Marc Alexander Lehmann
1 year ago
10 changed files with 493 additions and 82 deletions
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+3 -0Changes
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+51 -29ev.3
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+59 -37ev.c
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+10 -9ev.h
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+2 -2ev_epoll.c
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+2 -2ev_kqueue.c
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+342 -0ev_linuxaio.c
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+2 -2ev_poll.c
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+10 -1ev_vars.h
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+12 -0ev_wrap.h
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+ 51
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ev.3
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+ 59
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ev.c
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ev.h
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ev_epoll.c
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ev_kqueue.c
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ev_linuxaio.c
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| @ -0,0 +1,342 @@ | |||
| /* | |||
| * libev linux aio 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. | |||
| */ | |||
| #include <sys/time.h> /* actually linux/time.h, but we must assume they are compatible */ | |||
| #include <linux/aio_abi.h> | |||
| /* we try to fill 4kn pages exactly. | |||
| * the ring buffer header is 32 bytes, every io event is 32 bytes. | |||
| * the kernel takes the io event number, doubles it, adds 2, adds the ring buffer | |||
| * so the calculation below will use "exactly" 8kB for the ring buffer | |||
| */ | |||
| #define EV_LINUXAIO_DEPTH (256 / 2 - 2 - 1) /* max. number of io events per batch */ | |||
| /*****************************************************************************/ | |||
| /* syscall wrapdadoop */ | |||
| #include <sys/syscall.h> /* no glibc wrappers */ | |||
| /* aio_abi.h is not verioned in any way, so we cannot test for its existance */ | |||
| #define IOCB_CMD_POLL 5 | |||
| /* taken from linux/fs/aio.c */ | |||
| #define AIO_RING_MAGIC 0xa10a10a1 | |||
| #define AIO_RING_INCOMPAT_FEATURES 0 | |||
| struct aio_ring | |||
| { | |||
| unsigned id; /* kernel internal index number */ | |||
| unsigned nr; /* number of io_events */ | |||
| unsigned head; /* Written to by userland or by kernel. */ | |||
| unsigned tail; | |||
| unsigned magic; | |||
| unsigned compat_features; | |||
| unsigned incompat_features; | |||
| unsigned header_length; /* size of aio_ring */ | |||
| struct io_event io_events[0]; | |||
| }; | |||
| static int | |||
| ev_io_setup (unsigned nr_events, aio_context_t *ctx_idp) | |||
| { | |||
| return syscall (SYS_io_setup, nr_events, ctx_idp); | |||
| } | |||
| static int | |||
| ev_io_destroy (aio_context_t ctx_id) | |||
| { | |||
| return syscall (SYS_io_destroy, ctx_id); | |||
| } | |||
| static int | |||
| ev_io_submit (aio_context_t ctx_id, long nr, struct iocb *cbp[]) | |||
| { | |||
| return syscall (SYS_io_submit, ctx_id, nr, cbp); | |||
| } | |||
| static int | |||
| ev_io_cancel (aio_context_t ctx_id, struct iocb *cbp, struct io_event *result) | |||
| { | |||
| return syscall (SYS_io_cancel, ctx_id, cbp, result); | |||
| } | |||
| static int | |||
| ev_io_getevents (aio_context_t ctx_id, long min_nr, long nr, struct io_event *events, struct timespec *timeout) | |||
| { | |||
| return syscall (SYS_io_getevents, ctx_id, min_nr, nr, events, timeout); | |||
| } | |||
| typedef void (*ev_io_cb) (long nr, struct io_event *events); | |||
| /*****************************************************************************/ | |||
| /* actual backed implementation */ | |||
| /* two iocbs for every fd, one for read, one for write */ | |||
| typedef struct aniocb | |||
| { | |||
| struct iocb io; | |||
| /*int inuse;*/ | |||
| } *ANIOCBP; | |||
| inline_size | |||
| void | |||
| linuxaio_array_needsize_iocbp (ANIOCBP *base, int count) | |||
| { | |||
| /* TODO: quite the overhead to allocate every iocb separately */ | |||
| while (count--) | |||
| { | |||
| *base = (ANIOCBP)ev_malloc (sizeof (**base)); | |||
| memset (*base, 0, sizeof (**base)); | |||
| /* would be nice to initialize fd/data as well */ | |||
| (*base)->io.aio_lio_opcode = IOCB_CMD_POLL; | |||
| ++base; | |||
| } | |||
| } | |||
| static void | |||
| linuxaio_free_iocbp (EV_P) | |||
| { | |||
| while (linuxaio_iocbpmax--) | |||
| ev_free (linuxaio_iocbps [linuxaio_iocbpmax]); | |||
| linuxaio_iocbpmax = 0; | |||
| } | |||
| static void | |||
| linuxaio_modify (EV_P_ int fd, int oev, int nev) | |||
| { | |||
| /* TODO: full zero initialize required? */ | |||
| array_needsize (ANIOCBP, linuxaio_iocbps, linuxaio_iocbpmax, fd + 1, linuxaio_array_needsize_iocbp); | |||
| struct aniocb *iocb = linuxaio_iocbps [fd]; | |||
| if (iocb->io.aio_buf) | |||
| ev_io_cancel (linuxaio_ctx, &iocb->io, (void *)0); | |||
| if (nev) | |||
| { | |||
| iocb->io.aio_data = fd; | |||
| iocb->io.aio_fildes = fd; | |||
| iocb->io.aio_buf = | |||
| (nev & EV_READ ? POLLIN : 0) | |||
| | (nev & EV_WRITE ? POLLOUT : 0); | |||
| /* queue iocb up for io_submit */ | |||
| /* this assumes we only ever get one call per fd per loop iteration */ | |||
| ++linuxaio_submitcnt; | |||
| array_needsize (struct iocb *, linuxaio_submits, linuxaio_submitmax, linuxaio_submitcnt, array_needsize_noinit); | |||
| linuxaio_submits [linuxaio_submitcnt - 1] = &iocb->io; | |||
| } | |||
| } | |||
| static void | |||
| linuxaio_parse_events (EV_P_ struct io_event *ev, int nr) | |||
| { | |||
| while (nr) | |||
| { | |||
| int fd = ev->data; | |||
| int res = ev->res; | |||
| assert (("libev: iocb fd must be in-bounds", fd >= 0 && fd < anfdxmax)); | |||
| /* linux aio is oneshot: rearm fd */ | |||
| linuxaio_iocbps [fd]->io.aio_buf = 0; | |||
| anfds [fd].events = 0; | |||
| fd_change (EV_A_ fd, 0); | |||
| /* feed events, we do not expect or handle POLLNVAL */ | |||
| if (ecb_expect_false (res & POLLNVAL)) | |||
| fd_kill (EV_A_ fd); | |||
| else | |||
| fd_event ( | |||
| EV_A_ | |||
| fd, | |||
| (res & (POLLOUT | POLLERR | POLLHUP) ? EV_WRITE : 0) | |||
| | (res & (POLLIN | POLLERR | POLLHUP) ? EV_READ : 0) | |||
| ); | |||
| --nr; | |||
| ++ev; | |||
| } | |||
| } | |||
| /* get any events from ringbuffer, return true if any were handled */ | |||
| static int | |||
| linuxaio_get_events_from_ring (EV_P) | |||
| { | |||
| struct aio_ring *ring = (struct aio_ring *)linuxaio_ctx; | |||
| ECB_MEMORY_FENCE_ACQUIRE; | |||
| unsigned head = ring->head; | |||
| unsigned tail = *(volatile unsigned *)&ring->tail; | |||
| if (ring->magic != AIO_RING_MAGIC | |||
| || ring->incompat_features != AIO_RING_INCOMPAT_FEATURES | |||
| || ring->header_length != sizeof (struct aio_ring) /* TODO: or use it to find io_event[0]? */ | |||
| || head == tail) | |||
| return 0; | |||
| /* parse all available events, but only once, to avoid starvation */ | |||
| if (tail > head) /* normal case around */ | |||
| linuxaio_parse_events (EV_A_ ring->io_events + head, tail - head); | |||
| else | |||
| { | |||
| /* wrapped around */ | |||
| linuxaio_parse_events (EV_A_ ring->io_events + head, ring->nr - head); | |||
| linuxaio_parse_events (EV_A_ ring->io_events, tail); | |||
| } | |||
| ring->head = tail; | |||
| return 1; | |||
| } | |||
| /* read at least one event from kernel, or timeout */ | |||
| inline_size | |||
| void | |||
| linuxaio_get_events (EV_P_ ev_tstamp timeout) | |||
| { | |||
| struct timespec ts; | |||
| struct io_event ioev; | |||
| int res; | |||
| if (linuxaio_get_events_from_ring (EV_A)) | |||
| return; | |||
| /* no events, so wait for at least one, then poll ring buffer again */ | |||
| /* this degraded to one event per loop iteration */ | |||
| /* if the ring buffer changes layout, but so be it */ | |||
| ts.tv_sec = (long)timeout; | |||
| ts.tv_nsec = (long)((timeout - ts.tv_sec) * 1e9); | |||
| res = ev_io_getevents (linuxaio_ctx, 1, 1, &ioev, &ts); | |||
| if (res < 0) | |||
| ev_syserr ("(libev) io_getevents"); | |||
| else if (res) | |||
| { | |||
| /* at least one event received, handle it and any remaining ones in the ring buffer */ | |||
| linuxaio_parse_events (EV_A_ &ioev, 1); | |||
| linuxaio_get_events_from_ring (EV_A); | |||
| } | |||
| } | |||
| static void | |||
| linuxaio_poll (EV_P_ ev_tstamp timeout) | |||
| { | |||
| int submitted; | |||
| /* first phase: submit new iocbs */ | |||
| /* io_submit might return less than the requested number of iocbs */ | |||
| /* this is, afaics, only because of errors, but we go by the book and use a loop, */ | |||
| /* which allows us to pinpoint the errornous iocb */ | |||
| for (submitted = 0; submitted < linuxaio_submitcnt; ) | |||
| { | |||
| int res = ev_io_submit (linuxaio_ctx, linuxaio_submitcnt - submitted, linuxaio_submits + submitted); | |||
| if (res < 0) | |||
| if (errno == EAGAIN) | |||
| { | |||
| /* This happens when the ring buffer is full, at least. I assume this means | |||
| * that the event was queued synchronously during io_submit, and thus | |||
| * the buffer overflowd. | |||
| * In this case, we just try next loop iteration. | |||
| */ | |||
| memcpy (linuxaio_submits, linuxaio_submits + submitted, (linuxaio_submitcnt - submitted) * sizeof (*linuxaio_submits)); | |||
| linuxaio_submitcnt -= submitted; | |||
| timeout = 0; | |||
| break; | |||
| } | |||
| else | |||
| /* TODO: we get EAGAIN when the ring buffer is full for some reason */ | |||
| /* TODO: should we always just try next time? */ | |||
| ev_syserr ("(libev) io_submit"); | |||
| submitted += res; | |||
| } | |||
| linuxaio_submitcnt = 0; | |||
| /* second phase: fetch and parse events */ | |||
| linuxaio_get_events (EV_A_ timeout); | |||
| } | |||
| inline_size | |||
| int | |||
| linuxaio_init (EV_P_ int flags) | |||
| { | |||
| /* would be great to have a nice test for IOCB_CMD_POLL instead */ | |||
| if (ev_linux_version () < 0x041200) /* 4.18 introduced IOCB_CMD_POLL */ | |||
| return 0; | |||
| if (ev_io_setup (EV_LINUXAIO_DEPTH, &linuxaio_ctx) < 0) | |||
| return 0; | |||
| backend_modify = linuxaio_modify; | |||
| backend_poll = linuxaio_poll; | |||
| linuxaio_iocbpmax = 0; | |||
| linuxaio_iocbps = 0; | |||
| linuxaio_submits = 0; | |||
| linuxaio_submitmax = 0; | |||
| linuxaio_submitcnt = 0; | |||
| return EVBACKEND_LINUXAIO; | |||
| } | |||
| inline_size | |||
| void | |||
| linuxaio_destroy (EV_P) | |||
| { | |||
| linuxaio_free_iocbp (EV_A); | |||
| ev_io_destroy (linuxaio_ctx); | |||
| } | |||
| inline_size | |||
| void | |||
| linuxaio_fork (EV_P) | |||
| { | |||
| abort ();//D | |||
| } | |||