ladybird/Libraries/LibThreading/Thread.cpp

124 lines
4 KiB
C++

/*
* Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibThreading/Thread.h>
#include <pthread.h>
#include <string.h>
#include <unistd.h>
namespace Threading {
Thread::Thread(Function<intptr_t()> action, StringView thread_name)
: m_action(move(action))
, m_thread_name(thread_name.is_null() ? ""sv : thread_name)
{
}
Thread::~Thread()
{
if (needs_to_be_joined()) {
dbgln("Destroying {} while it is still running undetached!", *this);
[[maybe_unused]] auto res = join();
}
}
ErrorOr<void> Thread::set_priority(int priority)
{
// MacOS has an extra __opaque field, so list initialization will not compile on MacOS Lagom.
sched_param scheduling_parameters {};
scheduling_parameters.sched_priority = priority;
int result = pthread_setschedparam(m_tid, 0, &scheduling_parameters);
if (result != 0)
return Error::from_errno(result);
return {};
}
ErrorOr<int> Thread::get_priority() const
{
sched_param scheduling_parameters {};
int policy;
int result = pthread_getschedparam(m_tid, &policy, &scheduling_parameters);
if (result != 0)
return Error::from_errno(result);
return scheduling_parameters.sched_priority;
}
ByteString Thread::thread_name() const { return m_thread_name; }
pthread_t Thread::tid() const { return m_tid; }
ThreadState Thread::state() const { return m_state; }
bool Thread::is_started() const { return m_state != ThreadState::Startable; }
bool Threading::Thread::needs_to_be_joined() const
{
auto state = m_state.load();
return state == ThreadState::Running || state == ThreadState::Exited;
}
bool Threading::Thread::has_exited() const
{
auto state = m_state.load();
return state == ThreadState::Joined || state == ThreadState::Exited || state == ThreadState::DetachedExited;
}
void Thread::start()
{
VERIFY(!is_started());
// Set this first so that the other thread starts out seeing m_state == Running.
m_state = Threading::ThreadState::Running;
int rc = pthread_create(
&m_tid,
// FIXME: Use pthread_attr_t to start a thread detached if that was requested by the user before the call to start().
nullptr,
[](void* arg) -> void* {
auto self = adopt_ref(*static_cast<Thread*>(arg));
auto exit_code = self->m_action();
auto expected = Threading::ThreadState::Running;
// This code might race with a call to detach().
if (!self->m_state.compare_exchange_strong(expected, Threading::ThreadState::Exited)) {
// If the original state was Detached, we need to set to DetachedExited instead.
if (expected == Threading::ThreadState::Detached) {
if (!self->m_state.compare_exchange_strong(expected, Threading::ThreadState::DetachedExited)) {
dbgln("Thread logic bug: Found thread state {} while trying to set ExitedDetached state!", expected);
VERIFY_NOT_REACHED();
}
} else {
dbgln("Thread logic bug: Found thread state {} while trying to set Exited state!", expected);
VERIFY_NOT_REACHED();
}
}
return reinterpret_cast<void*>(exit_code);
},
&NonnullRefPtr(*this).leak_ref());
VERIFY(rc == 0);
}
void Thread::detach()
{
auto expected = Threading::ThreadState::Running;
// This code might race with the other thread exiting.
if (!m_state.compare_exchange_strong(expected, Threading::ThreadState::Detached)) {
if (expected == Threading::ThreadState::Exited)
return;
// Always report a precise error before crashing. These kinds of bugs are hard to reproduce.
dbgln("Thread logic bug: trying to detach {} in state {}, which is neither Started nor Exited", this, expected);
VERIFY_NOT_REACHED();
}
int rc = pthread_detach(m_tid);
VERIFY(rc == 0);
}
}