Fix crash caused by multithreading

Author: woin2ee

Sources/TaskStore/TaskStore.swift

@@ -46,6 +46,7 @@ public class TaskStore<Key: Hashable> {
     /// - Parameter predicate: <#predicate description#>
     /// - Returns: <#description#>
     public func tasks(where predicate: (Key) -> Bool) -> [CancellableTask] {
+        lock.lock(); defer { lock.unlock() }
         return taskMap
             .filter { key, _ in predicate(key) }
             .map(\.value)

Tests/TaskStoreTests/TaskStoreTests.swift

@@ -3,6 +3,29 @@ import XCTest
 
 final class TaskStoreTests: XCTestCase {
 
+    func test_concurrentAccess() {
+        let taskStore = TaskStore<String>()
+        let task = Task {
+            sleep(1)
+            throw TestError.test
+        }
+        taskStore.setTask(task, forKey: "TestKey")
+        
+        (1...100).forEach { _ in
+            DispatchQueue.global().async {
+                taskStore.setTask(task, forKey: "TestKey")
+                _ = taskStore.task(forKey: "TestKey")
+            }
+        }
+        
+        (1...100).forEach { _ in
+            DispatchQueue.global().async {
+                taskStore.setTask(task, forKey: "TestKey")
+                _ = taskStore.tasks(where: { $0 == "TestKey" })
+            }
+        }
+    }
+    
     func test_subscript() {
         let taskStore = TaskStore<Int>()
         taskStore.setTask(
@@ -14,7 +37,7 @@ final class TaskStoreTests: XCTestCase {
         XCTAssertNotNil(taskStore[0])
     }
 
-    func test_searchTasks() {
+    func test_searchTasksWithPredicate() {
         struct CustomKey: Hashable {
             let number: Int
         }

Tests/TaskStoreTests/TestError.swift

@@ -0,0 +1,5 @@
+import Foundation
+
+enum TestError: Error {
+    case test
+}