1 // Copyright (c) 2011 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 #include "content/common/gamepad_seqlock.h"
6
7 #include <stdlib.h>
8
9 #include "base/atomic_ref_count.h"
10 #include "base/threading/platform_thread.h"
11 #include "base/third_party/dynamic_annotations/dynamic_annotations.h"
12 #include "testing/gtest/include/gtest/gtest.h"
13
14 namespace base {
15
16 // Basic test to make sure that basic operation works correctly.
17
18 struct TestData {
19 unsigned a, b, c;
20 };
21
22 class BasicSeqLockTestThread : public PlatformThread::Delegate {
23 public:
BasicSeqLockTestThread()24 BasicSeqLockTestThread() {}
25
Init(content::GamepadSeqLock * seqlock,TestData * data,base::subtle::Atomic32 * ready)26 void Init(
27 content::GamepadSeqLock* seqlock,
28 TestData* data,
29 base::subtle::Atomic32* ready) {
30 seqlock_ = seqlock;
31 data_ = data;
32 ready_ = ready;
33 }
ThreadMain()34 virtual void ThreadMain() {
35 while (AtomicRefCountIsZero(ready_)) {
36 PlatformThread::YieldCurrentThread();
37 }
38
39 for (unsigned i = 0; i < 1000; ++i) {
40 TestData copy;
41 base::subtle::Atomic32 version;
42 do {
43 version = seqlock_->ReadBegin();
44 copy = *data_;
45 } while (seqlock_->ReadRetry(version));
46
47 EXPECT_EQ(copy.a + 100, copy.b);
48 EXPECT_EQ(copy.c, copy.b + copy.a);
49 }
50
51 AtomicRefCountDec(ready_);
52 }
53
54 private:
55 content::GamepadSeqLock* seqlock_;
56 TestData* data_;
57 base::AtomicRefCount* ready_;
58
59 DISALLOW_COPY_AND_ASSIGN(BasicSeqLockTestThread);
60 };
61
TEST(GamepadSeqLockTest,ManyThreads)62 TEST(GamepadSeqLockTest, ManyThreads) {
63 content::GamepadSeqLock seqlock;
64 TestData data = { 0, 0, 0 };
65 base::AtomicRefCount ready = 0;
66
67 ANNOTATE_BENIGN_RACE_SIZED(&data, sizeof(data), "Racey reads are discarded");
68
69 static const unsigned kNumReaderThreads = 10;
70 BasicSeqLockTestThread threads[kNumReaderThreads];
71 PlatformThreadHandle handles[kNumReaderThreads];
72
73 for (unsigned i = 0; i < kNumReaderThreads; ++i)
74 threads[i].Init(&seqlock, &data, &ready);
75 for (unsigned i = 0; i < kNumReaderThreads; ++i)
76 ASSERT_TRUE(PlatformThread::Create(0, &threads[i], &handles[i]));
77
78 // The main thread is the writer, and the spawned are readers.
79 unsigned counter = 0;
80 for (;;) {
81 seqlock.WriteBegin();
82 data.a = counter++;
83 data.b = data.a + 100;
84 data.c = data.b + data.a;
85 seqlock.WriteEnd();
86
87 if (counter == 1)
88 base::AtomicRefCountIncN(&ready, kNumReaderThreads);
89
90 if (AtomicRefCountIsZero(&ready))
91 break;
92 }
93
94 for (unsigned i = 0; i < kNumReaderThreads; ++i)
95 PlatformThread::Join(handles[i]);
96 }
97
98 } // namespace base
99