[libc-commits] [libc] [libc] Implement barriers for pthreads (PR #148948)

[Brooks Moses via libc-commits]

================
@@ -0,0 +1,117 @@
+//===-- Tests for pthread_barrier_t ---------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/pthread/pthread_barrier_destroy.h"
+#include "src/pthread/pthread_barrier_init.h"
+#include "src/pthread/pthread_barrier_wait.h"
+
+#include "src/__support/CPP/atomic.h"
+#include "src/pthread/pthread_create.h"
+#include "src/pthread/pthread_join.h"
+#include "src/pthread/pthread_mutex_destroy.h"
+#include "src/pthread/pthread_mutex_init.h"
+#include "src/pthread/pthread_mutex_lock.h"
+#include "src/pthread/pthread_mutex_unlock.h"
+#include "src/stdio/printf.h"
+
+#include "test/IntegrationTest/test.h"
+
+#include <pthread.h>
+
+pthread_barrier_t barrier;
+
+void smoke_test() {
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_barrier_init(&barrier, nullptr, 1), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_barrier_wait(&barrier),
+            PTHREAD_BARRIER_SERIAL_THREAD);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_barrier_destroy(&barrier), 0);
+}
+
+LIBC_NAMESPACE::cpp::Atomic<int> counter;
+void *increment_counter_and_wait(void *args) {
+  counter.fetch_add(1);
+  LIBC_NAMESPACE::pthread_barrier_wait(&barrier);
+  return 0;
+}
+
+void single_use_barrier() {
+  counter.set(0);
+  const int NUM_THREADS = 30;
+  pthread_t threads[NUM_THREADS];
+  ASSERT_EQ(
+      LIBC_NAMESPACE::pthread_barrier_init(&barrier, nullptr, NUM_THREADS + 1),
+      0);
+
+  for (int i = 0; i < NUM_THREADS; ++i)
+    LIBC_NAMESPACE::pthread_create(&threads[i], nullptr,
+                                   increment_counter_and_wait, nullptr);
+
+  LIBC_NAMESPACE::pthread_barrier_wait(&barrier);
+  ASSERT_EQ(counter.load(), NUM_THREADS);
+
+  for (int i = 0; i < NUM_THREADS; ++i)
+    LIBC_NAMESPACE::pthread_join(threads[i], nullptr);
+
+  LIBC_NAMESPACE::pthread_barrier_destroy(&barrier);
+}
+
+void reusable_barrier() {
----------------
brooksmoses wrote:

Nitpick: The barrier is always reusable.  Perhaps "reused_barrier"?

https://github.com/llvm/llvm-project/pull/148948