Mercurial > hg > nginx
view src/os/unix/ngx_writev_chain.c @ 4596:089cc5154c1e
IOV_MAX handling microoptimization.
We now stop on IOV_MAX iovec entries only if we are going to add new one,
i.e. next buffer can't be coalesced into last iovec.
This also fixes incorrect checks for trailer creation on FreeBSD and
Mac OS X, header.nelts was checked instead of trailer.nelts.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Tue, 17 Apr 2012 09:13:15 +0000 |
parents | 6cd5d4a279d6 |
children | f9c83484d9ce |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_event.h> #if (IOV_MAX > 64) #define NGX_IOVS 64 #else #define NGX_IOVS IOV_MAX #endif ngx_chain_t * ngx_writev_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit) { u_char *prev; ssize_t n, size, sent; off_t send, prev_send; ngx_uint_t eintr, complete; ngx_err_t err; ngx_array_t vec; ngx_chain_t *cl; ngx_event_t *wev; struct iovec *iov, iovs[NGX_IOVS]; wev = c->write; if (!wev->ready) { return in; } #if (NGX_HAVE_KQUEUE) if ((ngx_event_flags & NGX_USE_KQUEUE_EVENT) && wev->pending_eof) { (void) ngx_connection_error(c, wev->kq_errno, "kevent() reported about an closed connection"); wev->error = 1; return NGX_CHAIN_ERROR; } #endif /* the maximum limit size is the maximum size_t value - the page size */ if (limit == 0 || limit > (off_t) (NGX_MAX_SIZE_T_VALUE - ngx_pagesize)) { limit = NGX_MAX_SIZE_T_VALUE - ngx_pagesize; } send = 0; vec.elts = iovs; vec.size = sizeof(struct iovec); vec.nalloc = NGX_IOVS; vec.pool = c->pool; for ( ;; ) { prev = NULL; iov = NULL; eintr = 0; complete = 0; prev_send = send; vec.nelts = 0; /* create the iovec and coalesce the neighbouring bufs */ for (cl = in; cl && send < limit; cl = cl->next) { if (ngx_buf_special(cl->buf)) { continue; } #if 1 if (!ngx_buf_in_memory(cl->buf)) { ngx_debug_point(); } #endif size = cl->buf->last - cl->buf->pos; if (send + size > limit) { size = (ssize_t) (limit - send); } if (prev == cl->buf->pos) { iov->iov_len += size; } else { if (vec.nelts >= IOV_MAX) { break; } iov = ngx_array_push(&vec); if (iov == NULL) { return NGX_CHAIN_ERROR; } iov->iov_base = (void *) cl->buf->pos; iov->iov_len = size; } prev = cl->buf->pos + size; send += size; } n = writev(c->fd, vec.elts, vec.nelts); if (n == -1) { err = ngx_errno; switch (err) { case NGX_EAGAIN: break; case NGX_EINTR: eintr = 1; break; default: wev->error = 1; (void) ngx_connection_error(c, err, "writev() failed"); return NGX_CHAIN_ERROR; } ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, err, "writev() not ready"); } sent = n > 0 ? n : 0; ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "writev: %z", sent); if (send - prev_send == sent) { complete = 1; } c->sent += sent; for (cl = in; cl; cl = cl->next) { if (ngx_buf_special(cl->buf)) { continue; } if (sent == 0) { break; } size = cl->buf->last - cl->buf->pos; if (sent >= size) { sent -= size; cl->buf->pos = cl->buf->last; continue; } cl->buf->pos += sent; break; } if (eintr) { continue; } if (!complete) { wev->ready = 0; return cl; } if (send >= limit || cl == NULL) { return cl; } in = cl; } }