Attempt to fix ThreadIterator_AddFindRemove flake

runtime/vm/thread_test.cc

 // Copyright (c) 2012, 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.
 
 #include "platform/assert.h"
 #include "vm/isolate.h"
 #include "vm/lockers.h"
 #include "vm/unit_test.h"
 #include "vm/profiler.h"
 #include "vm/thread_pool.h"
@@ skipping 417 matching lines @@
       thread_count_1++;
     }
   }
 
   EXPECT(thread_count_0 > 0);
   EXPECT(thread_count_1 > 0);
   EXPECT(thread_count_0 >= thread_count_1);
 }
 
 
+static bool ThreadInList(Thread* thread) {
+  ThreadIterator it;
+  while (it.HasNext()) {
+    Thread* t = it.Next();
+    if (t == thread) {
+      return true;
+    }
+  }
+  return false;
+}
+
+
 TEST_CASE(ThreadIterator_FindSelf) {
   Thread* current = Thread::Current();
-
-  bool found_self = false;
-
-  {
-    ThreadIterator ti;
-    while (ti.HasNext()) {
-      Thread* thread = ti.Next();
-      EXPECT(thread != NULL);
-      if (thread == current) {
-        found_self = true;
-        break;
-      }
-    }
-  }
-
-  EXPECT(found_self);
+  EXPECT(ThreadInList(current));
 }
 
 
 struct ThreadIteratorTestParams {
   Isolate* isolate;
   Thread* spawned_thread;
   ThreadJoinId spawned_thread_join_id;
   Monitor* monitor;
 };
 
 
 void ThreadIteratorTestMain(uword parameter) {
   Thread::EnsureInit();
   ThreadIteratorTestParams* params =
       reinterpret_cast<ThreadIteratorTestParams*>(parameter);
   Isolate* isolate = params->isolate;
-  ASSERT(isolate != NULL);
+  EXPECT(isolate != NULL);
+  Thread* thread = Thread::Current();
+  EXPECT(thread != NULL);
 
-  Thread::EnterIsolateAsHelper(isolate);
-  Thread* thread = Thread::Current();
-  ASSERT(thread != NULL);
-
+  MonitorLocker ml(params->monitor);
   params->spawned_thread = thread;
   params->spawned_thread_join_id = OSThread::GetCurrentThreadJoinId();
-
-  {
-    MonitorLocker ml(params->monitor);
-    ml.Notify();
-  }
-
-  {
-    bool found_self = false;
-    ThreadIterator it;
-    while (it.HasNext()) {
-      Thread* t = it.Next();
-      if (t == thread) {
-        found_self = true;
-        break;
-      }
-    }
-    EXPECT(found_self);
-  }
-
-  Thread::ExitIsolateAsHelper();
+  EXPECT(params->spawned_thread_join_id != OSThread::kInvalidThreadJoinId);
+  EXPECT(ThreadInList(thread));
+  ml.Notify();
 }
 
 
 TEST_CASE(ThreadIterator_AddFindRemove) {
   Isolate* isolate = thread->isolate();
   ThreadIteratorTestParams params;
   params.isolate = isolate;
   params.spawned_thread = NULL;
   params.spawned_thread_join_id = OSThread::kInvalidThreadJoinId;
   params.monitor = new Monitor();
 
   {
     MonitorLocker ml(params.monitor);
     EXPECT(params.spawned_thread_join_id == OSThread::kInvalidThreadJoinId);
     EXPECT(params.spawned_thread == NULL);
     // Spawn thread and wait to receive the thread join id.
     OSThread::Start(ThreadIteratorTestMain, reinterpret_cast<uword>(&params));
     while (params.spawned_thread_join_id == OSThread::kInvalidThreadJoinId) {
       ml.Wait();
     }
     EXPECT(params.spawned_thread_join_id != OSThread::kInvalidThreadJoinId);
     EXPECT(params.spawned_thread != NULL);
     // Join thread.
     OSThread::Join(params.spawned_thread_join_id);
   }
 
-  ThreadIterator it;
-  bool found_spawned_thread = false;
-  while (it.HasNext()) {
-    Thread* t = it.Next();
-    if (t == params.spawned_thread) {
-      found_spawned_thread = true;
+  for (intptr_t i = 0; i < 10; i++) {
+    // Sleep for 10 milliseconds.
+    OS::Sleep(10);
+    if (!ThreadInList(params.spawned_thread)) {
       break;
     }
   }
 
-  EXPECT(!found_spawned_thread);
+  EXPECT(!ThreadInList(params.spawned_thread))
+
+  delete params.monitor;
 }
 
 
 // Test rendezvous of:
 // - helpers in VM code, and
 // - main thread in VM code,
 // organized by
 // - main thread, and
 // - helpers.
 TEST_CASE(SafepointTestVM2) {
@@ skipping 83 matching lines @@
       isolate->thread_registry()->CheckSafepoint();
       MonitorLocker ml(&done_monitor);
       if (done) {
         break;
       }
     }
   }
 }
 
 }  // namespace dart