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// Copyright (c) 2011 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.
#include "content/common/one_writer_seqlock.h"
#include <stdlib.h>
#include "base/atomic_ref_count.h"
#include "base/third_party/dynamic_annotations/dynamic_annotations.h"
#include "base/threading/platform_thread.h"
#include "testing/gtest/include/gtest/gtest.h"
namespace base {
// Basic test to make sure that basic operation works correctly.
struct TestData {
unsigned a, b, c;
};
class BasicSeqLockTestThread : public PlatformThread::Delegate {
public:
BasicSeqLockTestThread() {}
void Init(
content::OneWriterSeqLock* seqlock,
TestData* data,
base::subtle::Atomic32* ready) {
seqlock_ = seqlock;
data_ = data;
ready_ = ready;
}
void ThreadMain() override {
while (AtomicRefCountIsZero(ready_)) {
PlatformThread::YieldCurrentThread();
}
for (unsigned i = 0; i < 1000; ++i) {
TestData copy;
base::subtle::Atomic32 version;
do {
version = seqlock_->ReadBegin();
copy = *data_;
} while (seqlock_->ReadRetry(version));
EXPECT_EQ(copy.a + 100, copy.b);
EXPECT_EQ(copy.c, copy.b + copy.a);
}
AtomicRefCountDec(ready_);
}
private:
content::OneWriterSeqLock* seqlock_;
TestData* data_;
base::AtomicRefCount* ready_;
DISALLOW_COPY_AND_ASSIGN(BasicSeqLockTestThread);
};
TEST(OneWriterSeqLockTest, ManyThreads) {
content::OneWriterSeqLock seqlock;
TestData data = { 0, 0, 0 };
base::AtomicRefCount ready = 0;
ANNOTATE_BENIGN_RACE_SIZED(&data, sizeof(data), "Racey reads are discarded");
static const unsigned kNumReaderThreads = 10;
BasicSeqLockTestThread threads[kNumReaderThreads];
PlatformThreadHandle handles[kNumReaderThreads];
for (unsigned i = 0; i < kNumReaderThreads; ++i)
threads[i].Init(&seqlock, &data, &ready);
for (unsigned i = 0; i < kNumReaderThreads; ++i)
ASSERT_TRUE(PlatformThread::Create(0, &threads[i], &handles[i]));
// The main thread is the writer, and the spawned are readers.
unsigned counter = 0;
for (;;) {
seqlock.WriteBegin();
data.a = counter++;
data.b = data.a + 100;
data.c = data.b + data.a;
seqlock.WriteEnd();
if (counter == 1)
base::AtomicRefCountIncN(&ready, kNumReaderThreads);
if (AtomicRefCountIsZero(&ready))
break;
}
for (unsigned i = 0; i < kNumReaderThreads; ++i)
PlatformThread::Join(handles[i]);
}
} // namespace base
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