Merge of r4622, r4623: balancing changes. *) Upstream: smooth weighted round-robin balancing. For edge case weights like { 5, 1, 1 } we now produce { a, a, b, a, c, a, a } sequence instead of { c, b, a, a, a, a, a } produced previously. Algorithm is as follows: on each peer selection we increase current_weight of each eligible peer by its weight, select peer with greatest current_weight and reduce its current_weight by total number of weight points distributed among peers. In case of { 5, 1, 1 } weights this gives the following sequence of current_weight's: a b c 0 0 0 (initial state) 5 1 1 (a selected) -2 1 1 3 2 2 (a selected) -4 2 2 1 3 3 (b selected) 1 -4 3 6 -3 4 (a selected) -1 -3 4 4 -2 5 (c selected) 4 -2 -2 9 -1 -1 (a selected) 2 -1 -1 7 0 0 (a selected) 0 0 0 To preserve weight reduction in case of failures the effective_weight variable was introduced, which usually matches peer's weight, but is reduced temporarily on peer failures. This change also fixes loop with backup servers and proxy_next_upstream http_404 (ticket #47), and skipping alive upstreams in some cases if there are multiple dead ones (ticket #64). *) Upstream: fixed ip_hash rebalancing with the "down" flag. Due to weight being set to 0 for down peers, order of peers after sorting wasn't the same as without the "down" flag (with down peers at the end), resulting in client rebalancing for clients on other servers. The only rebalancing which should happen after adding "down" to a server is one for clients on the server. The problem was introduced in r1377 (which fixed endless loop by setting weight to 0 for down servers). The loop is no longer possible with new smooth algorithm, so preserving original weight is safe.

/*
 * 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_CMD_OPEN_CHANNEL   1
#define NGX_CMD_CLOSE_CHANNEL  2
#define NGX_CMD_QUIT           3
#define NGX_CMD_TERMINATE      4
#define NGX_CMD_REOPEN         5


#define NGX_PROCESS_SINGLE     0
#define NGX_PROCESS_MASTER     1
#define NGX_PROCESS_SIGNALLER  2
#define NGX_PROCESS_WORKER     3
#define NGX_PROCESS_HELPER     4


typedef struct {
    ngx_event_handler_pt       handler;
    char                      *name;
    ngx_msec_t                 delay;
} ngx_cache_manager_ctx_t;


void ngx_master_process_cycle(ngx_cycle_t *cycle);
void ngx_single_process_cycle(ngx_cycle_t *cycle);


extern ngx_uint_t      ngx_process;
extern ngx_pid_t       ngx_pid;
extern ngx_pid_t       ngx_new_binary;
extern ngx_uint_t      ngx_inherited;
extern ngx_uint_t      ngx_daemonized;
extern ngx_uint_t      ngx_threaded;
extern ngx_uint_t      ngx_exiting;

extern sig_atomic_t    ngx_reap;
extern sig_atomic_t    ngx_sigio;
extern sig_atomic_t    ngx_sigalrm;
extern sig_atomic_t    ngx_quit;
extern sig_atomic_t    ngx_debug_quit;
extern sig_atomic_t    ngx_terminate;
extern sig_atomic_t    ngx_noaccept;
extern sig_atomic_t    ngx_reconfigure;
extern sig_atomic_t    ngx_reopen;
extern sig_atomic_t    ngx_change_binary;


#endif /* _NGX_PROCESS_CYCLE_H_INCLUDED_ */