//go:build !noprom
package metrics
import (
"fmt"
"net/http"
prom "github.com/prometheus/client_golang/prometheus"
promhttp "github.com/prometheus/client_golang/prometheus/promhttp"
)
type promRecorder struct {
dbTotal *prom.CounterVec
dbSeconds *prom.HistogramVec
toolTotal *prom.CounterVec
toolSeconds *prom.HistogramVec
toolSize *prom.HistogramVec
stmtHit *prom.CounterVec
poolGauge *prom.GaugeVec
}
func (p *promRecorder) IncDBOpTotal(op string, success bool) {
p.dbTotal.WithLabelValues(op, fmt.Sprintf("%t", success)).Inc()
}
func (p *promRecorder) ObserveDBOpSeconds(op string, success bool, seconds float64) {
p.dbSeconds.WithLabelValues(op, fmt.Sprintf("%t", success)).Observe(seconds)
}
func (p *promRecorder) IncToolTotal(tool string, success bool) {
p.toolTotal.WithLabelValues(tool, fmt.Sprintf("%t", success)).Inc()
}
func (p *promRecorder) ObserveToolSeconds(tool string, success bool, seconds float64) {
p.toolSeconds.WithLabelValues(tool, fmt.Sprintf("%t", success)).Observe(seconds)
}
func (p *promRecorder) ObserveToolResultSize(tool string, size int) {
// Bucket sizes exponentially (bytes/items depending on context). Use generic buckets.
p.toolSize.WithLabelValues(tool).Observe(float64(size))
}
func (p *promRecorder) IncStmtCacheHit(op string) {
p.stmtHit.WithLabelValues(op, "hit").Inc()
}
func (p *promRecorder) IncStmtCacheMiss(op string) {
p.stmtHit.WithLabelValues(op, "miss").Inc()
}
func (p *promRecorder) ObservePoolStats(inUse, idle int) {
p.poolGauge.WithLabelValues("in_use").Set(float64(inUse))
p.poolGauge.WithLabelValues("idle").Set(float64(idle))
}
func enablePrometheus(addr string) error {
registry := prom.NewRegistry()
p := &promRecorder{
dbTotal: prom.NewCounterVec(prom.CounterOpts{
Name: "db_ops_total",
Help: "Total number of DB operations",
}, []string{"op", "success"}),
dbSeconds: prom.NewHistogramVec(prom.HistogramOpts{
Name: "db_op_seconds",
Help: "DB operation duration in seconds",
Buckets: prom.DefBuckets,
}, []string{"op", "success"}),
toolTotal: prom.NewCounterVec(prom.CounterOpts{
Name: "tool_calls_total",
Help: "Total number of tool handler calls",
}, []string{"tool", "success"}),
toolSeconds: prom.NewHistogramVec(prom.HistogramOpts{
Name: "tool_call_seconds",
Help: "Tool handler duration in seconds",
Buckets: prom.DefBuckets,
}, []string{"tool", "success"}),
toolSize: prom.NewHistogramVec(prom.HistogramOpts{
Name: "tool_result_size",
Help: "Tool result size (units: items/bytes depending on tool context)",
Buckets: []float64{1, 2, 5, 10, 20, 50, 100, 250, 500, 1000, 2500, 5000},
}, []string{"tool"}),
stmtHit: prom.NewCounterVec(prom.CounterOpts{
Name: "stmt_cache_events_total",
Help: "Statement cache hit/miss events",
}, []string{"op", "result"}),
poolGauge: prom.NewGaugeVec(prom.GaugeOpts{
Name: "db_pool_gauges",
Help: "Database pool gauges by state",
}, []string{"state"}),
}
registry.MustRegister(p.dbTotal, p.dbSeconds, p.toolTotal, p.toolSeconds, p.toolSize, p.stmtHit, p.poolGauge)
SetRecorder(p)
mux := http.NewServeMux()
mux.Handle("/metrics", promhttp.HandlerFor(registry, promhttp.HandlerOpts{}))
mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusOK)
_, _ = w.Write([]byte("ok"))
})
go func() { _ = http.ListenAndServe(addr, mux) }()
return nil
}
