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// SPDX-License-Identifier: GPL-2.0-or-later
// Copyright The Music Player Daemon Project
#include "PollBackend.hxx"
#include <cassert>
PollBackend::PollBackend() noexcept = default;
PollBackend::~PollBackend() noexcept = default;
static constexpr auto
MakePollfd(int fd, short events) noexcept
{
struct pollfd pfd{};
pfd.fd = fd;
pfd.events = events;
return pfd;
}
bool
PollBackend::Add(int fd, unsigned events, void *obj) noexcept
{
assert(items.find(fd) == items.end());
const std::size_t index = poll_events.size();
poll_events.push_back(MakePollfd(fd, events));
items.emplace(std::piecewise_construct,
std::forward_as_tuple(fd),
std::forward_as_tuple(index, obj));
return true;
}
bool
PollBackend::Modify(int fd, unsigned events, void *obj) noexcept
{
auto item_iter = items.find(fd);
assert(item_iter != items.end());
auto &item = item_iter->second;
item.obj = obj;
auto &e = poll_events[item.index];
e.events = events;
e.revents &= events;
return true;
}
bool
PollBackend::Remove(int fd) noexcept
{
auto item_iter = items.find(fd);
assert(item_iter != items.end());
const auto &item = item_iter->second;
std::size_t index = item.index;
std::size_t last_index = poll_events.size() - 1;
if (index != last_index) {
std::swap(poll_events[index], poll_events[last_index]);
items.find(poll_events[index].fd)->second.index = index;
}
poll_events.pop_back();
items.erase(item_iter);
return true;
}
PollResultGeneric
PollBackend::ReadEvents(int timeout_ms) noexcept
{
int n = poll(poll_events.empty() ? nullptr : &poll_events[0],
poll_events.size(), timeout_ms);
PollResultGeneric result;
for (std::size_t i = 0; n > 0 && i < poll_events.size(); ++i) {
const auto &e = poll_events[i];
if (e.revents != 0) {
auto it = items.find(e.fd);
assert(it != items.end());
assert(it->second.index == i);
result.Add(e.revents, it->second.obj);
--n;
}
}
return result;
}
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