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Fix possible race condition in PosixEventDriverEvents.trigger.

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Accessing the event slot should only be done from the owner thread, since the chunk index of the ChoppedVector could be updated at any time. Instead of a triggerAll field, this flag is now propagated through the underlying eventfd/socket pair.
This commit is contained in:
Sönke Ludwig 2019-04-13 16:57:04 +02:00
parent 1bbe244196
commit 48d083b20f
1 changed files with 14 additions and 21 deletions
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35
source/eventcore/drivers/posix/events.d
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@ -48,7 +48,7 @@ final class PosixEventDriverEvents(Loop : PosixEventLoop, Sockets : EventDriverS
auto id = cast(EventID)eid; auto id = cast(EventID)eid;
// FIXME: avoid dynamic memory allocation for the queue // FIXME: avoid dynamic memory allocation for the queue
m_loop.initFD(id, FDFlags.internal, m_loop.initFD(id, FDFlags.internal,
EventSlot(mallocT!(ConsumableQueue!EventCallback), false, is_internal)); EventSlot(mallocT!(ConsumableQueue!EventCallback), is_internal));
m_loop.registerFD(id, EventMask.read); m_loop.registerFD(id, EventMask.read);
m_loop.setNotifyCallback!(EventType.read)(id, &onEvent); m_loop.setNotifyCallback!(EventType.read)(id, &onEvent);
releaseRef(id); // setNotifyCallback increments the reference count, but we need a value of 1 upon return releaseRef(id); // setNotifyCallback increments the reference count, but we need a value of 1 upon return
@ -106,7 +106,7 @@ final class PosixEventDriverEvents(Loop : PosixEventLoop, Sockets : EventDriverS
catch (Exception e) assert(false, e.msg); catch (Exception e) assert(false, e.msg);
// FIXME: avoid dynamic memory allocation for the queue // FIXME: avoid dynamic memory allocation for the queue
m_loop.initFD(id, FDFlags.internal, m_loop.initFD(id, FDFlags.internal,
EventSlot(mallocT!(ConsumableQueue!EventCallback), false, is_internal, s)); EventSlot(mallocT!(ConsumableQueue!EventCallback), is_internal, s));
assert(getRC(id) == 1); assert(getRC(id) == 1);
return id; return id;
} }
@ -133,13 +133,10 @@ final class PosixEventDriverEvents(Loop : PosixEventLoop, Sockets : EventDriverS
final override void trigger(EventID event, bool notify_all) final override void trigger(EventID event, bool notify_all)
shared @trusted @nogc { shared @trusted @nogc {
import core.atomic : atomicStore; import core.atomic : atomicStore;
auto thisus = cast(PosixEventDriverEvents)this; long count = notify_all ? long.max : 1;
assert(event < thisus.m_loop.m_fds.length, "Invalid event ID passed to shared triggerEvent.");
long one = 1;
//log("emitting for all threads"); //log("emitting for all threads");
if (notify_all) atomicStore(thisus.getSlot(event).triggerAll, true); version (Posix) .write(cast(int)event, &count, count.sizeof);
version (Posix) .write(cast(int)event, &one, one.sizeof); else assert(send(cast(int)event, cast(const(ubyte*))&count, count.sizeof, 0) == count.sizeof);
else assert(send(cast(int)event, cast(const(ubyte*))&one, one.sizeof, 0) == one.sizeof);
} }
final override void wait(EventID event, EventCallback on_event) final override void wait(EventID event, EventCallback on_event)
@ -157,26 +154,23 @@ final class PosixEventDriverEvents(Loop : PosixEventLoop, Sockets : EventDriverS
getSlot(event).waiters.removePending(on_event); getSlot(event).waiters.removePending(on_event);
} }
private void onEvent(FD fd) version (linux) {
@trusted { private void onEvent(FD fd)
EventID event = cast(EventID)fd; @trusted {
version (linux) { EventID event = cast(EventID)fd;
ulong cnt; ulong cnt;
() @trusted { .read(cast(int)event, &cnt, cnt.sizeof); } (); () @trusted { .read(cast(int)event, &cnt, cnt.sizeof); } ();
trigger(event, cnt > 0);
} }
import core.atomic : cas; } else {
auto all = cas(&getSlot(event).triggerAll, true, false);
trigger(event, all);
}
version (linux) {}
else {
private void onSocketData(DatagramSocketFD s, IOStatus, size_t, scope RefAddress) private void onSocketData(DatagramSocketFD s, IOStatus, size_t, scope RefAddress)
@nogc { @nogc {
m_sockets.receiveNoGC(s, m_buf, IOMode.once, &onSocketData); m_sockets.receiveNoGC(s, m_buf, IOMode.once, &onSocketData);
try { try {
EventID evt = m_sockets.userData!EventID(s); EventID evt = m_sockets.userData!EventID(s);
scope doit = { onEvent(evt); }; // cast to nogc scope doit = {
trigger(evt, (cast(long[])m_buf)[0] > 1);
}; // cast to nogc
() @trusted { (cast(void delegate() @nogc)doit)(); } (); () @trusted { (cast(void delegate() @nogc)doit)(); } ();
} catch (Exception e) assert(false, e.msg); } catch (Exception e) assert(false, e.msg);
} }
@ -238,7 +232,6 @@ final class PosixEventDriverEvents(Loop : PosixEventLoop, Sockets : EventDriverS
package struct EventSlot { package struct EventSlot {
alias Handle = EventID; alias Handle = EventID;
ConsumableQueue!EventCallback waiters; ConsumableQueue!EventCallback waiters;
shared bool triggerAll;
bool isInternal; bool isInternal;
version (linux) {} version (linux) {}
else { else {