Add WithProcessKill DeleteOpt

Add an option that allows users for force kill and delete a process/task
when calling `Delete`

Fixes #1274

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

task_opts.go

@@ -2,6 +2,7 @@ package containerd
 
 import (
 	"context"
+	"syscall"
 
 	"github.com/containerd/containerd/linux/runcopts"
 	"github.com/containerd/containerd/mount"
@@ -25,3 +26,21 @@ func WithExit(r *CheckpointTaskInfo) error {
 	}
 	return nil
 }
+
+// ProcessDeleteOpts allows the caller to set options for the deletion of a task
+type ProcessDeleteOpts func(context.Context, Process) error
+
+// WithProcessKill will forcefully kill and delete a process
+func WithProcessKill(ctx context.Context, p Process) error {
+	s := make(chan struct{}, 1)
+	// ignore errors to wait and kill as we are forcefully killing
+	// the process and don't care about the exit status
+	go func() {
+		p.Wait(ctx)
+		close(s)
+	}()
+	p.Kill(ctx, syscall.SIGKILL)
+	// wait for the process to fully stop before letting the rest of the deletion complete
+	<-s
+	return nil
+}