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//===-- Tests for call_once -----------------------------------------------===//
//
// 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/threads/call_once.h"
#include "src/threads/mtx_destroy.h"
#include "src/threads/mtx_init.h"
#include "src/threads/mtx_lock.h"
#include "src/threads/mtx_unlock.h"
#include "src/threads/thrd_create.h"
#include "src/threads/thrd_join.h"
#include "test/IntegrationTest/test.h"
#include <threads.h>
static constexpr unsigned int NUM_THREADS = 5;
static LIBC_NAMESPACE::cpp::Atomic<unsigned int> thread_count;
static unsigned int call_count;
static void call_once_func() { ++call_count; }
static int func(void *) {
static once_flag flag = ONCE_FLAG_INIT;
LIBC_NAMESPACE::call_once(&flag, call_once_func);
thread_count.fetch_add(1);
return 0;
}
void call_from_5_threads() {
// Ensure the call count and thread count are 0 to begin with.
call_count = 0;
thread_count = 0;
thrd_t threads[NUM_THREADS];
for (unsigned int i = 0; i < NUM_THREADS; ++i) {
ASSERT_EQ(LIBC_NAMESPACE::thrd_create(threads + i, func, nullptr),
static_cast<int>(thrd_success));
}
for (unsigned int i = 0; i < NUM_THREADS; ++i) {
int retval;
ASSERT_EQ(LIBC_NAMESPACE::thrd_join(threads[i], &retval),
static_cast<int>(thrd_success));
ASSERT_EQ(retval, 0);
}
EXPECT_EQ(thread_count.val, 5U);
EXPECT_EQ(call_count, 1U);
}
static mtx_t once_func_blocker;
static void blocking_once_func() {
LIBC_NAMESPACE::mtx_lock(&once_func_blocker);
LIBC_NAMESPACE::mtx_unlock(&once_func_blocker);
}
static LIBC_NAMESPACE::cpp::Atomic<unsigned int> start_count;
static LIBC_NAMESPACE::cpp::Atomic<unsigned int> done_count;
static int once_func_caller(void *) {
static once_flag flag;
start_count.fetch_add(1);
LIBC_NAMESPACE::call_once(&flag, blocking_once_func);
done_count.fetch_add(1);
return 0;
}
// Test the synchronization aspect of the call_once function.
// This is not a fool proof test, but something which might be
// useful when we add a flakiness detection scheme to UnitTest.
void test_synchronization() {
start_count = 0;
done_count = 0;
ASSERT_EQ(LIBC_NAMESPACE::mtx_init(&once_func_blocker, mtx_plain),
static_cast<int>(thrd_success));
// Lock the blocking mutex so that the once func blocks.
ASSERT_EQ(LIBC_NAMESPACE::mtx_lock(&once_func_blocker),
static_cast<int>(thrd_success));
thrd_t t1, t2;
ASSERT_EQ(LIBC_NAMESPACE::thrd_create(&t1, once_func_caller, nullptr),
static_cast<int>(thrd_success));
ASSERT_EQ(LIBC_NAMESPACE::thrd_create(&t2, once_func_caller, nullptr),
static_cast<int>(thrd_success));
while (start_count.load() != 2)
; // Spin until both threads start.
// Since the once func is blocked, the threads should not be done yet.
EXPECT_EQ(done_count.val, 0U);
// Unlock the blocking mutex so that the once func blocks.
ASSERT_EQ(LIBC_NAMESPACE::mtx_unlock(&once_func_blocker),
static_cast<int>(thrd_success));
int retval;
ASSERT_EQ(LIBC_NAMESPACE::thrd_join(t1, &retval),
static_cast<int>(thrd_success));
ASSERT_EQ(retval, 0);
ASSERT_EQ(LIBC_NAMESPACE::thrd_join(t2, &retval),
static_cast<int>(thrd_success));
ASSERT_EQ(retval, 0);
ASSERT_EQ(done_count.val, 2U);
LIBC_NAMESPACE::mtx_destroy(&once_func_blocker);
}
TEST_MAIN() {
call_from_5_threads();
test_synchronization();
return 0;
}
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