fix(reload): broadcast shutdown signal (#8504)

* fix(reload): broadcast shutdown signal

Signed-off-by: alam0rt <sam@samlockart.com>

* fix(reload): scope shutdown state to instances

Signed-off-by: alam0rt <sam@samlockart.com>

---------

Signed-off-by: alam0rt <sam@samlockart.com>

plugin/reload/reload_test.go

@@ -30,11 +30,11 @@ func TestParseInvalidCorefile(t *testing.T) {
 func TestShutdownGate(t *testing.T) {
 	t.Parallel()
 
-	q := make(chan bool, 1)
+	q := make(chan struct{})
 	if shutdownRequested(q) {
 		t.Fatalf("expected no shutdown before signal")
 	}
-	q <- true
+	close(q)
 	if !shutdownRequested(q) {
 		t.Fatalf("expected shutdown after signal")
 	}
@@ -48,3 +48,64 @@ func TestHookIgnoresNonStartupEvent(t *testing.T) {
 		t.Fatalf("expected no error for non-startup event, got %v", err)
 	}
 }
+
+// TestShutdownRequestedBroadcastsClosedSignal ensures a shutdown remains visible to every observer.
+func TestShutdownRequestedBroadcastsClosedSignal(t *testing.T) {
+	quit := make(chan struct{})
+	close(quit)
+
+	if !shutdownRequested(quit) {
+		t.Fatal("expected first shutdownRequested call to observe shutdown")
+	}
+
+	if !shutdownRequested(quit) {
+		t.Fatal("expected second shutdownRequested call to observe shutdown as well")
+	}
+}
+
+// TestSetupCreatesIndependentReloadStates ensures one instance shutdown does not stop another.
+func TestSetupCreatesIndependentReloadStates(t *testing.T) {
+	c1 := caddy.NewTestController("dns", `reload 2s 0s`)
+	if err := setup(c1); err != nil {
+		t.Fatalf("expected first setup to succeed, got %v", err)
+	}
+	state1, ok := c1.Get(reloadStorageKey{}).(*reload)
+	if !ok {
+		t.Fatal("expected first controller to own reload state")
+	}
+
+	c2 := caddy.NewTestController("dns", `reload 2s 0s`)
+	if err := setup(c2); err != nil {
+		t.Fatalf("expected second setup to succeed, got %v", err)
+	}
+	state2, ok := c2.Get(reloadStorageKey{}).(*reload)
+	if !ok {
+		t.Fatal("expected second controller to own reload state")
+	}
+	if state1 == state2 {
+		t.Fatal("expected each controller to own independent reload state")
+	}
+
+	if err := state1.shutdown(); err != nil {
+		t.Fatalf("expected first state shutdown to succeed, got %v", err)
+	}
+	if shutdownRequested(state2.quit) {
+		t.Fatal("expected shutting down the first state not to stop the second")
+	}
+}
+
+// TestReloadStateShutdownIsIdempotent ensures repeated shutdown callbacks do not panic.
+func TestReloadStateShutdownIsIdempotent(t *testing.T) {
+	state := newReload()
+
+	if err := state.shutdown(); err != nil {
+		t.Fatalf("expected first shutdown to succeed, got %v", err)
+	}
+	if err := state.shutdown(); err != nil {
+		t.Fatalf("expected second shutdown to succeed, got %v", err)
+	}
+
+	if !shutdownRequested(state.quit) {
+		t.Fatal("expected shutdown after state shutdown")
+	}
+}