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305 lines
12 KiB
Plaintext
305 lines
12 KiB
Plaintext
/* -*- Mode: idl; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "nsISupports.idl"
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interface mozIStorageCompletionCallback;
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interface mozIStorageFunction;
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interface mozIStorageProgressHandler;
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interface mozIStorageBaseStatement;
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interface mozIStorageStatement;
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interface mozIStorageAsyncStatement;
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interface mozIStorageStatementCallback;
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interface mozIStoragePendingStatement;
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interface nsIFile;
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/**
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* mozIStorageAsyncConnection represents an asynchronous database
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* connection attached to a specific file or to an in-memory data
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* storage. It is the primary interface for interacting with a
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* database from the main thread, including creating prepared
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* statements, executing SQL, and examining database errors.
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*/
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[scriptable, uuid(8bfd34d5-4ddf-4e4b-89dd-9b14f33534c6)]
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interface mozIStorageAsyncConnection : nsISupports {
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/**
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* Transaction behavior constants.
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*/
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const int32_t TRANSACTION_DEFAULT = -1;
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const int32_t TRANSACTION_DEFERRED = 0;
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const int32_t TRANSACTION_IMMEDIATE = 1;
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const int32_t TRANSACTION_EXCLUSIVE = 2;
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/**
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* The default behavior for all transactions run on this connection. Defaults
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* to `TRANSACTION_DEFERRED`, and can be overridden for individual
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* transactions.
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*/
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attribute int32_t defaultTransactionType;
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/**
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* The maximum number of bound parameters for statements executed on this
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* connection. If your statement has more params than this limit, you'll
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* need to chunk them into multiple statements. See `PlacesUtils.chunkArray`
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* and its callers in Places for examples of how to do this, or read on for
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* an overview.
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*
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* Keep in mind that the variable limit is for the _total_ number of
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* parameters, including ones bound by name (using the `:VVV`, `@VVV`, or
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* `?VVV` syntax) and index (`?` and `?NNN`).
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*
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* This means, when chunking:
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*
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* - If you're binding 1 param per 1 value per chunk (for example, if you
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* have a list of GUIDs and a clause like `WHERE guid IN (?, ?, ?, ...)`,
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* your chunk length is just `variableLimit`.
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* - If you're binding 1 param per 1 value per chunk, but using that
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* param in multiple positions in the query (for example, `WHERE url_hash
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* IN (hash(?1), hash(?2), ...) AND url IN (?1, ?2, ...)`), you can use the
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* `?NNN` syntax with a chunk length of `variableLimit`.
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* - If you're binding N params per 1 value per chunk (for example, if you
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* have a list of items with GUIDs and parent GUIDs, and you want to bind
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* both), your chunk length is `variableLimit / N`, since you're binding
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* two params for each element.
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* - If you're binding K params per L values per chunk, plus M fixed ones
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* (for example, `WHERE parentGuid = :parentGuid AND guid IN (?, ?, ...)`),
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* your chunk length is `variableLimit - M`, to ensure there's space for the
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* fixed variables.
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*
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* If you bind more params than this limit, `create{Async}Statement` will
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* fail with a "too many SQL variables" error.
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*/
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readonly attribute int32_t variableLimit;
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/**
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* Returns true if a transaction is active on this connection.
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*
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* Note that this is true if a transaction is active on the connection,
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* regardless of how it was opened. There are several ways to open one:
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*
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* 1. Explicitly calling `beginTransaction` on a `mozIStorageConnection`.
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* 2. Calling `executeSimpleSQL("BEGIN")` or
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* `createStatement("BEGIN").execute()` on a `mozIStorageConnection`.
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* 3. Executing an async statement, like
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* `createAsyncStatement("BEGIN").executeAsync(...)`. This is what
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* `Sqlite.jsm` does under the hood.
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*
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* Because of this, it's important *not* to use this attribute to decide
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* whether to *commit* the active transaction, because the caller that opened
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* it may not expect that. This is why both `mozStorageTransaction` and
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* `Sqlite.jsm` use an internal variable (`mHasTransaction` for the former;
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* `_hasInProgressTransaction` for the latter) to check if their transaction
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* is already in progress, instead of just checking this attribute before
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* committing. Otherwise, mozStorage might accidentally commit (or roll back!)
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* a transaction started by `Sqlite.jsm`, and vice versa.
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*/
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readonly attribute boolean transactionInProgress;
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/**
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* Close this database connection, allowing all pending statements
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* to complete first.
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*
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* @param aCallback [optional]
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* A callback that will be notified when the close is completed,
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* with the following arguments:
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* - status: the status of the call
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* - value: |null|
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*
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* @throws NS_ERROR_NOT_SAME_THREAD
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* If called on a thread other than the one that opened it. The
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* callback will not be dispatched.
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* @throws NS_ERROR_NOT_INITIALIZED
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* If called on a connection that has already been closed or was
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* never properly opened. The callback will still be dispatched
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* to the main thread despite the returned error.
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* @note If this call should fail, the callback won't be invoked.
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*/
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void asyncClose([optional] in mozIStorageCompletionCallback aCallback);
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/**
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* Forcibly closes a database connection synchronously.
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* This should only be used when it's required to close and replace the
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* database synchronously to return control to the consumer, for example in
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* case of a detected corruption on database opening.
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* Since this spins the events loop, it should be used only in very particular
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* and rare situations, or it may cause unexpected consequences (crashes).
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*
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* @throws NS_ERROR_NOT_SAME_THREAD
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* If called on a thread other than the one that opened it.
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*/
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[noscript] void spinningSynchronousClose();
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/**
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* Clone a database and make the clone read only if needed.
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* SQL Functions and attached on-disk databases are applied to the new clone.
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*
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* @param aReadOnly
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* If true, the returned database should be put into read-only mode.
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*
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* @param aCallback
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* A callback that will be notified when the operation is complete,
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* with the following arguments:
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* - status: the status of the operation
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* - value: in case of success, an intance of
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* mozIStorageAsyncConnection cloned from this one.
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*
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* @throws NS_ERROR_NOT_SAME_THREAD
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* If is called on a thread other than the one that opened it.
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* @throws NS_ERROR_UNEXPECTED
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* If this connection is a memory database.
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*
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* @note If your connection is already read-only, you will get a read-only
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* clone.
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* @note The resulting connection will implement `mozIStorageConnection`, but
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* all synchronous methods will throw if called from the main thread.
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* @note Due to a bug in SQLite, if you use the shared cache
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* (see mozIStorageService), you end up with the same privileges as the
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* first connection opened regardless of what is specified in aReadOnly.
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* @note The following pragmas are copied over to a read-only clone:
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* - cache_size
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* - temp_store
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* The following pragmas are copied over to a writeable clone:
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* - cache_size
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* - temp_store
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* - foreign_keys
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* - journal_size_limit
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* - synchronous
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* - wal_autocheckpoint
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* All SQL functions are copied over to read-only and writeable clones.
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* Additionally, all temporary tables, triggers, and views, as well as
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* any indexes on temporary tables, are copied over to writeable clones.
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* For temporary tables, only the schemas are copied, not their
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* contents.
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*/
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void asyncClone(in boolean aReadOnly,
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in mozIStorageCompletionCallback aCallback);
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/**
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* The current database nsIFile. Null if the database
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* connection refers to an in-memory database.
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*/
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readonly attribute nsIFile databaseFile;
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/**
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* Causes any pending database operation to abort and return at the first
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* opportunity.
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* @note this cannot be used on mozIStorageConnection unless the connection is
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* explicitly marked as `interruptible`. For more details, please
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* refer to CONNECTION_INTERRUPTIBLE in mozIStorageService.
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* @note operations that are nearly complete may still be able to complete.
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* @throws if used on an unsupported connection type, or a closed connection.
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*/
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void interrupt();
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//////////////////////////////////////////////////////////////////////////////
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//// Statement creation
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/**
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* Create an asynchronous statement for the given SQL. An
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* asynchronous statement can only be used to dispatch asynchronous
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* requests to the asynchronous execution thread and cannot be used
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* to take any synchronous actions on the database.
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*
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* The expression may use ? to indicate sequential numbered arguments,
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* ?1, ?2 etc. to indicate specific numbered arguments or :name and
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* $var to indicate named arguments.
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*
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* @param aSQLStatement
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* The SQL statement to execute.
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* @return a new mozIStorageAsyncStatement
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* @note The statement is created lazily on first execution.
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*/
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mozIStorageAsyncStatement createAsyncStatement(in AUTF8String aSQLStatement);
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/**
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* Execute an array of statements created with this connection using
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* any currently bound parameters. When the array contains multiple
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* statements, the execution is wrapped in a single
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* transaction. These statements can be reused immediately, and
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* reset does not need to be called.
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*
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* @param aStatements
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* The array of statements to execute asynchronously, in the order they
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* are given in the array.
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* @param aCallback [optional]
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* The callback object that will be notified of progress, errors, and
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* completion.
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* @return an object that can be used to cancel the statements execution.
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*
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* @note If you have any custom defined functions, they must be
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* re-entrant since they can be called on multiple threads.
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*/
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mozIStoragePendingStatement executeAsync(
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in Array<mozIStorageBaseStatement> aStatements,
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[optional] in mozIStorageStatementCallback aCallback
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);
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/**
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* Execute asynchronously an SQL expression, expecting no arguments.
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*
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* @param aSQLStatement
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* The SQL statement to execute
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* @param aCallback [optional]
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* The callback object that will be notified of progress, errors, and
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* completion.
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* @return an object that can be used to cancel the statement execution.
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*/
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mozIStoragePendingStatement executeSimpleSQLAsync(
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in AUTF8String aSQLStatement,
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[optional] in mozIStorageStatementCallback aCallback);
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//////////////////////////////////////////////////////////////////////////////
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//// Functions
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/**
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* Create a new SQL function. If you use your connection on multiple threads,
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* your function needs to be threadsafe, or it should only be called on one
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* thread.
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*
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* @param aFunctionName
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* The name of function to create, as seen in SQL.
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* @param aNumArguments
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* The number of arguments the function takes. Pass -1 for
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* variable-argument functions.
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* @param aFunction
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* The instance of mozIStorageFunction, which implements the function
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* in question.
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*/
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void createFunction(in AUTF8String aFunctionName,
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in long aNumArguments,
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in mozIStorageFunction aFunction);
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/**
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* Delete custom SQL function.
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*
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* @param aFunctionName
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* The name of function to remove.
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*/
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void removeFunction(in AUTF8String aFunctionName);
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/**
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* Sets a progress handler. Only one handler can be registered at a time.
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* If you need more than one, you need to chain them yourself. This progress
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* handler should be threadsafe if you use this connection object on more than
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* one thread.
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*
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* @param aGranularity
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* The number of SQL virtual machine steps between progress handler
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* callbacks.
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* @param aHandler
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* The instance of mozIStorageProgressHandler.
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* @return previous registered handler.
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*/
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mozIStorageProgressHandler setProgressHandler(in int32_t aGranularity,
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in mozIStorageProgressHandler aHandler);
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/**
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* Remove a progress handler.
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*
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* @return previous registered handler.
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*/
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mozIStorageProgressHandler removeProgressHandler();
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};
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