Mojo: Base our epsilon timeouts off of TestTimeouts::tiny_timeout().

mojo/system/message_pipe_dispatcher_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // NOTE(vtl): Some of these tests are inherently flaky (e.g., if run on a
-// heavily-loaded system). Sorry. |kEpsilonMicros| may be increased to increase
-// tolerance and reduce observed flakiness.
+// heavily-loaded system). Sorry. |test::EpsilonTimeout()| may be increased to
+// increase tolerance and reduce observed flakiness (though doing so reduces the
+// meaningfulness of the test).
 
 #include "mojo/system/message_pipe_dispatcher.h"
 
 #include <string.h>
 
 #include <limits>
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_vector.h"
 #include "base/rand_util.h"
 #include "base/threading/platform_thread.h"  // For |Sleep()|.
 #include "base/threading/simple_thread.h"
 #include "base/time/time.h"
 #include "mojo/system/message_pipe.h"
 #include "mojo/system/test_utils.h"
 #include "mojo/system/waiter.h"
 #include "mojo/system/waiter_test_utils.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace mojo {
 namespace system {
 namespace {
 
-const int64_t kMicrosPerMs = 1000;
-const int64_t kEpsilonMicros = 30 * kMicrosPerMs;  // 30 ms.
-
 TEST(MessagePipeDispatcherTest, Basic) {
   test::Stopwatch stopwatch;
   int32_t buffer[1];
   const uint32_t kBufferSize = static_cast<uint32_t>(sizeof(buffer));
   uint32_t buffer_size;
-  int64_t elapsed_micros;
 
   // Run this test both with |d0| as port 0, |d1| as port 1 and vice versa.
   for (unsigned i = 0; i < 2; i++) {
     scoped_refptr<MessagePipeDispatcher> d0(new MessagePipeDispatcher());
     scoped_refptr<MessagePipeDispatcher> d1(new MessagePipeDispatcher());
     {
       scoped_refptr<MessagePipe> mp(new MessagePipe());
       d0->Init(mp, i);  // 0, 1.
       d1->Init(mp, i ^ 1);  // 1, 0.
     }
@@ skipping 10 matching lines @@
     w.Init();
     EXPECT_EQ(MOJO_RESULT_OK,
               d0->AddWaiter(&w, MOJO_WAIT_FLAG_READABLE, 1));
     buffer[0] = 123456789;
     EXPECT_EQ(MOJO_RESULT_OK,
               d1->WriteMessage(buffer, kBufferSize,
                                NULL,
                                MOJO_WRITE_MESSAGE_FLAG_NONE));
     stopwatch.Start();
     EXPECT_EQ(1, w.Wait(MOJO_DEADLINE_INDEFINITE));
-    elapsed_micros = stopwatch.Elapsed();
-    EXPECT_LT(elapsed_micros, kEpsilonMicros);
+    EXPECT_LT(stopwatch.Elapsed(), test::EpsilonTimeout());
     d0->RemoveWaiter(&w);
 
     // Try adding a readable waiter when already readable (from above).
     w.Init();
     EXPECT_EQ(MOJO_RESULT_ALREADY_EXISTS,
               d0->AddWaiter(&w, MOJO_WAIT_FLAG_READABLE, 2));
     // Shouldn't need to remove the waiter (it was not added).
 
     // Make |d0| no longer readable (by reading from it).
     buffer[0] = 0;
     buffer_size = kBufferSize;
     EXPECT_EQ(MOJO_RESULT_OK,
               d0->ReadMessage(buffer, &buffer_size,
                               0, NULL,
                               MOJO_READ_MESSAGE_FLAG_NONE));
     EXPECT_EQ(kBufferSize, buffer_size);
     EXPECT_EQ(123456789, buffer[0]);
 
     // Wait for zero time for readability on |d0| (will time out).
     w.Init();
     EXPECT_EQ(MOJO_RESULT_OK,
               d0->AddWaiter(&w, MOJO_WAIT_FLAG_READABLE, 3));
     stopwatch.Start();
     EXPECT_EQ(MOJO_RESULT_DEADLINE_EXCEEDED, w.Wait(0));
-    elapsed_micros = stopwatch.Elapsed();
-    EXPECT_LT(elapsed_micros, kEpsilonMicros);
+    EXPECT_LT(stopwatch.Elapsed(), test::EpsilonTimeout());
     d0->RemoveWaiter(&w);
 
     // Wait for non-zero, finite time for readability on |d0| (will time out).
     w.Init();
     EXPECT_EQ(MOJO_RESULT_OK,
               d0->AddWaiter(&w, MOJO_WAIT_FLAG_READABLE, 3));
     stopwatch.Start();
-    EXPECT_EQ(MOJO_RESULT_DEADLINE_EXCEEDED, w.Wait(2 * kEpsilonMicros));
-    elapsed_micros = stopwatch.Elapsed();
-    EXPECT_GT(elapsed_micros, (2-1) * kEpsilonMicros);
-    EXPECT_LT(elapsed_micros, (2+1) * kEpsilonMicros);
+    EXPECT_EQ(MOJO_RESULT_DEADLINE_EXCEEDED,
+              w.Wait(2 * test::EpsilonTimeout().InMicroseconds()));
+    base::TimeDelta elapsed = stopwatch.Elapsed();
+    EXPECT_GT(elapsed, (2-1) * test::EpsilonTimeout());
+    EXPECT_LT(elapsed, (2+1) * test::EpsilonTimeout());
     d0->RemoveWaiter(&w);
 
     EXPECT_EQ(MOJO_RESULT_OK, d0->Close());
     EXPECT_EQ(MOJO_RESULT_OK, d1->Close());
   }
 }
 
 TEST(MessagePipeDispatcherTest, InvalidParams) {
   char buffer[1];
 
@@ skipping 132 matching lines @@
 
     EXPECT_EQ(MOJO_RESULT_OK, d0->Close());
   }
 }
 
 TEST(MessagePipeDispatcherTest, BasicThreaded) {
   test::Stopwatch stopwatch;
   int32_t buffer[1];
   const uint32_t kBufferSize = static_cast<uint32_t>(sizeof(buffer));
   uint32_t buffer_size;
+  base::TimeDelta elapsed;
   bool did_wait;
   MojoResult result;
-  int64_t elapsed_micros;
 
   // Run this test both with |d0| as port 0, |d1| as port 1 and vice versa.
   for (unsigned i = 0; i < 2; i++) {
     scoped_refptr<MessagePipeDispatcher> d0(new MessagePipeDispatcher());
     scoped_refptr<MessagePipeDispatcher> d1(new MessagePipeDispatcher());
     {
       scoped_refptr<MessagePipe> mp(new MessagePipe());
       d0->Init(mp, i);  // 0, 1.
       d1->Init(mp, i ^ 1);  // 1, 0.
     }
 
     // Wait for readable on |d1|, which will become readable after some time.
     {
       test::WaiterThread thread(d1,
                                MOJO_WAIT_FLAG_READABLE,
                                MOJO_DEADLINE_INDEFINITE,
                                0,
                                &did_wait, &result);
       stopwatch.Start();
       thread.Start();
-      base::PlatformThread::Sleep(
-          base::TimeDelta::FromMicroseconds(2 * kEpsilonMicros));
+      base::PlatformThread::Sleep(2 * test::EpsilonTimeout());
       // Wake it up by writing to |d0|.
       buffer[0] = 123456789;
       EXPECT_EQ(MOJO_RESULT_OK,
                 d0->WriteMessage(buffer, kBufferSize,
                                  NULL,
                                  MOJO_WRITE_MESSAGE_FLAG_NONE));
     }  // Joins the thread.
-    elapsed_micros = stopwatch.Elapsed();
+    elapsed = stopwatch.Elapsed();
+    EXPECT_GT(elapsed, (2-1) * test::EpsilonTimeout());
+    EXPECT_LT(elapsed, (2+1) * test::EpsilonTimeout());
     EXPECT_TRUE(did_wait);
     EXPECT_EQ(0, result);
-    EXPECT_GT(elapsed_micros, (2-1) * kEpsilonMicros);
-    EXPECT_LT(elapsed_micros, (2+1) * kEpsilonMicros);
 
     // Now |d1| is already readable. Try waiting for it again.
     {
       test::WaiterThread thread(d1,
                                 MOJO_WAIT_FLAG_READABLE,
                                 MOJO_DEADLINE_INDEFINITE,
                                 1,
                                 &did_wait, &result);
       stopwatch.Start();
       thread.Start();
     }  // Joins the thread.
-    elapsed_micros = stopwatch.Elapsed();
+    EXPECT_LT(stopwatch.Elapsed(), test::EpsilonTimeout());
     EXPECT_FALSE(did_wait);
     EXPECT_EQ(MOJO_RESULT_ALREADY_EXISTS, result);
-    EXPECT_LT(elapsed_micros, kEpsilonMicros);
 
     // Consume what we wrote to |d0|.
     buffer[0] = 0;
     buffer_size = kBufferSize;
     EXPECT_EQ(MOJO_RESULT_OK,
               d1->ReadMessage(buffer, &buffer_size,
                               0, NULL,
                               MOJO_READ_MESSAGE_FLAG_NONE));
     EXPECT_EQ(kBufferSize, buffer_size);
     EXPECT_EQ(123456789, buffer[0]);
 
     // Wait for readable on |d1| and close |d0| after some time, which should
     // cancel that wait.
     {
       test::WaiterThread thread(d1,
                                 MOJO_WAIT_FLAG_READABLE,
                                 MOJO_DEADLINE_INDEFINITE,
                                 0,
                                 &did_wait, &result);
       stopwatch.Start();
       thread.Start();
-      base::PlatformThread::Sleep(
-          base::TimeDelta::FromMicroseconds(2 * kEpsilonMicros));
+      base::PlatformThread::Sleep(2 * test::EpsilonTimeout());
       EXPECT_EQ(MOJO_RESULT_OK, d0->Close());
     }  // Joins the thread.
-    elapsed_micros = stopwatch.Elapsed();
+    elapsed = stopwatch.Elapsed();
+    EXPECT_GT(elapsed, (2-1) * test::EpsilonTimeout());
+    EXPECT_LT(elapsed, (2+1) * test::EpsilonTimeout());
     EXPECT_TRUE(did_wait);
     EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION, result);
-    EXPECT_GT(elapsed_micros, (2-1) * kEpsilonMicros);
-    EXPECT_LT(elapsed_micros, (2+1) * kEpsilonMicros);
 
     EXPECT_EQ(MOJO_RESULT_OK, d1->Close());
   }
 
   for (unsigned i = 0; i < 2; i++) {
     scoped_refptr<MessagePipeDispatcher> d0(new MessagePipeDispatcher());
     scoped_refptr<MessagePipeDispatcher> d1(new MessagePipeDispatcher());
     {
       scoped_refptr<MessagePipe> mp(new MessagePipe());
       d0->Init(mp, i);  // 0, 1.
       d1->Init(mp, i ^ 1);  // 1, 0.
     }
 
     // Wait for readable on |d1| and close |d1| after some time, which should
     // cancel that wait.
     {
       test::WaiterThread thread(d1,
                                 MOJO_WAIT_FLAG_READABLE,
                                 MOJO_DEADLINE_INDEFINITE,
                                 0,
                                 &did_wait, &result);
       stopwatch.Start();
       thread.Start();
-      base::PlatformThread::Sleep(
-          base::TimeDelta::FromMicroseconds(2 * kEpsilonMicros));
+      base::PlatformThread::Sleep(2 * test::EpsilonTimeout());
       EXPECT_EQ(MOJO_RESULT_OK, d1->Close());
     }  // Joins the thread.
-    elapsed_micros = stopwatch.Elapsed();
+    elapsed = stopwatch.Elapsed();
+    EXPECT_GT(elapsed, (2-1) * test::EpsilonTimeout());
+    EXPECT_LT(elapsed, (2+1) * test::EpsilonTimeout());
     EXPECT_TRUE(did_wait);
     EXPECT_EQ(MOJO_RESULT_CANCELLED, result);
-    EXPECT_GT(elapsed_micros, (2-1) * kEpsilonMicros);
-    EXPECT_LT(elapsed_micros, (2+1) * kEpsilonMicros);
 
     EXPECT_EQ(MOJO_RESULT_OK, d0->Close());
   }
 }
 
 // Stress test -----------------------------------------------------------------
 
 const size_t kMaxMessageSize = 2000;
 
 class WriterThread : public base::SimpleThread {
@@ skipping 193 matching lines @@
   EXPECT_EQ(total_messages_written, total_messages_read);
   EXPECT_EQ(total_bytes_written, total_bytes_read);
 
   EXPECT_EQ(MOJO_RESULT_OK, d_write->Close());
   EXPECT_EQ(MOJO_RESULT_OK, d_read->Close());
 }
 
 }  // namespace
 }  // namespace system
 }  // namespace mojo