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src/os/unix/ngx_file_aio_read.c - nginx source code

Functions defined

Source code


  2. /*
  3. * Copyright (C) Igor Sysoev
  4. * Copyright (C) Nginx, Inc.
  5. */


  8. #include <ngx_config.h>
  9. #include <ngx_core.h>
  10. #include <ngx_event.h>


  13. /*
  14. * FreeBSD file AIO features and quirks:
  15. *
  16. *    if an asked data are already in VM cache, then aio_error() returns 0,
  17. *    and the data are already copied in buffer;
  18. *
  19. *    aio_read() preread in VM cache as minimum 16K (probably BKVASIZE);
  20. *    the first AIO preload may be up to 128K;
  21. *
  22. *    aio_read/aio_error() may return EINPROGRESS for just written data;
  23. *
  24. *    kqueue EVFILT_AIO filter is level triggered only: an event repeats
  25. *    until aio_return() will be called;
  26. *
  27. *    aio_cancel() cannot cancel file AIO: it returns AIO_NOTCANCELED always.
  28. */


  31. extern int  ngx_kqueue;


  34. static ssize_t ngx_file_aio_result(ngx_file_t *file, ngx_event_aio_t *aio,
  35.     ngx_event_t *ev);
  36. static void ngx_file_aio_event_handler(ngx_event_t *ev);


  39. ngx_int_t
  40. ‌ngx_file_aio_init(ngx_file_t *file, ngx_pool_t *pool)
  41. {
  42.     ngx_event_aio_t  *aio;

  44.     aio = ngx_pcalloc(pool, sizeof(ngx_event_aio_t));
  45.     if (aio == NULL) {
  46.         return NGX_ERROR;
  47.     }

  49.     aio->file = file;
  50.     aio->fd = file->fd;
  51.     aio->event.data = aio;
  52.     aio->event.ready = 1;
  53.     aio->event.log = file->log;

  55.     file->aio = aio;

  57.     return NGX_OK;
  58. }


  61. ssize_t
  62. ‌ngx_file_aio_read(ngx_file_t *file, u_char *buf, size_t size, off_t offset,
  63.     ngx_pool_t *pool)
  64. {
  65.     int               n;
  66.     ngx_event_t      *ev;
  67.     ngx_event_aio_t  *aio;

  69.     if (!ngx_file_aio) {
  70.         return ngx_read_file(file, buf, size, offset);
  71.     }

  73.     if (file->aio == NULL && ngx_file_aio_init(file, pool) != NGX_OK) {
  74.         return NGX_ERROR;
  75.     }

  77.     aio = file->aio;
  78.     ev = &aio->event;

  80.     if (!ev->ready) {
  81.         ngx_log_error(NGX_LOG_ALERT, file->log, 0,
  82.                       "second aio post for \"%V\"", &file->name);
  83.         return NGX_AGAIN;
  84.     }

  86.     ngx_log_debug4(NGX_LOG_DEBUG_CORE, file->log, 0,
  87.                    "aio complete:%d @%O:%uz %V",
  88.                    ev->complete, offset, size, &file->name);

  90.     if (ev->complete) {
  91.         ev->complete = 0;
  92.         ngx_set_errno(aio->err);

  94.         if (aio->err == 0) {
  95.             return aio->nbytes;
  96.         }

  98.         ngx_log_error(NGX_LOG_CRIT, file->log, ngx_errno,
  99.                       "aio read \"%s\" failed", file->name.data);

  101.         return NGX_ERROR;
  102.     }

  104.     ngx_memzero(&aio->aiocb, sizeof(struct aiocb));

  106.     aio->aiocb.aio_fildes = file->fd;
  107.     aio->aiocb.aio_offset = offset;
  108.     aio->aiocb.aio_buf = buf;
  109.     aio->aiocb.aio_nbytes = size;
  110. #if (NGX_HAVE_KQUEUE)
  111.     aio->aiocb.aio_sigevent.sigev_notify_kqueue = ngx_kqueue;
  112.     aio->aiocb.aio_sigevent.sigev_notify = SIGEV_KEVENT;
  113.     aio->aiocb.aio_sigevent.sigev_value.sival_ptr = ev;
  114. #endif
  115.     ev->handler = ngx_file_aio_event_handler;

  117.     n = aio_read(&aio->aiocb);

  119.     if (n == -1) {
  120.         n = ngx_errno;

  122.         if (n == NGX_EAGAIN) {
  123.             return ngx_read_file(file, buf, size, offset);
  124.         }

  126.         ngx_log_error(NGX_LOG_CRIT, file->log, n,
  127.                       "aio_read(\"%V\") failed", &file->name);

  129.         if (n == NGX_ENOSYS) {
  130.             ngx_file_aio = 0;
  131.             return ngx_read_file(file, buf, size, offset);
  132.         }

  134.         return NGX_ERROR;
  135.     }

  137.     ngx_log_debug2(NGX_LOG_DEBUG_CORE, file->log, 0,
  138.                    "aio_read: fd:%d %d", file->fd, n);

  140.     ev->active = 1;
  141.     ev->ready = 0;
  142.     ev->complete = 0;

  144.     return ngx_file_aio_result(aio->file, aio, ev);
  145. }


  148. static ssize_t
  149. ‌ngx_file_aio_result(ngx_file_t *file, ngx_event_aio_t *aio, ngx_event_t *ev)
  150. {
  151.     int        n;
  152.     ngx_err_t  err;

  154.     n = aio_error(&aio->aiocb);

  156.     ngx_log_debug2(NGX_LOG_DEBUG_CORE, file->log, 0,
  157.                    "aio_error: fd:%d %d", file->fd, n);

  159.     if (n == -1) {
  160.         err = ngx_errno;
  161.         aio->err = err;

  163.         ngx_log_error(NGX_LOG_ALERT, file->log, err,
  164.                       "aio_error(\"%V\") failed", &file->name);
  165.         return NGX_ERROR;
  166.     }

  168.     if (n == NGX_EINPROGRESS) {
  169.         if (ev->ready) {
  170.             ev->ready = 0;
  171.             ngx_log_error(NGX_LOG_ALERT, file->log, n,
  172.                           "aio_read(\"%V\") still in progress",
  173.                           &file->name);
  174.         }

  176.         return NGX_AGAIN;
  177.     }

  179.     n = aio_return(&aio->aiocb);

  181.     if (n == -1) {
  182.         err = ngx_errno;
  183.         aio->err = err;
  184.         ev->ready = 1;

  186.         ngx_log_error(NGX_LOG_CRIT, file->log, err,
  187.                       "aio_return(\"%V\") failed", &file->name);
  188.         return NGX_ERROR;
  189.     }

  191.     aio->err = 0;
  192.     aio->nbytes = n;
  193.     ev->ready = 1;
  194.     ev->active = 0;

  196.     ngx_log_debug2(NGX_LOG_DEBUG_CORE, file->log, 0,
  197.                    "aio_return: fd:%d %d", file->fd, n);

  199.     return n;
  200. }


  203. static void
  204. ‌ngx_file_aio_event_handler(ngx_event_t *ev)
  205. {
  206.     ngx_event_aio_t  *aio;

  208.     aio = ev->data;

  210.     ngx_log_debug2(NGX_LOG_DEBUG_CORE, ev->log, 0,
  211.                    "aio event handler fd:%d %V", aio->fd, &aio->file->name);

  213.     if (ngx_file_aio_result(aio->file, aio, ev) != NGX_AGAIN) {
  214.         aio->handler(ev);
  215.     }
  216. }

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