perf(lib): iterate s.policy.Bots by index to drop per-call heap copy (#1639)

Signed-off-by: jvoisin <julien.voisin@dustri.org>

lib/policy/bot.go

@@ -1,8 +1,6 @@
 package policy
 
 import (
-	"fmt"
-
 	"github.com/TecharoHQ/anubis/internal"
 	"github.com/TecharoHQ/anubis/lib/config"
 	"github.com/TecharoHQ/anubis/lib/policy/checker"
@@ -13,9 +11,22 @@ type Bot struct {
 	Challenge *config.ChallengeRules
 	Weight    *config.Weight
 	Name      string
-	Action    config.Rule
+	// hash caches the result of Hash() when populated at parse time, see ParseConfig
+	hash   string
+	Action config.Rule
 }
 
+// Hash returns a stable identifier for this Bot derived from its Name
+// and Rules. When the cached value is present (populated by
+// ParseConfig) it is returned directly; otherwise the hash is
+// recomputed on demand so callers do not have to know about the cache.
 func (b Bot) Hash() string {
-	return internal.FastHash(fmt.Sprintf("%s::%s", b.Name, b.Rules.Hash()))
+	if b.hash != "" {
+		return b.hash
+	}
+	var rulesHash string
+	if b.Rules != nil { // defensive, should never happen
+		rulesHash = b.Rules.Hash()
+	}
+	return internal.FastHash(b.Name + "::" + rulesHash)
 }