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#include "base/cpu_stats.h"

#include <atomic>
#include <cstdint>
#include <vector>

#include "absl/synchronization/notification.h"
#include "absl/time/clock.h"
#include "absl/time/time.h"
#include "base/thread.h"
#include "testing/gunit.h"

namespace mozc {
namespace {
TEST(CPUStats, CPUStatsTest) {
  CPUStats stats;
  EXPECT_GE(stats.GetSystemCPULoad(), 0.0);
  EXPECT_LE(stats.GetSystemCPULoad(), 1.0);

  EXPECT_GE(stats.GetCurrentProcessCPULoad(), 0.0);

  EXPECT_GE(stats.GetNumberOfProcessors(), 1);
}

TEST(CPUStats, MultiThreadTest) {
  absl::Notification cancel;

  constexpr int kDummyThreadsSize = 32;

  std::vector<mozc::Thread> threads;
  threads.reserve(kDummyThreadsSize);
  for (int i = 0; i < kDummyThreadsSize; ++i) {
    threads.push_back(mozc::Thread([&cancel] {
      std::atomic<uint64_t> n = 0;
      // Makes busy loop.
      while (!cancel.HasBeenNotified()) {
        ++n;
        --n;
      }
    }));
  }

  mozc::CPUStats stats;
  constexpr int kNumIterations = 10;
  for (int i = 0; i < kNumIterations; ++i) {
    EXPECT_GE(stats.GetSystemCPULoad(), 0.0);
    EXPECT_GE(stats.GetCurrentProcessCPULoad(), 0.0);
    EXPECT_GE(stats.GetNumberOfProcessors(), 1);
    absl::SleepFor(absl::Milliseconds(10));
  }

  cancel.Notify();

  for (mozc::Thread& thread : threads) {
    thread.Join();
  }
}
}  // namespace
}  // namespace mozc
