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[k2] fix false positive warning in io-scheduler #1674

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[k2] fix false positive warning in io-scheduler #1674

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18 changes: 13 additions & 5 deletions runtime-light/coroutine/io-scheduler.h
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Original file line number Diff line number Diff line change
Expand Up @@ -229,17 +229,25 @@ inline auto io_scheduler::process_update(k2::descriptor descriptor) noexcept ->
return process_timeout();
}

auto [first, last]{m_parked_polls.equal_range(descriptor)};
if (first == last) {
/*
* No tasks are waiting for updates on this descriptor. This is a harmless race: the platform may have queued
* the update before we cancelled our interest in the descriptor — e.g. an update for a timer that has already
* been cleared or re-armed earlier in this batch, or for a stream descriptor that was closed after its
* coroutine had been resumed. The descriptor may not even exist anymore, so querying its status could fail —
* just ignore such an update.
*/
kphp::log::debug("ignoring an update on descriptor {} since no tasks are waiting for it", descriptor);
return;
}

k2::StreamStatus stream_status{};
k2::stream_status(descriptor, std::addressof(stream_status));
if (stream_status.libc_errno != k2::errno_ok) [[unlikely]] {
return kphp::log::warning("error retrieving stream status: error code -> {}, stream descriptor -> {}", stream_status.libc_errno, descriptor);
}

auto [first, last]{m_parked_polls.equal_range(descriptor)};
if (first == last) { // no tasks waiting for updates on this descriptor
return;
}

static constexpr auto complete_poll_on_update{
[](io_scheduler& io_scheduler, kphp::coro::detail::poll_info& poll_info, kphp::coro::poll_status poll_status) noexcept {
std::visit(
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