xref: /freebsd/contrib/llvm-project/libcxx/src/mutex.cpp (revision 5f757f3f)

//===----------------------------------------------------------------------===//
//
// 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 <__assert>
#include <__thread/id.h>
#include <__utility/exception_guard.h>
#include <limits>
#include <mutex>

#include "include/atomic_support.h"

#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
#  pragma comment(lib, "pthread")
#endif

_LIBCPP_PUSH_MACROS
#include <__undef_macros>

_LIBCPP_BEGIN_NAMESPACE_STD

// ~mutex is defined elsewhere

void
mutex::lock()
{
    int ec = __libcpp_mutex_lock(&__m_);
    if (ec)
        __throw_system_error(ec, "mutex lock failed");
}

bool
mutex::try_lock() noexcept
{
    return __libcpp_mutex_trylock(&__m_);
}

void
mutex::unlock() noexcept
{
    int ec = __libcpp_mutex_unlock(&__m_);
    (void)ec;
    _LIBCPP_ASSERT_UNCATEGORIZED(ec == 0, "call to mutex::unlock failed");
}

// recursive_mutex

recursive_mutex::recursive_mutex()
{
    int ec = __libcpp_recursive_mutex_init(&__m_);
    if (ec)
        __throw_system_error(ec, "recursive_mutex constructor failed");
}

recursive_mutex::~recursive_mutex()
{
    int e = __libcpp_recursive_mutex_destroy(&__m_);
    (void)e;
    _LIBCPP_ASSERT_UNCATEGORIZED(e == 0, "call to ~recursive_mutex() failed");
}

void
recursive_mutex::lock()
{
    int ec = __libcpp_recursive_mutex_lock(&__m_);
    if (ec)
        __throw_system_error(ec, "recursive_mutex lock failed");
}

void
recursive_mutex::unlock() noexcept
{
    int e = __libcpp_recursive_mutex_unlock(&__m_);
    (void)e;
    _LIBCPP_ASSERT_UNCATEGORIZED(e == 0, "call to recursive_mutex::unlock() failed");
}

bool
recursive_mutex::try_lock() noexcept
{
    return __libcpp_recursive_mutex_trylock(&__m_);
}

// timed_mutex

timed_mutex::timed_mutex()
    : __locked_(false)
{
}

timed_mutex::~timed_mutex()
{
    lock_guard<mutex> _(__m_);
}

void
timed_mutex::lock()
{
    unique_lock<mutex> lk(__m_);
    while (__locked_)
        __cv_.wait(lk);
    __locked_ = true;
}

bool
timed_mutex::try_lock() noexcept
{
    unique_lock<mutex> lk(__m_, try_to_lock);
    if (lk.owns_lock() && !__locked_)
    {
        __locked_ = true;
        return true;
    }
    return false;
}

void
timed_mutex::unlock() noexcept
{
    lock_guard<mutex> _(__m_);
    __locked_ = false;
    __cv_.notify_one();
}

// recursive_timed_mutex

recursive_timed_mutex::recursive_timed_mutex()
    : __count_(0),
      __id_{}
{
}

recursive_timed_mutex::~recursive_timed_mutex()
{
    lock_guard<mutex> _(__m_);
}

void
recursive_timed_mutex::lock()
{
    __thread_id id = this_thread::get_id();
    unique_lock<mutex> lk(__m_);
    if (id ==__id_)
    {
        if (__count_ == numeric_limits<size_t>::max())
            __throw_system_error(EAGAIN, "recursive_timed_mutex lock limit reached");
        ++__count_;
        return;
    }
    while (__count_ != 0)
        __cv_.wait(lk);
    __count_ = 1;
    __id_ = id;
}

bool
recursive_timed_mutex::try_lock() noexcept
{
    __thread_id id = this_thread::get_id();
    unique_lock<mutex> lk(__m_, try_to_lock);
    if (lk.owns_lock() && (__count_ == 0 || id == __id_))
    {
        if (__count_ == numeric_limits<size_t>::max())
            return false;
        ++__count_;
        __id_ = id;
        return true;
    }
    return false;
}

void
recursive_timed_mutex::unlock() noexcept
{
    unique_lock<mutex> lk(__m_);
    if (--__count_ == 0)
    {
        __id_.__reset();
        lk.unlock();
        __cv_.notify_one();
    }
}

_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS