storage/mozIStorageAsyncConnection.idl

   1 /* -*- Mode: idl; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "nsISupports.idl"
   7
   8 interface mozIStorageCompletionCallback;
   9 interface mozIStorageFunction;
  10 interface mozIStorageProgressHandler;
  11 interface mozIStorageBaseStatement;
  12 interface mozIStorageStatement;
  13 interface mozIStorageAsyncStatement;
  14 interface mozIStorageStatementCallback;
  15 interface mozIStoragePendingStatement;
  16 interface nsIFile;
  17
  18 /**
  19  * mozIStorageAsyncConnection represents an asynchronous database
  20  * connection attached to a specific file or to an in-memory data
  21  * storage.  It is the primary interface for interacting with a
  22  * database from the main thread, including creating prepared
  23  * statements, executing SQL, and examining database errors.
  24  */
  25 [scriptable, uuid(8bfd34d5-4ddf-4e4b-89dd-9b14f33534c6)]
  26 interface mozIStorageAsyncConnection : nsISupports {
  27   /**
  28    * Transaction behavior constants.
  29    */
  30   const int32_t TRANSACTION_DEFAULT = -1;
  31   const int32_t TRANSACTION_DEFERRED = 0;
  32   const int32_t TRANSACTION_IMMEDIATE = 1;
  33   const int32_t TRANSACTION_EXCLUSIVE = 2;
  34
  35   /**
  36    * The default behavior for all transactions run on this connection. Defaults
  37    * to `TRANSACTION_DEFERRED`, and can be overridden for individual
  38    * transactions.
  39    */
  40   attribute int32_t defaultTransactionType;
  41
  42   /**
  43    * The maximum number of bound parameters for statements executed on this
  44    * connection. If your statement has more params than this limit, you'll
  45    * need to chunk them into multiple statements. See `PlacesUtils.chunkArray`
  46    * and its callers in Places for examples of how to do this, or read on for
  47    * an overview.
  48    *
  49    * Keep in mind that the variable limit is for the _total_ number of
  50    * parameters, including ones bound by name (using the `:VVV`, `@VVV`, or
  51    * `?VVV` syntax) and index (`?` and `?NNN`).
  52    *
  53    * This means, when chunking:
  54    *
  55    * - If you're binding 1 param per 1 value per chunk (for example, if you
  56    *   have a list of GUIDs and a clause like `WHERE guid IN (?, ?, ?, ...)`,
  57    *   your chunk length is just `variableLimit`.
  58    * - If you're binding 1 param per 1 value per chunk, but using that
  59    *   param in multiple positions in the query (for example, `WHERE url_hash
  60    *   IN (hash(?1), hash(?2), ...) AND url IN (?1, ?2, ...)`), you can use the
  61    *   `?NNN` syntax with a chunk length of `variableLimit`.
  62    * - If you're binding N params per 1 value per chunk (for example, if you
  63    *   have a list of items with GUIDs and parent GUIDs, and you want to bind
  64    *   both), your chunk length is `variableLimit / N`, since you're binding
  65    *   two params for each element.
  66    * - If you're binding K params per L values per chunk, plus M fixed ones
  67    *   (for example, `WHERE parentGuid = :parentGuid AND guid IN (?, ?, ...)`),
  68    *   your chunk length is `variableLimit - M`, to ensure there's space for the
  69    *   fixed variables.
  70    *
  71    * If you bind more params than this limit, `create{Async}Statement` will
  72    * fail with a "too many SQL variables" error.
  73    * It's possible to lower the limit, but it's not possible to set it higher
  74    * than the default value, passing an higher value will silently truncate to
  75    * the default. Lowering the limit is particularly useful for testing code
  76    * that may bind many variables.
  77    */
  78   attribute int32_t variableLimit;
  79
  80   /**
  81    * Returns true if a transaction is active on this connection.
  82    *
  83    * Note that this is true if a transaction is active on the connection,
  84    * regardless of how it was opened. There are several ways to open one:
  85    *
  86    * 1. Explicitly calling `beginTransaction` on a `mozIStorageConnection`.
  87    * 2. Calling `executeSimpleSQL("BEGIN")` or
  88    *    `createStatement("BEGIN").execute()` on a `mozIStorageConnection`.
  89    * 3. Executing an async statement, like
  90    *    `createAsyncStatement("BEGIN").executeAsync(...)`. This is what
  91    *    `Sqlite.sys.mjs` does under the hood.
  92    *
  93    * Because of this, it's important *not* to use this attribute to decide
  94    * whether to *commit* the active transaction, because the caller that opened
  95    * it may not expect that. This is why both `mozStorageTransaction` and
  96    * `Sqlite.sys.mjs` use an internal variable (`mHasTransaction` for the former;
  97    * `_hasInProgressTransaction` for the latter) to check if their transaction
  98    * is already in progress, instead of just checking this attribute before
  99    * committing. Otherwise, mozStorage might accidentally commit (or roll back!)
 100    * a transaction started by `Sqlite.sys.mjs`, and vice versa.
 101    */
 102   readonly attribute boolean transactionInProgress;
 103
 104   /**
 105    * Close this database connection, allowing all pending statements
 106    * to complete first.
 107    *
 108    * @param aCallback [optional]
 109    *        A callback that will be notified when the close is completed,
 110    *        with the following arguments:
 111    *        - status: the status of the call
 112    *        - value: |null|
 113    *
 114    * @throws NS_ERROR_NOT_SAME_THREAD
 115    *         If called on a thread other than the one that opened it.  The
 116    *         callback will not be dispatched.
 117    * @throws NS_ERROR_NOT_INITIALIZED
 118    *         If called on a connection that has already been closed or was
 119    *         never properly opened.  The callback will still be dispatched
 120    *         to the main thread despite the returned error.
 121    * @note If this call should fail, the callback won't be invoked.
 122    */
 123   void asyncClose([optional] in mozIStorageCompletionCallback aCallback);
 124
 125   /**
 126    * Forcibly closes a database connection synchronously.
 127    * This should only be used when it's required to close and replace the
 128    * database synchronously to return control to the consumer, for example in
 129    * case of a detected corruption on database opening.
 130    * Since this spins the events loop, it should be used only in very particular
 131    * and rare situations, or it may cause unexpected consequences (crashes).
 132    *
 133    * @throws NS_ERROR_NOT_SAME_THREAD
 134    *         If called on a thread other than the one that opened it.
 135    */
 136   [noscript] void spinningSynchronousClose();
 137
 138   /**
 139    * Clone a database connection and make the clone read only if needed.
 140    * SQL Functions and attached on-disk databases are applied to the new clone.
 141    *
 142    * @param aReadOnly
 143    *        If true, the returned database should be put into read-only mode.
 144    *
 145    * @param aCallback
 146    *        A callback that will be notified when the operation is complete,
 147    *        with the following arguments:
 148    *        - status: the status of the operation
 149    *        - value: in case of success, an intance of
 150    *             mozIStorageAsyncConnection cloned from this one.
 151    *
 152    * @throws NS_ERROR_NOT_SAME_THREAD
 153    *         If is called on a thread other than the one that opened it.
 154    * @throws NS_ERROR_UNEXPECTED
 155    *         If this connection is a memory database.
 156    *
 157    * @note If your connection is already read-only, you will get a read-only
 158    *       clone.
 159    * @note The resulting connection will implement `mozIStorageConnection`, but
 160    *       all synchronous methods will throw if called from the main thread.
 161    * @note Due to a bug in SQLite, if you use the shared cache
 162    *       (see mozIStorageService), you end up with the same privileges as the
 163    *       first connection opened regardless of what is specified in aReadOnly.
 164    * @note The following pragmas are copied over to a read-only clone:
 165    *        - cache_size
 166    *        - temp_store
 167    *       The following pragmas are copied over to a writeable clone:
 168    *        - cache_size
 169    *        - temp_store
 170    *        - foreign_keys
 171    *        - journal_size_limit
 172    *        - synchronous
 173    *        - wal_autocheckpoint
 174    *       All SQL functions are copied over to read-only and writeable clones.
 175    *       Additionally, all temporary tables, triggers, and views, as well as
 176    *       any indexes on temporary tables, are copied over to writeable clones.
 177    *       For temporary tables, only the schemas are copied, not their
 178    *       contents.
 179    */
 180   void asyncClone(in boolean aReadOnly,
 181                   in mozIStorageCompletionCallback aCallback);
 182
 183   /**
 184    * The current database nsIFile.  Null if the database
 185    * connection refers to an in-memory database.
 186    */
 187   readonly attribute nsIFile databaseFile;
 188
 189   /**
 190    * Causes any pending database operation to abort and return at the first
 191    * opportunity.
 192    * @note this cannot be used on mozIStorageConnection unless the connection is
 193    *       explicitly marked as `interruptible`. For more details, please
 194    *       refer to CONNECTION_INTERRUPTIBLE in mozIStorageService.
 195    * @note operations that are nearly complete may still be able to complete.
 196    * @throws if used on an unsupported connection type, or a closed connection.
 197    */
 198   void interrupt();
 199
 200   /**
 201    * Vacuum the main database plus all the attached one.
 202    * If the database is in auto_vacuum = INCREMENTAL mode, this executes an
 203    * incremental_vacuum, otherwise it will always execute a full vacuum.
 204    *
 205    * While it's possible to invoke this method directly, it's suggested, when
 206    * possible, to use the VacuumManager instead.
 207    * That means registering your component for the "vacuum-participant" XPCOM
 208    * category, and implement the mozIStorageVacuumParticipant interface.
 209    *
 210    * @param [aCallback] Completion callback invoked once the operation is
 211    *        complete.
 212    * @param [aUseIncremental] When set to true, this will try to convert the
 213    *        main schema to auto_vacuum = INCREMENTAL mode, if it's not set yet.
 214    *        When set to false, it will try to set auto_vacuum = NONE.
 215    *        Note a full vacuum will be executed if the auto_vacuum mode must be
 216    *        changed, otherwise an incremental vacuum will happen if the database
 217    *        is already in INCREMENTAL mode.
 218    * @param [aSetPageSize] This can be used to change the database page_size, a
 219    *        full vacuum will be executed to persist the change. If the page
 220    *        size is already correct, or you pass 0, this will be a no-op.
 221    * @throws If it's not possible to start the async vacuum operation, note in
 222    *         this case the callback won't be invoked.
 223    * @note Vacuum will fail inside a transaction, or if there is an ongoing
 224    *       read statement.
 225    */
 226   void asyncVacuum(
 227     [optional] in mozIStorageCompletionCallback aCallback,
 228     [optional] in boolean aUseIncremental,
 229     [optional] in long aSetPageSize
 230   );
 231
 232   //////////////////////////////////////////////////////////////////////////////
 233   //// Statement creation
 234
 235   /**
 236    * Create an asynchronous statement for the given SQL. An
 237    * asynchronous statement can only be used to dispatch asynchronous
 238    * requests to the asynchronous execution thread and cannot be used
 239    * to take any synchronous actions on the database.
 240    *
 241    * The expression may use ? to indicate sequential numbered arguments,
 242    * ?1, ?2 etc. to indicate specific numbered arguments or :name and
 243    * $var to indicate named arguments.
 244    *
 245    * @param aSQLStatement
 246    *        The SQL statement to execute.
 247    * @return a new mozIStorageAsyncStatement
 248    * @note The statement is created lazily on first execution.
 249    */
 250   mozIStorageAsyncStatement createAsyncStatement(in AUTF8String aSQLStatement);
 251
 252   /**
 253    * Execute an array of statements created with this connection using
 254    * any currently bound parameters. When the array contains multiple
 255    * statements, the execution is wrapped in a single
 256    * transaction. These statements can be reused immediately, and
 257    * reset does not need to be called.
 258    *
 259    * @param aStatements
 260    *        The array of statements to execute asynchronously, in the order they
 261    *        are given in the array.
 262    * @param aCallback [optional]
 263    *        The callback object that will be notified of progress, errors, and
 264    *        completion.
 265    * @return an object that can be used to cancel the statements execution.
 266    *
 267    * @note If you have any custom defined functions, they must be
 268    *        re-entrant since they can be called on multiple threads.
 269    */
 270   mozIStoragePendingStatement executeAsync(
 271     in Array<mozIStorageBaseStatement> aStatements,
 272     [optional] in mozIStorageStatementCallback aCallback
 273   );
 274
 275   /**
 276    * Execute asynchronously an SQL expression, expecting no arguments.
 277    *
 278    * @param aSQLStatement
 279    *        The SQL statement to execute
 280    * @param aCallback [optional]
 281    *        The callback object that will be notified of progress, errors, and
 282    *        completion.
 283    * @return an object that can be used to cancel the statement execution.
 284    */
 285   mozIStoragePendingStatement executeSimpleSQLAsync(
 286     in AUTF8String aSQLStatement,
 287     [optional] in mozIStorageStatementCallback aCallback);
 288
 289
 290   /**
 291    * Loads a Sqlite Run-Time Loadable Extension as defined at
 292    * https://www.sqlite.org/loadext.html.
 293    * Only a predetermined list of extensions can be loaded, that are statically
 294    * linked in the shared library containing SQLite. The currently supported
 295    * extensions are:
 296    *   - fts5
 297    *     A Full-Text search module, see https://www.sqlite.org/fts5.html
 298    *
 299    * New extensions can be added to the third_party/sqlite3/ext/ folder and then
 300    * to this list, after a Storage peer has reviewed the request by verifying
 301    * licensing, and code reliability.
 302    * Extensions that must be loaded for all the connections should instead use
 303    * sqlite3_auto_extension() (this must happen after sqlite3_config(), as it
 304    * implicitly calls sqlite3_initialize()).
 305    *
 306    * @param aExtensionName
 307    *        The extension to load, see the above list for supported values.
 308    * @param aCallback
 309    *        A callback that will be notified when the operation is complete,
 310    *        with the following arguments:
 311    *        - status: the status of the operation, use this to check if loading
 312    *          the extension was successful as it may be partly asynchronous.
 313    *        - value: unused.
 314    * @throws NS_ERROR_INVALID_ARG
 315    *         For unsupported extension names.
 316    * @throws NS_ERROR_NOT_INITIALIZED
 317    *         If the connection is not open.
 318    * @throws NS_ERROR_UEXPECTED
 319    *         If it was not possible to enable extensions loading.
 320    */
 321   void loadExtension(in AUTF8String aExtensionName,
 322                      [optional] in mozIStorageCompletionCallback aCallback);
 323
 324   //////////////////////////////////////////////////////////////////////////////
 325   //// Functions
 326
 327   /**
 328    * Create a new SQL function.  If you use your connection on multiple threads,
 329    * your function needs to be threadsafe, or it should only be called on one
 330    * thread.
 331    *
 332    * @param aFunctionName
 333    *        The name of function to create, as seen in SQL.
 334    * @param aNumArguments
 335    *        The number of arguments the function takes. Pass -1 for
 336    *        variable-argument functions.
 337    * @param aFunction
 338    *        The instance of mozIStorageFunction, which implements the function
 339    *        in question.
 340    */
 341   void createFunction(in AUTF8String aFunctionName,
 342                       in long aNumArguments,
 343                       in mozIStorageFunction aFunction);
 344
 345   /**
 346    * Delete custom SQL function.
 347    *
 348    * @param aFunctionName
 349    *        The name of function to remove.
 350    */
 351   void removeFunction(in AUTF8String aFunctionName);
 352
 353   /**
 354    * Sets a progress handler. Only one handler can be registered at a time.
 355    * If you need more than one, you need to chain them yourself.  This progress
 356    * handler should be threadsafe if you use this connection object on more than
 357    * one thread.
 358    *
 359    * @param aGranularity
 360    *        The number of SQL virtual machine steps between progress handler
 361    *        callbacks.
 362    * @param aHandler
 363    *        The instance of mozIStorageProgressHandler.
 364    * @return previous registered handler.
 365    */
 366   mozIStorageProgressHandler setProgressHandler(in int32_t aGranularity,
 367                                                 in mozIStorageProgressHandler aHandler);
 368
 369   /**
 370    * Remove a progress handler.
 371    *
 372    * @return previous registered handler.
 373    */
 374   mozIStorageProgressHandler removeProgressHandler();
 375
 376   /**
 377    * Makes a copy of a database asynchronously. This method can do an online
 378    * backup of the database file, even if there are open connections actively
 379    * using it (as a normal file copy can only be made if no connections are
 380    * open on the database).
 381    *
 382    * While the copy is in the process of being made, the destination file
 383    * will have a .tmp extension appended to it. In the event of a crash
 384    * during the copy, this .tmp file will continue to exist, but will be
 385    * an unusable partial copy.
 386    *
 387    * Once the copy has been completed, this method will automatically remove
 388    * the .tmp extension.
 389    *
 390    * @param aDestinationFile
 391    *        The destination on the file system to write the database copy.
 392    * @param aCallback
 393    *        A callback that will be notified when the operation is complete,
 394    *        with the following arguments:
 395    *        - status: the status of the operation, use this to check if making
 396    *                  the copy was successful.
 397    *        - value: unused.
 398    * @param [aPagesPerStep=5]
 399    *        The number of pages in the database to copy per step. Defaults to 5
 400    *        if omitted or set to 0.
 401    * @param [aStepDelayMs=250]
 402    *        The number of milliseconds to wait between each step. Defaults to
 403    *        250 if omitted or set to 0.
 404    * @throws NS_ERROR_ABORT
 405    *         If the application has begun the process of shutting down already.
 406    * @throws NS_ERROR_NOT_INITIALIZED
 407    *         If the connection has already started or completed closing.
 408    * @throws NS_ERROR_NOT_AVAILABLE
 409    *         If the database does not support asynchronous operations.
 410    * @throws NS_ERROR_NOT_INITIALIZED
 411    *         If the execution thread cannot be acquired.
 412    */
 413   void backupToFileAsync(in nsIFile aDestinationFile,
 414                          in mozIStorageCompletionCallback aCallback,
 415                          [optional] in unsigned long aPagesPerStep,
 416                          [optional] in unsigned long aStepDelayMs);
 417 };