GRPC Client Deadline Cancel Propagation

package main

import (
	"context"
	"fmt"
	"time"

	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"

	pb "example.com/proto/inventory/v1"
)

func reserveWithDeadline(
	ctx context.Context,
	client pb.InventoryClient,
	sku string, qty int32,
) (*pb.ReserveReply, error) {
	ctx, cancel := context.WithTimeout(ctx, 1200*time.Millisecond)
	defer cancel()

	reply, err := client.Reserve(ctx, &pb.ReserveRequest{
		Sku: sku, Quantity: qty,
	})
	if err != nil {
		st := status.Convert(err)
		switch st.Code() {
		case codes.DeadlineExceeded:
			return nil, fmt.Errorf("reserve timed out: %v", st.Message())
		case codes.Canceled:
			return nil, fmt.Errorf("reserve canceled by caller: %v", st.Message())
		case codes.Unavailable:
			return nil, fmt.Errorf("service unavailable, retry later: %v", st.Message())
		default:
			return nil, fmt.Errorf("reserve failed: %v", err)
		}
	}
	return reply, nil
}

func main() {
	conn, err := grpc.NewClient(
		"inventory.example.com:443",
		grpc.WithDefaultCallTimeout(5*time.Second),
	)
	if err != nil {
		fmt.Println(err)
		return
	}
	defer conn.Close()

	client := pb.NewInventoryClient(conn)

	parent, cancel := context.WithTimeout(context.Background(), 2*time.Second)
	defer cancel()

	reply, err := reserveWithDeadline(parent, client, "SKU-1", 3)
	fmt.Println(reply, err)
}