155 lines
3.6 KiB
C++
155 lines
3.6 KiB
C++
// SPDX-License-Identifier: GPL-2.0-or-later
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// Copyright The Music Player Daemon Project
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#include "WinSelectBackend.hxx"
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#include "WinSelectEvents.hxx"
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static constexpr int EVENT_READ = 0;
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static constexpr int EVENT_WRITE = 1;
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static constexpr
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bool HasEvent(unsigned events, int event_id) noexcept
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{
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return (events & (1 << event_id)) != 0;
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}
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WinSelectBackend::WinSelectBackend() noexcept = default;
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WinSelectBackend::~WinSelectBackend() noexcept = default;
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bool
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WinSelectBackend::CanModify(WinSelectBackend::Item &item,
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unsigned events, int event_id) const noexcept
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{
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if (item.index[event_id] < 0 && HasEvent(events, event_id))
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return !event_set[event_id].IsFull();
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return true;
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}
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void
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WinSelectBackend::Modify(WinSelectBackend::Item &item, SOCKET fd,
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unsigned events, int event_id) noexcept
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{
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int index = item.index[event_id];
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auto &set = event_set[event_id];
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if (index < 0 && HasEvent(events, event_id))
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item.index[event_id] = set.Add(fd);
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else if (index >= 0 && !HasEvent(events, event_id)) {
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if (size_t(index) != set.Size() - 1) {
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set.MoveToEnd(index);
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items.find(set[index])->second.index[event_id] = index;
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}
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set.RemoveLast();
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item.index[event_id] = -1;
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}
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}
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bool
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WinSelectBackend::Add(SOCKET fd, unsigned events, void *obj) noexcept
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{
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assert(items.find(fd) == items.end());
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auto i = items.emplace(std::piecewise_construct,
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std::forward_as_tuple(fd),
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std::forward_as_tuple(obj)).first;
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auto &item = i->second;
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if (!CanModify(item, events, EVENT_READ)) {
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items.erase(i);
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return false;
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}
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if (!CanModify(item, events, EVENT_WRITE)) {
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items.erase(i);
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return false;
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}
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Modify(item, fd, events, EVENT_READ);
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Modify(item, fd, events, EVENT_WRITE);
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return true;
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}
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bool
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WinSelectBackend::Modify(SOCKET fd, unsigned events, void *obj) noexcept
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{
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auto item_iter = items.find(fd);
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assert(item_iter != items.end());
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auto &item = item_iter->second;
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if (!CanModify(item, events, EVENT_READ))
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return false;
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if (!CanModify(item, events, EVENT_WRITE))
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return false;
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item.obj = obj;
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Modify(item, fd, events, EVENT_READ);
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Modify(item, fd, events, EVENT_WRITE);
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return true;
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}
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bool
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WinSelectBackend::Remove(SOCKET fd) noexcept
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{
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auto item_iter = items.find(fd);
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assert(item_iter != items.end());
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auto &item = item_iter->second;
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Modify(item, fd, 0, EVENT_READ);
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Modify(item, fd, 0, EVENT_WRITE);
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items.erase(item_iter);
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return true;
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}
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void
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WinSelectBackend::ApplyReady(const SocketSet &src, unsigned events) noexcept
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{
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for (const auto i : src) {
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auto it = items.find(i);
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assert(it != items.end());
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it->second.events |= events;
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}
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}
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PollResultGeneric
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WinSelectBackend::ReadEvents(int timeout_ms) noexcept
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{
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bool use_sleep = event_set[EVENT_READ].IsEmpty() &&
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event_set[EVENT_WRITE].IsEmpty();
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PollResultGeneric result;
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if (use_sleep) {
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Sleep(timeout_ms < 0 ? INFINITE : (DWORD) timeout_ms);
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return result;
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}
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SocketSet read_set(event_set[EVENT_READ]);
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SocketSet write_set(event_set[EVENT_WRITE]);
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SocketSet except_set(event_set[EVENT_WRITE]);
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timeval tv;
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if (timeout_ms >= 0) {
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tv.tv_sec = timeout_ms / 1000;
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tv.tv_usec = (timeout_ms % 1000) * 1000;
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}
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int ret = select(0,
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read_set.GetPtr(),
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write_set.GetPtr(),
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except_set.GetPtr(),
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timeout_ms < 0 ? nullptr : &tv);
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if (ret == 0 || ret == SOCKET_ERROR)
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return result;
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ApplyReady(read_set, WinSelectEvents::READ);
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ApplyReady(write_set, WinSelectEvents::WRITE);
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ApplyReady(except_set, WinSelectEvents::WRITE);
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for (auto &[key, item] : items)
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if (item.events != 0) {
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result.Add(item.events, item.obj);
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item.events = 0;
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}
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return result;
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}
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