Simple timeout module

[donatasm]

I'm trying to build a simple timeout module using nginx timers. At the
beginning of a request I'm firing up a timer and after time interval elapses
I want to check if request has already completed, and if not, finalize it,
for example it with NGX_HTTP_REQUEST_TIME_OUT. I have created a filter
module. I'm creating a timer in filter headers:

static ngx_int_t simple_timeout_filter_headers(ngx_http_request_t* request)
{
  ngx_event_t* timeout_event;

  timeout_event = ngx_pcalloc(request->pool, sizeof(ngx_event_t));
  if (timeout_event == NULL)
  {
    return NGX_ERROR;
  }

  timeout_event->handler = simple_timeout_handler;
  timeout_event->data = request;
  timeout_event->log = request->connection->log;

  ngx_log_debug0(NGX_LOG_DEBUG_HTTP, request->connection->log, 0,
      "SIMPLE TIMEOUT TIMER START");

  ngx_add_timer(timeout_event, 3000); /* wait for 3 seconds */

  return next_header_filter(request);
}

Simple timeout handler looks like this:

static void simple_timeout_handler(ngx_event_t* timeout_event)
{
  ngx_log_debug0(NGX_LOG_DEBUG_HTTP, timeout_event->log, 0,
      "SIMPLE TIMEOUT TIMER END");
}

And it works if I issue a request, and wait for a timer to fire. If I issue
several requests while the previous timer is already in progress, I get a
SEGFAULT. 

A SEGFAULT happens here, while inserting a node into rbtree:

ngx_rbtree_insert() at ngx_rbtree.c:32 0x40d3c0	
ngx_event_add_timer() at ngx_event_timer.h:84 0x42fc32	
ngx_http_init_connection() at ngx_http_request.c:363 0x42fc32	
ngx_event_accept() at ngx_event_accept.c:360 0x41c9ec	
ngx_epoll_process_events() at ngx_epoll_module.c:822 0x424a00	
ngx_process_events_and_timers() at ngx_event.c:248 0x41bb2c	
ngx_single_process_cycle() at ngx_process_cycle.c:308 0x423c8b	
main() at nginx.c:416 0x403bc6	


So what I'm missing in my simple_timeout_filter_headers method?

Nginx version 1.8

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,259019,259019#msg-259019