mirror of
https://github.com/postmannen/ctrl.git
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388 lines
13 KiB
Go
388 lines
13 KiB
Go
// Notes:
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package steward
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import (
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"bytes"
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"encoding/gob"
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"fmt"
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"log"
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"os"
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"sync"
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"time"
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"github.com/nats-io/nats.go"
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"github.com/prometheus/client_golang/prometheus"
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)
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type Message struct {
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ToNode node `json:"toNode" yaml:"toNode"`
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// The Unique ID of the message
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ID int `json:"id" yaml:"id"`
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// The actual data in the message
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// TODO: Change this to a slice instead...or maybe use an
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// interface type here to handle several data types ?
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Data []string `json:"data" yaml:"data"`
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// The type of the message being sent
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CommandOrEvent CommandOrEvent `json:"commandOrEvent" yaml:"commandOrEvent"`
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// method, what is this message doing, etc. shellCommand, syslog, etc.
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Method Method `json:"method" yaml:"method"`
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FromNode node
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// done is used to signal when a message is fully processed.
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// This is used when choosing when to move the message from
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// the ringbuffer into the time series log.
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done chan struct{}
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}
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// server is the structure that will hold the state about spawned
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// processes on a local instance.
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type server struct {
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natsConn *nats.Conn
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// TODO: sessions should probably hold a slice/map of processes ?
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processes map[subjectName]process
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// The last processID created
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lastProcessID int
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// The name of the node
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nodeName string
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// Mutex for locking when writing to the process map
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mu sync.Mutex
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// The channel where we receive new messages read from file.
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// We can than range this channel for new messages to process.
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inputFromFileCh chan []subjectAndMessage
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// errorKernel is doing all the error handling like what to do if
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// an error occurs.
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// TODO: Will also send error messages to cental error subscriber.
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errorKernel *errorKernel
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// used to check if the methods specified in message is valid
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methodsAvailable MethodsAvailable
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// Map who holds the command and event types available.
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// Used to check if the commandOrEvent specified in message is valid
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commandOrEventAvailable CommandOrEventAvailable
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// metric exporter
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metrics *metrics
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// subscriberServices are where we find the services and the API to
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// use services needed by subscriber.
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// For example, this can be a service that knows
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// how to forward the data for a received message of type log to a
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// central logger.
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subscriberServices *subscriberServices
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}
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// newServer will prepare and return a server type
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func NewServer(brokerAddress string, nodeName string, promHostAndPort string) (*server, error) {
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conn, err := nats.Connect(brokerAddress, nil)
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if err != nil {
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log.Printf("error: nats.Connect failed: %v\n", err)
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}
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var m Method
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var coe CommandOrEvent
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s := &server{
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nodeName: nodeName,
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natsConn: conn,
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processes: make(map[subjectName]process),
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inputFromFileCh: make(chan []subjectAndMessage),
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methodsAvailable: m.GetMethodsAvailable(),
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commandOrEventAvailable: coe.GetCommandOrEventAvailable(),
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metrics: newMetrics(promHostAndPort),
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subscriberServices: newSubscriberServices(),
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}
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return s, nil
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}
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// Start will spawn up all the predefined subscriber processes.
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// Spawning of publisher processes is done on the fly by checking
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// if there is publisher process for a given message subject, and
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// not exist it will spawn one.
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func (s *server) Start() {
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// Start the error kernel that will do all the error handling
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// not done within a process.
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s.errorKernel = newErrorKernel()
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s.errorKernel.startErrorKernel()
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// Start collecting the metrics
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go s.startMetrics()
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// Start the checking the input file for new messages from operator.
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go s.getMessagesFromFile("./", "inmsg.txt", s.inputFromFileCh)
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// Start the textLogging service that will run on the subscribers
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// TODO: This should only be started if the flag value provided when
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// starting asks to subscribe to TextLogging events.
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go s.subscriberServices.startTextLogging()
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// Start up the predefined subscribers.
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// TODO: What to subscribe on should be handled via flags, or config
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// files.
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s.subscribersStart()
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time.Sleep(time.Second * 2)
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s.printProcessesMap()
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// Start the processing of new messaging from an input channel.
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s.processNewMessages("./incommmingBuffer.db", s.inputFromFileCh)
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select {}
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}
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func (s *server) printProcessesMap() {
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fmt.Println("--------------------------------------------------------------------------------------------")
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fmt.Printf("*** Output of processes map :\n")
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for _, v := range s.processes {
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fmt.Printf("*** - : %v\n", v)
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}
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s.metrics.metricsCh <- metricType{
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metric: prometheus.NewGauge(prometheus.GaugeOpts{
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Name: "total_running_processes",
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Help: "The current number of total running processes",
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}),
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value: float64(len(s.processes)),
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}
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fmt.Println("--------------------------------------------------------------------------------------------")
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}
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type node string
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// subject contains the representation of a subject to be used with one
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// specific process
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type Subject struct {
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// node, the name of the node
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ToNode string `json:"node" yaml:"toNode"`
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// messageType, command/event
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CommandOrEvent CommandOrEvent `json:"commandOrEvent" yaml:"commandOrEvent"`
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// method, what is this message doing, etc. shellCommand, syslog, etc.
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Method Method `json:"method" yaml:"method"`
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// messageCh is the channel for receiving new content to be sent
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messageCh chan Message
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}
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// newSubject will return a new variable of the type subject, and insert
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// all the values given as arguments. It will also create the channel
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// to receive new messages on the specific subject.
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func newSubject(method Method, commandOrEvent CommandOrEvent, node string) Subject {
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return Subject{
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ToNode: node,
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CommandOrEvent: commandOrEvent,
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Method: method,
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messageCh: make(chan Message),
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}
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}
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// subjectName is the complete representation of a subject
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type subjectName string
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func (s Subject) name() subjectName {
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return subjectName(fmt.Sprintf("%s.%s.%s", s.Method, s.CommandOrEvent, s.ToNode))
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}
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// processKind are either kindSubscriber or kindPublisher, and are
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// used to distinguish the kind of process to spawn and to know
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// the process kind put in the process map.
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type processKind string
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const (
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processKindSubscriber processKind = "subscriber"
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processKindPublisher processKind = "publisher"
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)
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// process are represent the communication to one individual host
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type process struct {
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messageID int
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// the subject used for the specific process. One process
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// can contain only one sender on a message bus, hence
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// also one subject
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subject Subject
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// Put a node here to be able know the node a process is at.
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// NB: Might not be needed later on.
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node node
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// The processID for the current process
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processID int
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// errorCh is used to report errors from a process
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// NB: Implementing this as an int to report for testing
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errorCh chan errProcess
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processKind processKind
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}
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// prepareNewProcess will set the the provided values and the default
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// values for a process.
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func (s *server) processPrepareNew(subject Subject, errCh chan errProcess, processKind processKind) process {
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// create the initial configuration for a sessions communicating with 1 host process.
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s.lastProcessID++
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proc := process{
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messageID: 0,
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subject: subject,
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node: node(subject.ToNode),
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processID: s.lastProcessID,
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errorCh: errCh,
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processKind: processKind,
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//messageCh: make(chan Message),
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}
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return proc
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}
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// spawnWorkerProcess will spawn take care of spawning both publisher
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// and subscriber proesses.
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//It will give the process the next available ID, and also add the
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// process to the processes map.
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func (s *server) spawnWorkerProcess(proc process) {
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s.mu.Lock()
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// We use the full name of the subject to identify a unique
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// process. We can do that since a process can only handle
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// one message queue.
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s.processes[proc.subject.name()] = proc
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s.mu.Unlock()
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// TODO: I think it makes most sense that the messages would come to
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// here from some other message-pickup-process, and that process will
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// give the message to the correct publisher process. A channel that
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// is listened on in the for loop below could be used to receive the
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// messages from the message-pickup-process.
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//
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// Handle publisher workers
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if proc.processKind == processKindPublisher {
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s.publishMessages(proc)
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}
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// handle subscriber workers
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if proc.processKind == processKindSubscriber {
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s.subscribeMessages(proc)
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}
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}
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func messageDeliver(proc process, message Message, natsConn *nats.Conn) {
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for {
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dataPayload, err := gobEncodeMessage(message)
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if err != nil {
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log.Printf("error: createDataPayload: %v\n", err)
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}
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msg := &nats.Msg{
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Subject: string(proc.subject.name()),
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// Subject: fmt.Sprintf("%s.%s.%s", proc.node, "command", "shellCommand"),
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// Structure of the reply message are:
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// reply.<nodename>.<message type>.<method>
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Reply: fmt.Sprintf("reply.%s", proc.subject.name()),
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Data: dataPayload,
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}
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// The SubscribeSync used in the subscriber, will get messages that
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// are sent after it started subscribing, so we start a publisher
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// that sends out a message every second.
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//
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// Create a subscriber for the reply message.
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subReply, err := natsConn.SubscribeSync(msg.Reply)
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if err != nil {
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log.Printf("error: nc.SubscribeSync failed: %v\n", err)
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os.Exit(1)
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continue
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}
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// Publish message
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err = natsConn.PublishMsg(msg)
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if err != nil {
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log.Printf("error: publish failed: %v\n", err)
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continue
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}
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// If the message is an ACK type of message we must check that a
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// reply, and if it is not we don't wait here at all.
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if message.CommandOrEvent == CommandACK || message.CommandOrEvent == EventACK {
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// Wait up until 10 seconds for a reply,
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// continue and resend if to reply received.
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msgReply, err := subReply.NextMsg(time.Second * 10)
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if err != nil {
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log.Printf("error: subReply.NextMsg failed for node=%v, subject=%v: %v\n", proc.node, proc.subject.name(), err)
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// did not receive a reply, continuing from top again
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continue
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}
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log.Printf("info: publisher: received ACK for message: %s\n", msgReply.Data)
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}
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return
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}
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}
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// gobEncodePayload will encode the message structure along with its
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// valued in gob binary format.
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// TODO: Check if it adds value to compress with gzip.
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func gobEncodeMessage(m Message) ([]byte, error) {
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var buf bytes.Buffer
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gobEnc := gob.NewEncoder(&buf)
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err := gobEnc.Encode(m)
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if err != nil {
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return nil, fmt.Errorf("error: gob.Encode failed: %v", err)
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}
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return buf.Bytes(), nil
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}
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// handler will deserialize the message when a new message is received,
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// check the MessageType field in the message to decide what kind of
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// message it is and then it will check how to handle that message type,
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// and handle it.
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// This handler function should be started in it's own go routine,so
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// one individual handler is started per message received so we can keep
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// the state of the message being processed, and then reply back to the
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// correct sending process's reply, meaning so we ACK back to the correct
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// publisher.
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func (s *server) subscriberHandler(natsConn *nats.Conn, node string, msg *nats.Msg) {
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message := Message{}
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// Create a buffer to decode the gob encoded binary data back
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// to it's original structure.
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buf := bytes.NewBuffer(msg.Data)
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gobDec := gob.NewDecoder(buf)
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err := gobDec.Decode(&message)
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if err != nil {
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log.Printf("error: gob decoding failed: %v\n", err)
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}
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//fmt.Printf("%v\n", msg)
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// TODO: Maybe the handling of the errors within the subscriber
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// should also involve the error-kernel to report back centrally
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// that there was a problem like missing method to handle a specific
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// method etc.
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switch {
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case message.CommandOrEvent == CommandACK || message.CommandOrEvent == EventACK:
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log.Printf("info: subscriberHandler: message.CommandOrEvent received was = %v, preparing to call handler\n", message.CommandOrEvent)
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mf, ok := s.methodsAvailable.CheckIfExists(message.Method)
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if !ok {
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// TODO: Check how errors should be handled here!!!
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log.Printf("error: subscriberHandler: method type not available: %v\n", message.CommandOrEvent)
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}
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fmt.Printf("*** DEBUG: BEFORE CALLING HANDLER: ACK\n")
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out, err := mf.handler(s, message, node)
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if err != nil {
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// TODO: Send to error kernel ?
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log.Printf("error: subscriberHandler: failed to execute event: %v\n", err)
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}
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// Send a confirmation message back to the publisher
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natsConn.Publish(msg.Reply, out)
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case message.CommandOrEvent == CommandNACK || message.CommandOrEvent == EventNACK:
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log.Printf("info: subscriberHandler: message.CommandOrEvent received was = %v, preparing to call handler\n", message.CommandOrEvent)
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mf, ok := s.methodsAvailable.CheckIfExists(message.Method)
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if !ok {
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// TODO: Check how errors should be handled here!!!
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log.Printf("error: subscriberHandler: method type not available: %v\n", message.CommandOrEvent)
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}
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// since we don't send a reply for a NACK message, we don't care about the
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// out return when calling mf.handler
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fmt.Printf("*** DEBUG: BEFORE CALLING HANDLER: NACK\n")
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_, err := mf.handler(s, message, node)
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if err != nil {
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// TODO: Send to error kernel ?
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log.Printf("error: subscriberHandler: failed to execute event: %v\n", err)
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}
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default:
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log.Printf("info: did not find that specific type of command: %#v\n", message.CommandOrEvent)
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}
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}
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