event =
+      new CallbackComplete(aStatus,
+                           aValue,
+                           mCallback.forget());
+    return NS_DispatchToMainThread(event);
+  }
+
+  ~AsyncInitDatabase()
+  {
+    NS_ReleaseOnMainThread(mStorageFile.forget());
+    NS_ReleaseOnMainThread(mConnection.forget());
+
+    // Generally, the callback will be released by CallbackComplete.
+    // However, if for some reason Run() is not executed, we still
+    // need to ensure that it is released here.
+    NS_ReleaseOnMainThread(mCallback.forget());
+  }
+
+  RefPtr<Connection> mConnection;
+  nsCOMPtr<nsIFile> mStorageFile;
+  int32_t mGrowthIncrement;
+  RefPtr<mozIStorageCompletionCallback> mCallback;
+};
+
+} // namespace
+
+NS_IMETHODIMP
+Service::OpenAsyncDatabase(nsIVariant *aDatabaseStore,
+                           nsIPropertyBag2 *aOptions,
+                           mozIStorageCompletionCallback *aCallback)
+{
+  if (!NS_IsMainThread()) {
+    return NS_ERROR_NOT_SAME_THREAD;
+  }
+  NS_ENSURE_ARG(aDatabaseStore);
+  NS_ENSURE_ARG(aCallback);
+
+  nsresult rv;
+  bool shared = false;
+  bool readOnly = false;
+  bool ignoreLockingMode = false;
+  int32_t growthIncrement = -1;
+
+#define FAIL_IF_SET_BUT_INVALID(rv)\
+  if (NS_FAILED(rv) && rv != NS_ERROR_NOT_AVAILABLE) { \
+    return NS_ERROR_INVALID_ARG; \
+  }
+
+  // Deal with options first:
+  if (aOptions) {
+    rv = aOptions->GetPropertyAsBool(NS_LITERAL_STRING("readOnly"), &readOnly);
+    FAIL_IF_SET_BUT_INVALID(rv);
+
+    rv = aOptions->GetPropertyAsBool(NS_LITERAL_STRING("ignoreLockingMode"),
+                                     &ignoreLockingMode);
+    FAIL_IF_SET_BUT_INVALID(rv);
+    // Specifying ignoreLockingMode will force use of the readOnly flag:
+    if (ignoreLockingMode) {
+      readOnly = true;
+    }
+
+    rv = aOptions->GetPropertyAsBool(NS_LITERAL_STRING("shared"), &shared);
+    FAIL_IF_SET_BUT_INVALID(rv);
+
+    // NB: we re-set to -1 if we don't have a storage file later on.
+    rv = aOptions->GetPropertyAsInt32(NS_LITERAL_STRING("growthIncrement"),
+                                      &growthIncrement);
+    FAIL_IF_SET_BUT_INVALID(rv);
+  }
+  int flags = readOnly ? SQLITE_OPEN_READONLY : SQLITE_OPEN_READWRITE;
+
+  nsCOMPtr<nsIFile> storageFile;
+  nsCOMPtr<nsISupports> dbStore;
+  rv = aDatabaseStore->GetAsISupports(getter_AddRefs(dbStore));
+  if (NS_SUCCEEDED(rv)) {
+    // Generally, aDatabaseStore holds the database nsIFile.
+    storageFile = do_QueryInterface(dbStore, &rv);
+    if (NS_FAILED(rv)) {
+      return NS_ERROR_INVALID_ARG;
+    }
+
+    rv = storageFile->Clone(getter_AddRefs(storageFile));
+    MOZ_ASSERT(NS_SUCCEEDED(rv));
+
+    if (!readOnly) {
+      // Ensure that SQLITE_OPEN_CREATE is passed in for compatibility reasons.
+      flags |= SQLITE_OPEN_CREATE;
+    }
+
+    // Apply the shared-cache option.
+    flags |= shared ? SQLITE_OPEN_SHAREDCACHE : SQLITE_OPEN_PRIVATECACHE;
+  } else {
+    // Sometimes, however, it's a special database name.
+    nsAutoCString keyString;
+    rv = aDatabaseStore->GetAsACString(keyString);
+    if (NS_FAILED(rv) || !keyString.EqualsLiteral("memory")) {
+      return NS_ERROR_INVALID_ARG;
+    }
+
+    // Just fall through with nullptr storageFile, this will cause the storage
+    // connection to use a memory DB.
+  }
+
+  if (!storageFile && growthIncrement >= 0) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // Create connection on this thread, but initialize it on its helper thread.
+  RefPtr<Connection> msc = new Connection(this, flags, true,
+                                          ignoreLockingMode);
+  nsCOMPtr<nsIEventTarget> target = msc->getAsyncExecutionTarget();
+  MOZ_ASSERT(target, "Cannot initialize a connection that has been closed already");
+
+  RefPtr<AsyncInitDatabase> asyncInit =
+    new AsyncInitDatabase(msc,
+                          storageFile,
+                          growthIncrement,
+                          aCallback);
+  return target->Dispatch(asyncInit, nsIEventTarget::DISPATCH_NORMAL);
+}
+
+NS_IMETHODIMP
+Service::OpenDatabase(nsIFile *aDatabaseFile,
+                      mozIStorageConnection **_connection)
+{
+  NS_ENSURE_ARG(aDatabaseFile);
+
+  // Always ensure that SQLITE_OPEN_CREATE is passed in for compatibility
+  // reasons.
+  int flags = SQLITE_OPEN_READWRITE | SQLITE_OPEN_SHAREDCACHE |
+              SQLITE_OPEN_CREATE;
+  RefPtr<Connection> msc = new Connection(this, flags, false);
+
+  nsresult rv = msc->initialize(aDatabaseFile);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  msc.forget(_connection);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+Service::OpenUnsharedDatabase(nsIFile *aDatabaseFile,
+                              mozIStorageConnection **_connection)
+{
+  NS_ENSURE_ARG(aDatabaseFile);
+
+  // Always ensure that SQLITE_OPEN_CREATE is passed in for compatibility
+  // reasons.
+  int flags = SQLITE_OPEN_READWRITE | SQLITE_OPEN_PRIVATECACHE |
+              SQLITE_OPEN_CREATE;
+  RefPtr<Connection> msc = new Connection(this, flags, false);
+
+  nsresult rv = msc->initialize(aDatabaseFile);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  msc.forget(_connection);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+Service::OpenDatabaseWithFileURL(nsIFileURL *aFileURL,
+                                 mozIStorageConnection **_connection)
+{
+  NS_ENSURE_ARG(aFileURL);
+
+  // Always ensure that SQLITE_OPEN_CREATE is passed in for compatibility
+  // reasons.
+  int flags = SQLITE_OPEN_READWRITE | SQLITE_OPEN_SHAREDCACHE |
+              SQLITE_OPEN_CREATE | SQLITE_OPEN_URI;
+  RefPtr<Connection> msc = new Connection(this, flags, false);
+
+  nsresult rv = msc->initialize(aFileURL);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  msc.forget(_connection);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+Service::BackupDatabaseFile(nsIFile *aDBFile,
+                            const nsAString &aBackupFileName,
+                            nsIFile *aBackupParentDirectory,
+                            nsIFile **backup)
+{
+  nsresult rv;
+  nsCOMPtr<nsIFile> parentDir = aBackupParentDirectory;
+  if (!parentDir) {
+    // This argument is optional, and defaults to the same parent directory
+    // as the current file.
+    rv = aDBFile->GetParent(getter_AddRefs(parentDir));
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  nsCOMPtr<nsIFile> backupDB;
+  rv = parentDir->Clone(getter_AddRefs(backupDB));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = backupDB->Append(aBackupFileName);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = backupDB->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0600);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsAutoString fileName;
+  rv = backupDB->GetLeafName(fileName);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = backupDB->Remove(false);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  backupDB.forget(backup);
+
+  return aDBFile->CopyTo(parentDir, fileName);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+//// nsIObserver
+
+NS_IMETHODIMP
+Service::Observe(nsISupports *, const char *aTopic, const char16_t *)
+{
+  if (strcmp(aTopic, "memory-pressure") == 0) {
+    minimizeMemory();
+  } else if (strcmp(aTopic, "xpcom-shutdown") == 0) {
+    shutdown();
+  } else if (strcmp(aTopic, "xpcom-shutdown-threads") == 0) {
+    nsCOMPtr<nsIObserverService> os =
+      mozilla::services::GetObserverService();
+
+    for (size_t i = 0; i < ArrayLength(sObserverTopics); ++i) {
+      (void)os->RemoveObserver(this, sObserverTopics[i]);
+    }
+
+    bool anyOpen = false;
+    do {
+      nsTArray<RefPtr<Connection> > connections;
+      getConnections(connections);
+      anyOpen = false;
+      for (uint32_t i = 0; i < connections.Length(); i++) {
+        RefPtr<Connection> &conn = connections[i];
+        if (conn->isClosing()) {
+          anyOpen = true;
+          break;
+        }
+      }
+      if (anyOpen) {
+        nsCOMPtr<nsIThread> thread = do_GetCurrentThread();
+        NS_ProcessNextEvent(thread);
+      }
+    } while (anyOpen);
+
+    if (gShutdownChecks == SCM_CRASH) {
+      nsTArray<RefPtr<Connection> > connections;
+      getConnections(connections);
+      for (uint32_t i = 0, n = connections.Length(); i < n; i++) {
+        if (!connections[i]->isClosed()) {
+          MOZ_CRASH();
+        }
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+} // namespace storage
+} // namespace mozilla