Fix thread pool tests

runtime/vm/thread_pool_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 "vm/os.h"
 #include "vm/lockers.h"
 #include "vm/thread_pool.h"
 #include "vm/unit_test.h"
 
 namespace dart {
 
 DECLARE_FLAG(int, worker_timeout_millis);
 
 
 UNIT_TEST_CASE(ThreadPool_Create) {
   ThreadPool thread_pool;
 }
 
 
 class TestTask : public ThreadPool::Task {
  public:
   TestTask(Monitor* sync, bool* done)
       : sync_(sync), done_(done) {
   }
 
+  // Before running the task, *done_ should be true. This lets the caller
+  // ASSERT things knowing that the thread is still around. To unblock the
+  // thread, the caller should take the lock, set *done_ to false, and Notify()
+  // the monitor.
   virtual void Run() {
+    {
+      MonitorLocker ml(sync_);
+      while (*done_) {
+        ml.Wait();
+      }
+    }
     MonitorLocker ml(sync_);
     *done_ = true;
     ml.Notify();
   }
 
  private:
   Monitor* sync_;
   bool* done_;
 };
 
 
 UNIT_TEST_CASE(ThreadPool_RunOne) {
   ThreadPool thread_pool;
   Monitor sync;
-  bool done = false;
+  bool done = true;
   thread_pool.Run(new TestTask(&sync, &done));
   {
     MonitorLocker ml(&sync);
+    done = false;
+    ml.Notify();
     while (!done) {
       ml.Wait();
     }
   }
   EXPECT(done);
 
   // Do a sanity test on the worker stats.
   EXPECT_EQ(1U, thread_pool.workers_started());
   EXPECT_EQ(0U, thread_pool.workers_stopped());
 }
 
 
 UNIT_TEST_CASE(ThreadPool_RunMany) {
   const int kTaskCount = 100;
   ThreadPool thread_pool;
   Monitor sync[kTaskCount];
   bool done[kTaskCount];
 
   for (int i = 0; i < kTaskCount; i++) {
-    done[i] = false;
+    done[i] = true;
     thread_pool.Run(new TestTask(&sync[i], &done[i]));
   }
   for (int i = 0; i < kTaskCount; i++) {
     MonitorLocker ml(&sync[i]);
+    done[i] = false;
+    ml.Notify();
     while (!done[i]) {
       ml.Wait();
     }
     EXPECT(done[i]);
   }
 }
 
 
 class SleepTask : public ThreadPool::Task {
  public:
@@ skipping 71 matching lines @@
   // Adjust the worker timeout so that we timeout quickly.
   int saved_timeout = FLAG_worker_timeout_millis;
   FLAG_worker_timeout_millis = 1;
 
   ThreadPool thread_pool;
   EXPECT_EQ(0U, thread_pool.workers_started());
   EXPECT_EQ(0U, thread_pool.workers_stopped());
 
   // Run a worker.
   Monitor sync;
-  bool done = false;
+  bool done = true;
   thread_pool.Run(new TestTask(&sync, &done));
   EXPECT_EQ(1U, thread_pool.workers_started());
   EXPECT_EQ(0U, thread_pool.workers_stopped());
   {
     MonitorLocker ml(&sync);
+    done = false;
+    ml.Notify();
     while (!done) {
       ml.Wait();
     }
   }
   EXPECT(done);
 
   // Wait up to 5 seconds to see if a worker times out.
   const int kMaxWait = 5000;
   int waited = 0;
   while (thread_pool.workers_stopped() == 0 && waited < kMaxWait) {
@@ skipping 52 matching lines @@
   {
     MonitorLocker ml(&sync);
     while (done < kTotalTasks) {
       ml.Wait();
     }
   }
   EXPECT_EQ(kTotalTasks, done);
 }
 
 }  // namespace dart