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    */
  74   readonly attribute int32_t variableLimit;
  75
  76   /**
  77    * Returns true if a transaction is active on this connection.
  78    *
  79    * Note that this is true if a transaction is active on the connection,
  80    * regardless of how it was opened. There are several ways to open one:
  81    *
  82    * 1. Explicitly calling `beginTransaction` on a `mozIStorageConnection`.
  83    * 2. Calling `executeSimpleSQL("BEGIN")` or
  84    *    `createStatement("BEGIN").execute()` on a `mozIStorageConnection`.
  85    * 3. Executing an async statement, like
  86    *    `createAsyncStatement("BEGIN").executeAsync(...)`. This is what
  87    *    `Sqlite.sys.mjs` does under the hood.
  88    *
  89    * Because of this, it's important *not* to use this attribute to decide
  90    * whether to *commit* the active transaction, because the caller that opened
  91    * it may not expect that. This is why both `mozStorageTransaction` and
  92    * `Sqlite.sys.mjs` use an internal variable (`mHasTransaction` for the former;
  93    * `_hasInProgressTransaction` for the latter) to check if their transaction
  94    * is already in progress, instead of just checking this attribute before
  95    * committing. Otherwise, mozStorage might accidentally commit (or roll back!)
  96    * a transaction started by `Sqlite.sys.mjs`, and vice versa.
  97    */
  98   readonly attribute boolean transactionInProgress;
  99
 100   /**
 101    * Close this database connection, allowing all pending statements
 102    * to complete first.
 103    *
 104    * @param aCallback [optional]
 105    *        A callback that will be notified when the close is completed,
 106    *        with the following arguments:
 107    *        - status: the status of the call
 108    *        - value: |null|
 109    *
 110    * @throws NS_ERROR_NOT_SAME_THREAD
 111    *         If called on a thread other than the one that opened it.  The
 112    *         callback will not be dispatched.
 113    * @throws NS_ERROR_NOT_INITIALIZED
 114    *         If called on a connection that has already been closed or was
 115    *         never properly opened.  The callback will still be dispatched
 116    *         to the main thread despite the returned error.
 117    * @note If this call should fail, the callback won't be invoked.
 118    */
 119   void asyncClose([optional] in mozIStorageCompletionCallback aCallback);
 120
 121   /**
 122    * Forcibly closes a database connection synchronously.
 123    * This should only be used when it's required to close and replace the
 124    * database synchronously to return control to the consumer, for example in
 125    * case of a detected corruption on database opening.
 126    * Since this spins the events loop, it should be used only in very particular
 127    * and rare situations, or it may cause unexpected consequences (crashes).
 128    *
 129    * @throws NS_ERROR_NOT_SAME_THREAD
 130    *         If called on a thread other than the one that opened it.
 131    */
 132   [noscript] void spinningSynchronousClose();
 133
 134   /**
 135    * Clone a database and make the clone read only if needed.
 136    * SQL Functions and attached on-disk databases are applied to the new clone.
 137    *
 138    * @param aReadOnly
 139    *        If true, the returned database should be put into read-only mode.
 140    *
 141    * @param aCallback
 142    *        A callback that will be notified when the operation is complete,
 143    *        with the following arguments:
 144    *        - status: the status of the operation
 145    *        - value: in case of success, an intance of
 146    *             mozIStorageAsyncConnection cloned from this one.
 147    *
 148    * @throws NS_ERROR_NOT_SAME_THREAD
 149    *         If is called on a thread other than the one that opened it.
 150    * @throws NS_ERROR_UNEXPECTED
 151    *         If this connection is a memory database.
 152    *
 153    * @note If your connection is already read-only, you will get a read-only
 154    *       clone.
 155    * @note The resulting connection will implement `mozIStorageConnection`, but
 156    *       all synchronous methods will throw if called from the main thread.
 157    * @note Due to a bug in SQLite, if you use the shared cache
 158    *       (see mozIStorageService), you end up with the same privileges as the
 159    *       first connection opened regardless of what is specified in aReadOnly.
 160    * @note The following pragmas are copied over to a read-only clone:
 161    *        - cache_size
 162    *        - temp_store
 163    *       The following pragmas are copied over to a writeable clone:
 164    *        - cache_size
 165    *        - temp_store
 166    *        - foreign_keys
 167    *        - journal_size_limit
 168    *        - synchronous
 169    *        - wal_autocheckpoint
 170    *       All SQL functions are copied over to read-only and writeable clones.
 171    *       Additionally, all temporary tables, triggers, and views, as well as
 172    *       any indexes on temporary tables, are copied over to writeable clones.
 173    *       For temporary tables, only the schemas are copied, not their
 174    *       contents.
 175    */
 176   void asyncClone(in boolean aReadOnly,
 177                   in mozIStorageCompletionCallback aCallback);
 178
 179   /**
 180    * The current database nsIFile.  Null if the database
 181    * connection refers to an in-memory database.
 182    */
 183   readonly attribute nsIFile databaseFile;
 184
 185   /**
 186    * Causes any pending database operation to abort and return at the first
 187    * opportunity.
 188    * @note this cannot be used on mozIStorageConnection unless the connection is
 189    *       explicitly marked as `interruptible`. For more details, please
 190    *       refer to CONNECTION_INTERRUPTIBLE in mozIStorageService.
 191    * @note operations that are nearly complete may still be able to complete.
 192    * @throws if used on an unsupported connection type, or a closed connection.
 193    */
 194   void interrupt();
 195
 196   /**
 197    * Vacuum the main database plus all the attached one.
 198    * If the database is in auto_vacuum = INCREMENTAL mode, this executes an
 199    * incremental_vacuum, otherwise it will always execute a full vacuum.
 200    *
 201    * While it's possible to invoke this method directly, it's suggested, when
 202    * possible, to use the VacuumManager instead.
 203    * That means registering your component for the "vacuum-participant" XPCOM
 204    * category, and implement the mozIStorageVacuumParticipant interface.
 205    *
 206    * @param [aCallback] Completion callback invoked once the operation is
 207    *        complete.
 208    * @param [aUseIncremental] When set to true, this will try to convert the
 209    *        main schema to auto_vacuum = INCREMENTAL mode, if it's not set yet.
 210    *        When set to false, it will try to set auto_vacuum = NONE.
 211    *        Note a full vacuum will be executed if the auto_vacuum mode must be
 212    *        changed, otherwise an incremental vacuum will happen if the database
 213    *        is already in INCREMENTAL mode.
 214    * @param [aSetPageSize] This can be used to change the database page_size, a
 215    *        full vacuum will be executed to persist the change. If the page
 216    *        size is already correct, or you pass 0, this will be a no-op.
 217    * @throws If it's not possible to start the async vacuum operation, note in
 218    *         this case the callback won't be invoked.
 219    * @note Vacuum will fail inside a transaction, or if there is an ongoing
 220    *       read statement.
 221    */
 222   void asyncVacuum(
 223     [optional] in mozIStorageCompletionCallback aCallback,
 224     [optional] in boolean aUseIncremental,
 225     [optional] in long aSetPageSize
 226   );
 227
 228   //////////////////////////////////////////////////////////////////////////////
 229   //// Statement creation
 230
 231   /**
 232    * Create an asynchronous statement for the given SQL. An
 233    * asynchronous statement can only be used to dispatch asynchronous
 234    * requests to the asynchronous execution thread and cannot be used
 235    * to take any synchronous actions on the database.
 236    *
 237    * The expression may use ? to indicate sequential numbered arguments,
 238    * ?1, ?2 etc. to indicate specific numbered arguments or :name and
 239    * $var to indicate named arguments.
 240    *
 241    * @param aSQLStatement
 242    *        The SQL statement to execute.
 243    * @return a new mozIStorageAsyncStatement
 244    * @note The statement is created lazily on first execution.
 245    */
 246   mozIStorageAsyncStatement createAsyncStatement(in AUTF8String aSQLStatement);
 247
 248   /**
 249    * Execute an array of statements created with this connection using
 250    * any currently bound parameters. When the array contains multiple
 251    * statements, the execution is wrapped in a single
 252    * transaction. These statements can be reused immediately, and
 253    * reset does not need to be called.
 254    *
 255    * @param aStatements
 256    *        The array of statements to execute asynchronously, in the order they
 257    *        are given in the array.
 258    * @param aCallback [optional]
 259    *        The callback object that will be notified of progress, errors, and
 260    *        completion.
 261    * @return an object that can be used to cancel the statements execution.
 262    *
 263    * @note If you have any custom defined functions, they must be
 264    *        re-entrant since they can be called on multiple threads.
 265    */
 266   mozIStoragePendingStatement executeAsync(
 267     in Array<mozIStorageBaseStatement> aStatements,
 268     [optional] in mozIStorageStatementCallback aCallback
 269   );
 270
 271   /**
 272    * Execute asynchronously an SQL expression, expecting no arguments.
 273    *
 274    * @param aSQLStatement
 275    *        The SQL statement to execute
 276    * @param aCallback [optional]
 277    *        The callback object that will be notified of progress, errors, and
 278    *        completion.
 279    * @return an object that can be used to cancel the statement execution.
 280    */
 281   mozIStoragePendingStatement executeSimpleSQLAsync(
 282     in AUTF8String aSQLStatement,
 283     [optional] in mozIStorageStatementCallback aCallback);
 284
 285   //////////////////////////////////////////////////////////////////////////////
 286   //// Functions
 287
 288   /**
 289    * Create a new SQL function.  If you use your connection on multiple threads,
 290    * your function needs to be threadsafe, or it should only be called on one
 291    * thread.
 292    *
 293    * @param aFunctionName
 294    *        The name of function to create, as seen in SQL.
 295    * @param aNumArguments
 296    *        The number of arguments the function takes. Pass -1 for
 297    *        variable-argument functions.
 298    * @param aFunction
 299    *        The instance of mozIStorageFunction, which implements the function
 300    *        in question.
 301    */
 302   void createFunction(in AUTF8String aFunctionName,
 303                       in long aNumArguments,
 304                       in mozIStorageFunction aFunction);
 305
 306   /**
 307    * Delete custom SQL function.
 308    *
 309    * @param aFunctionName
 310    *        The name of function to remove.
 311    */
 312   void removeFunction(in AUTF8String aFunctionName);
 313
 314   /**
 315    * Sets a progress handler. Only one handler can be registered at a time.
 316    * If you need more than one, you need to chain them yourself.  This progress
 317    * handler should be threadsafe if you use this connection object on more than
 318    * one thread.
 319    *
 320    * @param aGranularity
 321    *        The number of SQL virtual machine steps between progress handler
 322    *        callbacks.
 323    * @param aHandler
 324    *        The instance of mozIStorageProgressHandler.
 325    * @return previous registered handler.
 326    */
 327   mozIStorageProgressHandler setProgressHandler(in int32_t aGranularity,
 328                                                 in mozIStorageProgressHandler aHandler);
 329
 330   /**
 331    * Remove a progress handler.
 332    *
 333    * @return previous registered handler.
 334    */
 335   mozIStorageProgressHandler removeProgressHandler();
 336 };