Merge pull request #1354 from ahoppen/timeout-indexstore-update

Time out updating the index store after 2 minutes

Author: ahoppen

Sources/SKSupport/AsyncUtils.swift

@@ -166,3 +166,28 @@ extension Collection where Element: Sendable {
     }
   }
 }
+
+public struct TimeoutError: Error, CustomStringConvertible {
+  public var description: String { "Timed out" }
+}
+
+/// Executes `body`. If it doesn't finish after `duration`, throws a `TimeoutError`.
+public func withTimeout<T: Sendable>(
+  _ duration: Duration,
+  _ body: @escaping @Sendable () async throws -> T
+) async throws -> T {
+  try await withThrowingTaskGroup(of: T.self) { taskGroup in
+    taskGroup.addTask {
+      try await Task.sleep(for: duration)
+      throw TimeoutError()
+    }
+    taskGroup.addTask {
+      return try await body()
+    }
+    for try await value in taskGroup {
+      taskGroup.cancelAll()
+      return value
+    }
+    throw CancellationError()
+  }
+}

Sources/SemanticIndex/UpdateIndexStoreTaskDescription.swift

@@ -341,7 +341,13 @@ public struct UpdateIndexStoreTaskDescription: IndexTaskDescription {
       arguments: processArguments,
       workingDirectory: workingDirectory
     )
-    let result = try await process.waitUntilExitSendingSigIntOnTaskCancellation()
+    // Time out updating of the index store after 2 minutes. We don't expect any single file compilation to take longer
+    // than 2 minutes in practice, so this indicates that the compiler has entered a loop and we probably won't make any
+    // progress here. We will try indexing the file again when it is edited or when the project is re-opened.
+    // 2 minutes have been chosen arbitrarily.
+    let result = try await withTimeout(.seconds(120)) {
+      try await process.waitUntilExitSendingSigIntOnTaskCancellation()
+    }
 
     indexProcessDidProduceResult(
       IndexProcessResult(

Tests/SKSupportTests/AsyncUtilsTests.swift

@@ -0,0 +1,31 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2018 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 LSPTestSupport
+import SKSupport
+import XCTest
+
+final class AsyncUtilsTests: XCTestCase {
+  func testWithTimeout() async throws {
+    let expectation = self.expectation(description: "withTimeout body finished")
+    await assertThrowsError(
+      try await withTimeout(.seconds(0.1)) {
+        try? await Task.sleep(for: .seconds(10))
+        XCTAssert(Task.isCancelled)
+        expectation.fulfill()
+      }
+    ) { error in
+      XCTAssert(error is TimeoutError, "Received unexpected error \(error)")
+    }
+    try await fulfillmentOfOrThrow([expectation])
+  }
+}