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.jsm` 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.jsm` 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.jsm`, 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    * This can only be used on read-only connections that don't implement
 189    * the mozIStorageConnection interface.
 190    * @note operations that are nearly complete may still be able to complete.
 191    * @throws if used on an unsupported connection type, or a closed connection.
 192    */
 193   void interrupt();
 194
 195   //////////////////////////////////////////////////////////////////////////////
 196   //// Statement creation
 197
 198   /**
 199    * Create an asynchronous statement for the given SQL. An
 200    * asynchronous statement can only be used to dispatch asynchronous
 201    * requests to the asynchronous execution thread and cannot be used
 202    * to take any synchronous actions on the database.
 203    *
 204    * The expression may use ? to indicate sequential numbered arguments,
 205    * ?1, ?2 etc. to indicate specific numbered arguments or :name and
 206    * $var to indicate named arguments.
 207    *
 208    * @param aSQLStatement
 209    *        The SQL statement to execute.
 210    * @return a new mozIStorageAsyncStatement
 211    * @note The statement is created lazily on first execution.
 212    */
 213   mozIStorageAsyncStatement createAsyncStatement(in AUTF8String aSQLStatement);
 214
 215   /**
 216    * Execute an array of statements created with this connection using
 217    * any currently bound parameters. When the array contains multiple
 218    * statements, the execution is wrapped in a single
 219    * transaction. These statements can be reused immediately, and
 220    * reset does not need to be called.
 221    *
 222    * @param aStatements
 223    *        The array of statements to execute asynchronously, in the order they
 224    *        are given in the array.
 225    * @param aCallback [optional]
 226    *        The callback object that will be notified of progress, errors, and
 227    *        completion.
 228    * @return an object that can be used to cancel the statements execution.
 229    *
 230    * @note If you have any custom defined functions, they must be
 231    *        re-entrant since they can be called on multiple threads.
 232    */
 233   mozIStoragePendingStatement executeAsync(
 234     in Array<mozIStorageBaseStatement> aStatements,
 235     [optional] in mozIStorageStatementCallback aCallback
 236   );
 237
 238   /**
 239    * Execute asynchronously an SQL expression, expecting no arguments.
 240    *
 241    * @param aSQLStatement
 242    *        The SQL statement to execute
 243    * @param aCallback [optional]
 244    *        The callback object that will be notified of progress, errors, and
 245    *        completion.
 246    * @return an object that can be used to cancel the statement execution.
 247    */
 248   mozIStoragePendingStatement executeSimpleSQLAsync(
 249     in AUTF8String aSQLStatement,
 250     [optional] in mozIStorageStatementCallback aCallback);
 251
 252   //////////////////////////////////////////////////////////////////////////////
 253   //// Functions
 254
 255   /**
 256    * Create a new SQL function.  If you use your connection on multiple threads,
 257    * your function needs to be threadsafe, or it should only be called on one
 258    * thread.
 259    *
 260    * @param aFunctionName
 261    *        The name of function to create, as seen in SQL.
 262    * @param aNumArguments
 263    *        The number of arguments the function takes. Pass -1 for
 264    *        variable-argument functions.
 265    * @param aFunction
 266    *        The instance of mozIStorageFunction, which implements the function
 267    *        in question.
 268    */
 269   void createFunction(in AUTF8String aFunctionName,
 270                       in long aNumArguments,
 271                       in mozIStorageFunction aFunction);
 272
 273   /**
 274    * Delete custom SQL function.
 275    *
 276    * @param aFunctionName
 277    *        The name of function to remove.
 278    */
 279   void removeFunction(in AUTF8String aFunctionName);
 280
 281   /**
 282    * Sets a progress handler. Only one handler can be registered at a time.
 283    * If you need more than one, you need to chain them yourself.  This progress
 284    * handler should be threadsafe if you use this connection object on more than
 285    * one thread.
 286    *
 287    * @param aGranularity
 288    *        The number of SQL virtual machine steps between progress handler
 289    *        callbacks.
 290    * @param aHandler
 291    *        The instance of mozIStorageProgressHandler.
 292    * @return previous registered handler.
 293    */
 294   mozIStorageProgressHandler setProgressHandler(in int32_t aGranularity,
 295                                                 in mozIStorageProgressHandler aHandler);
 296
 297   /**
 298    * Remove a progress handler.
 299    *
 300    * @return previous registered handler.
 301    */
 302   mozIStorageProgressHandler removeProgressHandler();
 303 };