redundancy_multi_site.h

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#ifndef REDUNDANCY_MULTI_SITE_H
#define REDUNDANCY_MULTI_SITE_H
 
#include <stdint.h>
#include <stdbool.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
/* ============================================================================
 * Site Identification
 * ========================================================================== */
 
typedef enum {
    SITE_WEST   = 0,  /* Primary / Online */
    SITE_EAST   = 1,  /* Backup / Standby */
} site_id_t;
 
typedef enum {
    SITE_STATE_ONLINE    = 0,  /* Active, processing commands */
    SITE_STATE_STANDBY   = 1,  /* Passive, synced but not voting */
    SITE_STATE_ISOLATED  = 2,  /* No comms with other site */
    SITE_STATE_FAULTY    = 3,  /* Self-detected fault, shutdown */
} site_state_t;
 
/* ============================================================================
 * Safety-Related Command (Same as 2oo2 example)
 * ========================================================================== */
 
typedef struct {
    uint32_t train_id;
    uint32_t position;
    uint8_t signal_state;      /* 0=red, 1=yellow, 2=green */
    uint8_t emergency_stop;
    uint16_t speed_limit;
    uint32_t timestamp_ms;
    uint32_t checksum;
    uint32_t sequence_number;  /* For ordering & replay detection */
} train_command_t;
 
/* ============================================================================
 * Per-Site Channel Configuration
 * ========================================================================== */
 
typedef struct {
    /* Vital channels (2oo2 voting) */
    train_command_t channel_a;  /* CPU0 computation */
    train_command_t channel_b;  /* CPU1 computation */
 
    /* Service channel (monitoring/output) */
    char service_output[256];   /* Printf output, logging, etc */
 
    /* Voting result */
    uint8_t voting_result;      /* 0=match, 1=mismatch, 2=timeout */
    train_command_t voted_command;  /* Result of 2oo2 voting */
} site_channels_t;
 
/* ============================================================================
 * Per-Site Statistics & Health
 * ========================================================================== */
 
typedef struct {
    uint32_t total_votes;
    uint32_t total_matches;
    uint32_t total_mismatches;
    uint32_t channel_a_errors;
    uint32_t channel_b_errors;
    uint32_t voting_timeouts;
    uint32_t sequence_number;   /* Last processed command sequence */
} site_stats_t;
 
typedef struct {
    site_id_t site_id;
    site_state_t state;
    site_channels_t channels;
    site_stats_t stats;
    uint32_t heartbeat_timestamp_ms;
    uint32_t heartbeat_miss_count;
} site_context_t;
 
/* ============================================================================
 * Multi-Site Voter Configuration
 * ========================================================================== */
 
typedef struct {
    /* Timing */
    uint32_t site_heartbeat_interval_ms;  /* How often to check peer */
    uint32_t heartbeat_timeout_ms;        /* If no response, site is down */
    uint32_t channel_timeout_ms;          /* Voting deadline per site */
 
    /* Failover thresholds */
    uint32_t max_heartbeat_misses;  /* Trigger failover after N misses */
    uint32_t max_voting_errors;     /* Shutdown site after N errors */
 
    /* Hardware info */
    const char *west_site_name;  /* E.g., "ERTMS-RBC-West (Madrid)" */
    const char *east_site_name;  /* E.g., "ERTMS-RBC-East (Barcelona)" */
} multi_site_config_t;
 
/* ============================================================================
 * Multi-Site Voter State
 * ========================================================================== */
 
typedef struct {
    multi_site_config_t config;
    site_context_t west;
    site_context_t east;
    site_id_t active_site;  /* Which site is online */
} multi_site_voter_t;
 
/* ============================================================================
 * Public API: Multi-Site Initialization
 * ========================================================================== */

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

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);

site_id_t multi_site_heartbeat(multi_site_voter_t *voter);

int multi_site_failover_request(multi_site_voter_t *voter,
                                 site_id_t new_active);

int multi_site_get_active_command(multi_site_voter_t *voter,
                                   train_command_t *cmd_out);

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

void multi_site_print_stats(const multi_site_voter_t *voter);

int multi_site_voter_shutdown(multi_site_voter_t *voter);
 
#ifdef __cplusplus
}
#endif
 
#endif /* REDUNDANCY_MULTI_SITE_H */