nsq源码阅读 nsqd源码一 apps/nsqd/nsqd.go

之前已经将NSQ的nsqlookupd模块源码大致的看了一遍了，现在开始阅读nsqd模块的源码。作为NSQ的核心模块，代码量也相对多点。废话不多说，开始读代码。

首先从mai()方法开始：

func main() {prg := &program{}if err := svc.Run(prg, syscall.SIGINT, syscall.SIGTERM); err != nil {log.Fatal(err)}}

main()方法很简单，就几行代码，但理解起来却不简单。大量的操作都封装在了svc.Run()里了，其主要作用是运行程序并阻塞，直到接受到SIGINT或SIGTERM信号，关闭程序。

关于系统调用和信号处理，可以看自己看看相关的介绍，就不再赘述了。

文采不行，写不出什么长篇大论的，还是老样子，直接贴代码吧：

package mainimport ("crypto/tls""flag""fmt""log""math/rand""os""path/filepath""strconv""strings""syscall""time""github.com/BurntSushi/toml""github.com/judwhite/go-svc/svc""github.com/mreiferson/options""github.com/nsqio/nsq/internal/app""github.com/nsqio/nsq/internal/version""github.com/nsqio/nsq/nsqd")type tlsRequiredOption intfunc (t *tlsRequiredOption) Set(s string) error {s = strings.ToLower(s)if s == "tcp-https" {*t = nsqd.TLSRequiredExceptHTTPreturn nil}required, err := strconv.ParseBool(s)if required {*t = nsqd.TLSRequired} else {*t = nsqd.TLSNotRequired}return err}func (t *tlsRequiredOption) Get() interface{} { return int(*t) }func (t *tlsRequiredOption) String() string {return strconv.FormatInt(int64(*t), 10)}func (t *tlsRequiredOption) IsBoolFlag() bool { return true }type tlsMinVersionOption uint16func (t *tlsMinVersionOption) Set(s string) error {s = strings.ToLower(s)switch s {case "":return nilcase "ssl3.0":*t = tls.VersionSSL30case "tls1.0":*t = tls.VersionTLS10case "tls1.1":*t = tls.VersionTLS11case "tls1.2":*t = tls.VersionTLS12default:return fmt.Errorf("unknown tlsVersionOption %q", s)}return nil}func (t *tlsMinVersionOption) Get() interface{} { return uint16(*t) }func (t *tlsMinVersionOption) String() string {return strconv.FormatInt(int64(*t), 10)}//通过命令行参数，修改默认配置func nsqdFlagSet(opts *nsqd.Options) *flag.FlagSet {flagSet := flag.NewFlagSet("nsqd", flag.ExitOnError)// basic optionsflagSet.Bool("version", false, "print version string")flagSet.Bool("verbose", false, "enable verbose logging")flagSet.String("config", "", "path to config file")flagSet.String("log-prefix", "[nsqd] ", "log message prefix")flagSet.Int64("node-id", opts.ID, "unique part for message IDs, (int) in range [0,1024) (default is hash of hostname)")flagSet.Bool("worker-id", false, "do NOT use this, use --node-id")flagSet.String("https-address", opts.HTTPSAddress, "<addr>:<port> to listen on for HTTPS clients")flagSet.String("http-address", opts.HTTPAddress, "<addr>:<port> to listen on for HTTP clients")flagSet.String("tcp-address", opts.TCPAddress, "<addr>:<port> to listen on for TCP clients")authHTTPAddresses := app.StringArray{}flagSet.Var(&authHTTPAddresses, "auth-http-address", "<addr>:<port> to query auth server (may be given multiple times)")flagSet.String("broadcast-address", opts.BroadcastAddress, "address that will be registered with lookupd (defaults to the OS hostname)")lookupdTCPAddrs := app.StringArray{}flagSet.Var(&lookupdTCPAddrs, "lookupd-tcp-address", "lookupd TCP address (may be given multiple times)")flagSet.Duration("http-client-connect-timeout", opts.HTTPClientConnectTimeout, "timeout for HTTP connect")flagSet.Duration("http-client-request-timeout", opts.HTTPClientRequestTimeout, "timeout for HTTP request")// diskqueue optionsflagSet.String("data-path", opts.DataPath, "path to store disk-backed messages")flagSet.Int64("mem-queue-size", opts.MemQueueSize, "number of messages to keep in memory (per topic/channel)")flagSet.Int64("max-bytes-per-file", opts.MaxBytesPerFile, "number of bytes per diskqueue file before rolling")flagSet.Int64("sync-every", opts.SyncEvery, "number of messages per diskqueue fsync")flagSet.Duration("sync-timeout", opts.SyncTimeout, "duration of time per diskqueue fsync")// msg and command optionsflagSet.String("msg-timeout", opts.MsgTimeout.String(), "duration to wait before auto-requeing a message")flagSet.Duration("max-msg-timeout", opts.MaxMsgTimeout, "maximum duration before a message will timeout")flagSet.Int64("max-msg-size", opts.MaxMsgSize, "maximum size of a single message in bytes")flagSet.Duration("max-req-timeout", opts.MaxReqTimeout, "maximum requeuing timeout for a message")flagSet.Int64("max-body-size", opts.MaxBodySize, "maximum size of a single command body")// client overridable configuration optionsflagSet.Duration("max-heartbeat-interval", opts.MaxHeartbeatInterval, "maximum client configurable duration of time between client heartbeats")flagSet.Int64("max-rdy-count", opts.MaxRdyCount, "maximum RDY count for a client")flagSet.Int64("max-output-buffer-size", opts.MaxOutputBufferSize, "maximum client configurable size (in bytes) for a client output buffer")flagSet.Duration("max-output-buffer-timeout", opts.MaxOutputBufferTimeout, "maximum client configurable duration of time between flushing to a client")// statsd integration optionsflagSet.String("statsd-address", opts.StatsdAddress, "UDP <addr>:<port> of a statsd daemon for pushing stats")flagSet.String("statsd-interval", opts.StatsdInterval.String(), "duration between pushing to statsd")flagSet.Bool("statsd-mem-stats", opts.StatsdMemStats, "toggle sending memory and GC stats to statsd")flagSet.String("statsd-prefix", opts.StatsdPrefix, "prefix used for keys sent to statsd (%s for host replacement)")// End to end percentile flagse2eProcessingLatencyPercentiles := app.FloatArray{}flagSet.Var(&e2eProcessingLatencyPercentiles, "e2e-processing-latency-percentile", "message processing time percentiles (as float (0, 1.0]) to track (can be specified multiple times or comma separated '1.0,0.99,0.95', default none)")flagSet.Duration("e2e-processing-latency-window-time", opts.E2EProcessingLatencyWindowTime, "calculate end to end latency quantiles for this duration of time (ie: 60s would only show quantile calculations from the past 60 seconds)")// TLS configflagSet.String("tls-cert", opts.TLSCert, "path to certificate file")flagSet.String("tls-key", opts.TLSKey, "path to key file")flagSet.String("tls-client-auth-policy", opts.TLSClientAuthPolicy, "client certificate auth policy ('require' or 'require-verify')")flagSet.String("tls-root-ca-file", opts.TLSRootCAFile, "path to certificate authority file")tlsRequired := tlsRequiredOption(opts.TLSRequired)tlsMinVersion := tlsMinVersionOption(opts.TLSMinVersion)flagSet.Var(&tlsRequired, "tls-required", "require TLS for client connections (true, false, tcp-https)")flagSet.Var(&tlsMinVersion, "tls-min-version", "minimum SSL/TLS version acceptable ('ssl3.0', 'tls1.0', 'tls1.1', or 'tls1.2')")// compressionflagSet.Bool("deflate", opts.DeflateEnabled, "enable deflate feature negotiation (client compression)")flagSet.Int("max-deflate-level", opts.MaxDeflateLevel, "max deflate compression level a client can negotiate (> values == > nsqd CPU usage)")flagSet.Bool("snappy", opts.SnappyEnabled, "enable snappy feature negotiation (client compression)")return flagSet}type config map[string]interface{}// Validate settings in the config file, and fatal on errorsfunc (cfg config) Validate() {// special validation/translationif v, exists := cfg["tls_required"]; exists {var t tlsRequiredOptionerr := t.Set(fmt.Sprintf("%v", v))if err == nil {cfg["tls_required"] = t.String()} else {log.Fatalf("ERROR: failed parsing tls required %v", v)}}if v, exists := cfg["tls_min_version"]; exists {var t tlsMinVersionOptionerr := t.Set(fmt.Sprintf("%v", v))if err == nil {newVal := fmt.Sprintf("%v", t.Get())if newVal != "0" {cfg["tls_min_version"] = newVal} else {delete(cfg, "tls_min_version")}} else {log.Fatalf("ERROR: failed parsing tls min version %v", v)}}}type program struct {nsqd *nsqd.NSQD}func main() {prg := &program{}//系统调用，向系统发送SIGINT、SIGTERM信号//SIGINT：用户发送INTR字符(Ctrl+C)触发//SIGTERM：结束程序(可以被捕获、阻塞或忽略)//程序将在这里阻塞，除非Ctrl+C或程序结束//查看svc.Run()方法源码，可知通过调用prg参数的Init()方法初始化，Start()方法开始程序，Stop()方法结束程序if err := svc.Run(prg, syscall.SIGINT, syscall.SIGTERM); err != nil {log.Fatal(err)}}func (p *program) Init(env svc.Environment) error {if env.IsWindowsService() {dir := filepath.Dir(os.Args[0])return os.Chdir(dir)}return nil}func (p *program) Start() error {//加载nsqd/options.go中的默认配置opts := nsqd.NewOptions()//修改默认配置flagSet := nsqdFlagSet(opts)flagSet.Parse(os.Args[1:])//TODO 随机数？？没明白这里，标记一下rand.Seed(time.Now().UTC().UnixNano())if flagSet.Lookup("version").Value.(flag.Getter).Get().(bool) {fmt.Println(version.String("nsqd"))os.Exit(0)}//解析配置文件var cfg configconfigFile := flagSet.Lookup("config").Value.String()if configFile != "" {_, err := toml.DecodeFile(configFile, &cfg)if err != nil {log.Fatalf("ERROR: failed to load config file %s - %s", configFile, err.Error())}}//验证配置是否合法，主要关于TLS的验证cfg.Validate()options.Resolve(opts, flagSet, cfg)//这里和上面导入的包命名一样，防止混淆，修改这里的变量名称//根据配置信息，新建nsqd实例nsqdInstance := nsqd.New(opts)//加载元数据err := nsqdInstance.LoadMetadata()if err != nil {log.Fatalf("ERROR: %s", err.Error())}//将元数据保存到本地err = nsqdInstance.PersistMetadata()if err != nil {log.Fatalf("ERROR: failed to persist metadata - %s", err.Error())}//nsqd的Main()方法nsqdInstance.Main()p.nsqd = nsqdInstancereturn nil}//终止程序func (p *program) Stop() error {if p.nsqd != nil {p.nsqd.Exit()}return nil}

关于TLS的一些验证，先忽略。这里有一篇关于SSL/TLS的文章，大家可以去看看。