services/mgmt/binary/impl/dispatcher.go

package impl

import (
	"crypto/md5"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"strings"

	"veyron2/ipc"
	"veyron2/security"
	"veyron2/services/mgmt/repository"
)

const (
	VersionFile = "VERSION"
	Version     = "1.0"
)

// dispatcher holds the state of the binary repository dispatcher.
type dispatcher struct {
	auth  security.Authorizer
	state *state
}

// newDispatcher is the dispatcher factory.
func NewDispatcher(root string, depth int, authorizer security.Authorizer) (*dispatcher, error) {
	if min, max := 0, md5.Size-1; min > depth || depth > max {
		return nil, fmt.Errorf("Unexpected depth, expected a value between %v and %v, got %v", min, max, depth)
	}
	if _, err := os.Stat(root); err != nil {
		return nil, fmt.Errorf("Stat(%v) failed: %v", root, err)
	}
	path := filepath.Join(root, VersionFile)
	output, err := ioutil.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("ReadFile(%v) failed: %v", path, err)
	}
	if expected, got := Version, strings.TrimSpace(string(output)); expected != got {
		return nil, fmt.Errorf("Unexpected version: expected %v, got %v", expected, got)
	}
	return &dispatcher{
		auth: authorizer,
		state: &state{
			depth: depth,
			root:  root,
		},
	}, nil
}

// DISPATCHER INTERFACE IMPLEMENTATION

func (d *dispatcher) Lookup(suffix string) (ipc.Invoker, security.Authorizer, error) {
	invoker := ipc.ReflectInvoker(repository.NewServerBinary(newInvoker(d.state, suffix)))
	return invoker, d.auth, nil
}