Add a maximum duration for sourcekitd requests

Sources/Diagnose/RunSourcekitdRequestCommand.swift

@@ -96,6 +96,9 @@ public struct RunSourceKitdRequestCommand: AsyncParsableCommand {
     case .requestCancelled:
       print("request cancelled")
       throw ExitCode(1)
+    case .timedOut:
+      print("request timed out")
+      throw ExitCode(1)
     case .missingRequiredSymbol:
       print("missing required symbol")
       throw ExitCode(1)

Sources/LanguageServerProtocol/Error.swift

@@ -81,7 +81,7 @@ public struct ErrorCode: RawRepresentable, Codable, Hashable, Sendable {
   /// It doesn't denote a real error code.
   public static let lspReservedErrorRangeEnd = ErrorCode(rawValue: -32800)
 
-  // MARK: SourceKit-LSP specifiic eror codes
+  // MARK: SourceKit-LSP specific error codes
   public static let workspaceNotOpen: ErrorCode = ErrorCode(rawValue: -32003)
 }
 

Sources/SKCore/SourceKitLSPOptions.swift

@@ -191,6 +191,10 @@ public struct SourceKitLSPOptions: Sendable, Codable {
   /// Whether background indexing is enabled.
   public var backgroundIndexing: Bool?
 
+  public var backgroundIndexingOrDefault: Bool {
+    return backgroundIndexing ?? false
+  }
+
   /// Experimental features that are enabled.
   public var experimentalFeatures: Set<ExperimentalFeature>? = nil
 
@@ -220,8 +224,21 @@ public struct SourceKitLSPOptions: Sendable, Codable {
     return .seconds(1)
   }
 
-  public var backgroundIndexingOrDefault: Bool {
-    return backgroundIndexing ?? false
+  /// The maximum duration that a sourcekitd request should be allowed to execute before being declared as timed out.
+  ///
+  /// In general, editors should cancel requests that they are no longer interested in, but in case editors don't cancel
+  /// requests, this ensures that a long-running non-cancelled request is not blocking sourcekitd and thus most semantic
+  /// functionality.
+  ///
+  /// In particular, VS Code does not cancel the semantic tokens request, which can cause a long-running AST build that
+  /// blocks sourcekitd.
+  public var sourcekitdRequestTimeout: Double? = nil
+
+  public var sourcekitdRequestTimeoutOrDefault: Duration {
+    if let sourcekitdRequestTimeout {
+      return .seconds(sourcekitdRequestTimeout)
+    }
+    return .seconds(120)
   }
 
   public init(
@@ -235,7 +252,8 @@ public struct SourceKitLSPOptions: Sendable, Codable {
     backgroundIndexing: Bool? = nil,
     experimentalFeatures: Set<ExperimentalFeature>? = nil,
     swiftPublishDiagnosticsDebounceDuration: Double? = nil,
-    workDoneProgressDebounceDuration: Double? = nil
+    workDoneProgressDebounceDuration: Double? = nil,
+    sourcekitdRequestTimeout: Double? = nil
   ) {
     self.swiftPM = swiftPM
     self.fallbackBuildSystem = fallbackBuildSystem
@@ -248,6 +266,7 @@ public struct SourceKitLSPOptions: Sendable, Codable {
     self.experimentalFeatures = experimentalFeatures
     self.swiftPublishDiagnosticsDebounceDuration = swiftPublishDiagnosticsDebounceDuration
     self.workDoneProgressDebounceDuration = workDoneProgressDebounceDuration
+    self.sourcekitdRequestTimeout = sourcekitdRequestTimeout
   }
 
   public init?(fromLSPAny lspAny: LSPAny?) throws {
@@ -300,7 +319,8 @@ public struct SourceKitLSPOptions: Sendable, Codable {
       swiftPublishDiagnosticsDebounceDuration: override?.swiftPublishDiagnosticsDebounceDuration
         ?? base.swiftPublishDiagnosticsDebounceDuration,
       workDoneProgressDebounceDuration: override?.workDoneProgressDebounceDuration
-        ?? base.workDoneProgressDebounceDuration
+        ?? base.workDoneProgressDebounceDuration,
+      sourcekitdRequestTimeout: override?.sourcekitdRequestTimeout ?? base.sourcekitdRequestTimeout
     )
   }
 

Sources/SourceKitD/SourceKitD.swift

@@ -83,31 +83,41 @@ public enum SKDError: Error, Equatable {
   /// The request was cancelled.
   case requestCancelled
 
+  /// The request exceeded the maximum allowed duration.
+  case timedOut
+
   /// Loading a required symbol from the sourcekitd library failed.
   case missingRequiredSymbol(String)
 }
 
 extension SourceKitD {
-
   // MARK: - Convenience API for requests.
 
   /// - Parameters:
-  ///   - req: The request to send to sourcekitd.
+  ///   - request: The request to send to sourcekitd.
+  ///   - timeout: The maximum duration how long to wait for a response. If no response is returned within this time,
+  ///     declare the request as having timed out.
   ///   - fileContents: The contents of the file that the request operates on. If sourcekitd crashes, the file contents
   ///     will be logged.
-  public func send(_ request: SKDRequestDictionary, fileContents: String?) async throws -> SKDResponseDictionary {
+  public func send(
+    _ request: SKDRequestDictionary,
+    timeout: Duration,
+    fileContents: String?
+  ) async throws -> SKDResponseDictionary {
     log(request: request)
 
-    let sourcekitdResponse: SKDResponse = try await withCancellableCheckedThrowingContinuation { continuation in
-      var handle: sourcekitd_api_request_handle_t? = nil
-      api.send_request(request.dict, &handle) { response in
-        continuation.resume(returning: SKDResponse(response!, sourcekitd: self))
-      }
-      return handle
-    } cancel: { handle in
-      if let handle {
-        logRequestCancellation(request: request)
-        api.cancel_request(handle)
+    let sourcekitdResponse = try await withTimeout(timeout) {
+      return try await withCancellableCheckedThrowingContinuation { continuation in
+        var handle: sourcekitd_api_request_handle_t? = nil
+        self.api.send_request(request.dict, &handle) { response in
+          continuation.resume(returning: SKDResponse(response!, sourcekitd: self))
+        }
+        return handle
+      } cancel: { handle in
+        if let handle {
+          self.logRequestCancellation(request: request)
+          self.api.cancel_request(handle)
+        }
       }
     }
 
@@ -117,6 +127,9 @@ extension SourceKitD {
       if sourcekitdResponse.error == .connectionInterrupted {
         log(crashedRequest: request, fileContents: fileContents)
       }
+      if sourcekitdResponse.error == .requestCancelled && !Task.isCancelled {
+        throw SKDError.timedOut
+      }
       throw sourcekitdResponse.error!
     }
 

Sources/SourceKitLSP/Rename.swift

@@ -359,7 +359,7 @@ extension SwiftLanguageService {
       keys.argNames: sourcekitd.array(name.parameters.map { $0.stringOrWildcard }),
     ])
 
-    let response = try await sourcekitd.send(req, fileContents: snapshot.text)
+    let response = try await sendSourcekitdRequest(req, fileContents: snapshot.text)
 
     guard let isZeroArgSelector: Int = response[keys.isZeroArgSelector],
       let selectorPieces: SKDResponseArray = response[keys.selectorPieces]
@@ -416,7 +416,7 @@ extension SwiftLanguageService {
       req.set(keys.baseName, to: name)
     }
 
-    let response = try await sourcekitd.send(req, fileContents: snapshot.text)
+    let response = try await sendSourcekitdRequest(req, fileContents: snapshot.text)
 
     guard let baseName: String = response[keys.baseName] else {
       throw NameTranslationError.malformedClangToSwiftTranslateNameResponse(response)
@@ -914,7 +914,7 @@ extension SwiftLanguageService {
       keys.renameLocations: locations,
     ])
 
-    let syntacticRenameRangesResponse = try await sourcekitd.send(skreq, fileContents: snapshot.text)
+    let syntacticRenameRangesResponse = try await sendSourcekitdRequest(skreq, fileContents: snapshot.text)
     guard let categorizedRanges: SKDResponseArray = syntacticRenameRangesResponse[keys.categorizedRanges] else {
       throw ResponseError.internalError("sourcekitd did not return categorized ranges")
     }

Sources/SourceKitLSP/Swift/CodeCompletion.swift

@@ -33,6 +33,7 @@ extension SwiftLanguageService {
     return try await CodeCompletionSession.completionList(
       sourcekitd: sourcekitd,
       snapshot: snapshot,
+      options: options,
       indentationWidth: inferredIndentationWidth,
       completionPosition: completionPos,
       completionUtf8Offset: offset,

Sources/SourceKitLSP/Swift/CodeCompletionSession.swift

@@ -13,6 +13,7 @@
 import Dispatch
 import LSPLogging
 import LanguageServerProtocol
+import SKCore
 import SKSupport
 import SourceKitD
 import SwiftExtensions
@@ -92,6 +93,7 @@ class CodeCompletionSession {
   static func completionList(
     sourcekitd: any SourceKitD,
     snapshot: DocumentSnapshot,
+    options: SourceKitLSPOptions,
     indentationWidth: Trivia?,
     completionPosition: Position,
     completionUtf8Offset: Int,
@@ -122,6 +124,7 @@ class CodeCompletionSession {
       let session = CodeCompletionSession(
         sourcekitd: sourcekitd,
         snapshot: snapshot,
+        options: options,
         indentationWidth: indentationWidth,
         utf8Offset: completionUtf8Offset,
         position: completionPosition,
@@ -139,6 +142,7 @@ class CodeCompletionSession {
 
   private let sourcekitd: any SourceKitD
   private let snapshot: DocumentSnapshot
+  private let options: SourceKitLSPOptions
   /// The inferred indentation width of the source file the completion is being performed in
   private let indentationWidth: Trivia?
   private let utf8StartOffset: Int
@@ -158,13 +162,15 @@ class CodeCompletionSession {
   private init(
     sourcekitd: any SourceKitD,
     snapshot: DocumentSnapshot,
+    options: SourceKitLSPOptions,
     indentationWidth: Trivia?,
     utf8Offset: Int,
     position: Position,
     compileCommand: SwiftCompileCommand?,
     clientSupportsSnippets: Bool
   ) {
     self.sourcekitd = sourcekitd
+    self.options = options
     self.indentationWidth = indentationWidth
     self.snapshot = snapshot
     self.utf8StartOffset = utf8Offset
@@ -193,7 +199,11 @@ class CodeCompletionSession {
       keys.compilerArgs: compileCommand?.compilerArgs as [SKDRequestValue]?,
     ])
 
-    let dict = try await sourcekitd.send(req, fileContents: snapshot.text)
+    let dict = try await sourcekitd.send(
+      req,
+      timeout: options.sourcekitdRequestTimeoutOrDefault,
+      fileContents: snapshot.text
+    )
     self.state = .open
 
     guard let completions: SKDResponseArray = dict[keys.results] else {
@@ -226,7 +236,11 @@ class CodeCompletionSession {
       keys.codeCompleteOptions: optionsDictionary(filterText: filterText),
     ])
 
-    let dict = try await sourcekitd.send(req, fileContents: snapshot.text)
+    let dict = try await sourcekitd.send(
+      req,
+      timeout: options.sourcekitdRequestTimeoutOrDefault,
+      fileContents: snapshot.text
+    )
     guard let completions: SKDResponseArray = dict[keys.results] else {
       return CompletionList(isIncomplete: false, items: [])
     }
@@ -269,7 +283,7 @@ class CodeCompletionSession {
         keys.name: snapshot.uri.pseudoPath,
       ])
       logger.info("Closing code completion session: \(self.description)")
-      _ = try? await sourcekitd.send(req, fileContents: nil)
+      _ = try? await sourcekitd.send(req, timeout: options.sourcekitdRequestTimeoutOrDefault, fileContents: nil)
       self.state = .closed
     }
   }

Sources/SourceKitLSP/Swift/CursorInfo.swift

@@ -159,7 +159,7 @@ extension SwiftLanguageService {
 
     appendAdditionalParameters?(skreq)
 
-    let dict = try await self.sourcekitd.send(skreq, fileContents: snapshot.text)
+    let dict = try await sendSourcekitdRequest(skreq, fileContents: snapshot.text)
 
     var cursorInfoResults: [CursorInfo] = []
     if let cursorInfo = CursorInfo(dict, sourcekitd: sourcekitd) {

Sources/SourceKitLSP/Swift/DiagnosticReportManager.swift

@@ -12,6 +12,7 @@
 
 import LSPLogging
 import LanguageServerProtocol
+import SKCore
 import SKSupport
 import SourceKitD
 import SwiftExtensions
@@ -22,6 +23,7 @@ actor DiagnosticReportManager {
   private typealias ReportTask = RefCountedCancellableTask<RelatedFullDocumentDiagnosticReport>
 
   private let sourcekitd: SourceKitD
+  private let options: SourceKitLSPOptions
   private let syntaxTreeManager: SyntaxTreeManager
   private let documentManager: DocumentManager
   private let clientHasDiagnosticsCodeDescriptionSupport: Bool
@@ -48,11 +50,13 @@ actor DiagnosticReportManager {
 
   init(
     sourcekitd: SourceKitD,
+    options: SourceKitLSPOptions,
     syntaxTreeManager: SyntaxTreeManager,
     documentManager: DocumentManager,
     clientHasDiagnosticsCodeDescriptionSupport: Bool
   ) {
     self.sourcekitd = sourcekitd
+    self.options = options
     self.syntaxTreeManager = syntaxTreeManager
     self.documentManager = documentManager
     self.clientHasDiagnosticsCodeDescriptionSupport = clientHasDiagnosticsCodeDescriptionSupport
@@ -104,7 +108,11 @@ actor DiagnosticReportManager {
       keys.compilerArgs: compilerArgs as [SKDRequestValue],
     ])
 
-    let dict = try await self.sourcekitd.send(skreq, fileContents: snapshot.text)
+    let dict = try await self.sourcekitd.send(
+      skreq,
+      timeout: options.sourcekitdRequestTimeoutOrDefault,
+      fileContents: snapshot.text
+    )
 
     try Task.checkCancellation()
 

Sources/SourceKitLSP/Swift/OpenInterface.swift

@@ -52,7 +52,7 @@ extension SwiftLanguageService {
         symbol: symbol
       )
       _ = await orLog("Closing generated interface") {
-        try await self.sourcekitd.send(closeDocumentSourcekitdRequest(uri: interfaceDocURI), fileContents: nil)
+        try await sendSourcekitdRequest(closeDocumentSourcekitdRequest(uri: interfaceDocURI), fileContents: nil)
       }
       return result
     }
@@ -80,7 +80,7 @@ extension SwiftLanguageService {
       keys.compilerArgs: await self.buildSettings(for: request.textDocument.uri)?.compilerArgs as [SKDRequestValue]?,
     ])
 
-    let dict = try await self.sourcekitd.send(skreq, fileContents: nil)
+    let dict = try await sendSourcekitdRequest(skreq, fileContents: nil)
     return GeneratedInterfaceInfo(contents: dict[keys.sourceText] ?? "")
   }
 
@@ -101,7 +101,7 @@ extension SwiftLanguageService {
         keys.usr: symbol,
       ])
 
-      let dict = try await self.sourcekitd.send(skreq, fileContents: snapshot.text)
+      let dict = try await sendSourcekitdRequest(skreq, fileContents: snapshot.text)
       if let offset: Int = dict[keys.offset] {
         return GeneratedInterfaceDetails(uri: uri, position: snapshot.positionOf(utf8Offset: offset))
       } else {

Sources/SourceKitLSP/Swift/Refactoring.swift

@@ -120,7 +120,7 @@ extension SwiftLanguageService {
       keys.compilerArgs: await self.buildSettings(for: snapshot.uri)?.compilerArgs as [SKDRequestValue]?,
     ])
 
-    let dict = try await self.sourcekitd.send(skreq, fileContents: snapshot.text)
+    let dict = try await sendSourcekitdRequest(skreq, fileContents: snapshot.text)
     guard let refactor = T.Response(refactorCommand.title, dict, snapshot, self.keys) else {
       throw SemanticRefactoringError.noEditsNeeded(uri)
     }

Sources/SourceKitLSP/Swift/RelatedIdentifiers.swift

@@ -74,7 +74,7 @@ extension SwiftLanguageService {
       keys.compilerArgs: await self.buildSettings(for: snapshot.uri)?.compilerArgs as [SKDRequestValue]?,
     ])
 
-    let dict = try await self.sourcekitd.send(skreq, fileContents: snapshot.text)
+    let dict = try await sendSourcekitdRequest(skreq, fileContents: snapshot.text)
 
     guard let results: SKDResponseArray = dict[self.keys.results] else {
       throw ResponseError.internalError("sourcekitd response did not contain results")

Sources/SourceKitLSP/Swift/SemanticTokens.swift

@@ -30,7 +30,7 @@ extension SwiftLanguageService {
       keys.compilerArgs: buildSettings.compilerArgs as [SKDRequestValue],
     ])
 
-    let dict = try await sourcekitd.send(skreq, fileContents: snapshot.text)
+    let dict = try await sendSourcekitdRequest(skreq, fileContents: snapshot.text)
 
     guard let skTokens: SKDResponseArray = dict[keys.semanticTokens] else {
       return nil

Sources/SourceKitLSP/Swift/SourceKitD+ResponseError.swift

@@ -18,6 +18,8 @@ extension ResponseError {
     switch value {
     case .requestCancelled:
       self = .cancelled
+    case .timedOut:
+      self = .unknown("sourcekitd request timed out")
     case .requestFailed(let desc):
       self = .unknown("sourcekitd request failed: \(desc)")
     case .requestInvalid(let desc):