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sourcekit-lsp/Sources/LanguageServerProtocol/Requests/BarrierRequest.swift
Alex Hoppen 996df8c597 Introduce a BarrierRequest that ensures all messages are handled before it replies
We could get into a race condition in `testAddFile` where the `DidChangeWatchedFilesNotification` would get handled after we try getting completion results that rely on it.

In a real-world use case, this is OK. Completion might still be incorrect until `DidChangeWatchedFilesNotification` gets handled but it will catch up eventually  - usually earlier than later because in real-world scenarios the `DidChangeWatchedFilesNotification` and completion request are more than a few milliseconds apart.

In test, however, we need to guarantee deterministic ordering. Introduce a `BarrierRequest` that has `TaskMetadata.globalConfigurationChange` and thus ensures that all notifications and requests before it have finished before returning. We can run this fake request after sending the `DidChangeWatchedFilesNotification` to make sure that it is handled.

An alternative would be to mark `DidChangeWatchedFilesNotification` as `TaskMetadata.globalConfigurationChange`. But I would really like to avoid introducing a global ordering barrier between requests for a notification that is, for example, sent whenever a `.swift` file in the `.build` directory changes (e.g. on every package update).
2023-10-26 18:23:41 -07:00

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Swift

//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
/// A no-op request that ensures all previous notifications and requests have been handled before any message
/// after the barrier request is handled.
public struct BarrierRequest: RequestType {
public static var method: String = "workspace/_barrier"
public typealias Response = VoidResponse
public init() {}
}