Detect and recover from infinite task loops

pkg/analyzer/test/src/task/driver_test.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library test.src.task.driver_test;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/src/cancelable_future.dart';
@@ skipping 242 matching lines @@
     expect(context.getCacheEntry(target).getValue(resultA), 10);
     expect(context.getCacheEntry(target).getValue(resultB), -2);
     // compute resultB
     expect(driver.performAnalysisTask(), true);
     expect(context.getCacheEntry(target).getValue(resultA), 10);
     expect(context.getCacheEntry(target).getValue(resultB), 20);
     // done
     expect(driver.performAnalysisTask(), false);
   }
 
+  test_performAnalysisTask_infiniteLoop() {
+    AnalysisTarget target = new TestSource();
+    ResultDescriptor resultA = new ResultDescriptor('resultA', -1);
+    ResultDescriptor resultB = new ResultDescriptor('resultB', -2);
+    // configure tasks
+    TestAnalysisTask task1;
+    TestAnalysisTask task2;
+    TaskDescriptor descriptor1 = new TaskDescriptor(
+        'task1', (context, target) => task1, (target) => {
+      'inputB': new SimpleTaskInput<int>(target, resultB)
+    }, [resultA]);
+    TaskDescriptor descriptor2 = new TaskDescriptor('task2',
+        (context, target) => task2, (target) => {
+      'inputA': new SimpleTaskInput<int>(target, resultA)
+    }, [resultB]);
+    task1 = new TestAnalysisTask(context, target, descriptor: descriptor1);
+    task2 = new TestAnalysisTask(context, target, descriptor: descriptor2);
+    manager.addTaskDescriptor(descriptor1);
+    manager.addTaskDescriptor(descriptor2);
+    context.explicitTargets.add(target);
+    manager.addGeneralResult(resultB);
+    // prepare work order
+    expect(driver.performAnalysisTask(), true);
+    expect(driver.performAnalysisTask(), true);
+    CaughtException exception = context.getCacheEntry(target).exception;
+    expect(exception, isNotNull);
+    expect(exception.exception, new isInstanceOf<InfiniteTaskLoopException>());
+  }
+
   test_performWorkItem_exceptionInTask() {
     AnalysisTarget target = new TestSource();
     ResultDescriptor result = new ResultDescriptor('result', null);
     CaughtException exception =
         new CaughtException(new AnalysisException(), null);
     TestAnalysisTask task;
     TaskDescriptor descriptor = new TaskDescriptor(
         'task', (context, target) => task, (target) => {}, [result]);
     task = new TestAnalysisTask(context, target,
         descriptor: descriptor, exception: exception);
@@ skipping 559 matching lines @@
   void setContents(Source source, String contents) {
     baseContext.setContents(source, contents);
   }
 
   @override
   void visitCacheItems(void callback(Source source, SourceEntry dartEntry,
       DataDescriptor rowDesc, CacheState state)) {
     baseContext.visitCacheItems(callback);
   }
 }