From 1ad21d029c6ff80fe7fda8f66bca041ec825fcd7 Mon Sep 17 00:00:00 2001
From: Matt Silverlock <matt@eatsleeprepeat.net>
Date: Sat, 11 Jul 2015 11:11:09 +0800
Subject: [PATCH] feature: expired sessions can be deleted via a background
 goroutine.

- Call defer store.StopCleanup(store.Cleanup(time.Minute * 5)) after store creation.
- Does not break the existing API (optional, but recommended)
- Based on https://github.com/yosssi/boltstore/reaper
- Deletes expired sessions (where expireson > now())
- Includes tests
---
 README.md       |  2 ++
 cleanup.go      | 64 +++++++++++++++++++++++++++++++++++++++++++++++++
 cleanup_test.go | 51 +++++++++++++++++++++++++++++++++++++++
 pgstore_test.go |  5 ++--
 4 files changed, 120 insertions(+), 2 deletions(-)
 create mode 100644 cleanup.go
 create mode 100644 cleanup_test.go

diff --git a/README.md b/README.md
index b335d77..7e66e94 100644
--- a/README.md
+++ b/README.md
@@ -17,6 +17,8 @@ See http://www.gorillatoolkit.org/pkg/sessions for full documentation on underly
     // Fetch new store.
     store := NewPGStore("postgres://user:password@127.0.0.1:5432/database?sslmode=verify-full", []byte("secret-key"))
     defer store.Close()
+    // Run a background goroutine to clean up expired sessions from the database.
+    defer store.StopCleanup(store.Cleanup(time.Minute * 5))
 
     // Get a session.
     session, err = store.Get(req, "session-key")
diff --git a/cleanup.go b/cleanup.go
new file mode 100644
index 0000000..e15dbc3
--- /dev/null
+++ b/cleanup.go
@@ -0,0 +1,64 @@
+package pgstore
+
+import (
+	"log"
+	"time"
+)
+
+var defaultInterval = time.Minute * 5
+
+// Cleanup runs a background goroutine every interval that deletes expired
+// sessions from the database.
+//
+// The design is based on https://github.com/yosssi/boltstore
+func (db *PGStore) Cleanup(interval time.Duration) (chan<- struct{}, <-chan struct{}) {
+	if interval <= 0 {
+		interval = defaultInterval
+	}
+
+	quit, done := make(chan struct{}), make(chan struct{})
+	go db.cleanup(interval, quit, done)
+	return quit, done
+}
+
+// StopCleanup stops the background cleanup from running.
+func (db *PGStore) StopCleanup(quit chan<- struct{}, done <-chan struct{}) {
+	quit <- struct{}{}
+	<-done
+}
+
+// cleanup deletes expired sessions at set intervals.
+func (db *PGStore) cleanup(interval time.Duration, quit <-chan struct{}, done chan<- struct{}) {
+	ticker := time.NewTicker(interval)
+
+	defer func() {
+		ticker.Stop()
+	}()
+
+	for {
+		select {
+		case <-quit:
+			// Handle the quit signal
+			done <- struct{}{}
+			return
+		case <-ticker.C:
+			// Delete expired sessions on each tick
+			err := db.deleteExpired()
+			if err != nil {
+				log.Printf("pgstore: unable to delete expired sessions: %v", err)
+			}
+		}
+
+	}
+
+}
+
+// deleteExpired deletes expired sessions from the database.
+func (db *PGStore) deleteExpired() error {
+	_, err := db.DbMap.Exec("DELETE FROM http_sessions WHERE expireson < now()")
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
diff --git a/cleanup_test.go b/cleanup_test.go
new file mode 100644
index 0000000..6ef53ae
--- /dev/null
+++ b/cleanup_test.go
@@ -0,0 +1,51 @@
+package pgstore
+
+import (
+	"net/http"
+	"os"
+	"testing"
+	"time"
+)
+
+func TestCleanup(t *testing.T) {
+	ss := NewPGStore(os.Getenv("PGSTORE_TEST_CONN"), []byte(secret))
+	if ss == nil {
+		t.Fatal("This test requires a real database")
+	}
+
+	defer ss.Close()
+	// Start the cleanup goroutine.
+	defer ss.StopCleanup(ss.Cleanup(time.Millisecond * 500))
+
+	req, err := http.NewRequest("GET", "http://www.example.com", nil)
+	if err != nil {
+		t.Fatal("Failed to create request", err)
+	}
+
+	session, err := ss.Get(req, "newsess")
+	if err != nil {
+		t.Fatal("Failed to create session", err)
+	}
+
+	// Expire the session
+	session.Options.MaxAge = 1
+
+	m := make(http.Header)
+	if err = ss.Save(req, headerOnlyResponseWriter(m), session); err != nil {
+		t.Fatal("failed to save session:", err.Error())
+	}
+
+	// Give the ticker a moment to run
+	time.Sleep(time.Second * 1)
+
+	// SELECT expired sessions. We should get a zero-length result slice back.
+	var results []int64
+	_, err = ss.DbMap.Select(&results, "SELECT id FROM http_sessions WHERE expireson < now()")
+	if err != nil {
+		t.Fatalf("failed to select expired sessions from DB: %v", err)
+	}
+
+	if len(results) > 0 {
+		t.Fatalf("ticker did not delete expired sessions: want 0 got %v", len(results))
+	}
+}
diff --git a/pgstore_test.go b/pgstore_test.go
index 75a1a9e..2adbb7a 100644
--- a/pgstore_test.go
+++ b/pgstore_test.go
@@ -1,11 +1,12 @@
 package pgstore
 
 import (
-	"github.com/gorilla/securecookie"
-	"github.com/gorilla/sessions"
 	"net/http"
 	"os"
 	"testing"
+
+	"github.com/gorilla/securecookie"
+	"github.com/gorilla/sessions"
 )
 
 type headerOnlyResponseWriter http.Header