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different strategy for console exit hang #6007

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different strategy for console exit hang #6007

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32 changes: 15 additions & 17 deletions library/Console-windows.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@ POSSIBILITY OF SUCH DAMAGE.
#include <stdio.h>
#include <fcntl.h>
#include <io.h>
#include <atomic>
#include <iostream>
#include <fstream>
#include <istream>
Expand Down Expand Up @@ -73,7 +74,7 @@ namespace DFHack
rawmode = 0;
console_in = 0;
console_out = 0;
exit_event = 0;
exiting = false;
ConsoleWindow = 0;
default_attributes = 0;
state = con_unclaimed;
Expand Down Expand Up @@ -282,21 +283,17 @@ namespace DFHack
inf.dwCursorPosition.X = (SHORT)plen;
SetConsoleCursorPosition(console_out, inf.dwCursorPosition);

// exit_event comes first so shutdown wins if input is also
// pending. The console input handle is signaled whenever its
// input queue is non-empty, so the read below cannot block.
const HANDLE wait_handles[] = { exit_event, console_in };
while (1)
{
INPUT_RECORD rec;
DWORD count;
lock->unlock();
DWORD wait_result = WaitForMultipleObjects(2, wait_handles, FALSE, INFINITE);
// shutdown() queues a dummy input record to wake this read;
// the exiting flag distinguishes the wake from real input.
BOOL success = ReadConsoleInputA(console_in, &rec, 1, &count);
lock->lock();
if (wait_result != WAIT_OBJECT_0 + 1
|| ReadConsoleInputA(console_in, &rec, 1, &count) == 0) {
if (exiting || !success)
return Console::SHUTDOWN;
}
if (rec.EventType != KEY_EVENT || !rec.Event.KeyEvent.bKeyDown)
continue;
switch (rec.Event.KeyEvent.wVirtualKeyCode)
Expand Down Expand Up @@ -402,7 +399,7 @@ namespace DFHack
int rawmode;
HANDLE console_in;
HANDLE console_out;
HANDLE exit_event;
std::atomic<bool> exiting;
HWND ConsoleWindow;
HWND MainWindow;
WORD default_attributes;
Expand Down Expand Up @@ -486,9 +483,6 @@ bool Console::init(bool)
d->console_owned = AllocConsole() != FALSE;
d->ConsoleWindow = GetConsoleWindow();
wlock = new std::recursive_mutex();
d->exit_event = CreateEventW(NULL, TRUE, FALSE, NULL);
if (!d->exit_event)
return false;
if (d->console_owned)
{
HMENU hm = GetSystemMenu(d->ConsoleWindow,false);
Expand Down Expand Up @@ -546,11 +540,15 @@ bool Console::init(bool)
bool Console::shutdown(void)
{
assert(inited);
d->exiting = true;
std::lock_guard<std::recursive_mutex> lock{*wlock};
// Wake any thread waiting on console input so it leaves prompt_loop
// before we detach or reconfigure the console below.
if (d->exit_event)
SetEvent(d->exit_event);
// Wake any thread blocked in ReadConsoleInputA by queueing a dummy
// input record, so it is no longer inside a console call and can
// observe the exiting flag before we detach the console below.
INPUT_RECORD rec = { 0 };
rec.EventType = FOCUS_EVENT;
DWORD written;
WriteConsoleInputA(d->console_in, &rec, 1, &written);
if (d->console_owned)
{
FreeConsole();
Expand Down
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