wehub-resource-sync
680845cb1c
Linux build / Determine Swift version (push) Waiting to run
Linux build / Linux compile check (push) Blocked by required conditions
Build containerization / Verify commit signatures (push) Has been skipped
Build containerization / containerization (push) Successful in 0s
62 lines
2.2 KiB
Swift
62 lines
2.2 KiB
Swift
//===----------------------------------------------------------------------===//
|
|
// Copyright © 2025-2026 Apple Inc. and the Containerization project authors.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// https://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
import Logging
|
|
|
|
/// `AsyncLock` provides a familiar locking API, with the main benefit being that it
|
|
/// is safe to call async methods while holding the lock. This is primarily used in spots
|
|
/// where an actor makes sense, but we may need to ensure we don't fall victim to actor
|
|
/// reentrancy issues.
|
|
public actor AsyncLock {
|
|
private var busy = false
|
|
private var queue: ArraySlice<CheckedContinuation<(), Never>> = []
|
|
private var log: Logger?
|
|
|
|
public struct Context: Sendable {
|
|
fileprivate init() {}
|
|
}
|
|
|
|
public init(log: Logger? = nil) {
|
|
self.log = log
|
|
}
|
|
|
|
/// withLock provides a scoped locking API to run a function while holding the lock.
|
|
public func withLock<T: Sendable>(logMetadata: Logger.Metadata? = nil, _ body: @Sendable @escaping (Context) async throws -> T) async rethrows -> T {
|
|
log?.debug("acquiring lock", metadata: logMetadata)
|
|
while self.busy {
|
|
await withCheckedContinuation { cc in
|
|
self.queue.append(cc)
|
|
}
|
|
}
|
|
|
|
self.busy = true
|
|
|
|
defer {
|
|
self.busy = false
|
|
if let next = self.queue.popFirst() {
|
|
next.resume(returning: ())
|
|
} else {
|
|
self.queue = []
|
|
}
|
|
}
|
|
|
|
log?.debug("holding lock", metadata: logMetadata)
|
|
defer { log?.debug("releasing lock", metadata: logMetadata) }
|
|
let context = Context()
|
|
return try await body(context)
|
|
}
|
|
}
|