feat: reusable rule engine to prevent memory reallocation

internal/proxy/director/layer/util/revisioned_rule_engine.go

@@ -0,0 +1,51 @@
+package util
+
+import (
+	"context"
+	"sync"
+
+	"forge.cadoles.com/cadoles/bouncer/internal/rule"
+	"github.com/pkg/errors"
+	"gitlab.com/wpetit/goweb/logger"
+)
+
+type RuleEngineFactoryFunc[V any, O any] func(ops O) (*rule.Engine[V], error)
+
+type RevisionedRuleEngine[V any, O any] struct {
+	mutex    sync.RWMutex
+	revision int
+	engine   *rule.Engine[V]
+	factory  RuleEngineFactoryFunc[V, O]
+}
+
+func (e *RevisionedRuleEngine[V, O]) Get(ctx context.Context, revision int, opts O) (*rule.Engine[V], error) {
+	e.mutex.RLock()
+	if revision == e.revision {
+		logger.Debug(ctx, "using cached rule engine", logger.F("layerRevision", revision))
+
+		defer e.mutex.RUnlock()
+		return e.engine, nil
+	}
+	e.mutex.RUnlock()
+
+	e.mutex.Lock()
+	defer e.mutex.Unlock()
+
+	logger.Debug(ctx, "creating rule engine", logger.F("layerRevision", revision))
+
+	engine, err := e.factory(opts)
+	if err != nil {
+		return nil, errors.WithStack(err)
+	}
+
+	e.engine = engine
+	e.revision = revision
+
+	return engine, nil
+}
+
+func NewRevisionedRuleEngine[V any, O any](factory RuleEngineFactoryFunc[V, O]) *RevisionedRuleEngine[V, O] {
+	return &RevisionedRuleEngine[V, O]{
+		factory: factory,
+	}
+}