zircon/system/utest/core/pthread-barrier/barrier.cc

// Copyright 2017 The Fuchsia 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 <errno.h>
#include <pthread.h>

#include <cstdlib>

#include <zxtest/zxtest.h>

namespace {

struct ThreadArgs {
  pthread_barrier_t* barrier;
  std::atomic<int> result;
};

void* BarrierWait(void* arg) {
  auto args = reinterpret_cast<ThreadArgs*>(arg);
  args->result = pthread_barrier_wait(args->barrier);

  return nullptr;
}

constexpr int kNumThreads = 16;
constexpr int kNumIterations = 128;
constexpr pthread_barrierattr_t* kDefaultBarrierAttrs = nullptr;
constexpr pthread_attr_t* kDefaultPthreadAttrs = nullptr;
constexpr void** kNoRetValue = nullptr;

TEST(PThreadBarrierTest, SingleThreadWinsBarrierObject) {
  pthread_barrier_t barrier;
  ASSERT_EQ(pthread_barrier_init(&barrier, kDefaultBarrierAttrs, kNumThreads), 0);

  pthread_t threads[kNumThreads];
  ThreadArgs args[kNumThreads];

  for (int idx = 0; idx < kNumThreads; ++idx) {
    args[idx].barrier = &barrier;
    ASSERT_EQ(pthread_create(&threads[idx], kDefaultPthreadAttrs, &BarrierWait,
                             static_cast<void*>(&args[idx])),
              0);
  }

  for (int idx = 0; idx < kNumThreads; ++idx) {
    ASSERT_EQ(pthread_join(threads[idx], kNoRetValue), 0);
  }

  int num_wins = 0;
  int num_zeros = 0;
  for (int idx = 0; idx < kNumThreads; ++idx) {
    int result = args[idx].result;
    if (result == PTHREAD_BARRIER_SERIAL_THREAD) {
      num_wins++;
    } else if (result == 0) {
      num_zeros++;
    } else {
      ASSERT_EQ(result, 0, "bad result for thread: %d result: %d\n", idx, result);
    }
  }
  ASSERT_EQ(num_wins, 1);
  ASSERT_EQ(num_zeros, kNumThreads - 1);
  ASSERT_EQ(pthread_barrier_destroy(&barrier), 0);
}

TEST(PThreadBarrierTest, SingleThreadWinsBarrierObjectResetsBetweenIterations) {
  pthread_barrier_t barrier;
  ASSERT_EQ(pthread_barrier_init(&barrier, kDefaultBarrierAttrs, kNumThreads), 0);

  for (int count = 0; count < kNumIterations; ++count) {
    pthread_t threads[kNumThreads];
    ThreadArgs args[kNumThreads];

    for (int idx = 0; idx < kNumThreads; ++idx) {
      args[idx].barrier = &barrier;
      ASSERT_EQ(pthread_create(&threads[idx], kDefaultPthreadAttrs, &BarrierWait,
                               static_cast<void*>(&args[idx])),
                0);
    }

    for (int idx = 0; idx < kNumThreads; ++idx) {
      ASSERT_EQ(pthread_join(threads[idx], kNoRetValue), 0);
    }

    int num_wins = 0;
    int num_zeros = 0;
    for (int idx = 0; idx < kNumThreads; ++idx) {
      int result = args[idx].result;
      if (result == PTHREAD_BARRIER_SERIAL_THREAD) {
        num_wins++;
      } else if (result == 0) {
        num_zeros++;
      } else {
        ASSERT_EQ(result, 0, "bad result for thread: %d result: %d\n", idx, result);
      }
    }
    ASSERT_EQ(num_wins, 1);
    ASSERT_EQ(num_zeros, kNumThreads - 1);
  }
  ASSERT_EQ(pthread_barrier_destroy(&barrier), 0);
}

TEST(PThreadBarrierTest, InitWithNoThreadsReturnsInval) {
  pthread_barrier_t barrier;
  constexpr int kThreadCount = 0;
  ASSERT_EQ(pthread_barrier_init(&barrier, kDefaultBarrierAttrs, kThreadCount), EINVAL,
            "zero thread count should fail");
}

}  // namespace