gecko/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"

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

/**
 * 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 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 aOptions A set of options (may be null). Options may contain:
   * - bool shared (defaults to |false|).
   *   -- If |true|, opens 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. In any cases
   *     where performance matter, working without a shared-cache will
   *     improve concurrency.  @see openUnsharedDatabase
   *
   * - int growthIncrement (defaults to none).
   *   -- Set the growth increment for the main database.  This hints SQLite to
   *      grow the database file by a given chunk size and may reduce
   *      filesystem fragmentation on large databases.
   *      @see mozIStorageConnection::setGrowthIncrement
   *
   * @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,
                         [optional] in nsIPropertyBag2 aOptions,
                         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".
   *
   * @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 string aStorageKey);

  /**
   * 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..
   *
   * @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);

  /**
   * 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.
   *
   * @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);

  /**
   * 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.
   */
  mozIStorageConnection openDatabaseWithFileURL(in nsIFileURL aFileURL);

  /*
   * Utilities
   */

  /**
   * Copies the specified database file to the specified parent directory with
   * the specified file name.  If the parent directory is not specified, it
   * places the backup in the same directory as the current file.  This function
   * ensures that the file being created is unique.
   *
   * @param aDBFile
   *        The database file that will be backed up.
   * @param aBackupFileName
   *        The name of the new backup file to create.
   * @param [optional] aBackupParentDirectory
   *        The directory you'd like the backup file to be placed.
   * @return The nsIFile representing the backup file.
   */
  nsIFile backupDatabaseFile(in nsIFile aDBFile, in AString aBackupFileName,
                             [optional] in nsIFile aBackupParentDirectory);
};

%{C++

#define MOZ_STORAGE_MEMORY_STORAGE_KEY    "memory"

%}