Stream: relaxed next upstream condition (ticket #1317). When switching to a next upstream, some buffers could be stuck in the middle of the filter chain. A condition existed that raised an error when this happened. As it turned out, this condition prevented switching to a next upstream if ssl preread was used with the TCP protocol (see the ticket). In fact, the condition does not make sense for TCP, since after successful connection to an upstream switching to another upstream never happens. As for UDP, the issue with stuck buffers is unlikely to happen, but is still possible. Specifically, if a filter delays sending data to upstream. The condition can be relaxed to only check the "buffered" bitmask of the upstream connection. The new condition is simpler and fixes the ticket issue as well. Additionally, the upstream_out chain is now reset for UDP prior to connecting to a new upstream to prevent repeating the client data twice.

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


#ifndef _NGX_PROCESS_CYCLE_H_INCLUDED_
#define _NGX_PROCESS_CYCLE_H_INCLUDED_


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


#define NGX_PROCESS_SINGLE     0
#define NGX_PROCESS_MASTER     1
#define NGX_PROCESS_SIGNALLER  2
#define NGX_PROCESS_WORKER     3


void ngx_master_process_cycle(ngx_cycle_t *cycle);
void ngx_single_process_cycle(ngx_cycle_t *cycle);
void ngx_close_handle(HANDLE h);


extern ngx_uint_t      ngx_process;
extern ngx_uint_t      ngx_worker;
extern ngx_pid_t       ngx_pid;
extern ngx_uint_t      ngx_exiting;

extern sig_atomic_t    ngx_quit;
extern sig_atomic_t    ngx_terminate;
extern sig_atomic_t    ngx_reopen;

extern ngx_uint_t      ngx_inherited;
extern ngx_pid_t       ngx_new_binary;


extern HANDLE          ngx_master_process_event;
extern char            ngx_master_process_event_name[];


#endif /* _NGX_PROCESS_CYCLE_H_INCLUDED_ */