1//===-- Tests for pthread_once --------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "src/__support/CPP/atomic.h"
10#include "src/pthread/pthread_create.h"
11#include "src/pthread/pthread_join.h"
12#include "src/pthread/pthread_mutex_destroy.h"
13#include "src/pthread/pthread_mutex_init.h"
14#include "src/pthread/pthread_mutex_lock.h"
15#include "src/pthread/pthread_mutex_unlock.h"
16#include "src/pthread/pthread_once.h"
17
18#include "test/IntegrationTest/test.h"
19
20#include <pthread.h>
21#include <stdint.h> // uintptr_t
22
23static constexpr unsigned int NUM_THREADS = 5;
24static LIBC_NAMESPACE::cpp::Atomic<unsigned int> thread_count;
25
26static unsigned int call_count;
27static void pthread_once_func() { ++call_count; }
28
29static void *func(void *) {
30 static pthread_once_t flag = PTHREAD_ONCE_INIT;
31 ASSERT_EQ(LIBC_NAMESPACE::pthread_once(&flag, pthread_once_func), 0);
32
33 thread_count.fetch_add(1);
34
35 return nullptr;
36}
37
38void call_from_5_threads() {
39 // Ensure the call count and thread count are 0 to begin with.
40 call_count = 0;
41 thread_count = 0;
42
43 pthread_t threads[NUM_THREADS];
44 for (unsigned int i = 0; i < NUM_THREADS; ++i) {
45 ASSERT_EQ(
46 LIBC_NAMESPACE::pthread_create(threads + i, nullptr, func, nullptr), 0);
47 }
48
49 for (unsigned int i = 0; i < NUM_THREADS; ++i) {
50 void *retval;
51 ASSERT_EQ(LIBC_NAMESPACE::pthread_join(threads[i], &retval), 0);
52 ASSERT_EQ(uintptr_t(retval), uintptr_t(0));
53 }
54
55 EXPECT_EQ(thread_count.val, 5U);
56 EXPECT_EQ(call_count, 1U);
57}
58
59static pthread_mutex_t once_func_blocker;
60static void blocking_once_func() {
61 LIBC_NAMESPACE::pthread_mutex_lock(&once_func_blocker);
62 LIBC_NAMESPACE::pthread_mutex_unlock(&once_func_blocker);
63}
64
65static LIBC_NAMESPACE::cpp::Atomic<unsigned int> start_count;
66static LIBC_NAMESPACE::cpp::Atomic<unsigned int> done_count;
67static void *once_func_caller(void *) {
68 static pthread_once_t flag;
69 start_count.fetch_add(1);
70 LIBC_NAMESPACE::pthread_once(&flag, blocking_once_func);
71 done_count.fetch_add(1);
72 return nullptr;
73}
74
75// Test the synchronization aspect of the pthread_once function.
76// This is not a fool proof test, but something which might be
77// useful when we add a flakiness detection scheme to UnitTest.
78void test_synchronization() {
79 start_count = 0;
80 done_count = 0;
81
82 ASSERT_EQ(LIBC_NAMESPACE::pthread_mutex_init(&once_func_blocker, nullptr), 0);
83 // Lock the blocking mutex so that the once func blocks.
84 ASSERT_EQ(LIBC_NAMESPACE::pthread_mutex_lock(&once_func_blocker), 0);
85
86 pthread_t t1, t2;
87 ASSERT_EQ(
88 LIBC_NAMESPACE::pthread_create(&t1, nullptr, once_func_caller, nullptr),
89 0);
90 ASSERT_EQ(
91 LIBC_NAMESPACE::pthread_create(&t2, nullptr, once_func_caller, nullptr),
92 0);
93
94 while (start_count.load() != 2)
95 ; // Spin until both threads start.
96
97 // Since the once func is blocked, the threads should not be done yet.
98 EXPECT_EQ(done_count.val, 0U);
99
100 // Unlock the blocking mutex so that the once func blocks.
101 ASSERT_EQ(LIBC_NAMESPACE::pthread_mutex_unlock(&once_func_blocker), 0);
102
103 void *retval;
104 ASSERT_EQ(LIBC_NAMESPACE::pthread_join(t1, &retval), uintptr_t(0));
105 ASSERT_EQ(uintptr_t(retval), 0);
106 ASSERT_EQ(LIBC_NAMESPACE::pthread_join(t2, &retval), uintptr_t(0));
107 ASSERT_EQ(uintptr_t(retval), 0);
108
109 ASSERT_EQ(done_count.val, 2U);
110
111 LIBC_NAMESPACE::pthread_mutex_destroy(&once_func_blocker);
112}
113
114TEST_MAIN() {
115 call_from_5_threads();
116 test_synchronization();
117 return 0;
118}
119

source code of libc/test/integration/src/pthread/pthread_once_test.cpp