metrics.h

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#ifndef __CWIST_METRICS_H__
#define __CWIST_METRICS_H__
 
#include <stddef.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdatomic.h>
 
struct cwist_http_response;
 
#ifdef __cplusplus
extern "C" {
#endif
 
/* -------------------------------------------------------------------------
 * Metric types
 * ---------------------------------------------------------------------- */
 
typedef enum cwist_metric_type {
    CWIST_METRIC_COUNTER,   
    CWIST_METRIC_GAUGE,     
    CWIST_METRIC_HISTOGRAM, 
} cwist_metric_type_t;
 
typedef struct cwist_metric_value {
    atomic_uintmax_t raw;   
} cwist_metric_value_t;
 
typedef struct cwist_metric {
    const char *name;       
    const char *help;       
    cwist_metric_type_t type;
    cwist_metric_value_t value;
    atomic_uintmax_t count; 
    atomic_uintmax_t sum;   
} cwist_metric_t;
 
typedef enum cwist_metric_id {
    CWIST_METRIC_URING_SQES_PENDING,      
    CWIST_METRIC_URING_BUFFERS_ACTIVE,    
    CWIST_METRIC_STREAMS_HTTP2,           
    CWIST_METRIC_STREAMS_HTTP3,           
    CWIST_METRIC_FLOW_WINDOW_HEALTH,      
    CWIST_METRIC_VALIDATION_ERRORS,       
    CWIST_METRIC_REQUESTS_TOTAL,          
    CWIST_METRIC_REQUEST_DURATION_NS,     
    CWIST_METRIC_HTTP_HEADER_OVERFLOW, 
    CWIST_METRIC_H2_HEADERS_DROPPED, 
    CWIST_METRIC_HTTP_CONTINUATION_SHED, 
    CWIST_METRIC_TLS_HANDSHAKES_TOTAL,      
    CWIST_METRIC_TLS_HANDSHAKES_RESUMED,    
    CWIST_METRIC_TLS_CONNECTIONS_ACTIVE,    
    CWIST_METRIC_TLS_HANDSHAKES_TLS12,      
    CWIST_METRIC_TLS_HANDSHAKES_TLS13,      
    CWIST_METRIC_TLS_CIPHERS_AES128_GCM,    
    CWIST_METRIC_TLS_CIPHERS_AES256_GCM,    
    CWIST_METRIC_TLS_CIPHERS_CHACHA20,      
    CWIST_METRIC_TLS_CIPHERS_OTHER,         
    CWIST_METRIC_COUNT
} cwist_metric_id_t;
 
/* -------------------------------------------------------------------------
 * Registry API
 * ---------------------------------------------------------------------- */
 
typedef struct cwist_metrics_registry cwist_metrics_registry_t;
 
cwist_metrics_registry_t *cwist_metrics_registry(void);
 
void cwist_metrics_reset(cwist_metrics_registry_t *reg);
 
/* -------------------------------------------------------------------------
 * Lock-free updates
 * ---------------------------------------------------------------------- */
 
void cwist_metric_inc(cwist_metrics_registry_t *reg, cwist_metric_id_t id);
 
void cwist_metric_add(cwist_metrics_registry_t *reg, cwist_metric_id_t id, uintmax_t delta);
 
void cwist_metric_set(cwist_metrics_registry_t *reg, cwist_metric_id_t id, long double value);
 
void cwist_metric_observe(cwist_metrics_registry_t *reg, cwist_metric_id_t id, long double value);
 
uintmax_t cwist_metric_load(const cwist_metrics_registry_t *reg, cwist_metric_id_t id);
 
/* -------------------------------------------------------------------------
 * Prometheus exposition
 * ---------------------------------------------------------------------- */
 
char *cwist_metrics_render_prometheus(const cwist_metrics_registry_t *reg);
 
void cwist_metrics_serve_http(struct cwist_http_response *res);
 
#ifdef __cplusplus
}
#endif
 
#endif /* __CWIST_METRICS_H__ */