refactoring

src/with/ctx.go

@@ -0,0 +1,17 @@
+package with
+
+import (
+	"context"
+	"os/signal"
+	"syscall"
+)
+
+func Context(foo func(context.Context) error) error {
+	ctx, can := signal.NotifyContext(context.Background(), syscall.SIGINT)
+	defer can()
+
+	if err := foo(ctx); err != nil && ctx.Err() == nil {
+		return err
+	}
+	return nil
+}

src/with/pg.go

@@ -0,0 +1,51 @@
+package with
+
+import (
+	"context"
+	"database/sql"
+	"log"
+	"time"
+
+	_ "github.com/lib/pq"
+)
+
+func PSQL(ctx context.Context, conn string, foo func(db *sql.DB) error) error {
+	log.Println("opening...")
+	pg, err := sql.Open("postgres", conn)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		log.Println("closed:", pg.Close())
+	}()
+
+	func() {
+		pinged := make(chan bool)
+		defer close(pinged)
+		for {
+			log.Println("pinging...")
+			go func() {
+				err := pg.PingContext(ctx)
+				if err != nil {
+					log.Println("!", err)
+				}
+				select {
+				case pinged <- err == nil:
+				case <-ctx.Done():
+				case <-time.After(time.Second * 5):
+				}
+			}()
+			select {
+			case <-ctx.Done():
+				return
+			case ok := <-pinged:
+				if ok {
+					return
+				}
+			case <-time.After(time.Second * 5):
+			}
+		}
+	}()
+
+	return foo(pg)
+}