Naive bridge to listen for blockconnected notifications and invoke an executable.

blocknotifybridge.go

// Copyright (c) 2016 The btcsuite developers
// Copyright (c) 2015-2016 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.

package main

import (
	"io/ioutil"
	"log"
	"os/exec"
	"path/filepath"
	"time"

	"github.com/decred/dcrd/chaincfg/chainhash"
	"github.com/decred/dcrrpcclient"
	"github.com/decred/dcrutil"
)

const (
	processName = "blocknotify"
)

func main() {
	// Only override the handlers for notifications you care about.
	// Also note most of these handlers will only be called if you register
	// for notifications.  See the documentation of the dcrrpcclient
	// NotificationHandlers type for more details about each handler.
	ntfnHandlers := dcrrpcclient.NotificationHandlers{
		OnBlockConnected: func(hash *chainhash.Hash, height int32, time time.Time, vb uint16) {
			// Find the process path.
			cmd := exec.Command(processName, "1574", hash.String())
			if err := cmd.Run(); err != nil {
				log.Fatalln(err)
			}
			log.Printf("Block connected: %v (%d)", hash, height)
		},
	}

	// Connect to local dcrd RPC server using websockets.
	dcrdHomeDir := dcrutil.AppDataDir("dcrd", false)
	certs, err := ioutil.ReadFile(filepath.Join(dcrdHomeDir, "rpc.cert"))
	if err != nil {
		log.Fatal(err)
	}
	connCfg := &dcrrpcclient.ConnConfig{
		Host:         "localhost:9109",
		Endpoint:     "ws",
		User:         "test",
		Pass:         "tabc",
		Certificates: certs,
	}
	client, err := dcrrpcclient.New(connCfg, &ntfnHandlers)
	if err != nil {
		log.Fatalln(err)
	}

	// Register for block connect and disconnect notifications.
	if err := client.NotifyBlocks(); err != nil {
		log.Fatalln(err)
	}
	log.Println("NotifyBlocks: Registration Complete")

	// Wait until the client either shuts down gracefully (or the user
	// terminates the process with Ctrl+C).
	client.WaitForShutdown()
}