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/* -*- 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 mozIStorageCompletionCallback;
interface mozIStorageFunction;
interface mozIStorageProgressHandler;
interface mozIStorageBaseStatement;
interface mozIStorageStatement;
interface mozIStorageAsyncStatement;
interface mozIStorageStatementCallback;
interface mozIStoragePendingStatement;
interface nsIFile;
/**
* mozIStorageAsyncConnection represents an asynchronous database
* connection attached to a specific file or to an in-memory data
* storage. It is the primary interface for interacting with a
* database from the main thread, including creating prepared
* statements, executing SQL, and examining database errors.
*/
[scriptable, uuid(8bfd34d5-4ddf-4e4b-89dd-9b14f33534c6)]
interface mozIStorageAsyncConnection : nsISupports {
/**
* Transaction behavior constants.
*/
const int32_t TRANSACTION_DEFAULT = -1;
const int32_t TRANSACTION_DEFERRED = 0;
const int32_t TRANSACTION_IMMEDIATE = 1;
const int32_t TRANSACTION_EXCLUSIVE = 2;
/**
* The default behavior for all transactions run on this connection. Defaults
* to `TRANSACTION_DEFERRED`, and can be overridden for individual
* transactions.
*/
attribute int32_t defaultTransactionType;
/**
* The maximum number of bound parameters for statements executed on this
* connection. If your statement has more params than this limit, you'll
* need to chunk them into multiple statements. See `PlacesUtils.chunkArray`
* and its callers in Places for examples of how to do this, or read on for
* an overview.
*
* Keep in mind that the variable limit is for the _total_ number of
* parameters, including ones bound by name (using the `:VVV`, `@VVV`, or
* `?VVV` syntax) and index (`?` and `?NNN`).
*
* This means, when chunking:
*
* - If you're binding 1 param per 1 value per chunk (for example, if you
* have a list of GUIDs and a clause like `WHERE guid IN (?, ?, ?, ...)`,
* your chunk length is just `variableLimit`.
* - If you're binding 1 param per 1 value per chunk, but using that
* param in multiple positions in the query (for example, `WHERE url_hash
* IN (hash(?1), hash(?2), ...) AND url IN (?1, ?2, ...)`), you can use the
* `?NNN` syntax with a chunk length of `variableLimit`.
* - If you're binding N params per 1 value per chunk (for example, if you
* have a list of items with GUIDs and parent GUIDs, and you want to bind
* both), your chunk length is `variableLimit / N`, since you're binding
* two params for each element.
* - If you're binding K params per L values per chunk, plus M fixed ones
* (for example, `WHERE parentGuid = :parentGuid AND guid IN (?, ?, ...)`),
* your chunk length is `variableLimit - M`, to ensure there's space for the
* fixed variables.
*
* If you bind more params than this limit, `create{Async}Statement` will
* fail with a "too many SQL variables" error.
*/
readonly attribute int32_t variableLimit;
/**
* Returns true if a transaction is active on this connection.
*
* Note that this is true if a transaction is active on the connection,
* regardless of how it was opened. There are several ways to open one:
*
* 1. Explicitly calling `beginTransaction` on a `mozIStorageConnection`.
* 2. Calling `executeSimpleSQL("BEGIN")` or
* `createStatement("BEGIN").execute()` on a `mozIStorageConnection`.
* 3. Executing an async statement, like
* `createAsyncStatement("BEGIN").executeAsync(...)`. This is what
* `Sqlite.jsm` does under the hood.
*
* Because of this, it's important *not* to use this attribute to decide
* whether to *commit* the active transaction, because the caller that opened
* it may not expect that. This is why both `mozStorageTransaction` and
* `Sqlite.jsm` use an internal variable (`mHasTransaction` for the former;
* `_hasInProgressTransaction` for the latter) to check if their transaction
* is already in progress, instead of just checking this attribute before
* committing. Otherwise, mozStorage might accidentally commit (or roll back!)
* a transaction started by `Sqlite.jsm`, and vice versa.
*/
readonly attribute boolean transactionInProgress;
/**
* Close this database connection, allowing all pending statements
* to complete first.
*
* @param aCallback [optional]
* A callback that will be notified when the close is completed,
* with the following arguments:
* - status: the status of the call
* - value: |null|
*
* @throws NS_ERROR_NOT_SAME_THREAD
* If called on a thread other than the one that opened it. The
* callback will not be dispatched.
* @throws NS_ERROR_NOT_INITIALIZED
* If called on a connection that has already been closed or was
* never properly opened. The callback will still be dispatched
* to the main thread despite the returned error.
* @note If this call should fail, the callback won't be invoked.
*/
void asyncClose([optional] in mozIStorageCompletionCallback aCallback);
/**
* Forcibly closes a database connection synchronously.
* This should only be used when it's required to close and replace the
* database synchronously to return control to the consumer, for example in
* case of a detected corruption on database opening.
* Since this spins the events loop, it should be used only in very particular
* and rare situations, or it may cause unexpected consequences (crashes).
*
* @throws NS_ERROR_NOT_SAME_THREAD
* If called on a thread other than the one that opened it.
*/
[noscript] void spinningSynchronousClose();
/**
* Clone a database and make the clone read only if needed.
* SQL Functions and attached on-disk databases are applied to the new clone.
*
* @param aReadOnly
* If true, the returned database should be put into read-only mode.
*
* @param aCallback
* A callback that will be notified when the operation is complete,
* with the following arguments:
* - status: the status of the operation
* - value: in case of success, an intance of
* mozIStorageAsyncConnection cloned from this one.
*
* @throws NS_ERROR_NOT_SAME_THREAD
* If is called on a thread other than the one that opened it.
* @throws NS_ERROR_UNEXPECTED
* If this connection is a memory database.
*
* @note If your connection is already read-only, you will get a read-only
* clone.
* @note The resulting connection will implement `mozIStorageConnection`, but
* all synchronous methods will throw if called from the main thread.
* @note Due to a bug in SQLite, if you use the shared cache
* (see mozIStorageService), you end up with the same privileges as the
* first connection opened regardless of what is specified in aReadOnly.
* @note The following pragmas are copied over to a read-only clone:
* - cache_size
* - temp_store
* The following pragmas are copied over to a writeable clone:
* - cache_size
* - temp_store
* - foreign_keys
* - journal_size_limit
* - synchronous
* - wal_autocheckpoint
* All SQL functions are copied over to read-only and writeable clones.
* Additionally, all temporary tables, triggers, and views, as well as
* any indexes on temporary tables, are copied over to writeable clones.
* For temporary tables, only the schemas are copied, not their
* contents.
*/
void asyncClone(in boolean aReadOnly,
in mozIStorageCompletionCallback aCallback);
/**
* The current database nsIFile. Null if the database
* connection refers to an in-memory database.
*/
readonly attribute nsIFile databaseFile;
/**
* Causes any pending database operation to abort and return at the first
* opportunity.
* This can only be used on read-only connections that don't implement
* the mozIStorageConnection interface.
* @note operations that are nearly complete may still be able to complete.
* @throws if used on an unsupported connection type, or a closed connection.
*/
void interrupt();
//////////////////////////////////////////////////////////////////////////////
//// Statement creation
/**
* Create an asynchronous statement for the given SQL. An
* asynchronous statement can only be used to dispatch asynchronous
* requests to the asynchronous execution thread and cannot be used
* to take any synchronous actions on the database.
*
* The expression may use ? to indicate sequential numbered arguments,
* ?1, ?2 etc. to indicate specific numbered arguments or :name and
* $var to indicate named arguments.
*
* @param aSQLStatement
* The SQL statement to execute.
* @return a new mozIStorageAsyncStatement
* @note The statement is created lazily on first execution.
*/
mozIStorageAsyncStatement createAsyncStatement(in AUTF8String aSQLStatement);
/**
* Execute an array of statements created with this connection using
* any currently bound parameters. When the array contains multiple
* statements, the execution is wrapped in a single
* transaction. These statements can be reused immediately, and
* reset does not need to be called.
*
* @param aStatements
* The array of statements to execute asynchronously, in the order they
* are given in the array.
* @param aCallback [optional]
* The callback object that will be notified of progress, errors, and
* completion.
* @return an object that can be used to cancel the statements execution.
*
* @note If you have any custom defined functions, they must be
* re-entrant since they can be called on multiple threads.
*/
mozIStoragePendingStatement executeAsync(
in Array<mozIStorageBaseStatement> aStatements,
[optional] in mozIStorageStatementCallback aCallback
);
/**
* Execute asynchronously an SQL expression, expecting no arguments.
*
* @param aSQLStatement
* The SQL statement to execute
* @param aCallback [optional]
* The callback object that will be notified of progress, errors, and
* completion.
* @return an object that can be used to cancel the statement execution.
*/
mozIStoragePendingStatement executeSimpleSQLAsync(
in AUTF8String aSQLStatement,
[optional] in mozIStorageStatementCallback aCallback);
//////////////////////////////////////////////////////////////////////////////
//// Functions
/**
* Create a new SQL function. If you use your connection on multiple threads,
* your function needs to be threadsafe, or it should only be called on one
* thread.
*
* @param aFunctionName
* The name of function to create, as seen in SQL.
* @param aNumArguments
* The number of arguments the function takes. Pass -1 for
* variable-argument functions.
* @param aFunction
* The instance of mozIStorageFunction, which implements the function
* in question.
*/
void createFunction(in AUTF8String aFunctionName,
in long aNumArguments,
in mozIStorageFunction aFunction);
/**
* Delete custom SQL function.
*
* @param aFunctionName
* The name of function to remove.
*/
void removeFunction(in AUTF8String aFunctionName);
/**
* Sets a progress handler. Only one handler can be registered at a time.
* If you need more than one, you need to chain them yourself. This progress
* handler should be threadsafe if you use this connection object on more than
* one thread.
*
* @param aGranularity
* The number of SQL virtual machine steps between progress handler
* callbacks.
* @param aHandler
* The instance of mozIStorageProgressHandler.
* @return previous registered handler.
*/
mozIStorageProgressHandler setProgressHandler(in int32_t aGranularity,
in mozIStorageProgressHandler aHandler);
/**
* Remove a progress handler.
*
* @return previous registered handler.
*/
mozIStorageProgressHandler removeProgressHandler();
};