gecko-dev/storage/mozIStorageService.idl

/* -*- Mode: idl; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 "nsISupports.idl"

%{C++

#include "nsLiteralString.h"

%}

interface mozIStorageConnection;
interface nsIFile;
interface nsIFileURL;
interface nsIPropertyBag2;
interface nsIVariant;
interface mozIStorageCompletionCallback;

/**
 * PRIVACY WARNING
 * ===============
 *
 * Database file names can be exposed through telemetry and in crash reports on
 * the https://crash-stats.mozilla.org site, to allow recognizing the affected
 * database.
 * if your database name may contain privacy sensitive information, e.g. an
 * URL origin, you should use openDatabaseWithFileURL and pass an explicit
 * TelemetryFilename to it. That name will be used both for telemetry and for
 * thread names in crash reports.
 * If you have different needs (e.g. using the javascript module or an async
 * connection from the main thread) please coordinate with the mozStorage peers.
 */

/**
 * The mozIStorageService interface is intended to be implemented by
 * a service that can create storage connections (mozIStorageConnection)
 * to either a well-known profile database or to a specific database file.
 *
 * This is the only way to open a database connection.
 *
 * @note The first reference to mozIStorageService must be made on the main
 * thread.
 */
[scriptable, uuid(07b6b2f5-6d97-47b4-9584-e65bc467fe9e)]
interface mozIStorageService : nsISupports {
  /**
   * Open the database with default flags in default mode.
   */
  const unsigned long OPEN_DEFAULT = 0;

  /**
   * Open the database with a shared cache. The shared-cache mode
   * is more memory-efficient when many connections to the same database
   * are expected, though, the connections will contend the cache resource.
   * When performance matters, working without a shared-cache will
   * improve concurrency.  @see openUnsharedDatabase
   */
  const unsigned long OPEN_SHARED = 1 << 0;

  /**
   * Open the underlying database in read-only mode.
   */
  const unsigned long OPEN_READONLY = 1 << 1;

  /**
   * Allow simultaneous access to an asynchronous read-only database
   * without any file locking.
   *
   * For synchronous database, the flag has no effect.
   *
   * Specifying the OPEN_IGNORE_LOCKING_MODE flag will automatically
   * turn on the OPEN_READONLY flag.
   */
  const unsigned long OPEN_IGNORE_LOCKING_MODE = 1 << 2;

  /**
   * Allow multi-process access to the database file.
   * Normally this option is disabled as exclusive locking performs better
   * and provides some protection against third party manipulation of hot
   * databases. Note however this option only shows its effects on Unix
   * systems because exclusive locking is not yet implemented on Windows.
   */
  const unsigned long OPEN_NOT_EXCLUSIVE = 1 << 3;

  /**
   * All optional connection object features are off.
   */
  const unsigned long CONNECTION_DEFAULT = 0;

  /**
   * Enable Interrupt-method for the synchronous connection object
   * returned by openDatabase, openSpecialDatabase, openUnsharedDatabase
   * or openDatabaseWithFileURL calls.
   *
   * When this flag is not set, Interrupt-method of a
   * synchronous connection must not be used.
   *
   * Asynchronous connection is always interruptible and the flag
   * does not change anything.
   *
   * The following are among the potential risks side effects of
   * calling the Interrupt-method:
   *   - new queries started on a different thread after the
   *     interrupt call, but before its completion, are interrupted as if
   *     they had been running prior to the interrupt call. Thus thread
   *     synchronization is necessary.
   *   - calls to close the database will wait until the interruption
   *     finishes.
   */
  const unsigned long CONNECTION_INTERRUPTIBLE = 1 << 0;

  /**
   * Open an asynchronous connection to a database.
   *
   * This method MUST be called from the main thread. The connection object
   * returned by this function is not threadsafe. You MUST use it only from
   * the main thread.
   *
   * If you have more than one connection to a file, you MUST use the EXACT
   * SAME NAME for the file each time, including case. The sqlite code uses
   * a simple string compare to see if there is already a connection. Opening
   * a connection to "Foo.sqlite" and "foo.sqlite" will CORRUPT YOUR DATABASE.
   *
   * @param aDatabaseStore Either a nsIFile representing the file that contains
   * the database or a special string to open a special database. The special
   * string may be:
   * - "memory" to open an in-memory database.
   *
   * @param aOpenFlags
   *        A set of flags to open the database with optional features.
   *        See OPEN_* options above.
   *        For full details, please refer to the documentation of the flags.
   *
   * @param aConnectionFlags
   *        A set of flags to enable optional features for the returned
   *        asynchronous connection object.
   *        Currently supports CONNECTION_INTERRUPTIBLE flag.
   *        For full details, please refer to the documentation of the flag.
   *
   * @param aCallback A callback that will receive the result of the operation.
   *  In case of error, it may receive as status:
   *  - NS_ERROR_OUT_OF_MEMORY if allocating a new storage object fails.
   *  - NS_ERROR_FILE_CORRUPTED if the database file is corrupted.
   *  In case of success, it receives as argument the new database
   *  connection, as an instance of |mozIStorageAsyncConnection|.
   *
   * @throws NS_ERROR_INVALID_ARG if |aDatabaseStore| is neither a file nor
   *         one of the special strings understood by this method, or if one of
   *         the options passed through |aOptions| does not have
   *         the right type.
   * @throws NS_ERROR_NOT_SAME_THREAD if called from a thread other than the
   *         main thread.
   */
  void openAsyncDatabase(in nsIVariant aDatabaseStore,
                         in unsigned long aOpenFlags,
                         in unsigned long aConnectionFlags,
                         in mozIStorageCompletionCallback aCallback);

  /**
   * Get a connection to a named special database storage.
   *
   * @param aStorageKey a string key identifying the type of storage
   * requested.  Valid values include: "memory".
   *
   * @param aName an optional string identifying the name of the database.
   * If omitted, a filename of ":memory:" will be used which results in a
   * private in-memory database specific to this connection, making it
   * impossible to clone the in-memory database. If you want to be able to
   * clone the connection (or otherwise connect to the in-memory database from
   * a connection), then you must pick a name that's sufficiently unique within
   * the process to not collide with other mozStorage users.
   *
   * @param [optional] aConnectionFlags
   *        A set of flags to enable optional features for the returned
   *        synchronous connection object.
   *        Currently supports CONNECTION_INTERRUPTIBLE flag.
   *        For full details, please refer to the documentation of the flag.
   *
   * @see openDatabase for restrictions on how database connections may be
   * used. For the profile database, you should only access it from the main
   * thread since other callers may also have connections.
   *
   * @returns a new mozIStorageConnection for the requested
   * storage database.
   *
   * @throws NS_ERROR_INVALID_ARG if aStorageKey is invalid.
   */
  mozIStorageConnection openSpecialDatabase(
      in ACString aStorageKey,
      [optional] in ACString aName,
      [optional] in unsigned long aConnectionFlags);

  /**
   * Open a connection to the specified file.
   *
   * Consumers should check mozIStorageConnection::connectionReady to ensure
   * that they can use the database.  If this value is false, it is strongly
   * recommended that the database be backed up with
   * mozIStorageConnection::backupDB so user data is not lost.
   *
   * ==========
   *   DANGER
   * ==========
   *
   * If you have more than one connection to a file, you MUST use the EXACT
   * SAME NAME for the file each time, including case. The sqlite code uses
   * a simple string compare to see if there is already a connection. Opening
   * a connection to "Foo.sqlite" and "foo.sqlite" will CORRUPT YOUR DATABASE.
   *
   * The connection object returned by this function is not threadsafe. You
   * must use it only from the thread you created it from.
   *
   * @param aDatabaseFile
   *        A nsIFile that represents the database that is to be opened.
   * @param [optional] aConnectionFlags
   *        A set of flags to enable optional features for the returned
   *        synchronous connection object.
   *        Currently supports CONNECTION_INTERRUPTIBLE flag.
   *        For full details, please refer to the documentation of the flag.
   *
   * @returns a mozIStorageConnection for the requested database file.
   *
   * @throws NS_ERROR_OUT_OF_MEMORY
   *         If allocating a new storage object fails.
   * @throws NS_ERROR_FILE_CORRUPTED
   *         If the database file is corrupted.
   */
  mozIStorageConnection openDatabase(
      in nsIFile aDatabaseFile, [optional] in unsigned long aConnectionFlags);

  /**
   * Open a connection to the specified file that doesn't share a sqlite cache.
   *
   * Without a shared-cache, each connection uses its own pages cache, which
   * may be memory inefficient with a large number of connections, in such a
   * case so you should use openDatabase instead.  On the other side, if cache
   * contention may be an issue, for instance when concurrency is important to
   * ensure responsiveness, using unshared connections may be a
   * performance win.
   *
   * ==========
   *   DANGER
   * ==========
   *
   * If you have more than one connection to a file, you MUST use the EXACT
   * SAME NAME for the file each time, including case. The sqlite code uses
   * a simple string compare to see if there is already a connection. Opening
   * a connection to "Foo.sqlite" and "foo.sqlite" will CORRUPT YOUR DATABASE.
   *
   * The connection object returned by this function is not threadsafe. You
   * must use it only from the thread you created it from.
   *
   * @param aDatabaseFile
   *        A nsIFile that represents the database that is to be opened.
   * @param [optional] aConnectionFlags
   *        A set of flags to enable optional features for the returned
   *        synchronous connection object.
   *        Currently supports CONNECTION_INTERRUPTIBLE flag.
   *        For full details, please refer to the documentation of the flag.
   *
   * @returns a mozIStorageConnection for the requested database file.
   *
   * @throws NS_ERROR_OUT_OF_MEMORY
   *         If allocating a new storage object fails.
   * @throws NS_ERROR_FILE_CORRUPTED
   *         If the database file is corrupted.
   */
  mozIStorageConnection openUnsharedDatabase(
      in nsIFile aDatabaseFile, [optional] in unsigned long aConnectionFlags);

  /**
   * See openDatabase(). Exactly the same only initialized with a file URL.
   * Custom parameters can be passed to SQLite and VFS implementations through
   * the query part of the URL.
   *
   * @param aURL
   *        A nsIFileURL that represents the database that is to be opened.
   * @param [optional] aTelemetryFilename
   *        The name to use for the database in telemetry. Only needed if the
   *        actual filename can contain sensitive information.
   * @param [optional] aConnectionFlags
   *        A set of flags to enable optional features for the returned
   *        synchronous connection object.
   *        Currently supports CONNECTION_INTERRUPTIBLE flag.
   *        For full details, please refer to the documentation of the flag.
   */
  mozIStorageConnection openDatabaseWithFileURL(
      in nsIFileURL aFileURL, [optional] in ACString aTelemetryFilename,
      [optional] in unsigned long aConnectionFlags);
};

%{C++

constexpr auto kMozStorageMemoryStorageKey = "memory"_ns;

%}