[libc-commits] [libc] [libc] add rwlock (PR #94156)

[Michael Jones via libc-commits]

================
@@ -0,0 +1,443 @@
+//===-- Tests for pthread_rwlock ------------------------------------------===//
+//
+// 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/__support/CPP/atomic.h"
+#include "src/__support/threads/sleep.h"
+#include "src/pthread/pthread_create.h"
+#include "src/pthread/pthread_join.h"
+#include "src/pthread/pthread_rwlock_destroy.h"
+#include "src/pthread/pthread_rwlock_init.h"
+#include "src/pthread/pthread_rwlock_rdlock.h"
+#include "src/pthread/pthread_rwlock_timedrdlock.h"
+#include "src/pthread/pthread_rwlock_timedwrlock.h"
+#include "src/pthread/pthread_rwlock_tryrdlock.h"
+#include "src/pthread/pthread_rwlock_trywrlock.h"
+#include "src/pthread/pthread_rwlock_unlock.h"
+#include "src/pthread/pthread_rwlock_wrlock.h"
+#include "src/pthread/pthread_rwlockattr_destroy.h"
+#include "src/pthread/pthread_rwlockattr_init.h"
+#include "src/pthread/pthread_rwlockattr_setkind_np.h"
+#include "src/pthread/pthread_rwlockattr_setpshared.h"
+#include "src/stdlib/exit.h"
+#include "src/sys/mman/mmap.h"
+#include "src/sys/mman/munmap.h"
+#include "src/sys/random/getrandom.h"
+#include "src/sys/wait/waitpid.h"
+#include "src/time/clock_gettime.h"
+#include "src/unistd/fork.h"
+#include "test/IntegrationTest/test.h"
+#include <errno.h>
+#include <pthread.h>
+#include <time.h>
+
+static void smoke_test() {
+  pthread_rwlock_t rwlock = PTHREAD_RWLOCK_INITIALIZER;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_init(&rwlock, nullptr), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_rdlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_tryrdlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_trywrlock(&rwlock), EBUSY);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_unlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_unlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_wrlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_rdlock(&rwlock), EDEADLK);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_wrlock(&rwlock), EDEADLK);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_tryrdlock(&rwlock), EBUSY);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_trywrlock(&rwlock), EBUSY);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_unlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_destroy(&rwlock), 0);
+}
+
+static void deadlock_detection_test() {
+  pthread_rwlock_t rwlock = PTHREAD_RWLOCK_INITIALIZER;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_init(&rwlock, nullptr), 0);
+  // We only detect RAW, WAW deadlocks.
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_wrlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_wrlock(&rwlock), EDEADLK);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_unlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_destroy(&rwlock), 0);
+}
+
+static void try_lock_test() {
+  pthread_rwlock_t rwlock = PTHREAD_RWLOCK_INITIALIZER;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_init(&rwlock, nullptr), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_wrlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_trywrlock(&rwlock), EBUSY);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_tryrdlock(&rwlock), EBUSY);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_unlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_tryrdlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_rdlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_tryrdlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_trywrlock(&rwlock), EBUSY);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_unlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_unlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_unlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_destroy(&rwlock), 0);
+}
+
+static void destroy_before_unlock_test() {
+  pthread_rwlock_t rwlock = PTHREAD_RWLOCK_INITIALIZER;
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_init(&rwlock, nullptr), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_wrlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_destroy(&rwlock), EBUSY);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_unlock(&rwlock), 0);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_destroy(&rwlock), 0);
+}
+
+static void nullptr_test() {
+  timespec ts = {};
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_rdlock(nullptr), EINVAL);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_wrlock(nullptr), EINVAL);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_timedrdlock(nullptr, &ts), EINVAL);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_timedwrlock(nullptr, &ts), EINVAL);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_tryrdlock(nullptr), EINVAL);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_trywrlock(nullptr), EINVAL);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_unlock(nullptr), EINVAL);
+  ASSERT_EQ(LIBC_NAMESPACE::pthread_rwlock_destroy(nullptr), EINVAL);
+}
+
+// If you are a user reading this code, please do not do something like this.
+// We manually modify the internal state of the rwlock to test high reader
+// counts.
+static void high_reader_count_test() {
+  pthread_rwlock_t rwlock = PTHREAD_RWLOCK_INITIALIZER;
+  rwlock.__state = 0b01111111'11111111'11111111'11111100;
----------------
michaelrj-google wrote:

would it be reasonable to add a testing-only function to set the number of readers to make this less dependent on the specific bit-pattern of the current implementation?

https://github.com/llvm/llvm-project/pull/94156