angd-dev/data-raft
1
0
Fork 0
Code Pull Requests Releases Activity

Add database change notification

Browse Source
This commit is contained in:
Oleksii Zghurskyi
2025-11-09 17:23:08 +02:00
parent 5bbb722b20
commit df17d21ec4
6 changed files with 84 additions and 112 deletions
Download Patch File Download Diff File Expand all files Collapse all files

142
Sources/DataRaft/Classes/DatabaseService.swift
View File

@@ -2,17 +2,17 @@ import Foundation
import DataLiteCore
import DataLiteC
/// A base database service handling transactions and event notifications.
/// A base database service that handles transactions and posts change notifications.
///
/// ## Overview
///
/// `DatabaseService` provides a foundational layer for performing transactional database operations
/// within a thread-safe execution context. It automatically posts lifecycle notifications — such as
/// commit, rollback, and content changes — allowing observers to react to database updates in real
/// time. By default, it routes events through ``Foundation/NotificationCenter/database`` so that
/// clients can subscribe via a dedicated channel. This service is designed to be subclassed by
/// higher-level data managers that encapsulate domain logic while relying on consistent connection
/// and transaction handling.
/// `DatabaseService` provides a lightweight transactional layer for performing database operations
/// within a thread-safe execution context. It automatically detects modifications to the database
/// and posts a ``databaseDidChange`` notification database updates, allowing observers to react to
/// updates.
///
/// This class is intended to be subclassed by higher-level data managers that encapsulate domain
/// logic while relying on consistent connection and transaction handling.
///
/// ## Usage
///
@@ -57,9 +57,6 @@ import DataLiteC
/// ### Notifications
///
/// - ``databaseDidChange``
/// - ``databaseWillCommit``
/// - ``databaseDidRollback``
/// - ``databaseDidPerform``
open class DatabaseService:
ConnectionService,
DatabaseServiceProtocol,
@@ -70,47 +67,26 @@ open class DatabaseService:
private let center: NotificationCenter
/// Notification posted after the database content changes.
///
/// Observers listen to this event to refresh cached data or update dependent components once
/// modifications are committed. The notification’s `userInfo` may include
/// ``Foundation/Notification/UserInfoKey/action`` describing the SQLite action.
/// Notification posted after the database content changes with this service.
public static let databaseDidChange = Notification.Name("DatabaseService.databaseDidChange")
/// Notification posted immediately before a transaction commits.
///
/// Observers can perform validation or prepare for an upcoming state change while the
/// transaction is still in progress.
public static let databaseWillCommit = Notification.Name("DatabaseService.databaseWillCommit")
/// Notification posted after a transaction rolls back.
///
/// Observers use this event to revert in-memory state or reset caches that rely on pending
/// changes.
public static let databaseDidRollback = Notification.Name("DatabaseService.databaseDidRollback")
/// Notification posted after any database operation completes, regardless of outcome.
///
/// The service emits this event after finishing a `perform(_:)` block so observers can
/// synchronize state even when the operation is read-only or aborted.
///
/// - Important: Confirm that the associated transaction was not rolled back before relying on
/// side effects.
public static let databaseDidPerform = Notification.Name("DatabaseService.databaseDidPerform")
// MARK: - Inits
/// Creates a database service that posts lifecycle events to the provided notification center.
/// Creates a database service with a specified notification center.
///
/// The underlying connection handling matches ``ConnectionService``; the connection is created
/// lazily and all work executes on the managed serial queue.
/// Configures an internal serial queue for thread-safe access to the database. The connection
/// itself is not created during initialization — it is established lazily on first use (for
/// example, inside ``perform(_:)``).
///
/// The internal queue is created with QoS `.utility`. If `queue` is provided, it becomes the
/// target of the internal queue.
///
/// - Parameters:
/// - provider: A closure that returns a new database connection.
/// - config: An optional configuration closure called after the connection is established and
/// the encryption key is applied.
/// - queue: An optional target queue for the internal serial queue.
/// - center: A notification center for posting database events.
/// - queue: An optional target queue for the internal one.
/// - center: The notification center used to post database change notifications.
public init(
provider: @escaping ConnectionProvider,
config: ConnectionConfig? = nil,
@@ -121,39 +97,54 @@ open class DatabaseService:
super.init(provider: provider, config: config, queue: queue)
}
/// Creates a database service that posts lifecycle events to the shared database notification
/// center.
/// Creates a database service using the default database notification center.
///
/// The connection is established lazily on first access and all work executes on the internal
/// queue defined in ``ConnectionService``.
/// Configures an internal serial queue for thread-safe access to the database. The connection
/// itself is not created during initialization — it is established lazily on first use (for
/// example, inside ``perform(_:)``).
///
/// The service posts change notifications through ``Foundation/NotificationCenter/databaseCenter``,
/// which provides a shared channel for observing database events across the application.
///
/// The internal queue is created with QoS `.utility`. If `queue` is provided, it becomes the
/// target of the internal queue.
///
/// - Parameters:
/// - provider: A closure that returns a new database connection.
/// - config: An optional configuration closure called after the connection is established and
/// the encryption key is applied.
/// - queue: An optional target queue for the internal serial queue.
/// - queue: An optional target queue for the internal one.
public required init(
provider: @escaping ConnectionProvider,
config: ConnectionConfig? = nil,
queue: DispatchQueue? = nil
) {
self.center = .database
self.center = .databaseCenter
super.init(provider: provider, config: config, queue: queue)
}
// MARK: - Performing Operations
/// Executes a closure with a managed database connection and posts a completion notification.
/// Executes a closure within the context of a managed database connection.
///
/// The override mirrors ``ConnectionService/perform(_:)`` for queue-confined execution while
/// ensuring ``DatabaseService/databaseDidPerform`` is delivered after the closure completes.
/// Runs the operation on the service’s internal queue and ensures that the connection is valid
/// before use. If the connection is unavailable or fails during execution, this method throws
/// an error.
///
/// - Parameter closure: The operation to execute using the open connection.
/// - Returns: The value returned by the closure.
/// - Throws: Errors thrown by the closure or underlying connection.
/// After the closure completes, if the database content has changed, the service posts a
/// ``databaseDidChange`` notification through its configured notification center.
///
/// - Parameter closure: The operation to perform using the connection.
/// - Returns: The result produced by the closure.
/// - Throws: An error thrown by the closure or the connection.
public override func perform<T>(_ closure: Perform<T>) throws -> T {
try super.perform { connection in
defer { center.post(name: Self.databaseDidPerform, object: self) }
let changes = connection.totalChanges
defer {
if changes != connection.totalChanges {
center.post(name: Self.databaseDidChange, object: self)
}
}
return try closure(connection)
}
}
@@ -221,28 +212,43 @@ open class DatabaseService:
// MARK: - ConnectionDelegate
/// Posts ``DatabaseService/databaseDidChange`` when the database content updates.
/// Handles database updates reported by the active connection.
///
/// Called after an SQL statement modifies the database content. Subclasses can override this
/// method to observe specific actions (for example, inserts, updates, or deletes).
///
/// - Important: This method must not execute SQL statements or otherwise alter the connection
/// state.
///
/// - Parameters:
/// - connection: The connection that performed the change.
/// - action: The SQLite action describing the modification.
public func connection(_ connection: any ConnectionProtocol, didUpdate action: SQLiteAction) {
let userInfo = [Notification.UserInfoKey.action: action]
center.post(name: Self.databaseDidChange, object: self, userInfo: userInfo)
/// - connection: The connection that performed the update.
/// - action: The SQLite action describing the change.
open func connection(_ connection: any ConnectionProtocol, didUpdate action: SQLiteAction) {
}
/// Posts ``DatabaseService/databaseWillCommit`` before a transaction commits.
/// Called immediately before the connection commits a transaction.
///
/// Subclasses can override this method to perform validation or consistency checks prior to
/// committing. Throwing an error cancels the commit and triggers a rollback.
///
/// - Important: This method must not execute SQL statements or otherwise alter the connection
/// state.
///
/// - Parameter connection: The connection preparing to commit.
public func connectionWillCommit(_ connection: any ConnectionProtocol) throws {
center.post(name: Self.databaseWillCommit, object: self)
/// - Throws: An error to cancel the commit and roll back the transaction.
open func connectionWillCommit(_ connection: any ConnectionProtocol) throws {
}
/// Posts ``DatabaseService/databaseDidRollback`` after a transaction rollback.
/// Called after the connection rolls back a transaction.
///
/// - Parameter connection: The connection that rolled back.
public func connectionDidRollback(_ connection: any ConnectionProtocol) {
center.post(name: Self.databaseDidRollback, object: self)
/// Subclasses can override this method to handle cleanup or recovery logic following a
/// rollback.
///
/// - Important: This method must not execute SQL statements or otherwise alter the connection
/// state.
///
/// - Parameter connection: The connection that rolled back the transaction.
open func connectionDidRollback(_ connection: any ConnectionProtocol) {
}
// MARK: - Internal Methods