From c0c3eda2901d2d2fbfac41b8ef13b802824223e9 Mon Sep 17 00:00:00 2001
From: Jimmy Zelinskie <jimmyzelinskie@gmail.com>
Date: Fri, 18 Sep 2015 00:42:14 -0400
Subject: [PATCH] config: make reaping configurable

This allows for configurable reaping rates and changes the default to
what many public trackers use in the wild.
---
 config/config.go      |  4 ++++
 example_config.json   |  2 ++
 http/announce_test.go |  7 +++----
 tracker/tracker.go    | 11 ++---------
 4 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/config/config.go b/config/config.go
index 9740d1b..e9a613a 100644
--- a/config/config.go
+++ b/config/config.go
@@ -81,6 +81,8 @@ type TrackerConfig struct {
 	PurgeInactiveTorrents bool     `json:"purge_inactive_torrents"`
 	Announce              Duration `json:"announce"`
 	MinAnnounce           Duration `json:"min_announce"`
+	ReapInterval          Duration `json:"reap_interval"`
+	ReapRatio             float64  `json:"reap_ratio"`
 	NumWantFallback       int      `json:"default_num_want"`
 	TorrentMapShards      int      `json:"torrent_map_shards"`
 
@@ -121,6 +123,8 @@ var DefaultConfig = Config{
 		PurgeInactiveTorrents: true,
 		Announce:              Duration{30 * time.Minute},
 		MinAnnounce:           Duration{15 * time.Minute},
+		ReapInterval:          Duration{60 * time.Second},
+		ReapRatio:             1.25,
 		NumWantFallback:       50,
 		TorrentMapShards:      1,
 
diff --git a/example_config.json b/example_config.json
index c71042b..bf24235 100644
--- a/example_config.json
+++ b/example_config.json
@@ -5,6 +5,8 @@
   "purge_inactive_torrents": true,
   "announce": "30m",
   "min_announce": "15m",
+  "reap_interval": "60s",
+  "reap_ratio": "1.25",
   "default_num_want": 50,
   "torrent_map_shards": 1,
   "allow_ip_spoofing": true,
diff --git a/http/announce_test.go b/http/announce_test.go
index 55edb84..1406cea 100644
--- a/http/announce_test.go
+++ b/http/announce_test.go
@@ -84,9 +84,8 @@ func TestTorrentPurging(t *testing.T) {
 
 func TestStalePeerPurging(t *testing.T) {
 	cfg := config.DefaultConfig
-	cfg.Announce = config.Duration{
-		Duration: 10 * time.Millisecond,
-	}
+	cfg.MinAnnounce = config.Duration{10 * time.Millisecond}
+	cfg.ReapInterval = config.Duration{10 * time.Millisecond}
 
 	srv, err := setupTracker(&cfg)
 	if err != nil {
@@ -110,7 +109,7 @@ func TestStalePeerPurging(t *testing.T) {
 	// Add a leecher.
 	peer2 := makePeerParams("peer2", false)
 	expected := makeResponse(1, 1, peer1)
-	expected["interval"] = int64(0)
+	expected["min interval"] = int64(0)
 	checkAnnounce(peer2, expected, srv, t)
 
 	// Let them both expire.
diff --git a/tracker/tracker.go b/tracker/tracker.go
index 35eecbe..d01ef22 100644
--- a/tracker/tracker.go
+++ b/tracker/tracker.go
@@ -49,8 +49,8 @@ func New(cfg *config.Config) (*Tracker, error) {
 
 	go tkr.purgeInactivePeers(
 		cfg.PurgeInactiveTorrents,
-		cfg.Announce.Duration*2,
-		cfg.Announce.Duration,
+		time.Duration(float64(cfg.MinAnnounce.Duration)*cfg.ReapRatio),
+		cfg.ReapInterval.Duration,
 	)
 
 	if cfg.ClientWhitelistEnabled {
@@ -86,13 +86,6 @@ type Writer interface {
 
 // purgeInactivePeers periodically walks the torrent database and removes
 // peers that haven't announced recently.
-//
-// The default threshold is 2x the announce interval, which gives delayed
-// peers a chance to stay alive, while ensuring the majority of responses
-// contain active peers.
-//
-// The default interval is equal to the announce interval, since this is a
-// relatively expensive operation.
 func (tkr *Tracker) purgeInactivePeers(purgeEmptyTorrents bool, threshold, interval time.Duration) {
 	for _ = range time.NewTicker(interval).C {
 		before := time.Now().Add(-threshold)