middleware, config: re-add support for min interval

example_config.yaml

@@ -3,6 +3,10 @@ chihaya:
   # frequently they should announce in between client events.
   announce_interval: 30m
 
+  # The interval communicated with BitTorrent clients informing them of the
+  # minimal duration between announces.
+  min_announce_interval: 15m
+
   # The network interface that will bind to an HTTP endpoint that can be
   # scraped by an instance of the Prometheus time series database.
   # For more info see: https://prometheus.io

middleware/middleware.go

@@ -16,6 +16,7 @@ import (
 // Config holds the configuration common across all middleware.
 type Config struct {
 	AnnounceInterval    time.Duration `yaml:"announce_interval"`
+	MinAnnounceInterval time.Duration `yaml:"min_announce_interval"`
 }
 
 var _ frontend.TrackerLogic = &Logic{}
@@ -25,6 +26,7 @@ var _ frontend.TrackerLogic = &Logic{}
 func NewLogic(cfg Config, peerStore storage.PeerStore, preHooks, postHooks []Hook) *Logic {
 	return &Logic{
 		announceInterval:    cfg.AnnounceInterval,
+		minAnnounceInterval: cfg.MinAnnounceInterval,
 		peerStore:           peerStore,
 		preHooks:            append(preHooks, &responseHook{store: peerStore}),
 		postHooks:           append(postHooks, &swarmInteractionHook{store: peerStore}),
@@ -35,6 +37,7 @@ func NewLogic(cfg Config, peerStore storage.PeerStore, preHooks, postHooks []Hoo
 // executing a series of middleware hooks.
 type Logic struct {
 	announceInterval    time.Duration
+	minAnnounceInterval time.Duration
 	peerStore           storage.PeerStore
 	preHooks            []Hook
 	postHooks           []Hook
@@ -44,7 +47,7 @@ type Logic struct {
 func (l *Logic) HandleAnnounce(ctx context.Context, req *bittorrent.AnnounceRequest) (_ context.Context, resp *bittorrent.AnnounceResponse, err error) {
 	resp = &bittorrent.AnnounceResponse{
 		Interval:    l.announceInterval,
-		MinInterval: l.announceInterval,
+		MinInterval: l.minAnnounceInterval,
 		Compact:     req.Compact,
 	}
 	for _, h := range l.preHooks {