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authorMarc Alexander Lehmann <libev@schmorp.de>2019-07-02 06:07:54 +0000
committerMarc Alexander Lehmann <libev@schmorp.de>2019-07-02 06:07:54 +0000
commitc799314f3623af5025ce3d9118de9c4aad6f241f (patch)
tree92063831b8be3a4e1bedc9bb09f880d21c82d300 /ev_iouring.c
parenta242c417796633953fb89f97110c3dd5a09d7e77 (diff)
downloadlibev-c799314f3623af5025ce3d9118de9c4aad6f241f.tar.gz
libev-c799314f3623af5025ce3d9118de9c4aad6f241f.zip
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+/*
+ * libev linux io_uring fd activity backend
+ *
+ * Copyright (c) 2019 Marc Alexander Lehmann <libev@schmorp.de>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modifica-
+ * tion, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
+ * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+ * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
+ * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
+ * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * the GNU General Public License ("GPL") version 2 or any later version,
+ * in which case the provisions of the GPL are applicable instead of
+ * the above. If you wish to allow the use of your version of this file
+ * only under the terms of the GPL and not to allow others to use your
+ * version of this file under the BSD license, indicate your decision
+ * by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL. If you do not delete the
+ * provisions above, a recipient may use your version of this file under
+ * either the BSD or the GPL.
+ */
+
+/*
+ * general notes about linux io_uring:
+ *
+ * a) it's the best interface I have seen so far. on linux.
+ * b) best is not necessarily very good.
+ * c) it's better than the aio mess, doesn't suffer from the fork problems
+ * of linux aio or epoll and so on and so on. and you could do event stuff
+ * without any syscalls. what's not to like?
+ * d) ok, it's vastly more complex, but that's ok, really.
+ * e) why 3 mmaps instead of one? one would be more space-efficient,
+ * and I can't see what benefit three would have (other than being
+ * somehow resizable/relocatable, but that's apparently not possible).
+ * f) hmm, it's practiclaly undebuggable (gdb can't access the memory, and
+ the bizarre way structure offsets are commuinicated makes it hard to
+ * just print the ring buffer heads, even *iff* the memory were visible
+ * in gdb. but then, that's also ok, really.
+ * g) well, you cannot specify a timeout when waiting for events. no,
+ * seriously, the interface doesn't support a timeout. never seen _that_
+ * before. sure, you can use a timerfd, but that's another syscall
+ * you could have avoided. overall, this bizarre omission smells
+ * like a ยต-optimisation by the io_uring author for his personal
+ * applications, to the detriment of everybody else who just wants
+ * an event loop. but, umm, ok, if that's all, it could be worse.
+ * h) there is a hardcoded limit of 4096 outstanding events. okay,
+ * at least there is no arbitrary low system-wide limit...
+ * i) unlike linux aio, you *can* register more then the limit
+ * of fd events, and the kernel will "gracefully" signal an
+ * overflow, after which you could destroy and recreate the kernel
+ * state, a bit bigger, or fall back to e.g. poll. thats not
+ * totally insane, but kind of questions the point a high
+ * performance I/O framework when it doesn't really work
+ * under stress.
+ * j) but, oh my! is has exactly the same bugs as the linux aio backend,
+ * where some undocumented poll combinations just fail.
+ * so we need epoll AGAIN as a fallback. AGAIN! epoll!! and of course,
+ * this is completely undocumented, have I mantioned this already?
+ * k) overall, the *API* itself is, I dare to say, not a total trainwreck.
+ * the big isuess with it are the bugs requiring epoll, which might
+ * or might not get fixed (do I hold my breath?).
+ */
+
+#include <sys/timerfd.h>
+#include <sys/mman.h>
+#include <poll.h>
+
+#define IOURING_INIT_ENTRIES 32
+
+/*****************************************************************************/
+/* syscall wrapdadoop - this section has the raw api/abi definitions */
+
+#include <linux/fs.h>
+#include <linux/types.h>
+
+/* mostly directly taken from the kernel or documentation */
+
+struct io_uring_sqe
+{
+ __u8 opcode;
+ __u8 flags;
+ __u16 ioprio;
+ __s32 fd;
+ __u64 off;
+ __u64 addr;
+ __u32 len;
+ union {
+ __kernel_rwf_t rw_flags;
+ __u32 fsync_flags;
+ __u16 poll_events;
+ __u32 sync_range_flags;
+ __u32 msg_flags;
+ };
+ __u64 user_data;
+ union {
+ __u16 buf_index;
+ __u64 __pad2[3];
+ };
+};
+
+struct io_uring_cqe
+{
+ __u64 user_data;
+ __s32 res;
+ __u32 flags;
+};
+
+struct io_sqring_offsets
+{
+ __u32 head;
+ __u32 tail;
+ __u32 ring_mask;
+ __u32 ring_entries;
+ __u32 flags;
+ __u32 dropped;
+ __u32 array;
+ __u32 resv1;
+ __u64 resv2;
+};
+
+struct io_cqring_offsets
+{
+ __u32 head;
+ __u32 tail;
+ __u32 ring_mask;
+ __u32 ring_entries;
+ __u32 overflow;
+ __u32 cqes;
+ __u64 resv[2];
+};
+
+struct io_uring_params
+{
+ __u32 sq_entries;
+ __u32 cq_entries;
+ __u32 flags;
+ __u32 sq_thread_cpu;
+ __u32 sq_thread_idle;
+ __u32 resv[5];
+ struct io_sqring_offsets sq_off;
+ struct io_cqring_offsets cq_off;
+};
+
+#define IORING_OP_POLL_ADD 6
+#define IORING_OP_POLL_REMOVE 7
+
+#define IORING_ENTER_GETEVENTS 0x01
+
+#define IORING_OFF_SQ_RING 0x00000000ULL
+#define IORING_OFF_CQ_RING 0x08000000ULL
+#define IORING_OFF_SQES 0x10000000ULL
+
+inline_size
+int
+evsys_io_uring_setup (unsigned entries, struct io_uring_params *params)
+{
+ return ev_syscall2 (SYS_io_uring_setup, entries, params);
+}
+
+inline_size
+int
+evsys_io_uring_enter (int fd, unsigned to_submit, unsigned min_complete, unsigned flags, const sigset_t *sig, size_t sigsz)
+{
+ return ev_syscall6 (SYS_io_uring_enter, fd, to_submit, min_complete, flags, sig, sigsz);
+}
+
+/*****************************************************************************/
+/* actual backed implementation */
+
+/* we hope that volatile will make the compiler access this variables only once */
+#define EV_SQ_VAR(name) *(volatile unsigned *)((char *)iouring_sq_ring + iouring_sq_ ## name)
+#define EV_CQ_VAR(name) *(volatile unsigned *)((char *)iouring_cq_ring + iouring_cq_ ## name)
+
+/* the index array */
+#define EV_SQ_ARRAY ((unsigned *)((char *)iouring_sq_ring + iouring_sq_array))
+
+/* the submit/completion queue entries */
+#define EV_SQES ((struct io_uring_sqe *) iouring_sqes)
+#define EV_CQES ((struct io_uring_cqe *)((char *)iouring_cq_ring + iouring_cq_cqes))
+
+static
+struct io_uring_sqe *
+iouring_sqe_get (EV_P)
+{
+ unsigned tail = EV_SQ_VAR (tail);
+
+ if (tail + 1 - EV_SQ_VAR (head) > EV_SQ_VAR (ring_entries))
+ {
+ /* queue full, flush */
+ evsys_io_uring_enter (iouring_fd, iouring_to_submit, 0, 0, 0, 0);
+ iouring_to_submit = 0;
+ }
+
+ assert (("libev: io_uring queue full after flush", tail + 1 - EV_SQ_VAR (head) <= EV_SQ_VAR (ring_entries)));
+
+ return EV_SQES + (tail & EV_SQ_VAR (ring_mask));
+}
+
+inline_size
+struct io_uring_sqe *
+iouring_sqe_submit (EV_P_ struct io_uring_sqe *sqe)
+{
+ unsigned idx = sqe - EV_SQES;
+
+ EV_SQ_ARRAY [idx] = idx;
+ ECB_MEMORY_FENCE_RELEASE;
+ ++EV_SQ_VAR (tail);
+ /*ECB_MEMORY_FENCE_RELEASE; /* for the time being we assume this is not needed */
+ ++iouring_to_submit;
+}
+
+/*****************************************************************************/
+
+/* when the timerfd expires we simply note the fact,
+ * as the purpose of the timerfd is to wake us up, nothing else.
+ * the next iteration should re-set it.
+ */
+static void
+iouring_tfd_cb (EV_P_ struct ev_io *w, int revents)
+{
+ iouring_tfd_to = EV_TSTAMP_HUGE;
+}
+
+static void
+iouring_epoll_cb (EV_P_ struct ev_io *w, int revents)
+{
+ epoll_poll (EV_A_ 0);
+}
+
+/* called for full and partial cleanup */
+ecb_cold
+static int
+iouring_internal_destroy (EV_P)
+{
+ close (iouring_tfd);
+ close (iouring_fd);
+
+ if (iouring_sq_ring != MAP_FAILED) munmap (iouring_sq_ring, iouring_sq_ring_size);
+ if (iouring_cq_ring != MAP_FAILED) munmap (iouring_cq_ring, iouring_cq_ring_size);
+ if (iouring_sqes != MAP_FAILED) munmap (iouring_sqes , iouring_sqes_size );
+
+ if (ev_is_active (&iouring_epoll_w)) ev_ref (EV_A); ev_io_stop (EV_A_ &iouring_epoll_w);
+ if (ev_is_active (&iouring_tfd_w )) ev_ref (EV_A); ev_io_stop (EV_A_ &iouring_tfd_w );
+}
+
+ecb_cold
+static int
+iouring_internal_init (EV_P)
+{
+ struct io_uring_params params = { 0 };
+
+ iouring_to_submit = 0;
+
+ iouring_tfd = -1;
+ iouring_sq_ring = MAP_FAILED;
+ iouring_cq_ring = MAP_FAILED;
+ iouring_sqes = MAP_FAILED;
+
+ for (;;)
+ {
+ iouring_fd = evsys_io_uring_setup (iouring_entries, &params);
+
+ if (iouring_fd >= 0)
+ break; /* yippie */
+
+ if (errno != EINVAL)
+ return -1; /* we failed */
+
+ /* EINVAL: lots of possible reasons, but maybe
+ * it is because we hit the unqueryable hardcoded size limit
+ */
+
+ /* we hit the limit already, give up */
+ if (iouring_max_entries)
+ return -1;
+
+ /* first time we hit EINVAL? assume we hit the limit, so go back and retry */
+ iouring_entries >>= 1;
+ iouring_max_entries = iouring_entries;
+ }
+
+ iouring_sq_ring_size = params.sq_off.array + params.sq_entries * sizeof (unsigned);
+ iouring_cq_ring_size = params.cq_off.cqes + params.cq_entries * sizeof (struct io_uring_cqe);
+ iouring_sqes_size = params.sq_entries * sizeof (struct io_uring_sqe);
+
+ iouring_sq_ring = mmap (0, iouring_sq_ring_size, PROT_READ | PROT_WRITE,
+ MAP_SHARED | MAP_POPULATE, iouring_fd, IORING_OFF_SQ_RING);
+ iouring_cq_ring = mmap (0, iouring_cq_ring_size, PROT_READ | PROT_WRITE,
+ MAP_SHARED | MAP_POPULATE, iouring_fd, IORING_OFF_CQ_RING);
+ iouring_sqes = mmap (0, iouring_sqes_size, PROT_READ | PROT_WRITE,
+ MAP_SHARED | MAP_POPULATE, iouring_fd, IORING_OFF_SQES);
+
+ if (iouring_sq_ring == MAP_FAILED || iouring_cq_ring == MAP_FAILED || iouring_sqes == MAP_FAILED)
+ return -1;
+
+ iouring_sq_head = params.sq_off.head;
+ iouring_sq_tail = params.sq_off.tail;
+ iouring_sq_ring_mask = params.sq_off.ring_mask;
+ iouring_sq_ring_entries = params.sq_off.ring_entries;
+ iouring_sq_flags = params.sq_off.flags;
+ iouring_sq_dropped = params.sq_off.dropped;
+ iouring_sq_array = params.sq_off.array;
+
+ iouring_cq_head = params.cq_off.head;
+ iouring_cq_tail = params.cq_off.tail;
+ iouring_cq_ring_mask = params.cq_off.ring_mask;
+ iouring_cq_ring_entries = params.cq_off.ring_entries;
+ iouring_cq_overflow = params.cq_off.overflow;
+ iouring_cq_cqes = params.cq_off.cqes;
+
+ iouring_tfd = timerfd_create (CLOCK_MONOTONIC, TFD_CLOEXEC);
+
+ if (iouring_tfd < 0)
+ return iouring_tfd;
+
+ iouring_tfd_to = EV_TSTAMP_HUGE;
+
+ return 0;
+}
+
+ecb_cold
+static void
+iouring_fork (EV_P)
+{
+ iouring_internal_destroy (EV_A);
+
+ while (iouring_internal_init (EV_A) < 0)
+ ev_syserr ("(libev) io_uring_setup");
+
+ /* forking epoll should also effectively unregister all fds from the backend */
+ epoll_fork (EV_A);
+ /* epoll_fork already did this. hopefully */
+ /*fd_rearm_all (EV_A);*/
+
+ ev_io_stop (EV_A_ &iouring_epoll_w);
+ ev_io_set (EV_A_ &iouring_epoll_w, backend_fd, EV_READ);
+ ev_io_start (EV_A_ &iouring_epoll_w);
+
+ ev_io_stop (EV_A_ &iouring_tfd_w);
+ ev_io_set (EV_A_ &iouring_tfd_w, iouring_tfd, EV_READ);
+ ev_io_start (EV_A_ &iouring_tfd_w);
+}
+
+/*****************************************************************************/
+
+static void
+iouring_modify (EV_P_ int fd, int oev, int nev)
+{
+ fprintf (stderr,"modify %d (%d, %d) %d\n", fd, oev,nev, anfds[fd].eflags);//D
+ if (ecb_expect_false (anfds [fd].eflags))
+ {
+ /* we handed this fd over to epoll, so undo this first */
+ /* we do it manually because the optimisations on epoll_modify won't do us any good */
+ epoll_ctl (iouring_fd, EPOLL_CTL_DEL, fd, 0);
+ anfds [fd].eflags = 0;
+ oev = 0;
+ }
+
+ if (oev)
+ {
+ /* we assume the sqe's are all "properly" initialised */
+ struct io_uring_sqe *sqe = iouring_sqe_get (EV_A);
+ sqe->opcode = IORING_OP_POLL_REMOVE;
+ sqe->fd = fd;
+ sqe->user_data = -1;
+ iouring_sqe_submit (EV_A_ sqe);
+ }
+
+ /* increment generation counter to avoid handling old events */
+ ++anfds [fd].egen;
+
+ if (nev)
+ {
+ struct io_uring_sqe *sqe = iouring_sqe_get (EV_A);
+ sqe->opcode = IORING_OP_POLL_ADD;
+ sqe->fd = fd;
+ sqe->user_data = (uint32_t)fd | ((__u64)anfds [fd].egen << 32);
+ sqe->poll_events =
+ (nev & EV_READ ? POLLIN : 0)
+ | (nev & EV_WRITE ? POLLOUT : 0);
+ iouring_sqe_submit (EV_A_ sqe);
+ }
+}
+
+inline_size
+void
+iouring_tfd_update (EV_P_ ev_tstamp timeout)
+{
+ ev_tstamp tfd_to = mn_now + timeout;
+
+ /* we assume there will be many iterations per timer change, so
+ * we only re-set the timerfd when we have to because its expiry
+ * is too late.
+ */
+ if (ecb_expect_false (tfd_to < iouring_tfd_to))
+ {
+ struct itimerspec its;
+
+ iouring_tfd_to = tfd_to;
+ EV_TS_SET (its.it_interval, 0.);
+ EV_TS_SET (its.it_value, tfd_to);
+
+ if (timerfd_settime (iouring_tfd, TFD_TIMER_ABSTIME, &its, 0) < 0)
+ assert (("libev: iouring timerfd_settime failed", 0));
+ }
+}
+
+inline_size
+void
+iouring_process_cqe (EV_P_ struct io_uring_cqe *cqe)
+{
+ int fd = cqe->user_data & 0xffffffffU;
+ uint32_t gen = cqe->user_data >> 32;
+ int res = cqe->res;
+
+ /* ignore fd removal events, if there are any. TODO: verify */
+ if (cqe->user_data == (__u64)-1)
+ abort ();//D
+
+ assert (("libev: io_uring fd must be in-bounds", fd >= 0 && fd < anfdmax));
+
+ /* documentation lies, of course. the result value is NOT like
+ * normal syscalls, but like linux raw syscalls, i.e. negative
+ * error numbers. fortunate, as otherwise there would be no way
+ * to get error codes at all. still, why not document this?
+ */
+
+ /* ignore event if generation doesn't match */
+ /* this should actually be very rare */
+ if (ecb_expect_false ((uint32_t)anfds [fd].egen != gen))
+ return;
+
+ if (ecb_expect_false (res < 0))
+ {
+ if (res == -EINVAL)
+ {
+ /* we assume this error code means the fd/poll combination is buggy
+ * and fall back to epoll.
+ * this error code might also indicate a bug, but the kernel doesn't
+ * distinguish between those two conditions, so... sigh...
+ */
+
+ epoll_modify (EV_A_ fd, 0, anfds [fd].events);
+ }
+ else if (res == -EBADF)
+ {
+ assert (("libev: event loop rejected bad fd", res != -EBADF));
+ fd_kill (EV_A_ fd);
+ }
+ else
+ {
+ errno = -res;
+ ev_syserr ("(libev) IORING_OP_POLL_ADD");
+ }
+
+ return;
+ }
+
+ fprintf (stderr, "fd %d event, rearm\n", fd);//D
+
+ /* feed events, we do not expect or handle POLLNVAL */
+ fd_event (
+ EV_A_
+ fd,
+ (res & (POLLOUT | POLLERR | POLLHUP) ? EV_WRITE : 0)
+ | (res & (POLLIN | POLLERR | POLLHUP) ? EV_READ : 0)
+ );
+
+ /* io_uring is oneshot, so we need to re-arm the fd next iteration */
+ /* this also means we usually have to do at least one syscall per iteration */
+ anfds [fd].events = 0;
+ fd_change (EV_A_ fd, EV_ANFD_REIFY);
+}
+
+/* called when the event queue overflows */
+ecb_cold
+static void
+iouring_overflow (EV_P)
+{
+ /* we have two options, resize the queue (by tearing down
+ * everything and recreating it, or living with it
+ * and polling.
+ * we implement this by resizing tghe queue, and, if that fails,
+ * we just recreate the state on every failure, which
+ * kind of is a very inefficient poll.
+ * one danger is, due to the bios toward lower fds,
+ * we will only really get events for those, so
+ * maybe we need a poll() fallback, after all.
+ */
+ /*EV_CQ_VAR (overflow) = 0;*/ /* need to do this if we keep the state and poll manually */
+
+ fd_rearm_all (EV_A);
+
+ /* we double the size until we hit the hard-to-probe maximum */
+ if (!iouring_max_entries)
+ {
+ iouring_entries <<= 1;
+ iouring_fork (EV_A);
+ }
+ else
+ {
+ /* we hit the kernel limit, we should fall back to something else.
+ * we can either poll() a few times and hope for the best,
+ * poll always, or switch to epoll.
+ * since we use epoll anyways, go epoll.
+ */
+
+ iouring_internal_destroy (EV_A);
+
+ /* this should make it so that on return, we don'T call any uring functions */
+ iouring_to_submit = 0;
+
+ for (;;)
+ {
+ backend = epoll_init (EV_A_ 0);
+
+ if (backend)
+ break;
+
+ ev_syserr ("(libev) iouring switch to epoll");
+ }
+ }
+}
+
+/* handle any events in the completion queue, return true if there were any */
+static int
+iouring_handle_cq (EV_P)
+{
+ unsigned head, tail, mask;
+
+ head = EV_CQ_VAR (head);
+ ECB_MEMORY_FENCE_ACQUIRE;
+ tail = EV_CQ_VAR (tail);
+
+ if (head == tail)
+ return 0;
+
+ /* it can only overflow if we have events, yes, yes? */
+ if (ecb_expect_false (EV_CQ_VAR (overflow)))
+ {
+ iouring_overflow (EV_A);
+ return 1;
+ }
+
+ mask = EV_CQ_VAR (ring_mask);
+
+ do
+ iouring_process_cqe (EV_A_ &EV_CQES [head++ & mask]);
+ while (head != tail);
+
+ EV_CQ_VAR (head) = head;
+ ECB_MEMORY_FENCE_RELEASE;
+
+ return 1;
+}
+
+static void
+iouring_poll (EV_P_ ev_tstamp timeout)
+{
+ /* if we have events, no need for extra syscalls, but we might have to queue events */
+ if (iouring_handle_cq (EV_A))
+ timeout = 0.;
+ else
+ /* no events, so maybe wait for some */
+ iouring_tfd_update (EV_A_ timeout);
+
+ /* only enter the kernel if we have somethign to submit, or we need to wait */
+ if (timeout || iouring_to_submit)
+ {
+ int res;
+
+ EV_RELEASE_CB;
+
+ res = evsys_io_uring_enter (iouring_fd, iouring_to_submit, 1,
+ timeout ? IORING_ENTER_GETEVENTS : 0, 0, 0);
+ iouring_to_submit = 0;
+
+ EV_ACQUIRE_CB;
+
+ if (ecb_expect_false (res < 0))
+ if (errno == EINTR)
+ /* ignore */;
+ else
+ ev_syserr ("(libev) iouring setup");
+ else
+ iouring_handle_cq (EV_A);
+ }
+}
+
+inline_size
+int
+iouring_init (EV_P_ int flags)
+{
+ if (!epoll_init (EV_A_ 0))
+ return 0;
+
+ ev_io_init (EV_A_ &iouring_epoll_w, iouring_epoll_cb, backend_fd, EV_READ);
+ ev_set_priority (&iouring_epoll_w, EV_MAXPRI);
+
+ ev_io_init (&iouring_tfd_w, iouring_tfd_cb, iouring_tfd, EV_READ);
+ ev_set_priority (&iouring_tfd_w, EV_MAXPRI);
+
+ iouring_entries = IOURING_INIT_ENTRIES;
+ iouring_max_entries = 0;
+
+ if (iouring_internal_init (EV_A) < 0)
+ {
+ iouring_internal_destroy (EV_A);
+ return 0;
+ }
+
+ ev_io_start (EV_A_ &iouring_epoll_w);
+ ev_unref (EV_A); /* watcher should not keep loop alive */
+
+ ev_io_start (EV_A_ &iouring_tfd_w);
+ ev_unref (EV_A); /* watcher should not keep loop alive */
+
+ backend_modify = iouring_modify;
+ backend_poll = iouring_poll;
+
+ return EVBACKEND_IOURING;
+}
+
+inline_size
+void
+iouring_destroy (EV_P)
+{
+ iouring_internal_destroy (EV_A);
+ epoll_destroy (EV_A);
+}
+