Use buildTarget/inverseSources from BSP to get targets of a source file

Author: ahoppen

Sources/BuildServerProtocol/BuildTargets.swift

@@ -211,44 +211,3 @@ public struct OutputsItem: Codable, Hashable, Sendable {
   /// The output paths for sources that belong to this build target.
   public var outputPaths: [URI]
 }
-
-/// The build target changed notification is sent from the server to the client
-/// to signal a change in a build target. The server communicates during the
-/// initialize handshake whether this method is supported or not.
-public struct BuildTargetsChangedNotification: NotificationType {
-  public static let method: String = "buildTarget/didChange"
-
-  public var changes: [BuildTargetEvent]
-
-  public init(changes: [BuildTargetEvent]) {
-    self.changes = changes
-  }
-}
-
-public struct BuildTargetEvent: Codable, Hashable, Sendable {
-  /// The identifier for the changed build target.
-  public var target: BuildTargetIdentifier
-
-  /// The kind of change for this build target.
-  public var kind: BuildTargetEventKind?
-
-  /// Any additional metadata about what information changed.
-  public var data: LSPAny?
-
-  public init(target: BuildTargetIdentifier, kind: BuildTargetEventKind?, data: LSPAny?) {
-    self.target = target
-    self.kind = kind
-    self.data = data
-  }
-}
-
-public enum BuildTargetEventKind: Int, Codable, Hashable, Sendable {
-  /// The build target is new.
-  case created = 1
-
-  /// The build target has changed.
-  case changed = 2
-
-  /// The build target has been deleted.
-  case deleted = 3
-}

Sources/BuildServerProtocol/CMakeLists.txt

@@ -1,8 +1,10 @@
 add_library(BuildServerProtocol STATIC
   BuildTargets.swift
+  DidChangeBuildTargetNotification.swift
   DidChangeWatchedFilesNotification.swift
   FileOptions.swift
   InitializeBuild.swift
+  InverseSourcesRequest.swift
   Messages.swift
   RegisterForChangeNotifications.swift
   ShutdownBuild.swift)

Sources/BuildServerProtocol/DidChangeBuildTargetNotification.swift

@@ -0,0 +1,60 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2024 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
+//
+//===----------------------------------------------------------------------===//
+
+import LanguageServerProtocol
+
+/// The build target changed notification is sent from the server to the client
+/// to signal a change in a build target. The server communicates during the
+/// initialize handshake whether this method is supported or not.
+public struct DidChangeBuildTargetNotification: NotificationType, Equatable {
+  public static let method: String = "buildTarget/didChange"
+
+  /// **(BSP Extension)**
+  /// `changes` can be `nil` to indicate that all targets might have changed.
+  public var changes: [BuildTargetEvent]?
+
+  public init(changes: [BuildTargetEvent]?) {
+    self.changes = changes
+  }
+}
+
+public struct BuildTargetEvent: Codable, Hashable, Sendable {
+  /// The identifier for the changed build target.
+  public var target: BuildTargetIdentifier
+
+  /// The kind of change for this build target.
+  public var kind: BuildTargetEventKind?
+
+  /// Kind of data to expect in the `data` field. If this field is not set, the kind of data is not specified.
+  public var dataKind: String?
+
+  /// Any additional metadata about what information changed.
+  public var data: LSPAny?
+
+  public init(target: BuildTargetIdentifier, kind: BuildTargetEventKind?, dataKind: String?, data: LSPAny?) {
+    self.target = target
+    self.kind = kind
+    self.dataKind = dataKind
+    self.data = data
+  }
+}
+
+public enum BuildTargetEventKind: Int, Codable, Hashable, Sendable {
+  /// The build target is new.
+  case created = 1
+
+  /// The build target has changed.
+  case changed = 2
+
+  /// The build target has been deleted.
+  case deleted = 3
+}

Sources/BuildServerProtocol/InverseSourcesRequest.swift

@@ -0,0 +1,45 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2024 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
+//
+//===----------------------------------------------------------------------===//
+
+import LanguageServerProtocol
+
+public struct TextDocumentIdentifier: Codable, Sendable, Hashable {
+  /// The text document's URI.
+  public var uri: URI
+
+  public init(uri: URI) {
+    self.uri = uri
+  }
+}
+
+/// The inverse sources request is sent from the client to the server to query for the list of build targets containing
+/// a text document. The server communicates during the initialize handshake whether this method is supported or not.
+/// This request can be viewed as the inverse of buildTarget/sources, except it only works for text documents and not
+/// directories.
+public struct InverseSourcesRequest: RequestType, Hashable {
+  public static let method: String = "buildTarget/inverseSources"
+  public typealias Response = InverseSourcesResponse
+
+  public var textDocument: TextDocumentIdentifier
+
+  public init(textDocument: TextDocumentIdentifier) {
+    self.textDocument = textDocument
+  }
+}
+
+public struct InverseSourcesResponse: ResponseType, Hashable {
+  public var targets: [BuildTargetIdentifier]
+
+  public init(targets: [BuildTargetIdentifier]) {
+    self.targets = targets
+  }
+}

Sources/BuildServerProtocol/Messages.swift

@@ -12,17 +12,18 @@
 import LanguageServerProtocol
 
 fileprivate let requestTypes: [_RequestType.Type] = [
-  BuildTargets.self,
   BuildTargetOutputPaths.self,
+  BuildTargets.self,
   BuildTargetSources.self,
   InitializeBuild.self,
+  InverseSourcesRequest.self,
   RegisterForChanges.self,
   ShutdownBuild.self,
   SourceKitOptions.self,
 ]
 
 fileprivate let notificationTypes: [NotificationType.Type] = [
-  BuildTargetsChangedNotification.self,
+  DidChangeBuildTargetNotification.self,
   ExitBuildNotification.self,
   FileOptionsChangedNotification.self,
   InitializedBuildNotification.self,

Sources/BuildSystemIntegration/BuildServerBuildSystem.swift

@@ -200,7 +200,7 @@ package actor BuildServerBuildSystem: MessageHandler {
       """
     )
     bspMessageHandlingQueue.async {
-      if let params = params as? BuildTargetsChangedNotification {
+      if let params = params as? DidChangeBuildTargetNotification {
         await self.handleBuildTargetsChanged(params)
       } else if let params = params as? FileOptionsChangedNotification {
         await self.handleFileOptionsChanged(params)
@@ -225,10 +225,8 @@ package actor BuildServerBuildSystem: MessageHandler {
     reply(.failure(ResponseError.methodNotFound(R.method)))
   }
 
-  func handleBuildTargetsChanged(
-    _ notification: BuildTargetsChangedNotification
-  ) async {
-    await self.delegate?.buildTargetsChanged(notification.changes)
+  func handleBuildTargetsChanged(_ notification: DidChangeBuildTargetNotification) async {
+    await self.messageHandler?.sendNotificationToSourceKitLSP(notification)
   }
 
   func handleFileOptionsChanged(
@@ -283,8 +281,8 @@ extension BuildServerBuildSystem: BuiltInBuildSystem {
     return nil
   }
 
-  package func targets(for document: DocumentURI) async -> [BuildTargetIdentifier] {
-    return [BuildTargetIdentifier.dummy]
+  package func inverseSources(_ request: InverseSourcesRequest) -> InverseSourcesResponse {
+    return InverseSourcesResponse(targets: [BuildTargetIdentifier.dummy])
   }
 
   package func generateBuildGraph() {}

Sources/BuildSystemIntegration/BuildSystem.swift

@@ -110,8 +110,8 @@ package protocol BuiltInBuildSystem: AnyObject, Sendable {
     language: Language
   ) async throws -> FileBuildSettings?
 
-  /// Return the list of targets and run destinations that the given document can be built for.
-  func targets(for document: DocumentURI) async -> [BuildTargetIdentifier]
+  /// Return the list of targets that the given document can be built for.
+  func inverseSources(_ request: InverseSourcesRequest) async -> InverseSourcesResponse
 
   /// Re-generate the build graph.
   func generateBuildGraph() async throws

Sources/BuildSystemIntegration/BuildSystemDelegate.swift

@@ -13,13 +13,27 @@ import BuildServerProtocol
 import LanguageServerProtocol
 
 /// Handles build system events, such as file build settings changes.
+// FIXME: (BSP migration) The build system should exclusively communicate back to SourceKit-LSP using BSP and this protocol should be deleted.
 package protocol BuildSystemDelegate: AnyObject, Sendable {
-  /// Notify the delegate that the build targets have changed.
+  /// Notify the delegate that the given files' build settings have changed.
+  func fileBuildSettingsChanged(_ changedFiles: Set<DocumentURI>) async
+
+  /// Notify the delegate that the dependencies of the given files have changed
+  /// and that ASTs may need to be refreshed. If the given set is empty, assume
+  /// that all watched files are affected.
   ///
-  /// The callee should request new sources and outputs for the build targets of
-  /// interest.
-  func buildTargetsChanged(_ changes: [BuildTargetEvent]) async
+  /// The callee should refresh ASTs unless it is able to determine that a
+  /// refresh is not necessary.
+  func filesDependenciesUpdated(_ changedFiles: Set<DocumentURI>) async
+
+  /// Notify the delegate that the file handling capability of this build system
+  /// for some file has changed. The delegate should discard any cached file
+  /// handling capability.
+  func fileHandlingCapabilityChanged() async
+}
 
+/// Handles build system events, such as file build settings changes.
+package protocol BuildSystemManagerDelegate: AnyObject, Sendable {
   /// Notify the delegate that the given files' build settings have changed.
   func fileBuildSettingsChanged(_ changedFiles: Set<DocumentURI>) async
 

Sources/BuildSystemIntegration/BuildSystemManager.swift

@@ -23,6 +23,39 @@ import struct TSCBasic.AbsolutePath
 import os
 #endif
 
+fileprivate class RequestCache<Request: RequestType & Hashable> {
+  private var storage: [Request: Task<Request.Response, Error>] = [:]
+
+  func get(
+    _ key: Request,
+    isolation: isolated any Actor = #isolation,
+    compute: @Sendable @escaping (Request) async throws(Error) -> Request.Response
+  ) async throws(Error) -> Request.Response {
+    let task: Task<Request.Response, Error>
+    if let cached = storage[key] {
+      task = cached
+    } else {
+      task = Task {
+        try await compute(key)
+      }
+      storage[key] = task
+    }
+    return try await task.value
+  }
+
+  func clear(where condition: (Request) -> Bool, isolation: isolated any Actor = #isolation) {
+    for key in storage.keys {
+      if condition(key) {
+        storage[key] = nil
+      }
+    }
+  }
+
+  func clearAll(isolation: isolated any Actor = #isolation) {
+    storage.removeAll()
+  }
+}
+
 /// `BuildSystem` that integrates client-side information such as main-file lookup as well as providing
 ///  common functionality such as caching.
 ///
@@ -56,13 +89,15 @@ package actor BuildSystemManager: BuiltInBuildSystemAdapterDelegate {
   var mainFilesProvider: MainFilesProvider?
 
   /// Build system delegate that will receive notifications about setting changes, etc.
-  var delegate: BuildSystemDelegate?
+  var delegate: BuildSystemManagerDelegate?
 
   /// The list of toolchains that are available.
   ///
   /// Used to determine which toolchain to use for a given document.
   private let toolchainRegistry: ToolchainRegistry
 
+  private var cachedTargetsForDocument = RequestCache<InverseSourcesRequest>()
+
   /// The root of the project that this build system manages. For example, for SwiftPM packages, this is the folder
   /// containing Package.swift. For compilation databases it is the root folder based on which the compilation database
   /// was found.
@@ -108,7 +143,12 @@ package actor BuildSystemManager: BuiltInBuildSystemAdapterDelegate {
   ///
   /// - Important: Do not call directly.
   package func handle(_ notification: some LanguageServerProtocol.NotificationType) {
-    logger.error("Ignoring unknown notification \(type(of: notification).method) from build system")
+    switch notification {
+    case let notification as DidChangeBuildTargetNotification:
+      self.didChangeTextDocumentTargets(notification: notification)
+    default:
+      logger.error("Ignoring unknown notification \(type(of: notification).method)")
+    }
   }
 
   /// Implementation of `MessageHandler`, handling requests from the build system.
@@ -119,7 +159,7 @@ package actor BuildSystemManager: BuiltInBuildSystemAdapterDelegate {
   }
 
   /// - Note: Needed so we can set the delegate from a different isolation context.
-  package func setDelegate(_ delegate: BuildSystemDelegate?) {
+  package func setDelegate(_ delegate: BuildSystemManagerDelegate?) {
     self.delegate = delegate
   }
 
@@ -160,9 +200,23 @@ package actor BuildSystemManager: BuiltInBuildSystemAdapterDelegate {
     }
   }
 
-  /// Returns all the `BuildTargetIdentifier`s that the document is part of.
+  /// Returns all the `ConfiguredTarget`s that the document is part of.
   package func targets(for document: DocumentURI) async -> [BuildTargetIdentifier] {
-    return await buildSystem?.underlyingBuildSystem.targets(for: document) ?? []
+    guard let buildSystem else {
+      return []
+    }
+
+    // FIXME: (BSP migration) Only use `InverseSourcesRequest` if the BSP server declared it can handle it in the
+    // capabilities
+    let request = InverseSourcesRequest(textDocument: TextDocumentIdentifier(uri: document))
+    do {
+      let response = try await cachedTargetsForDocument.get(request) { document in
+        return try await buildSystem.send(request)
+      }
+      return response.targets
+    } catch {
+      return []
+    }
   }
 
   /// Returns the `BuildTargetIdentifier` that should be used for semantic functionality of the given document.
@@ -390,17 +444,17 @@ extension BuildSystemManager: BuildSystemDelegate {
     }
   }
 
-  package func buildTargetsChanged(_ changes: [BuildTargetEvent]) async {
-    if let delegate = self.delegate {
-      await delegate.buildTargetsChanged(changes)
-    }
-  }
-
   package func fileHandlingCapabilityChanged() async {
     if let delegate = self.delegate {
       await delegate.fileHandlingCapabilityChanged()
     }
   }
+
+  private func didChangeTextDocumentTargets(notification: DidChangeBuildTargetNotification) {
+    // Every `DidChangeBuildTargetNotification` notification needs to invalidate the cache since the changed target
+    // might gained a source file.
+    self.cachedTargetsForDocument.clearAll()
+  }
 }
 
 extension BuildSystemManager {