redundancy_multi_site.h File Reference

Multi-Site 2oo2 Redundancy with Active/Standby Failover. More...

#include <stdint.h>
#include <stdbool.h>

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Data Structures
struct	train_command_t
struct	site_channels_t
struct	site_stats_t
struct	site_context_t
struct	multi_site_config_t
struct	multi_site_voter_t

Enumerations
enum	site_id_t { SITE_WEST = 0 , SITE_EAST = 1 }
enum	site_state_t { SITE_STATE_ONLINE = 0 , SITE_STATE_STANDBY = 1 , SITE_STATE_ISOLATED = 2 , SITE_STATE_FAULTY = 3 }

Functions
int	multi_site_voter_init (multi_site_voter_t *voter, const multi_site_config_t *config)
	Initialize multi-site voter with West online, East standby.
int	multi_site_vote_cycle (multi_site_voter_t *voter, site_id_t site, const train_command_t *cmd_a, const train_command_t *cmd_b)
	Process voting cycle on one site.
site_id_t	multi_site_heartbeat (multi_site_voter_t *voter)
	Check heartbeat between sites and trigger failover if needed.
int	multi_site_failover_request (multi_site_voter_t *voter, site_id_t new_active)
	Trigger manual failover (for maintenance).
int	multi_site_get_active_command (multi_site_voter_t *voter, train_command_t *cmd_out)
	Get voted command from currently active site.
int	multi_site_get_service_output (multi_site_voter_t *voter, char *output_buf, uint32_t buf_size)
	Get service output from active site (for printf, logging).
void	multi_site_print_stats (const multi_site_voter_t *voter)
	Print multi-site statistics for diagnostics.
int	multi_site_voter_shutdown (multi_site_voter_t *voter)
	Shutdown multi-site voter.

Detailed Description

Multi-Site 2oo2 Redundancy with Active/Standby Failover.

Implements geographic redundancy for railway control systems:

• West site (ONLINE): Active processing channel
• East site (STANDBY): Backup ready to take over
• Each site has 2oo2 voting (channels A, B) + service channel C
• Automatic failover on site failure

Typical deployment: ERTMS RBC with dual control centers

• West: Primary RBC (Madrid)
• East: Backup RBC (Barcelona) - standby, synced via heartbeat

Definition in file redundancy_multi_site.h.

Enumeration Type Documentation

site_id_t

enum site_id_t

Definition at line 32 of file redundancy_multi_site.h.

site_state_t

enum site_state_t

Definition at line 37 of file redundancy_multi_site.h.

Function Documentation

multi_site_voter_init()

int multi_site_voter_init	(	multi_site_voter_t *	voter,
		const multi_site_config_t *	config )

Initialize multi-site voter with West online, East standby.

Parameters

voter	Multi-site voter state
config	Configuration

Returns

0 if OK, -1 on error

Definition at line 138 of file redundancy_multi_site.c.

multi_site_vote_cycle()

int multi_site_vote_cycle	(	multi_site_voter_t *	voter,
		site_id_t	site,
		const train_command_t *	cmd_a,
		const train_command_t *	cmd_b )

Process voting cycle on one site.

Each site independently:

1. Receives/computes commands from channels A, B
2. Votes (2oo2 comparison)
3. Outputs result via service channel C

Parameters

voter	Multi-site state
site	Which site (WEST or EAST)
cmd_a	Channel A command
cmd_b	Channel B command

Returns

0 if voting OK, -1 on fatal error

Definition at line 173 of file redundancy_multi_site.c.

multi_site_heartbeat()

site_id_t multi_site_heartbeat

(

multi_site_voter_t *

voter

)

Check heartbeat between sites and trigger failover if needed.

Called periodically to:

• Check if standby site is still responsive
• Detect if active site has failed
• Transition standby to ONLINE if active is down

Parameters

voter

Multi-site state

Returns

SITE_WEST or SITE_EAST (current active site)

Definition at line 195 of file redundancy_multi_site.c.

multi_site_failover_request()

int multi_site_failover_request	(	multi_site_voter_t *	voter,
		site_id_t	new_active )

Trigger manual failover (for maintenance).

Parameters

voter	Multi-site state
new_active	New active site

Returns

0 if OK

Allows graceful switchover without waiting for timeout. Example: "Switch to East for maintenance on West"

Definition at line 254 of file redundancy_multi_site.c.

multi_site_get_active_command()

int multi_site_get_active_command	(	multi_site_voter_t *	voter,
		train_command_t *	cmd_out )

Get voted command from currently active site.

Parameters

voter	Multi-site state
cmd_out	Receives voted command

Returns

0 if OK

Definition at line 285 of file redundancy_multi_site.c.

multi_site_get_service_output()

int multi_site_get_service_output	(	multi_site_voter_t *	voter,
		char *	output_buf,
		uint32_t	buf_size )

Get service output from active site (for printf, logging).

Parameters

voter	Multi-site state
output_buf	Buffer to receive output
buf_size	Size of buffer

Returns

Number of bytes written

Definition at line 303 of file redundancy_multi_site.c.

multi_site_print_stats()

void multi_site_print_stats

(

const multi_site_voter_t *

voter

)

Print multi-site statistics for diagnostics.

Parameters

voter

Multi-site state

Definition at line 324 of file redundancy_multi_site.c.

multi_site_voter_shutdown()

int multi_site_voter_shutdown

(

multi_site_voter_t *

voter

)

Shutdown multi-site voter.

Parameters

voter

Multi-site state

Returns

0 if OK

Definition at line 364 of file redundancy_multi_site.c.