84 lines
3.1 KiB
Swift
84 lines
3.1 KiB
Swift
//
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// EphemeralPreferenceStore.swift
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//
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// Copyright 2026 Brendan Szymanski <hello@bscubed.dev>
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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//
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// SPDX-License-Identifier: GPL-3.0-or-later
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//
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/// An ordered in-memory preference backend for tests and persistence fallback.
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package actor EphemeralPreferenceStore: PreferenceStoring {
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package nonisolated let initialSnapshot: [String: StoredPreference]
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private var values: [String: StoredPreference]
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private nonisolated let continuation: AsyncStream<PreferenceWrite>.Continuation
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/// Creates an in-memory store seeded with optional raw values.
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///
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/// - Parameter initialSnapshot: Values available before the first write.
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package init(initialSnapshot: [String: StoredPreference] = [:]) {
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self.initialSnapshot = initialSnapshot
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values = initialSnapshot
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let (stream, continuation) = AsyncStream<PreferenceWrite>.makeStream(bufferingPolicy: .unbounded)
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self.continuation = continuation
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Task { [weak self] in
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for await write in stream {
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guard let self else { break }
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await self.apply(write)
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}
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}
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}
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deinit {
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continuation.finish()
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}
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/// Queues a value update or deletion without blocking the caller.
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package nonisolated func enqueue(_ key: String, _ value: StoredPreference?) {
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continuation.yield(.set(key: key, value: value))
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}
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/// Returns after queued writes have been applied to the in-memory values.
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///
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/// - Throws: Never; the in-memory backend has no write failure mode.
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package nonisolated func flush() async throws {
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try await withCheckedThrowingContinuation { (continuation: CheckedContinuation<Void, any Error>) in
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self.continuation.yield(
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.barrier { error in
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if let error {
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continuation.resume(throwing: error)
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} else {
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continuation.resume(returning: ())
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}
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})
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}
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}
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/// The values currently held, for assertions.
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package var storedValues: [String: StoredPreference] { values }
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private func apply(_ write: PreferenceWrite) {
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switch write {
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case .set(let key, let value):
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if let value {
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values[key] = value
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} else {
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values.removeValue(forKey: key)
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}
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case .barrier(let resume):
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resume(nil)
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}
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}
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}
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