diff options
author | Valentin Bartenev <vbart@nginx.com> | 2015-03-19 19:29:43 +0300 |
---|---|---|
committer | Valentin Bartenev <vbart@nginx.com> | 2015-03-19 19:29:43 +0300 |
commit | cc569b92528373694ae3ebc3649b35c9fb6ba540 (patch) | |
tree | d7c730171a8f7b2c65328d6e835968192131906b /src/core/ngx_log.c | |
parent | babd64e344331ec4751dcb191eb4e847e3b36a4a (diff) |
Core: added cyclic memory buffer support for error_log.
Example of usage:
error_log memory:16m debug;
This allows to configure debug logging with minimum impact on performance.
It's especially useful when rare crashes are experienced under high load.
The log can be extracted from a coredump using the following gdb script:
set $log = ngx_cycle->log
while $log->writer != ngx_log_memory_writer
set $log = $log->next
end
set $buf = (ngx_log_memory_buf_t *) $log->wdata
dump binary memory debug_log.txt $buf->start $buf->end
Diffstat (limited to 'src/core/ngx_log.c')
-rw-r--r-- | src/core/ngx_log.c | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/src/core/ngx_log.c b/src/core/ngx_log.c index bfda8eea3..bf0050885 100644 --- a/src/core/ngx_log.c +++ b/src/core/ngx_log.c @@ -14,6 +14,23 @@ static char *ngx_log_set_levels(ngx_conf_t *cf, ngx_log_t *log); static void ngx_log_insert(ngx_log_t *log, ngx_log_t *new_log); +#if (NGX_DEBUG) + +static void ngx_log_memory_writer(ngx_log_t *log, ngx_uint_t level, + u_char *buf, size_t len); +static void ngx_log_memory_cleanup(void *data); + + +typedef struct { + u_char *start; + u_char *end; + u_char *pos; + ngx_atomic_t written; +} ngx_log_memory_buf_t; + +#endif + + static ngx_command_t ngx_errlog_commands[] = { {ngx_string("error_log"), @@ -568,6 +585,64 @@ ngx_log_set_log(ngx_conf_t *cf, ngx_log_t **head) return NGX_CONF_ERROR; } + } else if (ngx_strncmp(value[1].data, "memory:", 7) == 0) { + +#if (NGX_DEBUG) + size_t size, needed; + ngx_pool_cleanup_t *cln; + ngx_log_memory_buf_t *buf; + + value[1].len -= 7; + value[1].data += 7; + + needed = sizeof("MEMLOG :" NGX_LINEFEED) + + cf->conf_file->file.name.len + + NGX_SIZE_T_LEN + + NGX_INT_T_LEN + + NGX_MAX_ERROR_STR; + + size = ngx_parse_size(&value[1]); + + if (size == (size_t) NGX_ERROR || size < needed) { + ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, + "invalid buffer size \"%V\"", &value[1]); + return NGX_CONF_ERROR; + } + + buf = ngx_palloc(cf->pool, sizeof(ngx_log_memory_buf_t)); + if (buf == NULL) { + return NGX_CONF_ERROR; + } + + buf->start = ngx_pnalloc(cf->pool, size); + if (buf->start == NULL) { + return NGX_CONF_ERROR; + } + + buf->end = buf->start + size; + + buf->pos = ngx_slprintf(buf->start, buf->end, "MEMLOG %uz %V:%ui%N", + size, &cf->conf_file->file.name, + cf->conf_file->line); + + ngx_memset(buf->pos, ' ', buf->end - buf->pos); + + cln = ngx_pool_cleanup_add(cf->pool, 0); + if (cln == NULL) { + return NGX_CONF_ERROR; + } + + cln->data = new_log; + cln->handler = ngx_log_memory_cleanup; + + new_log->writer = ngx_log_memory_writer; + new_log->wdata = buf; + +#else + ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, + "nginx was built without debug support"); + return NGX_CONF_ERROR; +#endif } else if (ngx_strncmp(value[1].data, "syslog:", 7) == 0) { peer = ngx_pcalloc(cf->pool, sizeof(ngx_syslog_peer_t)); @@ -633,3 +708,48 @@ ngx_log_insert(ngx_log_t *log, ngx_log_t *new_log) log->next = new_log; } + + +#if (NGX_DEBUG) + +static void +ngx_log_memory_writer(ngx_log_t *log, ngx_uint_t level, u_char *buf, + size_t len) +{ + u_char *p; + size_t avail, written; + ngx_log_memory_buf_t *mem; + + mem = log->wdata; + + if (mem == NULL) { + return; + } + + written = ngx_atomic_fetch_add(&mem->written, len); + + p = mem->pos + written % (mem->end - mem->pos); + + avail = mem->end - p; + + if (avail >= len) { + ngx_memcpy(p, buf, len); + + } else { + ngx_memcpy(p, buf, avail); + ngx_memcpy(mem->pos, buf + avail, len - avail); + } +} + + +static void +ngx_log_memory_cleanup(void *data) +{ + ngx_log_t *log = data; + + ngx_log_debug0(NGX_LOG_DEBUG_CORE, log, 0, "destroy memory log buffer"); + + log->wdata = NULL; +} + +#endif |