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#pragma once
#include <sys/epoll.h>
namespace NActors {
enum {
ReadExpected = 1,
ReadHit = 2,
WriteExpected = 4,
WriteHit = 8,
};
class TEpollThread : public TPollerThreadBase<TEpollThread> {
// epoll file descriptor
int EpollDescriptor;
public:
TEpollThread(TActorSystem *actorSystem)
: TPollerThreadBase(actorSystem)
{
EpollDescriptor = epoll_create1(EPOLL_CLOEXEC);
Y_ABORT_UNLESS(EpollDescriptor != -1, "epoll_create1() failed with %s", strerror(errno));
epoll_event event;
event.data.ptr = nullptr;
event.events = EPOLLIN;
if (epoll_ctl(EpollDescriptor, EPOLL_CTL_ADD, ReadEnd, &event) == -1) {
Y_ABORT("epoll_ctl(EPOLL_CTL_ADD) failed with %s", strerror(errno));
}
ISimpleThread::Start(); // start poller thread
}
~TEpollThread() {
Stop();
close(EpollDescriptor);
}
bool ProcessEventsInLoop() {
// preallocated array for events
std::array<epoll_event, 256> events;
// wait indefinitely for event to arrive
LWPROBE(EpollStartWaitIn);
int numReady = epoll_wait(EpollDescriptor, events.data(), events.size(), -1);
LWPROBE(EpollFinishWaitIn, numReady);
// check return status for any errors
if (numReady == -1) {
if (errno == EINTR) {
return false; // restart the call a bit later
} else {
Y_ABORT("epoll_wait() failed with %s", strerror(errno));
}
}
bool res = false;
for (int i = 0; i < numReady; ++i) {
const epoll_event& ev = events[i];
if (auto *record = static_cast<TSocketRecord*>(ev.data.ptr)) {
const bool read = ev.events & (EPOLLIN | EPOLLHUP | EPOLLRDHUP | EPOLLERR);
const bool write = ev.events & (EPOLLOUT | EPOLLERR);
UpdateFlags(record, (read ? ReadHit : 0) | (write ? WriteHit : 0), false /*suppressNotify*/,
false /*checkQueues*/);
} else {
res = true;
}
}
return res;
}
bool UpdateFlags(TSocketRecord *record, ui32 addMask, bool suppressNotify, bool checkQueues) {
ui32 flags = record->Flags.load(std::memory_order_acquire);
for (;;) {
ui32 updated = flags | addMask;
static constexpr ui32 fullRead = ReadExpected | ReadHit;
static constexpr ui32 fullWrite = WriteExpected | WriteHit;
bool read = (updated & fullRead) == fullRead;
bool write = (updated & fullWrite) == fullWrite;
updated &= ~((read ? fullRead : 0) | (write ? fullWrite : 0));
if (record->Flags.compare_exchange_weak(flags, updated, std::memory_order_acq_rel)) {
if (suppressNotify) {
return read || write;
} else {
if (checkQueues) {
pollfd fd;
fd.fd = record->Socket->GetDescriptor();
const bool queryRead = updated & ReadExpected && !read;
const bool queryWrite = updated & WriteExpected && !write;
if (queryRead || queryWrite) {
fd.events = (queryRead ? POLLIN : 0) | (queryWrite ? POLLOUT : 0);
if (poll(&fd, 1, 0) != -1) {
read = queryRead && fd.revents & (POLLIN | POLLHUP | POLLRDHUP | POLLERR);
write = queryWrite && fd.revents & (POLLOUT | POLLERR);
}
}
}
Notify(record, read, write);
return false;
}
}
}
}
void UnregisterSocketInLoop(const TIntrusivePtr<TSharedDescriptor>& socket) {
if (epoll_ctl(EpollDescriptor, EPOLL_CTL_DEL, socket->GetDescriptor(), nullptr) == -1) {
Y_ABORT("epoll_ctl(EPOLL_CTL_DEL) failed with %s", strerror(errno));
}
}
void RegisterSocket(const TIntrusivePtr<TSocketRecord>& record) {
epoll_event event;
event.events = EPOLLET | EPOLLRDHUP | EPOLLIN | EPOLLOUT;
event.data.ptr = record.Get();
if (epoll_ctl(EpollDescriptor, EPOLL_CTL_ADD, record->Socket->GetDescriptor(), &event) == -1) {
Y_ABORT("epoll_ctl(EPOLL_CTL_ADD) failed with %s", strerror(errno));
}
}
bool Request(const TIntrusivePtr<TSocketRecord>& record, bool read, bool write, bool suppressNotify,
bool afterWouldBlock) {
return UpdateFlags(record.Get(), (read ? ReadExpected : 0) | (write ? WriteExpected : 0), suppressNotify,
!afterWouldBlock);
}
};
using TPollerThread = TEpollThread;
} // namespace NActors
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