================
@@ -31,6 +34,122 @@ static DWORD
ToTimeout(std::optional<MainLoopWindows::TimePoint> point) {
return ceil<milliseconds>(dur).count();
}
+namespace {
+
+class PipeEvent : public MainLoopWindows::IOEvent {
+public:
+ explicit PipeEvent(HANDLE handle)
+ : IOEvent((IOObject::WaitableHandle)CreateEventW(
+ NULL, /*bManualReset=*/FALSE,
+ /*bInitialState=*/FALSE, NULL)),
+ m_handle(handle), m_ready(CreateEventW(NULL, /*bManualReset=*/FALSE,
+ /*bInitialState=*/FALSE, NULL))
{
+ assert(m_event && m_ready);
+ }
+
+ ~PipeEvent() override {
+ if (m_monitor_thread.joinable()) {
+ m_stopped = true;
+ SetEvent(m_ready);
+ // Keep trying to cancel ReadFile() until the thread exits.
+ do {
+ CancelIoEx((HANDLE)m_handle, /*lpOverlapped=*/NULL);
+ } while (WaitForSingleObject(m_monitor_thread.native_handle(), 1) ==
+ WAIT_TIMEOUT);
+ m_monitor_thread.join();
+ }
+ CloseHandle((HANDLE)m_event);
+ CloseHandle(m_ready);
+ }
+
+ void WillPoll() override {
+ if (!m_monitor_thread.joinable())
+ m_monitor_thread = std::thread(&PipeEvent::Monitor, this);
+ }
+
+ void Disarm() override { SetEvent(m_ready); }
+
+ /// Monitors the handle performing a zero byte read to determine when data is
+ /// avaiable.
+ void Monitor() {
+ do {
+ char buf[1];
+ DWORD bytes_read = 0;
+ OVERLAPPED ov = {0};
+ // Block on a 0-byte read; this will only resume when data is
+ // available in the pipe. The pipe must be PIPE_WAIT or this thread
+ // will spin.
+ BOOL success =
+ ReadFile(m_handle, buf, /*nNumberOfBytesToRead=*/0, &bytes_read,
&ov);
+ DWORD bytes_available = 0;
+ DWORD err = GetLastError();
----------------
slydiman wrote:
Don't call GetLastError() if ReadFile returned TRUE!
https://github.com/llvm/llvm-project/pull/145621
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