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Attempt to fix crash in thread based DNS lookup.

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Depending on the timing of starting and finishing DNS queries, `Thread.join` could be called on an instance that had already been `destroy`ed. To avoid this, the thread instance is now explicitly set to null, as well as resetting the "done" field to avoid redundant work for unused slots.

See vibe-d/vibe.d#2378.
This commit is contained in:
Sönke Ludwig 2019-10-25 09:27:22 +02:00
parent f6ac56664d
commit 14a896be5d
1 changed files with 13 additions and 5 deletions
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18
source/eventcore/drivers/posix/dns.d
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@ -67,6 +67,8 @@ final class EventDriverDNS_GAI(Events : EventDriverEvents, Signals : EventDriver
auto handle = getFreeHandle();
if (handle > m_maxHandle) m_maxHandle = handle;
assert(on_lookup_finished !is null, "Null callback passed to lookupHost");
setupEvent();
assert(!m_lookups[handle].result);
@ -105,6 +107,8 @@ final class EventDriverDNS_GAI(Events : EventDriverEvents, Signals : EventDriver
if (m_lookup.retcode == -1)
version (CRuntime_Glibc) version (linux) __res_init();
assert(m_lookup.retcode != 0 || m_lookup.result !is null);
atomicStore(m_lookup.done, true);
atomicFence(); // synchronize the other fields in m_lookup with the main thread
m_events.trigger(m_event, true);
@ -141,11 +145,14 @@ final class EventDriverDNS_GAI(Events : EventDriverEvents, Signals : EventDriver
// synchronize the other fields in m_lookup with the lookup thread
atomicFence();
try {
l.thread.join();
destroy(l.thread);
} catch (Exception e) {
debug (EventCoreLogDNS) print("Failed to join DNS thread: %s", e.msg);
if (l.thread !is null) {
try {
l.thread.join();
destroy(l.thread);
} catch (Exception e) {
debug (EventCoreLogDNS) print("Failed to join DNS thread: %s", e.msg);
}
l.thread = null;
}
if (l.callback) {
@ -161,6 +168,7 @@ final class EventDriverDNS_GAI(Events : EventDriverEvents, Signals : EventDriver
l.callback = null;
l.result = null;
l.retcode = 0;
l.done = false;
if (i == m_maxHandle) m_maxHandle = lastmax;
m_events.loop.m_waiterCount--;
passToDNSCallback(cast(DNSLookupID)cast(int)i, cb, status, ai);