1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 // This file provides a macro ONLY for use in testing. 6 // DO NOT USE IN PRODUCTION CODE. There are much better ways to wait. 7 8 // This code is very helpful in testing multi-threaded code, without depending 9 // on almost any primitives. This is especially helpful if you are testing 10 // those primitive multi-threaded constructs. 11 12 // We provide a simple one argument spin wait (for 1 second), and a generic 13 // spin wait (for longer periods of time). 14 15 #ifndef BASE_SYNCHRONIZATION_SPIN_WAIT_H_ 16 #define BASE_SYNCHRONIZATION_SPIN_WAIT_H_ 17 18 #include "base/threading/platform_thread.h" 19 #include "base/time/time.h" 20 21 // Provide a macro that will wait no longer than 1 second for an asynchronous 22 // change is the value of an expression. 23 // A typical use would be: 24 // 25 // SPIN_FOR_1_SECOND_OR_UNTIL_TRUE(0 == f(x)); 26 // 27 // The expression will be evaluated repeatedly until it is true, or until 28 // the time (1 second) expires. 29 // Since tests generally have a 5 second watch dog timer, this spin loop is 30 // typically used to get the padding needed on a given test platform to assure 31 // that the test passes, even if load varies, and external events vary. 32 33 #define SPIN_FOR_1_SECOND_OR_UNTIL_TRUE(expression) \ 34 SPIN_FOR_TIMEDELTA_OR_UNTIL_TRUE(base::TimeDelta::FromSeconds(1), \ 35 (expression)) 36 37 #define SPIN_FOR_TIMEDELTA_OR_UNTIL_TRUE(delta, expression) do { \ 38 base::TimeTicks start = base::TimeTicks::Now(); \ 39 const base::TimeDelta kTimeout = delta; \ 40 while (!(expression)) { \ 41 if (kTimeout < base::TimeTicks::Now() - start) { \ 42 EXPECT_LE((base::TimeTicks::Now() - start).InMilliseconds(), \ 43 kTimeout.InMilliseconds()) << "Timed out"; \ 44 break; \ 45 } \ 46 base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(50)); \ 47 } \ 48 } while (0) 49 50 #endif // BASE_SYNCHRONIZATION_SPIN_WAIT_H_ 51
