| // Copyright 2015 The Vanadium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package factory |
| |
| import ( |
| "fmt" |
| "os" |
| |
| "v.io/v23/discovery" |
| |
| idiscovery "v.io/x/ref/lib/discovery" |
| ) |
| |
| // New returns a new Discovery instance with the given protocols. |
| // |
| // We instantiate a discovery instance lazily so that we do not turn it on |
| // until it is actually used. |
| func New(protocols ...string) (discovery.T, error) { |
| if injectedInstance != nil { |
| return injectedInstance, nil |
| } |
| |
| host, _ := os.Hostname() |
| if len(host) == 0 { |
| // TODO(jhahn): Should we handle error here? |
| host = "v23" |
| } |
| |
| if len(protocols) == 0 { |
| // TODO(jhahn): Enable all protocols that are supported by the runtime. |
| protocols = []string{"mdns"} |
| } |
| |
| // Verify protocols. |
| for _, p := range protocols { |
| if _, exists := pluginFactories[p]; !exists { |
| return nil, fmt.Errorf("discovery protocol %q is not supported", p) |
| } |
| } |
| |
| return newLazyFactory(func() (discovery.T, error) { return newInstance(host, protocols) }), nil |
| } |
| |
| func newInstance(host string, protocols []string) (discovery.T, error) { |
| plugins := make([]idiscovery.Plugin, 0, len(protocols)) |
| for _, p := range protocols { |
| plugin, err := pluginFactories[p](host) |
| if err != nil { |
| return nil, err |
| } |
| plugins = append(plugins, plugin) |
| } |
| return idiscovery.NewWithPlugins(plugins), nil |
| } |
| |
| var injectedInstance discovery.T |
| |
| // InjectDiscovery allows a runtime to use the given discovery instance. This |
| // should be called before the runtime is initialized. Mostly used for testing. |
| func InjectDiscovery(d discovery.T) { |
| injectedInstance = d |
| } |