Event engines refactoring.

1 files changed, 1021 insertions, 0 deletions

diff --git a/src/nxt_kqueue_engine.c b/src/nxt_kqueue_engine.c
new file mode 100644
index 00000000..b4057389
--- /dev/null
+++ b/src/nxt_kqueue_engine.c
@@ -0,0 +1,1021 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ * Copyright (C) NGINX, Inc.
+ */
+
+#include <nxt_main.h>
+
+
+/*
+ * kqueue()      has been introduced in FreeBSD 4.1 and then was ported
+ *               to OpenBSD 2.9, MacOSX 10.3 (Panther), and NetBSD 2.0.
+ *               DragonFlyBSD inherited it with FreeBSD 4 code base.
+ *
+ * NOTE_REVOKE   has been introduced in FreeBSD 4.3 and then was ported
+ *               to OpenBSD 2.9, MacOSX 10.3 (Panther), and NetBSD 2.0.
+ *               DragonFlyBSD inherited it with FreeBSD 4 code base.
+ *
+ * EVFILT_TIMER  has been introduced in FreeBSD 4.4-STABLE and then was
+ *               ported to NetBSD 2.0, MacOSX 10.4 (Tiger), and OpenBSD 4.2.
+ *               DragonFlyBSD inherited it with FreeBSD 4 code base.
+ *
+ * EVFILT_USER and EV_DISPATCH have been introduced in MacOSX 10.6 (Snow
+ *               Leopard) as part of the Grand Central Dispatch framework
+ *               and then were ported to FreeBSD 8.0-STABLE as part of the
+ *               libdispatch support.
+ */
+
+
+/*
+ * EV_DISPATCH is better because it just disables an event on delivery
+ * whilst EV_ONESHOT deletes the event.  This eliminates in-kernel memory
+ * deallocation and probable subsequent allocation with a lock acquiring.
+ */
+#ifdef EV_DISPATCH
+#define NXT_KEVENT_ONESHOT  EV_DISPATCH
+#else
+#define NXT_KEVENT_ONESHOT  EV_ONESHOT
+#endif
+
+
+#if (NXT_NETBSD)
+/* NetBSD defines the kevent.udata field as intptr_t. */
+
+#define nxt_kevent_set_udata(udata)  (intptr_t) (udata)
+#define nxt_kevent_get_udata(udata)  (void *) (udata)
+
+#else
+#define nxt_kevent_set_udata(udata)  (void *) (udata)
+#define nxt_kevent_get_udata(udata)  (udata)
+#endif
+
+
+static nxt_int_t nxt_kqueue_create(nxt_event_engine_t *engine,
+    nxt_uint_t mchanges, nxt_uint_t mevents);
+static void nxt_kqueue_free(nxt_event_engine_t *engine);
+static void nxt_kqueue_enable(nxt_event_engine_t *engine, nxt_fd_event_t *ev);
+static void nxt_kqueue_disable(nxt_event_engine_t *engine, nxt_fd_event_t *ev);
+static void nxt_kqueue_delete(nxt_event_engine_t *engine, nxt_fd_event_t *ev);
+static nxt_bool_t nxt_kqueue_close(nxt_event_engine_t *engine,
+    nxt_fd_event_t *ev);
+static void nxt_kqueue_enable_read(nxt_event_engine_t *engine,
+    nxt_fd_event_t *ev);
+static void nxt_kqueue_enable_write(nxt_event_engine_t *engine,
+    nxt_fd_event_t *ev);
+static void nxt_kqueue_disable_read(nxt_event_engine_t *engine,
+    nxt_fd_event_t *ev);
+static void nxt_kqueue_disable_write(nxt_event_engine_t *engine,
+    nxt_fd_event_t *ev);
+static void nxt_kqueue_block_read(nxt_event_engine_t *engine,
+    nxt_fd_event_t *ev);
+static void nxt_kqueue_block_write(nxt_event_engine_t *engine,
+    nxt_fd_event_t *ev);
+static void nxt_kqueue_oneshot_read(nxt_event_engine_t *engine,
+    nxt_fd_event_t *ev);
+static void nxt_kqueue_oneshot_write(nxt_event_engine_t *engine,
+    nxt_fd_event_t *ev);
+static void nxt_kqueue_enable_accept(nxt_event_engine_t *engine,
+    nxt_fd_event_t *ev);
+static void nxt_kqueue_enable_file(nxt_event_engine_t *engine,
+    nxt_event_file_t *ev);
+static void nxt_kqueue_close_file(nxt_event_engine_t *engine,
+    nxt_event_file_t *ev);
+static void nxt_kqueue_fd_set(nxt_event_engine_t *engine, nxt_fd_event_t *ev,
+    nxt_int_t filter, nxt_uint_t flags);
+static struct kevent *nxt_kqueue_get_kevent(nxt_event_engine_t *engine);
+static void nxt_kqueue_error(nxt_event_engine_t *engine);
+static void nxt_kqueue_fd_error_handler(nxt_task_t *task, void *obj,
+    void *data);
+static void nxt_kqueue_file_error_handler(nxt_task_t *task, void *obj,
+    void *data);
+static nxt_int_t nxt_kqueue_add_signal(nxt_event_engine_t *engine,
+    const nxt_sig_event_t *sigev);
+#if (NXT_HAVE_EVFILT_USER)
+static nxt_int_t nxt_kqueue_enable_post(nxt_event_engine_t *engine,
+    nxt_work_handler_t handler);
+static void nxt_kqueue_signal(nxt_event_engine_t *engine, nxt_uint_t signo);
+#endif
+static void nxt_kqueue_poll(nxt_event_engine_t *engine, nxt_msec_t timeout);
+
+static void nxt_kqueue_event_conn_io_connect(nxt_task_t *task, void *obj,
+    void *data);
+static void nxt_kqueue_event_conn_connected(nxt_task_t *task, void *obj,
+    void *data);
+static void nxt_kqueue_listen_handler(nxt_task_t *task, void *obj, void *data);
+static void nxt_kqueue_event_conn_io_accept(nxt_task_t *task, void *obj,
+    void *data);
+static void nxt_kqueue_event_conn_io_read(nxt_task_t *task, void *obj,
+    void *data);
+static ssize_t nxt_kqueue_event_conn_io_recvbuf(nxt_event_conn_t *c,
+    nxt_buf_t *b);
+
+
+static nxt_event_conn_io_t  nxt_kqueue_event_conn_io = {
+    nxt_kqueue_event_conn_io_connect,
+    nxt_kqueue_event_conn_io_accept,
+
+    nxt_kqueue_event_conn_io_read,
+    nxt_kqueue_event_conn_io_recvbuf,
+    nxt_event_conn_io_recv,
+
+    nxt_event_conn_io_write,
+    nxt_event_conn_io_write_chunk,
+
+#if (NXT_HAVE_FREEBSD_SENDFILE)
+    nxt_freebsd_event_conn_io_sendfile,
+#elif (NXT_HAVE_MACOSX_SENDFILE)
+    nxt_macosx_event_conn_io_sendfile,
+#else
+    nxt_event_conn_io_sendbuf,
+#endif
+
+    nxt_event_conn_io_writev,
+    nxt_event_conn_io_send,
+
+    nxt_event_conn_io_shutdown,
+};
+
+
+const nxt_event_interface_t  nxt_kqueue_engine = {
+    "kqueue",
+    nxt_kqueue_create,
+    nxt_kqueue_free,
+    nxt_kqueue_enable,
+    nxt_kqueue_disable,
+    nxt_kqueue_delete,
+    nxt_kqueue_close,
+    nxt_kqueue_enable_read,
+    nxt_kqueue_enable_write,
+    nxt_kqueue_disable_read,
+    nxt_kqueue_disable_write,
+    nxt_kqueue_block_read,
+    nxt_kqueue_block_write,
+    nxt_kqueue_oneshot_read,
+    nxt_kqueue_oneshot_write,
+    nxt_kqueue_enable_accept,
+    nxt_kqueue_enable_file,
+    nxt_kqueue_close_file,
+#if (NXT_HAVE_EVFILT_USER)
+    nxt_kqueue_enable_post,
+    nxt_kqueue_signal,
+#else
+    NULL,
+    NULL,
+#endif
+    nxt_kqueue_poll,
+
+    &nxt_kqueue_event_conn_io,
+
+    NXT_FILE_EVENTS,
+    NXT_SIGNAL_EVENTS,
+};
+
+
+static nxt_int_t
+nxt_kqueue_create(nxt_event_engine_t *engine, nxt_uint_t mchanges,
+    nxt_uint_t mevents)
+{
+    const nxt_sig_event_t  *sigev;
+
+    engine->u.kqueue.fd = -1;
+    engine->u.kqueue.mchanges = mchanges;
+    engine->u.kqueue.mevents = mevents;
+    engine->u.kqueue.pid = nxt_pid;
+
+    engine->u.kqueue.changes = nxt_malloc(sizeof(struct kevent) * mchanges);
+    if (engine->u.kqueue.changes == NULL) {
+        goto fail;
+    }
+
+    engine->u.kqueue.events = nxt_malloc(sizeof(struct kevent) * mevents);
+    if (engine->u.kqueue.events == NULL) {
+        goto fail;
+    }
+
+    engine->u.kqueue.fd = kqueue();
+    if (engine->u.kqueue.fd == -1) {
+        nxt_log(&engine->task, NXT_LOG_CRIT, "kqueue() failed %E", nxt_errno);
+        goto fail;
+    }
+
+    nxt_debug(&engine->task, "kqueue(): %d", engine->u.kqueue.fd);
+
+    if (engine->signals != NULL) {
+        for (sigev = engine->signals->sigev; sigev->signo != 0; sigev++) {
+            if (nxt_kqueue_add_signal(engine, sigev) != NXT_OK) {
+                goto fail;
+            }
+        }
+    }
+
+    return NXT_OK;
+
+fail:
+
+    nxt_kqueue_free(engine);
+
+    return NXT_ERROR;
+}
+
+
+static void
+nxt_kqueue_free(nxt_event_engine_t *engine)
+{
+    nxt_fd_t  fd;
+
+    fd = engine->u.kqueue.fd;
+
+    nxt_debug(&engine->task, "kqueue %d free", fd);
+
+    if (fd != -1 && engine->u.kqueue.pid == nxt_pid) {
+        /* kqueue is not inherited by fork() */
+
+        if (close(fd) != 0) {
+            nxt_log(&engine->task, NXT_LOG_CRIT, "kqueue close(%d) failed %E",
+                    fd, nxt_errno);
+        }
+    }
+
+    nxt_free(engine->u.kqueue.events);
+    nxt_free(engine->u.kqueue.changes);
+
+    nxt_memzero(&engine->u.kqueue, sizeof(nxt_kqueue_engine_t));
+}
+
+
+static void
+nxt_kqueue_enable(nxt_event_engine_t *engine, nxt_fd_event_t *ev)
+{
+    nxt_kqueue_enable_read(engine, ev);
+    nxt_kqueue_enable_write(engine, ev);
+}
+
+
+/*
+ * EV_DISABLE is better because it eliminates in-kernel memory
+ * deallocation and probable subsequent allocation with a lock acquiring.
+ */
+
+static void
+nxt_kqueue_disable(nxt_event_engine_t *engine, nxt_fd_event_t *ev)
+{
+    if (ev->read != NXT_EVENT_INACTIVE) {
+        ev->read = NXT_EVENT_INACTIVE;
+        nxt_kqueue_fd_set(engine, ev, EVFILT_READ, EV_DISABLE);
+    }
+
+    if (ev->write != NXT_EVENT_INACTIVE) {
+        ev->write = NXT_EVENT_INACTIVE;
+        nxt_kqueue_fd_set(engine, ev, EVFILT_WRITE, EV_DISABLE);
+    }
+}
+
+
+static void
+nxt_kqueue_delete(nxt_event_engine_t *engine, nxt_fd_event_t *ev)
+{
+    if (ev->read != NXT_EVENT_INACTIVE) {
+        ev->read = NXT_EVENT_INACTIVE;
+        nxt_kqueue_fd_set(engine, ev, EVFILT_READ, EV_DELETE);
+    }
+
+    if (ev->write != NXT_EVENT_INACTIVE) {
+        ev->write = NXT_EVENT_INACTIVE;
+        nxt_kqueue_fd_set(engine, ev, EVFILT_WRITE, EV_DELETE);
+    }
+}
+
+
+/*
+ * kqueue(2):
+ *
+ *   Calling close() on a file descriptor will remove any kevents that
+ *   reference the descriptor.
+ *
+ * nxt_kqueue_close() always returns true as there are pending events on
+ * closing file descriptor because kevent() passes whole change list at once.
+ */
+
+static nxt_bool_t
+nxt_kqueue_close(nxt_event_engine_t *engine, nxt_fd_event_t *ev)
+{
+    ev->read = NXT_EVENT_INACTIVE;
+    ev->write = NXT_EVENT_INACTIVE;
+
+    return 1;
+}
+
+
+/*
+ * The kqueue event engine uses only three states: inactive, blocked, and
+ * active.  An active oneshot event is marked as it is in the default
+ * state.  The event will be converted eventually to the default EV_CLEAR
+ * mode after it will become inactive after delivery.
+ */
+
+static void
+nxt_kqueue_enable_read(nxt_event_engine_t *engine, nxt_fd_event_t *ev)
+{
+    if (ev->read == NXT_EVENT_INACTIVE) {
+        nxt_kqueue_fd_set(engine, ev, EVFILT_READ,
+                          EV_ADD | EV_ENABLE | EV_CLEAR);
+    }
+
+    ev->read = NXT_EVENT_ACTIVE;
+}
+
+
+static void
+nxt_kqueue_enable_write(nxt_event_engine_t *engine, nxt_fd_event_t *ev)
+{
+    if (ev->write == NXT_EVENT_INACTIVE) {
+        nxt_kqueue_fd_set(engine, ev, EVFILT_WRITE,
+                          EV_ADD | EV_ENABLE | EV_CLEAR);
+    }
+
+    ev->write = NXT_EVENT_ACTIVE;
+}
+
+
+static void
+nxt_kqueue_disable_read(nxt_event_engine_t *engine, nxt_fd_event_t *ev)
+{
+    ev->read = NXT_EVENT_INACTIVE;
+
+    nxt_kqueue_fd_set(engine, ev, EVFILT_READ, EV_DISABLE);
+}
+
+
+static void
+nxt_kqueue_disable_write(nxt_event_engine_t *engine, nxt_fd_event_t *ev)
+{
+    ev->write = NXT_EVENT_INACTIVE;
+
+    nxt_kqueue_fd_set(engine, ev, EVFILT_WRITE, EV_DISABLE);
+}
+
+
+static void
+nxt_kqueue_block_read(nxt_event_engine_t *engine, nxt_fd_event_t *ev)
+{
+    if (ev->read != NXT_EVENT_INACTIVE) {
+        ev->read = NXT_EVENT_BLOCKED;
+    }
+}
+
+
+static void
+nxt_kqueue_block_write(nxt_event_engine_t *engine, nxt_fd_event_t *ev)
+{
+    if (ev->write != NXT_EVENT_INACTIVE) {
+        ev->write = NXT_EVENT_BLOCKED;
+    }
+}
+
+
+static void
+nxt_kqueue_oneshot_read(nxt_event_engine_t *engine, nxt_fd_event_t *ev)
+{
+    ev->write = NXT_EVENT_ACTIVE;
+
+    nxt_kqueue_fd_set(engine, ev, EVFILT_WRITE,
+                      EV_ADD | EV_ENABLE | NXT_KEVENT_ONESHOT);
+}
+
+
+static void
+nxt_kqueue_oneshot_write(nxt_event_engine_t *engine, nxt_fd_event_t *ev)
+{
+    ev->write = NXT_EVENT_ACTIVE;
+
+    nxt_kqueue_fd_set(engine, ev, EVFILT_WRITE,
+                      EV_ADD | EV_ENABLE | NXT_KEVENT_ONESHOT);
+}
+
+
+static void
+nxt_kqueue_enable_accept(nxt_event_engine_t *engine, nxt_fd_event_t *ev)
+{
+    ev->read = NXT_EVENT_ACTIVE;
+    ev->read_handler = nxt_kqueue_listen_handler;
+
+    nxt_kqueue_fd_set(engine, ev, EVFILT_READ, EV_ADD | EV_ENABLE);
+}
+
+
+static void
+nxt_kqueue_enable_file(nxt_event_engine_t *engine, nxt_event_file_t *ev)
+{
+    struct kevent  *kev;
+
+    const nxt_int_t   flags = EV_ADD | EV_ENABLE | EV_ONESHOT;
+    const nxt_uint_t  fflags = NOTE_DELETE | NOTE_WRITE | NOTE_EXTEND
+                               | NOTE_ATTRIB | NOTE_RENAME | NOTE_REVOKE;
+
+    nxt_debug(&engine->task, "kevent(%d) set: id:%d ft:%i fl:%04Xd, ff:%04XuD",
+              engine->u.kqueue.fd, ev->file->fd, EVFILT_VNODE, flags, fflags);
+
+    kev = nxt_kqueue_get_kevent(engine);
+
+    kev->ident = ev->file->fd;
+    kev->filter = EVFILT_VNODE;
+    kev->flags = flags;
+    kev->fflags = fflags;
+    kev->data = 0;
+    kev->udata = nxt_kevent_set_udata(ev);
+}
+
+
+static void
+nxt_kqueue_close_file(nxt_event_engine_t *engine, nxt_event_file_t *ev)
+{
+    /* TODO: pending event. */
+}
+
+
+static void
+nxt_kqueue_fd_set(nxt_event_engine_t *engine, nxt_fd_event_t *ev,
+    nxt_int_t filter, nxt_uint_t flags)
+{
+    struct kevent  *kev;
+
+    nxt_debug(ev->task, "kevent(%d) set event: id:%d ft:%i fl:%04Xui",
+              engine->u.kqueue.fd, ev->fd, filter, flags);
+
+    kev = nxt_kqueue_get_kevent(engine);
+
+    kev->ident = ev->fd;
+    kev->filter = filter;
+    kev->flags = flags;
+    kev->fflags = 0;
+    kev->data = 0;
+    kev->udata = nxt_kevent_set_udata(ev);
+}
+
+
+static struct kevent *
+nxt_kqueue_get_kevent(nxt_event_engine_t *engine)
+{
+    int  ret, nchanges;
+
+    nchanges = engine->u.kqueue.nchanges;
+
+    if (nxt_slow_path(nchanges >= engine->u.kqueue.mchanges)) {
+
+        nxt_debug(&engine->task, "kevent(%d) changes:%d",
+                  engine->u.kqueue.fd, nchanges);
+
+        ret = kevent(engine->u.kqueue.fd, engine->u.kqueue.changes, nchanges,
+                     NULL, 0, NULL);
+
+        if (nxt_slow_path(ret != 0)) {
+            nxt_log(&engine->task, NXT_LOG_CRIT, "kevent(%d) failed %E",
+                    engine->u.kqueue.fd, nxt_errno);
+
+            nxt_kqueue_error(engine);
+        }
+
+        engine->u.kqueue.nchanges = 0;
+    }
+
+    return &engine->u.kqueue.changes[engine->u.kqueue.nchanges++];
+}
+
+
+static void
+nxt_kqueue_error(nxt_event_engine_t *engine)
+{
+    struct kevent     *kev, *end;
+    nxt_fd_event_t    *ev;
+    nxt_event_file_t  *fev;
+    nxt_work_queue_t  *wq;
+
+    wq = &engine->fast_work_queue;
+    end = &engine->u.kqueue.changes[engine->u.kqueue.nchanges];
+
+    for (kev = engine->u.kqueue.changes; kev < end; kev++) {
+
+        switch (kev->filter) {
+
+        case EVFILT_READ:
+        case EVFILT_WRITE:
+            ev = nxt_kevent_get_udata(kev->udata);
+            nxt_work_queue_add(wq, nxt_kqueue_fd_error_handler,
+                               ev->task, ev, ev->data);
+            break;
+
+        case EVFILT_VNODE:
+            fev = nxt_kevent_get_udata(kev->udata);
+            nxt_work_queue_add(wq, nxt_kqueue_file_error_handler,
+                               fev->task, fev, fev->data);
+            break;
+        }
+    }
+}
+
+
+static void
+nxt_kqueue_fd_error_handler(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_fd_event_t  *ev;
+
+    ev = obj;
+
+    if (ev->kq_eof && ev->kq_errno != 0) {
+        ev->error = ev->kq_errno;
+        nxt_log(task, nxt_socket_error_level(ev->kq_errno, ev->log_error),
+                "kevent() reported error on descriptor %d %E",
+                ev->fd, ev->kq_errno);
+    }
+
+    ev->read = NXT_EVENT_INACTIVE;
+    ev->write = NXT_EVENT_INACTIVE;
+    ev->error = ev->kq_errno;
+
+    ev->error_handler(task, ev, data);
+}
+
+
+static void
+nxt_kqueue_file_error_handler(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_event_file_t  *ev;
+
+    ev = obj;
+
+    ev->handler(task, ev, data);
+}
+
+
+static nxt_int_t
+nxt_kqueue_add_signal(nxt_event_engine_t *engine, const nxt_sig_event_t *sigev)
+{
+    int               signo;
+    struct kevent     kev;
+    struct sigaction  sa;
+
+    signo = sigev->signo;
+
+    nxt_memzero(&sa, sizeof(struct sigaction));
+    sigemptyset(&sa.sa_mask);
+
+    /*
+     * SIGCHLD must not be set to SIG_IGN, since kqueue cannot catch
+     * this signal.  It should be set to SIG_DFL instead.  And although
+     * SIGCHLD default action is also ignoring, nevertheless SIG_DFL
+     * allows kqueue to catch the signal.
+     */
+    sa.sa_handler = (signo == SIGCHLD) ? SIG_DFL : SIG_IGN;
+
+    if (sigaction(signo, &sa, NULL) != 0) {
+        nxt_log(&engine->task, NXT_LOG_CRIT, "sigaction(%d) failed %E",
+                signo, nxt_errno);
+
+        return NXT_ERROR;
+    }
+
+    nxt_debug(&engine->task, "kevent(%d) signo:%d (%s)",
+              engine->u.kqueue.fd, signo, sigev->name);
+
+    kev.ident = signo;
+    kev.filter = EVFILT_SIGNAL;
+    kev.flags = EV_ADD;
+    kev.fflags = 0;
+    kev.data = 0;
+    kev.udata = nxt_kevent_set_udata(sigev);
+
+    if (kevent(engine->u.kqueue.fd, &kev, 1, NULL, 0, NULL) == 0) {
+        return NXT_OK;
+    }
+
+    nxt_log(&engine->task, NXT_LOG_CRIT, "kevent(%d) failed %E",
+            kqueue, nxt_errno);
+
+    return NXT_ERROR;
+}
+
+
+#if (NXT_HAVE_EVFILT_USER)
+
+static nxt_int_t
+nxt_kqueue_enable_post(nxt_event_engine_t *engine, nxt_work_handler_t handler)
+{
+    struct kevent  kev;
+
+    /* EVFILT_USER must be added to a kqueue before it can be triggered. */
+
+    kev.ident = 0;
+    kev.filter = EVFILT_USER;
+    kev.flags = EV_ADD | EV_CLEAR;
+    kev.fflags = 0;
+    kev.data = 0;
+    kev.udata = NULL;
+
+    engine->u.kqueue.post_handler = handler;
+
+    if (kevent(engine->u.kqueue.fd, &kev, 1, NULL, 0, NULL) == 0) {
+        return NXT_OK;
+    }
+
+    nxt_log(&engine->task, NXT_LOG_CRIT, "kevent(%d) failed %E",
+            engine->u.kqueue.fd, nxt_errno);
+
+    return NXT_ERROR;
+}
+
+
+static void
+nxt_kqueue_signal(nxt_event_engine_t *engine, nxt_uint_t signo)
+{
+    struct kevent  kev;
+
+    /*
+     * kqueue has a builtin signal processing support, so the function
+     * is used only to post events and the signo argument is ignored.
+     */
+
+    kev.ident = 0;
+    kev.filter = EVFILT_USER;
+    kev.flags = 0;
+    kev.fflags = NOTE_TRIGGER;
+    kev.data = 0;
+    kev.udata = NULL;
+
+    if (kevent(engine->u.kqueue.fd, &kev, 1, NULL, 0, NULL) != 0) {
+        nxt_log(&engine->task, NXT_LOG_CRIT, "kevent(%d) failed %E",
+                engine->u.kqueue.fd, nxt_errno);
+    }
+}
+
+#endif
+
+
+static void
+nxt_kqueue_poll(nxt_event_engine_t *engine, nxt_msec_t timeout)
+{
+    int                 nevents;
+    void                *obj, *data;
+    nxt_int_t           i;
+    nxt_err_t           err;
+    nxt_uint_t          level;
+    nxt_bool_t          error, eof;
+    nxt_task_t          *task;
+    struct kevent       *kev;
+    nxt_fd_event_t      *ev;
+    nxt_sig_event_t     *sigev;
+    struct timespec     ts, *tp;
+    nxt_event_file_t    *fev;
+    nxt_work_queue_t    *wq;
+    nxt_work_handler_t  handler;
+
+    if (timeout == NXT_INFINITE_MSEC) {
+        tp = NULL;
+
+    } else {
+        ts.tv_sec = timeout / 1000;
+        ts.tv_nsec = (timeout % 1000) * 1000000;
+        tp = &ts;
+    }
+
+    nxt_debug(&engine->task, "kevent(%d) changes:%d timeout:%M",
+              engine->u.kqueue.fd, engine->u.kqueue.nchanges, timeout);
+
+    nevents = kevent(engine->u.kqueue.fd,
+                     engine->u.kqueue.changes, engine->u.kqueue.nchanges,
+                     engine->u.kqueue.events, engine->u.kqueue.mevents, tp);
+
+    err = (nevents == -1) ? nxt_errno : 0;
+
+    nxt_thread_time_update(engine->task.thread);
+
+    nxt_debug(&engine->task, "kevent(%d): %d", engine->u.kqueue.fd, nevents);
+
+    if (nevents == -1) {
+        level = (err == NXT_EINTR) ? NXT_LOG_INFO : NXT_LOG_CRIT;
+
+        nxt_log(&engine->task, level, "kevent(%d) failed %E",
+                engine->u.kqueue.fd, err);
+
+        nxt_kqueue_error(engine);
+        return;
+    }
+
+    engine->u.kqueue.nchanges = 0;
+
+    for (i = 0; i < nevents; i++) {
+
+        kev = &engine->u.kqueue.events[i];
+
+        nxt_debug(&engine->task,
+                  (kev->ident > 0x8000000 && kev->ident != (uintptr_t) -1) ?
+                      "kevent: id:%p ft:%d fl:%04Xd ff:%d d:%d ud:%p":
+                      "kevent: id:%d ft:%d fl:%04Xd ff:%d d:%d ud:%p",
+                  kev->ident, kev->filter, kev->flags, kev->fflags,
+                  kev->data, kev->udata);
+
+        error = (kev->flags & EV_ERROR);
+
+        if (nxt_slow_path(error)) {
+            nxt_log(&engine->task, NXT_LOG_CRIT,
+                    "kevent(%d) error %E on ident:%d filter:%d",
+                    engine->u.kqueue.fd, kev->data, kev->ident, kev->filter);
+        }
+
+        task = &engine->task;
+        wq = &engine->fast_work_queue;
+        handler = nxt_kqueue_fd_error_handler;
+        obj = nxt_kevent_get_udata(kev->udata);
+
+        switch (kev->filter) {
+
+        case EVFILT_READ:
+            ev = obj;
+            ev->read_ready = 1;
+            ev->kq_available = (int32_t) kev->data;
+            err = kev->fflags;
+            eof = (kev->flags & EV_EOF) != 0;
+            ev->kq_errno = err;
+            ev->kq_eof = eof;
+
+            if (ev->read == NXT_EVENT_BLOCKED) {
+                nxt_debug(ev->task, "blocked read event fd:%d", ev->fd);
+                continue;
+            }
+
+            if ((kev->flags & NXT_KEVENT_ONESHOT) != 0) {
+                ev->read = NXT_EVENT_INACTIVE;
+            }
+
+            if (nxt_slow_path(ev->kq_available == 0 && eof && err != 0)) {
+                error = 1;
+            }
+
+            if (nxt_fast_path(!error)) {
+                handler = ev->read_handler;
+                wq = ev->read_work_queue;
+            }
+
+            task = ev->task;
+            data = ev->data;
+
+            break;
+
+        case EVFILT_WRITE:
+            ev = obj;
+            ev->write_ready = 1;
+            err = kev->fflags;
+            eof = (kev->flags & EV_EOF) != 0;
+            ev->kq_errno = err;
+            ev->kq_eof = eof;
+
+            if (ev->write == NXT_EVENT_BLOCKED) {
+                nxt_debug(ev->task, "blocked write event fd:%d", ev->fd);
+                continue;
+            }
+
+            if ((kev->flags & NXT_KEVENT_ONESHOT) != 0) {
+                ev->write = NXT_EVENT_INACTIVE;
+            }
+
+            if (nxt_slow_path(eof && err != 0)) {
+                error = 1;
+            }
+
+            if (nxt_fast_path(!error)) {
+                handler = ev->write_handler;
+                wq = ev->write_work_queue;
+            }
+
+            task = ev->task;
+            data = ev->data;
+
+            break;
+
+        case EVFILT_VNODE:
+            fev = obj;
+            handler = fev->handler;
+            task = fev->task;
+            data = fev->data;
+            break;
+
+        case EVFILT_SIGNAL:
+            sigev = obj;
+            obj = (void *) kev->ident;
+            handler = sigev->handler;
+            data = (void *) sigev->name;
+            break;
+
+#if (NXT_HAVE_EVFILT_USER)
+
+        case EVFILT_USER:
+            handler = engine->u.kqueue.post_handler;
+            data = NULL;
+            break;
+
+#endif
+
+        default:
+
+#if (NXT_DEBUG)
+            nxt_log(&engine->task, NXT_LOG_CRIT,
+                    "unexpected kevent(%d) filter %d on ident %d",
+                    engine->u.kqueue.fd, kev->filter, kev->ident);
+#endif
+
+            continue;
+        }
+
+        nxt_work_queue_add(wq, handler, task, obj, data);
+    }
+}
+
+
+/*
+ * nxt_kqueue_event_conn_io_connect() eliminates the
+ * getsockopt() syscall to test pending connect() error.
+ */
+
+static void
+nxt_kqueue_event_conn_io_connect(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_event_conn_t              *c;
+    nxt_event_engine_t            *engine;
+    nxt_work_handler_t            handler;
+    const nxt_event_conn_state_t  *state;
+
+    c = obj;
+
+    state = c->write_state;
+
+    switch (nxt_socket_connect(c->socket.fd, c->remote) ){
+
+    case NXT_OK:
+        c->socket.write_ready = 1;
+        handler = state->ready_handler;
+        break;
+
+    case NXT_AGAIN:
+        c->socket.write_handler = nxt_kqueue_event_conn_connected;
+        c->socket.error_handler = nxt_event_conn_connect_error;
+
+        engine = task->thread->engine;
+        nxt_event_conn_timer(engine, c, state, &c->write_timer);
+
+        nxt_kqueue_enable_write(engine, &c->socket);
+        return;
+
+    case NXT_DECLINED:
+        handler = state->close_handler;
+        break;
+
+    default: /* NXT_ERROR */
+        handler = state->error_handler;
+        break;
+    }
+
+    nxt_event_conn_io_handle(task->thread, c->write_work_queue, handler, task,
+                             c, data);
+}
+
+
+static void
+nxt_kqueue_event_conn_connected(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_event_conn_t  *c;
+
+    c = obj;
+
+    nxt_debug(task, "kqueue event conn connected fd:%d", c->socket.fd);
+
+    c->socket.write = NXT_EVENT_BLOCKED;
+
+    if (c->write_state->autoreset_timer) {
+        nxt_timer_disable(task->thread->engine, &c->write_timer);
+    }
+
+    nxt_work_queue_add(c->write_work_queue, c->write_state->ready_handler,
+                       task, c, data);
+}
+
+
+static void
+nxt_kqueue_listen_handler(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_event_conn_listen_t  *cls;
+
+    cls = obj;
+
+    nxt_debug(task, "kevent fd:%d avail:%D",
+              cls->socket.fd, cls->socket.kq_available);
+
+    cls->ready = nxt_min(cls->batch, (uint32_t) cls->socket.kq_available);
+
+    nxt_kqueue_event_conn_io_accept(task, cls, data);
+}
+
+
+static void
+nxt_kqueue_event_conn_io_accept(nxt_task_t *task, void *obj, void *data)
+{
+    socklen_t                len;
+    nxt_socket_t             s;
+    struct sockaddr          *sa;
+    nxt_event_conn_t         *c;
+    nxt_event_conn_listen_t  *cls;
+
+    cls = obj;
+    c = data;
+
+    cls->ready--;
+    cls->socket.read_ready = (cls->ready != 0);
+
+    cls->socket.kq_available--;
+    cls->socket.read_ready = (cls->socket.kq_available != 0);
+
+    len = nxt_socklen(c->remote);
+
+    if (len >= sizeof(struct sockaddr)) {
+        sa = &c->remote->u.sockaddr;
+
+    } else {
+        sa = NULL;
+        len = 0;
+    }
+
+    s = accept(cls->socket.fd, sa, &len);
+
+    if (s != -1) {
+        c->socket.fd = s;
+
+        nxt_debug(task, "accept(%d): %d", cls->socket.fd, s);
+
+        nxt_event_conn_accept(task, cls, c);
+        return;
+    }
+
+    nxt_event_conn_accept_error(task, cls, "accept", nxt_errno);
+}
+
+
+/*
+ * nxt_kqueue_event_conn_io_read() is just a wrapper to eliminate the
+ * readv() or recv() syscall if a remote side just closed connection.
+ */
+
+static void
+nxt_kqueue_event_conn_io_read(nxt_task_t *task, void *obj, void *data)
+{
+    nxt_event_conn_t  *c;
+
+    c = obj;
+
+    nxt_debug(task, "kqueue event conn read fd:%d", c->socket.fd);
+
+    if (c->socket.kq_available == 0 && c->socket.kq_eof) {
+        nxt_debug(task, "kevent fd:%d eof", c->socket.fd);
+
+        c->socket.closed = 1;
+        nxt_work_queue_add(c->read_work_queue, c->read_state->close_handler,
+                           task, c, data);
+        return;
+    }
+
+    nxt_event_conn_io_read(task, c, data);
+}
+
+
+/*
+ * nxt_kqueue_event_conn_io_recvbuf() is just wrapper around standard
+ * nxt_event_conn_io_recvbuf() to eliminate the readv() or recv() syscalls
+ * if there is no pending data or a remote side closed connection.
+ */
+
+static ssize_t
+nxt_kqueue_event_conn_io_recvbuf(nxt_event_conn_t *c, nxt_buf_t *b)
+{
+    ssize_t  n;
+
+    if (c->socket.kq_available == 0 && c->socket.kq_eof) {
+        c->socket.closed = 1;
+        return 0;
+    }
+
+    n = nxt_event_conn_io_recvbuf(c, b);
+
+    if (n > 0) {
+        c->socket.kq_available -= n;
+
+        if (c->socket.kq_available < 0) {
+            c->socket.kq_available = 0;
+        }
+
+        nxt_debug(c->socket.task, "kevent fd:%d avail:%D eof:%d",
+                  c->socket.fd, c->socket.kq_available, c->socket.kq_eof);
+
+        c->socket.read_ready = (c->socket.kq_available != 0
+                                || c->socket.kq_eof);
+    }
+
+    return n;
+}