kakoune/src/event_manager.cc
Maxime Coste 4a59018dcd Do not select on non-urgent fd when handling only urgent events
This avoids 100% CPU usage when we have pending fifo input while running
a shell process, as we will not end-up busy looping in pselect but not
reading the available data due to being only processing urgent events.
2021-03-11 09:02:02 +11:00

175 lines
4.6 KiB
C++

#include "event_manager.hh"
#include "flags.hh"
#include "ranges.hh"
#if defined(__sun__)
#include <cstring>
#endif
#include <unistd.h>
namespace Kakoune
{
FDWatcher::FDWatcher(int fd, FdEvents events, EventMode mode, Callback callback)
: m_fd{fd}, m_events{events}, m_mode{mode}, m_callback{std::move(callback)}
{
EventManager::instance().m_fd_watchers.push_back(this);
}
FDWatcher::~FDWatcher()
{
unordered_erase(EventManager::instance().m_fd_watchers, this);
}
void FDWatcher::run(FdEvents events, EventMode mode)
{
m_callback(*this, events, mode);
}
void FDWatcher::close_fd()
{
if (m_fd != -1)
{
close(m_fd);
m_fd = -1;
}
}
Timer::Timer(TimePoint date, Callback callback, EventMode mode)
: m_date{date}, m_mode(mode), m_callback{std::move(callback)}
{
if (m_callback and EventManager::has_instance())
EventManager::instance().m_timers.push_back(this);
}
Timer::~Timer()
{
if (m_callback and EventManager::has_instance())
unordered_erase(EventManager::instance().m_timers, this);
}
void Timer::run(EventMode mode)
{
kak_assert(m_callback);
if (mode == m_mode)
{
m_date = TimePoint::max();
m_callback(*this);
}
else // try again a little later
m_date = Clock::now() + std::chrono::milliseconds{10};
}
EventManager::EventManager()
{
FD_ZERO(&m_forced_fd);
}
EventManager::~EventManager()
{
kak_assert(m_fd_watchers.empty());
kak_assert(m_timers.empty());
}
bool EventManager::handle_next_events(EventMode mode, sigset_t* sigmask, bool block)
{
int max_fd = 0;
fd_set rfds, wfds, efds;
FD_ZERO(&rfds); FD_ZERO(&wfds); FD_ZERO(&efds);
for (auto& watcher : m_fd_watchers)
{
if (watcher->mode() == EventMode::Normal and mode == EventMode::Urgent)
continue;
const int fd = watcher->fd();
if (fd != -1)
{
max_fd = std::max(fd, max_fd);
auto events = watcher->events();
if (events & FdEvents::Read)
FD_SET(fd, &rfds);
if (events & FdEvents::Write)
FD_SET(fd, &wfds);
if (events & FdEvents::Except)
FD_SET(fd, &efds);
}
}
bool with_timeout = false;
if (m_has_forced_fd)
block = false;
timespec ts{};
if (block and not m_timers.empty())
{
auto next_date = (*std::min_element(
m_timers.begin(), m_timers.end(), [](Timer* lhs, Timer* rhs) {
return lhs->next_date() < rhs->next_date();
}))->next_date();
if (next_date != TimePoint::max())
{
with_timeout = true;
using namespace std::chrono; using ns = std::chrono::nanoseconds;
auto nsecs = std::max(ns(0), duration_cast<ns>(next_date - Clock::now()));
auto secs = duration_cast<seconds>(nsecs);
ts = timespec{ (time_t)secs.count(), (long)(nsecs - secs).count() };
}
}
int res = pselect(max_fd + 1, &rfds, &wfds, &efds,
not block or with_timeout ? &ts : nullptr, sigmask);
// copy forced fds *after* select, so that signal handlers can write to
// m_forced_fd, interupt select, and directly be serviced.
m_has_forced_fd = false;
fd_set forced = m_forced_fd;
FD_ZERO(&m_forced_fd);
for (int fd = 0; fd < max_fd + 1; ++fd)
{
auto events = FD_ISSET(fd, &forced) ? FdEvents::Read : FdEvents::None;
if (res > 0)
events |= (FD_ISSET(fd, &rfds) ? FdEvents::Read : FdEvents::None) |
(FD_ISSET(fd, &wfds) ? FdEvents::Write : FdEvents::None) |
(FD_ISSET(fd, &efds) ? FdEvents::Except : FdEvents::None);
if (events != FdEvents::None)
{
auto it = find_if(m_fd_watchers,
[fd](const FDWatcher* w){return w->fd() == fd; });
if (it != m_fd_watchers.end())
(*it)->run(events, mode);
}
}
TimePoint now = Clock::now();
auto timers = m_timers; // copy timers in case m_timers gets mutated
for (auto& timer : timers)
{
if (contains(m_timers, timer) and timer->next_date() <= now)
timer->run(mode);
}
return res > 0;
}
void EventManager::force_signal(int fd)
{
FD_SET(fd, &m_forced_fd);
m_has_forced_fd = true;
}
SignalHandler set_signal_handler(int signum, SignalHandler handler)
{
struct sigaction new_action, old_action;
sigemptyset(&new_action.sa_mask);
new_action.sa_handler = handler;
new_action.sa_flags = SA_RESTART;
sigaction(signum, &new_action, &old_action);
return old_action.sa_handler;
}
}