88 lines
4.0 KiB
Go
88 lines
4.0 KiB
Go
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// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package node_test
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import (
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"fmt"
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"log"
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"github.com/ethereum/go-ethereum/node"
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"github.com/ethereum/go-ethereum/p2p"
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"github.com/ethereum/go-ethereum/p2p/discover"
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)
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// SampleService is a trivial network service that can be attached to a node for
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// life cycle management.
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//
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// The following methods are needed to implement a node.Service:
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// - Protocols() []p2p.Protocol - devp2p protocols the service can communicate on
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// - Start() error - method invoked when the node is ready to start the service
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// - Stop() error - method invoked when the node terminates the service
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type SampleService struct{}
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func (s *SampleService) Protocols() []p2p.Protocol { return nil }
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func (s *SampleService) Start() error { fmt.Println("Sample service starting..."); return nil }
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func (s *SampleService) Stop() error { fmt.Println("Sample service stopping..."); return nil }
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func ExampleUsage() {
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// Create a network node to run protocols with the default values. The below list
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// is only used to display each of the configuration options. All of these could
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// have been ommited if the default behavior is desired.
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nodeConfig := &node.Config{
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DataDir: "", // Empty uses ephemeral storage
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PrivateKey: nil, // Nil generates a node key on the fly
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Name: "", // Any textual node name is allowed
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NoDiscovery: false, // Can disable discovering remote nodes
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BootstrapNodes: []*discover.Node{}, // List of bootstrap nodes to use
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ListenAddr: ":0", // Network interface to listen on
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NAT: nil, // UPnP port mapper to use for crossing firewalls
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Dialer: nil, // Custom dialer to use for establishing peer connections
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NoDial: false, // Can prevent this node from dialing out
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MaxPeers: 0, // Number of peers to allow
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MaxPendingPeers: 0, // Number of peers allowed to handshake concurrently
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}
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stack, err := node.New(nodeConfig)
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if err != nil {
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log.Fatalf("Failed to create network node: %v", err)
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}
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// Create and register a simple network service. This is done through the definition
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// of a node.ServiceConstructor that will instantiate a node.Service. The reason for
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// the factory method approach is to support service restarts without relying on the
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// individual implementations' support for such operations.
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constructor := func(context *node.ServiceContext) (node.Service, error) {
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return new(SampleService), nil
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}
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if err := stack.Register("my sample service", constructor); err != nil {
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log.Fatalf("Failed to register service: %v", err)
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}
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// Boot up the entire protocol stack, do a restart and terminate
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if err := stack.Start(); err != nil {
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log.Fatalf("Failed to start the protocol stack: %v", err)
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}
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if err := stack.Restart(); err != nil {
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log.Fatalf("Failed to restart the protocol stack: %v", err)
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}
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if err := stack.Stop(); err != nil {
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log.Fatalf("Failed to stop the protocol stack: %v", err)
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}
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// Output:
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// Sample service starting...
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// Sample service stopping...
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// Sample service starting...
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// Sample service stopping...
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}
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