release/src/router/nginx/src/os/unix/ngx_aio_write_chain.c

   1
   2 /*
   3  * Copyright (C) Igor Sysoev
   4  * Copyright (C) Nginx, Inc.
   5  */
   6
   7
   8 #include <ngx_config.h>
   9 #include <ngx_core.h>
  10 #include <ngx_event.h>
  11
  12
  13 ngx_chain_t *
  14 ngx_aio_write_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
  15 {
  16     u_char       *buf, *prev;
  17     off_t         send, sent;
  18     size_t        len;
  19     ssize_t       n, size;
  20     ngx_chain_t  *cl;
  21
  22     /* the maximum limit size is the maximum size_t value - the page size */
  23
  24     if (limit == 0 || limit > (off_t) (NGX_MAX_SIZE_T_VALUE - ngx_pagesize)) {
  25         limit = NGX_MAX_SIZE_T_VALUE - ngx_pagesize;
  26     }
  27
  28     send = 0;
  29     sent = 0;
  30     cl = in;
  31
  32     while (cl) {
  33
  34         if (cl->buf->pos == cl->buf->last) {
  35             cl = cl->next;
  36             continue;
  37         }
  38
  39         /* we can post the single aio operation only */
  40
  41         if (!c->write->ready) {
  42             return cl;
  43         }
  44
  45         buf = cl->buf->pos;
  46         prev = buf;
  47         len = 0;
  48
  49         /* coalesce the neighbouring bufs */
  50
  51         while (cl && prev == cl->buf->pos && send < limit) {
  52             if (ngx_buf_special(cl->buf)) {
  53                 continue;
  54             }
  55
  56             size = cl->buf->last - cl->buf->pos;
  57
  58             if (send + size > limit) {
  59                 size = limit - send;
  60             }
  61
  62             len += size;
  63             prev = cl->buf->pos + size;
  64             send += size;
  65             cl = cl->next;
  66         }
  67
  68         n = ngx_aio_write(c, buf, len);
  69
  70         ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "aio_write: %z", n);
  71
  72         if (n == NGX_ERROR) {
  73             return NGX_CHAIN_ERROR;
  74         }
  75
  76         if (n > 0) {
  77             sent += n;
  78             c->sent += n;
  79         }
  80
  81         ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
  82                        "aio_write sent: %O", c->sent);
  83
  84         for (cl = in; cl; cl = cl->next) {
  85
  86             if (sent >= cl->buf->last - cl->buf->pos) {
  87                 sent -= cl->buf->last - cl->buf->pos;
  88                 cl->buf->pos = cl->buf->last;
  89
  90                 continue;
  91             }
  92
  93             cl->buf->pos += sent;
  94
  95             break;
  96         }
  97     }
  98
  99     return cl;
 100 }