Modernise code

.github/workflows/test.yml

@@ -6,6 +6,8 @@ on:
   pull_request:
     branches:
       - main
+permissions:
+  contents: read
 jobs:
-  reuse:
-    uses: bsm/misc/.github/workflows/test-go.yaml@main
+  go:
+    uses: bsm/misc/.github/workflows/test-go.yml@main

README.md

@@ -10,6 +10,7 @@ Wait for servers to terminate gracefully.
 ```go
 import (
 	"context"
+	"errors"
 	"log"
 	"net/http"
 	"time"
@@ -26,7 +27,7 @@ func main() {
 	// Wait for either SIGINT/SIGTERM or ListenAndServe to exit.
 	// Handle errors.
 	err := shutdown.Wait(srv.ListenAndServe)
-	if err != nil && err != http.ErrServerClosed {
+	if err != nil && !errors.Is(err, http.ErrServerClosed) {
 		log.Fatalln("Server error", err)
 	}
 

README.md.tpl

@@ -10,12 +10,13 @@ Wait for servers to terminate gracefully.
 ```go
 import (
 	"context"
+	"errors"
 	"log"
 	"net/http"
 	"time"
 
 	"github.com/bsm/shutdown"
 )
 
-func main() {{ "Example" | code }}
+func main() {{ "ExampleWait" | code }}
 ```

graceful.go

@@ -36,7 +36,10 @@ func GracefulContext(ctx context.Context, start StartFunc, shutdown ShutdownFunc
 		return err
 	}
 
-	timeout, cancel := context.WithTimeout(context.Background(), DefaultShutdownTimeout)
+	// Detach the parent's cancellation/deadline so shutdown always gets the full
+	// timeout (the parent may already be cancelled, e.g. by the signal that
+	// triggered the shutdown), while still preserving any values it carries.
+	timeout, cancel := context.WithTimeout(context.WithoutCancel(ctx), DefaultShutdownTimeout)
 	defer cancel()
 
 	if err := shutdown(timeout); err != nil {

graceful_test.go

@@ -1,8 +1,11 @@
 package shutdown_test
 
 import (
+	"context"
+	"errors"
 	"log"
 	"net/http"
+	"testing"
 
 	"github.com/bsm/shutdown"
 )
@@ -17,3 +20,55 @@ func ExampleGraceful() {
 		log.Fatalln("Server error", err)
 	}
 }
+
+func TestGracefulContext_start_error(t *testing.T) {
+	boom := errors.New("boom")
+
+	// Unexpected start errors are surfaced and shutdown is not invoked.
+	called := false
+	err := shutdown.GracefulContext(context.Background(),
+		func() error { return boom },
+		func(context.Context) error { called = true; return nil },
+	)
+	if !errors.Is(err, boom) {
+		t.Fatalf("expected boom, got %v", err)
+	}
+	if called {
+		t.Fatal("shutdown should not run when start fails unexpectedly")
+	}
+
+	// Expected start errors are swallowed.
+	err = shutdown.GracefulContext(context.Background(),
+		func() error { return boom },
+		func(context.Context) error { return nil },
+		boom,
+	)
+	if err != nil {
+		t.Fatalf("expected nil, got %v", err)
+	}
+}
+
+type ctxKey string
+
+func TestGracefulContext_shutdown_detached(t *testing.T) {
+	// A cancelled parent triggers shutdown; the shutdown context must remain
+	// live (fresh timeout) yet still carry the parent's values.
+	parent, cancel := context.WithCancel(context.WithValue(context.Background(), ctxKey("k"), "v"))
+	cancel()
+
+	err := shutdown.GracefulContext(parent,
+		func() error { <-parent.Done(); return nil },
+		func(ctx context.Context) error {
+			if ctx.Err() != nil {
+				t.Errorf("shutdown context already cancelled: %v", ctx.Err())
+			}
+			if got := ctx.Value(ctxKey("k")); got != "v" {
+				t.Errorf("parent value not preserved, got %v", got)
+			}
+			return nil
+		},
+	)
+	if err != nil {
+		t.Fatalf("expected nil, got %v", err)
+	}
+}

shutdown_test.go

@@ -2,7 +2,7 @@ package shutdown_test
 
 import (
 	"context"
-	"fmt"
+	"errors"
 	"log"
 	"net/http"
 	"testing"
@@ -20,7 +20,7 @@ func ExampleWait() {
 	// Wait for either SIGINT/SIGTERM or ListenAndServe to exit.
 	// Handle errors.
 	err := shutdown.Wait(srv.ListenAndServe)
-	if err != nil && err != http.ErrServerClosed {
+	if err != nil && !errors.Is(err, http.ErrServerClosed) {
 		log.Fatalln("Server error", err)
 	}
 
@@ -35,11 +35,12 @@ func ExampleWait() {
 }
 
 func TestWait_fails_immediately(t *testing.T) {
-	err := shutdown.Wait(func() error { return fmt.Errorf("doh!") })
+	sentinel := errors.New("doh!")
+	err := shutdown.Wait(func() error { return sentinel })
 	if err == nil {
 		t.Fatalf("expected error, got nil")
-	} else if err.Error() != "doh!" {
-		t.Fatalf("expected speficic error, got %v", err)
+	} else if !errors.Is(err, sentinel) {
+		t.Fatalf("expected specific error, got %v", err)
 	}
 }
 
@@ -56,7 +57,7 @@ func TestWaitContext_nil_callback(t *testing.T) {
 	}
 	if err := ctx.Err(); err == nil {
 		t.Fatalf("expected error, got nil")
-	} else if err != context.Canceled {
-		t.Fatalf("expected speficic error, got %v", err)
+	} else if !errors.Is(err, context.Canceled) {
+		t.Fatalf("expected specific error, got %v", err)
 	}
 }