view src/core/ngx_output_chain.c @ 9225:1c9264603adc

Syslog: introduced ngx_syslog_send() error logging moderation. Errors when logging to syslog are now logged at most once per second. This ensures that persistent errors won't flood other logs, and spontaneous errors, such as ENOBUFS as observed on BSD systems when syslogd cannot cope with load, or EAGAIN as seen in similar situation on Linux, won't further overload logging subsystem, leading to more errors. Further, errors now can only trigger reconnects at most once per second. This ensures that persistent errors, which cannot be fixed with reconnects, don't trigger too much unneeded work. Additionally, in case of connection errors, such as when syslogd is not running, connection attempts are only made once per second.
author Maxim Dounin <mdounin@mdounin.ru>
date Fri, 01 Mar 2024 05:42:12 +0300
parents b002ad258f1d
children
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>


#if 0
#define NGX_SENDFILE_LIMIT  4096
#endif

/*
 * When DIRECTIO is enabled FreeBSD, Solaris, and MacOSX read directly
 * to an application memory from a device if parameters are aligned
 * to device sector boundary (512 bytes).  They fallback to usual read
 * operation if the parameters are not aligned.
 * Linux allows DIRECTIO only if the parameters are aligned to a filesystem
 * sector boundary, otherwise it returns EINVAL.  The sector size is
 * usually 512 bytes, however, on XFS it may be 4096 bytes.
 */

#define NGX_NONE            1


static ngx_inline ngx_int_t
    ngx_output_chain_as_is(ngx_output_chain_ctx_t *ctx, ngx_buf_t *buf);
static ngx_int_t ngx_output_chain_add_copy(ngx_pool_t *pool,
    ngx_chain_t **chain, ngx_chain_t *in);
static ngx_int_t ngx_output_chain_align_file_buf(ngx_output_chain_ctx_t *ctx,
    off_t bsize);
static ngx_int_t ngx_output_chain_get_buf(ngx_output_chain_ctx_t *ctx,
    off_t bsize);
static ngx_int_t ngx_output_chain_copy_buf(ngx_output_chain_ctx_t *ctx);


ngx_int_t
ngx_output_chain(ngx_output_chain_ctx_t *ctx, ngx_chain_t *in)
{
    off_t         bsize;
    ngx_int_t     rc, last;
    ngx_chain_t  *cl, *out, **last_out;

    if (ctx->in == NULL && ctx->busy == NULL
#if (NGX_HAVE_FILE_AIO || NGX_THREADS)
        && !ctx->aio
#endif
       )
    {
        /*
         * the short path for the case when the ctx->in and ctx->busy chains
         * are empty, the incoming chain is empty too or has the single buf
         * that does not require the copy
         */

        if (in == NULL) {
            return ctx->output_filter(ctx->filter_ctx, in);
        }

        if (in->next == NULL
#if (NGX_SENDFILE_LIMIT)
            && !(in->buf->in_file && in->buf->file_last > NGX_SENDFILE_LIMIT)
#endif
            && ngx_output_chain_as_is(ctx, in->buf))
        {
            return ctx->output_filter(ctx->filter_ctx, in);
        }
    }

    /* add the incoming buf to the chain ctx->in */

    if (in) {
        if (ngx_output_chain_add_copy(ctx->pool, &ctx->in, in) == NGX_ERROR) {
            return NGX_ERROR;
        }
    }

    out = NULL;
    last_out = &out;
    last = NGX_NONE;

    for ( ;; ) {

#if (NGX_HAVE_FILE_AIO || NGX_THREADS)
        if (ctx->aio) {
            return NGX_AGAIN;
        }
#endif

        while (ctx->in) {

            /*
             * cycle while there are the ctx->in bufs
             * and there are the free output bufs to copy in
             */

            bsize = ngx_buf_size(ctx->in->buf);

            if (bsize == 0 && !ngx_buf_special(ctx->in->buf)) {

                ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, 0,
                              "zero size buf in output "
                              "t:%d r:%d f:%d %p %p-%p %p %O-%O",
                              ctx->in->buf->temporary,
                              ctx->in->buf->recycled,
                              ctx->in->buf->in_file,
                              ctx->in->buf->start,
                              ctx->in->buf->pos,
                              ctx->in->buf->last,
                              ctx->in->buf->file,
                              ctx->in->buf->file_pos,
                              ctx->in->buf->file_last);

                ngx_debug_point();

                ctx->in = ctx->in->next;

                continue;
            }

            if (bsize < 0) {

                ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, 0,
                              "negative size buf in output "
                              "t:%d r:%d f:%d %p %p-%p %p %O-%O",
                              ctx->in->buf->temporary,
                              ctx->in->buf->recycled,
                              ctx->in->buf->in_file,
                              ctx->in->buf->start,
                              ctx->in->buf->pos,
                              ctx->in->buf->last,
                              ctx->in->buf->file,
                              ctx->in->buf->file_pos,
                              ctx->in->buf->file_last);

                ngx_debug_point();

                return NGX_ERROR;
            }

            if (ngx_output_chain_as_is(ctx, ctx->in->buf)) {

                /* move the chain link to the output chain */

                cl = ctx->in;
                ctx->in = cl->next;

                *last_out = cl;
                last_out = &cl->next;
                cl->next = NULL;

                continue;
            }

            if (ctx->buf == NULL) {

                rc = ngx_output_chain_align_file_buf(ctx, bsize);

                if (rc == NGX_ERROR) {
                    return NGX_ERROR;
                }

                if (rc != NGX_OK) {

                    if (ctx->free) {

                        /* get the free buf */

                        cl = ctx->free;
                        ctx->buf = cl->buf;
                        ctx->free = cl->next;

                        ngx_free_chain(ctx->pool, cl);

                    } else if (out || ctx->allocated == ctx->bufs.num) {

                        break;

                    } else if (ngx_output_chain_get_buf(ctx, bsize) != NGX_OK) {
                        return NGX_ERROR;
                    }
                }
            }

            rc = ngx_output_chain_copy_buf(ctx);

            if (rc == NGX_ERROR) {
                return rc;
            }

            if (rc == NGX_AGAIN) {
                if (out) {
                    break;
                }

                return rc;
            }

            /* delete the completed buf from the ctx->in chain */

            if (ngx_buf_size(ctx->in->buf) == 0) {
                ctx->in = ctx->in->next;
            }

            cl = ngx_alloc_chain_link(ctx->pool);
            if (cl == NULL) {
                return NGX_ERROR;
            }

            cl->buf = ctx->buf;
            cl->next = NULL;
            *last_out = cl;
            last_out = &cl->next;
            ctx->buf = NULL;
        }

        if (out == NULL && last != NGX_NONE) {

            if (ctx->in) {
                return NGX_AGAIN;
            }

            return last;
        }

        last = ctx->output_filter(ctx->filter_ctx, out);

        if (last == NGX_ERROR || last == NGX_DONE) {
            return last;
        }

        ngx_chain_update_chains(ctx->pool, &ctx->free, &ctx->busy, &out,
                                ctx->tag);
        last_out = &out;
    }
}


static ngx_inline ngx_int_t
ngx_output_chain_as_is(ngx_output_chain_ctx_t *ctx, ngx_buf_t *buf)
{
    ngx_uint_t  sendfile;

    if (ngx_buf_special(buf)) {
        return 1;
    }

#if (NGX_THREADS)
    if (buf->in_file) {
        buf->file->thread_handler = ctx->thread_handler;
        buf->file->thread_ctx = ctx->filter_ctx;
    }
#endif

    sendfile = ctx->sendfile;

#if (NGX_SENDFILE_LIMIT)

    if (buf->in_file && buf->file_pos >= NGX_SENDFILE_LIMIT) {
        sendfile = 0;
    }

#endif

#if !(NGX_HAVE_SENDFILE_NODISKIO)

    /*
     * With DIRECTIO, disable sendfile() unless sendfile(SF_NOCACHE)
     * is available.
     */

    if (buf->in_file && buf->file->directio) {
        sendfile = 0;
    }

#endif

    if (!sendfile) {

        if (!ngx_buf_in_memory(buf)) {
            return 0;
        }

        buf->in_file = 0;
    }

    if (ctx->need_in_memory && !ngx_buf_in_memory(buf)) {
        return 0;
    }

    if (ctx->need_in_temp && (buf->memory || buf->mmap)) {
        return 0;
    }

    return 1;
}


static ngx_int_t
ngx_output_chain_add_copy(ngx_pool_t *pool, ngx_chain_t **chain,
    ngx_chain_t *in)
{
    ngx_chain_t  *cl, **ll;
#if (NGX_SENDFILE_LIMIT)
    ngx_buf_t    *b, *buf;
#endif

    ll = chain;

    for (cl = *chain; cl; cl = cl->next) {
        ll = &cl->next;
    }

    while (in) {

        cl = ngx_alloc_chain_link(pool);
        if (cl == NULL) {
            return NGX_ERROR;
        }

#if (NGX_SENDFILE_LIMIT)

        buf = in->buf;

        if (buf->in_file
            && buf->file_pos < NGX_SENDFILE_LIMIT
            && buf->file_last > NGX_SENDFILE_LIMIT)
        {
            /* split a file buf on two bufs by the sendfile limit */

            b = ngx_calloc_buf(pool);
            if (b == NULL) {
                return NGX_ERROR;
            }

            ngx_memcpy(b, buf, sizeof(ngx_buf_t));

            if (ngx_buf_in_memory(buf)) {
                buf->pos += (ssize_t) (NGX_SENDFILE_LIMIT - buf->file_pos);
                b->last = buf->pos;
            }

            buf->file_pos = NGX_SENDFILE_LIMIT;
            b->file_last = NGX_SENDFILE_LIMIT;

            cl->buf = b;

        } else {
            cl->buf = buf;
            in = in->next;
        }

#else
        cl->buf = in->buf;
        in = in->next;

#endif

        cl->next = NULL;
        *ll = cl;
        ll = &cl->next;
    }

    return NGX_OK;
}


static ngx_int_t
ngx_output_chain_align_file_buf(ngx_output_chain_ctx_t *ctx, off_t bsize)
{
    size_t      size;
    ngx_buf_t  *in;

    in = ctx->in->buf;

    if (in->file == NULL || !in->file->directio) {
        return NGX_DECLINED;
    }

    ctx->directio = 1;

    size = (size_t) (in->file_pos - (in->file_pos & ~(ctx->alignment - 1)));

    if (size == 0) {

        if (bsize >= (off_t) ctx->bufs.size) {
            return NGX_DECLINED;
        }

        size = (size_t) bsize;

    } else {
        size = (size_t) ctx->alignment - size;

        if ((off_t) size > bsize) {
            size = (size_t) bsize;
        }
    }

    ctx->buf = ngx_create_temp_buf(ctx->pool, size);
    if (ctx->buf == NULL) {
        return NGX_ERROR;
    }

    /*
     * we do not set ctx->buf->tag, because we do not want
     * to reuse the buf via ctx->free list
     */

#if (NGX_HAVE_ALIGNED_DIRECTIO)
    ctx->unaligned = 1;
#endif

    return NGX_OK;
}


static ngx_int_t
ngx_output_chain_get_buf(ngx_output_chain_ctx_t *ctx, off_t bsize)
{
    size_t       size;
    ngx_buf_t   *b, *in;
    ngx_uint_t   recycled;

    in = ctx->in->buf;
    size = ctx->bufs.size;
    recycled = 1;

    if (in->last_in_chain) {

        if (bsize < (off_t) size) {

            /*
             * allocate a small temp buf for a small last buf
             * or its small last part
             */

            size = (size_t) bsize;
            recycled = 0;

        } else if (!ctx->directio
                   && ctx->bufs.num == 1
                   && (bsize < (off_t) (size + size / 4)))
        {
            /*
             * allocate a temp buf that equals to a last buf,
             * if there is no directio, the last buf size is lesser
             * than 1.25 of bufs.size and the temp buf is single
             */

            size = (size_t) bsize;
            recycled = 0;
        }
    }

    b = ngx_calloc_buf(ctx->pool);
    if (b == NULL) {
        return NGX_ERROR;
    }

    if (ctx->directio) {

        /*
         * allocate block aligned to a disk sector size to enable
         * userland buffer direct usage conjunctly with directio
         */

        b->start = ngx_pmemalign(ctx->pool, size, (size_t) ctx->alignment);
        if (b->start == NULL) {
            return NGX_ERROR;
        }

    } else {
        b->start = ngx_palloc(ctx->pool, size);
        if (b->start == NULL) {
            return NGX_ERROR;
        }
    }

    b->pos = b->start;
    b->last = b->start;
    b->end = b->last + size;
    b->temporary = 1;
    b->tag = ctx->tag;
    b->recycled = recycled;

    ctx->buf = b;
    ctx->allocated++;

    return NGX_OK;
}


static ngx_int_t
ngx_output_chain_copy_buf(ngx_output_chain_ctx_t *ctx)
{
    off_t        size;
    ssize_t      n;
    ngx_buf_t   *src, *dst;
    ngx_uint_t   sendfile;

    src = ctx->in->buf;
    dst = ctx->buf;

    size = ngx_buf_size(src);
    size = ngx_min(size, dst->end - dst->pos);

    sendfile = ctx->sendfile && !ctx->directio;

#if (NGX_SENDFILE_LIMIT)

    if (src->in_file && src->file_pos >= NGX_SENDFILE_LIMIT) {
        sendfile = 0;
    }

#endif

    if (ngx_buf_in_memory(src)) {
        ngx_memcpy(dst->pos, src->pos, (size_t) size);
        src->pos += (size_t) size;
        dst->last += (size_t) size;

        if (src->in_file) {

            if (sendfile) {
                dst->in_file = 1;
                dst->file = src->file;
                dst->file_pos = src->file_pos;
                dst->file_last = src->file_pos + size;

            } else {
                dst->in_file = 0;
            }

            src->file_pos += size;

        } else {
            dst->in_file = 0;
        }

        if (src->pos == src->last) {
            dst->flush = src->flush;
            dst->last_buf = src->last_buf;
            dst->last_in_chain = src->last_in_chain;
        }

    } else {

#if (NGX_HAVE_ALIGNED_DIRECTIO)

        if (ctx->unaligned) {
            if (ngx_directio_off(src->file->fd) == NGX_FILE_ERROR) {
                ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, ngx_errno,
                              ngx_directio_off_n " \"%s\" failed",
                              src->file->name.data);
            }
        }

#endif

#if (NGX_HAVE_FILE_AIO)
        if (ctx->aio_handler) {
            n = ngx_file_aio_read(src->file, dst->pos, (size_t) size,
                                  src->file_pos, ctx->pool);
            if (n == NGX_AGAIN) {
                ctx->aio_handler(ctx, src->file);
                return NGX_AGAIN;
            }

        } else
#endif
#if (NGX_THREADS)
        if (ctx->thread_handler) {
            src->file->thread_task = ctx->thread_task;
            src->file->thread_handler = ctx->thread_handler;
            src->file->thread_ctx = ctx->filter_ctx;

            n = ngx_thread_read(src->file, dst->pos, (size_t) size,
                                src->file_pos, ctx->pool);
            if (n == NGX_AGAIN) {
                ctx->thread_task = src->file->thread_task;
                return NGX_AGAIN;
            }

        } else
#endif
        {
            n = ngx_read_file(src->file, dst->pos, (size_t) size,
                              src->file_pos);
        }

#if (NGX_HAVE_ALIGNED_DIRECTIO)

        if (ctx->unaligned) {
            ngx_err_t  err;

            err = ngx_errno;

            if (ngx_directio_on(src->file->fd) == NGX_FILE_ERROR) {
                ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, ngx_errno,
                              ngx_directio_on_n " \"%s\" failed",
                              src->file->name.data);
            }

            ngx_set_errno(err);

            ctx->unaligned = 0;
        }

#endif

        if (n == NGX_ERROR) {
            return (ngx_int_t) n;
        }

        if (n != size) {
            ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, 0,
                          ngx_read_file_n " read only %z of %O from \"%s\"",
                          n, size, src->file->name.data);
            return NGX_ERROR;
        }

        dst->last += n;

        if (sendfile) {
            dst->in_file = 1;
            dst->file = src->file;
            dst->file_pos = src->file_pos;
            dst->file_last = src->file_pos + n;

        } else {
            dst->in_file = 0;
        }

        src->file_pos += n;

        if (src->file_pos == src->file_last) {
            dst->flush = src->flush;
            dst->last_buf = src->last_buf;
            dst->last_in_chain = src->last_in_chain;
        }
    }

    return NGX_OK;
}


ngx_int_t
ngx_chain_writer(void *data, ngx_chain_t *in)
{
    ngx_chain_writer_ctx_t *ctx = data;

    off_t              size;
    ngx_chain_t       *cl, *ln, *chain;
    ngx_connection_t  *c;

    c = ctx->connection;

    for (size = 0; in; in = in->next) {

        if (ngx_buf_size(in->buf) == 0 && !ngx_buf_special(in->buf)) {

            ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, 0,
                          "zero size buf in chain writer "
                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
                          in->buf->temporary,
                          in->buf->recycled,
                          in->buf->in_file,
                          in->buf->start,
                          in->buf->pos,
                          in->buf->last,
                          in->buf->file,
                          in->buf->file_pos,
                          in->buf->file_last);

            ngx_debug_point();

            continue;
        }

        if (ngx_buf_size(in->buf) < 0) {

            ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, 0,
                          "negative size buf in chain writer "
                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
                          in->buf->temporary,
                          in->buf->recycled,
                          in->buf->in_file,
                          in->buf->start,
                          in->buf->pos,
                          in->buf->last,
                          in->buf->file,
                          in->buf->file_pos,
                          in->buf->file_last);

            ngx_debug_point();

            return NGX_ERROR;
        }

        size += ngx_buf_size(in->buf);

        ngx_log_debug2(NGX_LOG_DEBUG_CORE, c->log, 0,
                       "chain writer buf fl:%d s:%uO",
                       in->buf->flush, ngx_buf_size(in->buf));

        cl = ngx_alloc_chain_link(ctx->pool);
        if (cl == NULL) {
            return NGX_ERROR;
        }

        cl->buf = in->buf;
        cl->next = NULL;
        *ctx->last = cl;
        ctx->last = &cl->next;
    }

    ngx_log_debug1(NGX_LOG_DEBUG_CORE, c->log, 0,
                   "chain writer in: %p", ctx->out);

    for (cl = ctx->out; cl; cl = cl->next) {

        if (ngx_buf_size(cl->buf) == 0 && !ngx_buf_special(cl->buf)) {

            ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, 0,
                          "zero size buf in chain writer "
                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
                          cl->buf->temporary,
                          cl->buf->recycled,
                          cl->buf->in_file,
                          cl->buf->start,
                          cl->buf->pos,
                          cl->buf->last,
                          cl->buf->file,
                          cl->buf->file_pos,
                          cl->buf->file_last);

            ngx_debug_point();

            continue;
        }

        if (ngx_buf_size(cl->buf) < 0) {

            ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, 0,
                          "negative size buf in chain writer "
                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
                          cl->buf->temporary,
                          cl->buf->recycled,
                          cl->buf->in_file,
                          cl->buf->start,
                          cl->buf->pos,
                          cl->buf->last,
                          cl->buf->file,
                          cl->buf->file_pos,
                          cl->buf->file_last);

            ngx_debug_point();

            return NGX_ERROR;
        }

        size += ngx_buf_size(cl->buf);
    }

    if (size == 0 && !c->buffered) {
        return NGX_OK;
    }

    chain = c->send_chain(c, ctx->out, ctx->limit);

    ngx_log_debug1(NGX_LOG_DEBUG_CORE, c->log, 0,
                   "chain writer out: %p", chain);

    if (chain == NGX_CHAIN_ERROR) {
        return NGX_ERROR;
    }

    if (chain && c->write->ready) {
        ngx_post_event(c->write, &ngx_posted_next_events);
    }

    for (cl = ctx->out; cl && cl != chain; /* void */) {
        ln = cl;
        cl = cl->next;
        ngx_free_chain(ctx->pool, ln);
    }

    ctx->out = chain;

    if (ctx->out == NULL) {
        ctx->last = &ctx->out;

        if (!c->buffered) {
            return NGX_OK;
        }
    }

    return NGX_AGAIN;
}