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Start a thread for each DNS lookup. Fixes vibe-d/vibe.d#2378.

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std.parallelism.Task.executeInNewThread leaks the thread's resources instead of reusing it in later calls. As a workaround, this commit starts a new thread for every lookup and properly tears it down afterwards. At a later point, this code should be changed to reuse the thread(s), if possible, to avoid the startup overhead.
This commit is contained in:
Sönke Ludwig 2019-10-07 11:09:16 +02:00
parent f38a8cdb5a
commit 5255645455
1 changed files with 54 additions and 18 deletions
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72
source/eventcore/drivers/posix/dns.d
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@ -28,13 +28,16 @@ version (Posix)
final class EventDriverDNS_GAI(Events : EventDriverEvents, Signals : EventDriverSignals) : EventDriverDNS {
import std.parallelism : task, taskPool;
import std.string : toStringz;
import core.thread : Thread;
private {
static struct Lookup {
bool done;
DNSLookupCallback callback;
addrinfo* result;
int retcode;
string name;
Thread thread;
}
ChoppedVector!Lookup m_lookups;
Events m_events;
@ -69,30 +72,54 @@ final class EventDriverDNS_GAI(Events : EventDriverEvents, Signals : EventDriver
Lookup* l = () @trusted { return &m_lookups[handle]; } ();
l.name = name;
l.callback = on_lookup_finished;
l.done = false;
auto events = () @trusted { return cast(shared)m_events; } ();
auto t = task!taskFun(l, AddressFamily.UNSPEC, events, m_event);
try t.executeInNewThread();//taskPool.put(t);
catch (Exception e) return DNSLookupID.invalid;
try {
auto thr = new class(l, AddressFamily.UNSPEC, events, m_event) Thread {
Lookup* m_lookup;
AddressFamily m_family;
shared(Events) m_events;
EventID m_event;
this(Lookup* l, AddressFamily af, shared(Events) events, EventID event)
{
m_lookup = l;
m_family = af;
m_events = events;
m_event = event;
super(&perform);
this.name = "Eventcore DNS Lookup";
l.thread = this;
}
void perform()
nothrow {
debug (EventCoreLogDNS) print("lookup %s start", m_lookup.name);
addrinfo hints;
hints.ai_flags = AI_ADDRCONFIG;
version (linux) hints.ai_flags |= AI_V4MAPPED;
hints.ai_family = m_family;
() @trusted { m_lookup.retcode = getaddrinfo(m_lookup.name.toStringz(), null, m_family == AddressFamily.UNSPEC ? null : &hints, &m_lookup.result); } ();
if (m_lookup.retcode == -1)
version (CRuntime_Glibc) version (linux) __res_init();
m_lookup.done = true;
m_events.trigger(m_event, true);
debug (EventCoreLogDNS) print("lookup %s finished", m_lookup.name);
}
};
() @trusted { thr.start(); } ();
} catch (Exception e) {
return DNSLookupID.invalid;
}
debug (EventCoreLogDNS) print("lookup handle: %s", handle);
m_events.loop.m_waiterCount++;
return handle;
}
/// public
static void taskFun(Lookup* lookup, int af, shared(Events) events, EventID event)
{
debug (EventCoreLogDNS) print("lookup %s start", lookup.name);
addrinfo hints;
hints.ai_flags = AI_ADDRCONFIG;
version (linux) hints.ai_flags |= AI_V4MAPPED;
hints.ai_family = af;
() @trusted { lookup.retcode = getaddrinfo(lookup.name.toStringz(), null, af == AddressFamily.UNSPEC ? null : &hints, &lookup.result); } ();
if (lookup.retcode == -1)
version (CRuntime_Glibc) version (linux) __res_init();
events.trigger(event, true);
debug (EventCoreLogDNS) print("lookup %s finished", lookup.name);
}
override void cancelLookup(DNSLookupID handle)
{
m_lookups[handle].callback = null;
@ -107,6 +134,15 @@ final class EventDriverDNS_GAI(Events : EventDriverEvents, Signals : EventDriver
size_t lastmax;
foreach (i, ref l; m_lookups) {
if (i > m_maxHandle) break;
if (!l.done) continue;
try {
l.thread.join();
destroy(l.thread);
} catch (Exception e) {
debug (EventCoreLogDNS) print("Failed to join DNS thread: %s", e.msg);
}
if (l.callback) {
if (l.result || l.retcode) {
debug (EventCoreLogDNS) print("found finished lookup %s for %s", i, l.name);