Mercurial > hg > nginx
view src/os/unix/ngx_errno.c @ 7583:efd71d49bde0
Events: available bytes calculation via ioctl(FIONREAD).
This makes it possible to avoid looping for a long time while working
with a fast enough peer when data are added to the socket buffer faster
than we are able to read and process them (ticket #1431). This is
basically what we already do on FreeBSD with kqueue, where information
about the number of bytes in the socket buffer is returned by
the kevent() call.
With other event methods rev->available is now set to -1 when the socket
is ready for reading. Later in ngx_recv() and ngx_recv_chain(), if
full buffer is received, real number of bytes in the socket buffer is
retrieved using ioctl(FIONREAD). Reading more than this number of bytes
ensures that even with edge-triggered event methods the event will be
triggered again, so it is safe to stop processing of the socket and
switch to other connections.
Using ioctl(FIONREAD) only after reading a full buffer is an optimization.
With this approach we only call ioctl(FIONREAD) when there are at least
two recv()/readv() calls.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Thu, 17 Oct 2019 16:02:19 +0300 |
parents | f1a0de6eb505 |
children | 8cc5b0365ee5 |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> /* * The strerror() messages are copied because: * * 1) strerror() and strerror_r() functions are not Async-Signal-Safe, * therefore, they cannot be used in signal handlers; * * 2) a direct sys_errlist[] array may be used instead of these functions, * but Linux linker warns about its usage: * * warning: `sys_errlist' is deprecated; use `strerror' or `strerror_r' instead * warning: `sys_nerr' is deprecated; use `strerror' or `strerror_r' instead * * causing false bug reports. */ static ngx_str_t *ngx_sys_errlist; static ngx_str_t ngx_unknown_error = ngx_string("Unknown error"); u_char * ngx_strerror(ngx_err_t err, u_char *errstr, size_t size) { ngx_str_t *msg; msg = ((ngx_uint_t) err < NGX_SYS_NERR) ? &ngx_sys_errlist[err]: &ngx_unknown_error; size = ngx_min(size, msg->len); return ngx_cpymem(errstr, msg->data, size); } ngx_int_t ngx_strerror_init(void) { char *msg; u_char *p; size_t len; ngx_err_t err; /* * ngx_strerror() is not ready to work at this stage, therefore, * malloc() is used and possible errors are logged using strerror(). */ len = NGX_SYS_NERR * sizeof(ngx_str_t); ngx_sys_errlist = malloc(len); if (ngx_sys_errlist == NULL) { goto failed; } for (err = 0; err < NGX_SYS_NERR; err++) { msg = strerror(err); len = ngx_strlen(msg); p = malloc(len); if (p == NULL) { goto failed; } ngx_memcpy(p, msg, len); ngx_sys_errlist[err].len = len; ngx_sys_errlist[err].data = p; } return NGX_OK; failed: err = errno; ngx_log_stderr(0, "malloc(%uz) failed (%d: %s)", len, err, strerror(err)); return NGX_ERROR; }