1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
|
//==--- C11.cpp - Threading abstraction implementation --------- -*-C++ -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2022 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// Implements threading support for C11 threads
//
//===----------------------------------------------------------------------===//
#if SWIFT_THREADING_C11
#include "swift/Threading/Impl.h"
#include "swift/Threading/Errors.h"
namespace {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wglobal-constructors"
class C11ThreadingHelper {
private:
thrd_t mainThread_;
mtx_t onceMutex_;
cnd_t onceCond_;
public:
C11ThreadingHelper() {
mainThread_ = thrd_current();
SWIFT_C11THREADS_CHECK(::mtx_init(&onceMutex_, ::mtx_plain));
SWIFT_C11THREADS_CHECK(::cnd_init(&onceCond_));
}
thrd_t main_thread() const { return mainThread_; }
void once_lock() { SWIFT_C11THREADS_CHECK(mtx_lock(&onceMutex_)); }
void once_unlock() { SWIFT_C11THREADS_CHECK(mtx_unlock(&onceMutex_)); }
void once_broadcast() { SWIFT_C11THREADS_CHECK(cnd_broadcast(&onceCond_)); }
void once_wait() {
// The mutex must be locked when this function is entered. It will
// be locked again before the function returns.
SWIFT_C11THREADS_CHECK(cnd_wait(&onceCond_, &onceMutex_));
}
};
C11ThreadingHelper helper;
#pragma clang diagnostic pop
} // namespace
using namespace swift;
using namespace threading_impl;
bool swift::threading_impl::thread_is_main() {
return thrd_equal(thrd_current(), helper.main_thread());
}
void swift::threading_impl::once_slow(once_t &predicate, void (*fn)(void *),
void *context) {
std::intptr_t zero = 0;
if (predicate.compare_exchange_strong(zero, (std::intptr_t)1,
std::memory_order_relaxed,
std::memory_order_relaxed)) {
fn(context);
predicate.store((std::intptr_t)-1, std::memory_order_release);
helper.once_lock();
helper.once_unlock();
helper.once_broadcast();
return;
}
helper.once_lock();
while (predicate.load(std::memory_order_acquire) >= (std::intptr_t)0) {
helper.once_wait();
}
helper.once_unlock();
}
#endif // SWIFT_THREADING_C11
|
