handle signals - write pending records on shutdown

cmd/daemon/main.go

@@ -70,10 +70,12 @@ func main() {
 		log.Fatal("Could not create pidfile", err)
 	}
 	runServer(config, historyPath)
+	log.Println("main: Removing pidfile ...")
 	err = os.Remove(pidfilePath)
 	if err != nil {
 		log.Println("Could not delete pidfile", err)
 	}
+	log.Println("main: Shutdown - bye")
 }
 
 func statusHandler(w http.ResponseWriter, r *http.Request) {
@@ -92,7 +94,7 @@ func killDaemon(pidfile string) error {
 	if err != nil {
 		log.Fatal("Pidfile contents are malformed", err)
 	}
-	cmd := exec.Command("kill", strconv.Itoa(pid))
+	cmd := exec.Command("kill", "-s", "sigint", strconv.Itoa(pid))
 	err = cmd.Run()
 	if err != nil {
 		log.Printf("Command finished with error: %v", err)

cmd/daemon/run-server.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"net/http"
+	"os"
 	"strconv"
 
 	"github.com/curusarn/resh/pkg/cfg"
@@ -9,12 +10,16 @@ import (
 	"github.com/curusarn/resh/pkg/records"
 	"github.com/curusarn/resh/pkg/sesshist"
 	"github.com/curusarn/resh/pkg/sesswatch"
+	"github.com/curusarn/resh/pkg/signalhandler"
 )
 
 func runServer(config cfg.Config, historyPath string) {
 	var recordSubscribers []chan records.Record
 	var sessionInitSubscribers []chan records.Record
 	var sessionDropSubscribers []chan string
+	var signalSubscribers []chan os.Signal
+
+	shutdown := make(chan string)
 
 	// sessshist
 	sesshistSessionsToInit := make(chan records.Record)
@@ -29,7 +34,9 @@ func runServer(config cfg.Config, historyPath string) {
 	recordSubscribers = append(recordSubscribers, histfileRecords)
 	histfileSessionsToDrop := make(chan string)
 	sessionDropSubscribers = append(sessionDropSubscribers, histfileSessionsToDrop)
-	histfileBox := histfile.New(histfileRecords, historyPath, 10000, histfileSessionsToDrop)
+	histfileSignals := make(chan os.Signal)
+	signalSubscribers = append(signalSubscribers, histfileSignals)
+	histfileBox := histfile.New(histfileRecords, historyPath, 10000, histfileSessionsToDrop, histfileSignals, shutdown)
 
 	// sesshist New
 	sesshistDispatch := sesshist.NewDispatch(sesshistSessionsToInit, sesshistSessionsToDrop, sesshistRecords, histfileBox, config.SesshistInitHistorySize)
@@ -40,9 +47,15 @@ func runServer(config cfg.Config, historyPath string) {
 	sesswatch.Go(sesswatchSessionsToWatch, sessionDropSubscribers, config.SesswatchPeriodSeconds)
 
 	// handlers
-	http.HandleFunc("/status", statusHandler)
-	http.Handle("/record", &recordHandler{subscribers: recordSubscribers})
-	http.Handle("/session_init", &sessionInitHandler{subscribers: sessionInitSubscribers})
-	http.Handle("/recall", &recallHandler{sesshistDispatch: sesshistDispatch})
-	http.ListenAndServe(":"+strconv.Itoa(config.Port), nil)
+	mux := http.NewServeMux()
+	mux.HandleFunc("/status", statusHandler)
+	mux.Handle("/record", &recordHandler{subscribers: recordSubscribers})
+	mux.Handle("/session_init", &sessionInitHandler{subscribers: sessionInitSubscribers})
+	mux.Handle("/recall", &recallHandler{sesshistDispatch: sesshistDispatch})
+
+	server := &http.Server{Addr: ":" + strconv.Itoa(config.Port), Handler: mux}
+	go server.ListenAndServe()
+
+	// signalhandler - takes over the main goroutine so when signal handler exists the whole program exits
+	signalhandler.Run(signalSubscribers, shutdown, server)
 }

pkg/histfile/histfile.go

@@ -23,14 +23,16 @@ type Histfile struct {
 }
 
 // New creates new histfile and runs two gorutines on it
-func New(input chan records.Record, historyPath string, initHistSize int, sessionsToDrop chan string) *Histfile {
+func New(input chan records.Record, historyPath string, initHistSize int, sessionsToDrop chan string,
+	signals chan os.Signal, shutdownDone chan string) *Histfile {
+
 	hf := Histfile{
 		sessions:          map[string]records.Record{},
 		historyPath:       historyPath,
 		cmdLinesLastIndex: map[string]int{},
 	}
 	go hf.loadHistory(initHistSize)
-	go hf.writer(input)
+	go hf.writer(input, signals, shutdownDone)
 	go hf.sessionGC(sessionsToDrop)
 	return &hf
 }
@@ -61,33 +63,52 @@ func (h *Histfile) sessionGC(sessionsToDrop chan string) {
 }
 
 // writer reads records from channel, merges them and writes them to file
-func (h *Histfile) writer(input chan records.Record) {
+func (h *Histfile) writer(input chan records.Record, signals chan os.Signal, shutdownDone chan string) {
 	for {
 		func() {
-			record := <-input
-			h.sessionsMutex.Lock()
-			defer h.sessionsMutex.Unlock()
+			select {
+			case record := <-input:
+				h.sessionsMutex.Lock()
+				defer h.sessionsMutex.Unlock()
 
-			// allows nested sessions to merge records properly
-			mergeID := record.SessionID + "_" + strconv.Itoa(record.Shlvl)
-			if record.PartOne {
-				if _, found := h.sessions[mergeID]; found {
-					log.Println("histfile WARN: Got another first part of the records before merging the previous one - overwriting! " +
-						"(this happens in bash because bash-preexec runs when it's not supposed to)")
-				}
-				h.sessions[mergeID] = record
-			} else {
-				if part1, found := h.sessions[mergeID]; found == false {
-					log.Println("histfile ERROR: Got second part of records and nothing to merge it with - ignoring! (mergeID:", mergeID, ")")
+				// allows nested sessions to merge records properly
+				mergeID := record.SessionID + "_" + strconv.Itoa(record.Shlvl)
+				if record.PartOne {
+					if _, found := h.sessions[mergeID]; found {
+						log.Println("histfile WARN: Got another first part of the records before merging the previous one - overwriting! " +
+							"(this happens in bash because bash-preexec runs when it's not supposed to)")
+					}
+					h.sessions[mergeID] = record
 				} else {
-					delete(h.sessions, mergeID)
-					go h.mergeAndWriteRecord(part1, record)
+					if part1, found := h.sessions[mergeID]; found == false {
+						log.Println("histfile ERROR: Got second part of records and nothing to merge it with - ignoring! (mergeID:", mergeID, ")")
+					} else {
+						delete(h.sessions, mergeID)
+						go h.mergeAndWriteRecord(part1, record)
+					}
 				}
+			case sig := <-signals:
+				log.Println("histfile: Got signal " + sig.String())
+				h.sessionsMutex.Lock()
+				defer h.sessionsMutex.Unlock()
+				log.Println("histfile DEBUG: Unlocked mutex")
+
+				for sessID, record := range h.sessions {
+					log.Panicln("histfile WARN: Writing incomplete record for session " + sessID)
+					h.writeRecord(record)
+				}
+				log.Println("histfile DEBUG: Shutdown success")
+				shutdownDone <- "histfile"
+				return
 			}
 		}()
 	}
 }
 
+func (h *Histfile) writeRecord(part1 records.Record) {
+	writeRecord(part1, h.historyPath)
+}
+
 func (h *Histfile) mergeAndWriteRecord(part1, part2 records.Record) {
 	err := part1.Merge(part2)
 	if err != nil {

pkg/signalhandler/signalhander.go

@@ -0,0 +1,57 @@
+package signalhandler
+
+import (
+	"context"
+	"log"
+	"net/http"
+	"os"
+	"os/signal"
+	"strconv"
+	"syscall"
+	"time"
+)
+
+func sendSignals(sig os.Signal, subscribers []chan os.Signal, done chan string) {
+	for _, sub := range subscribers {
+		sub <- sig
+	}
+	chanCount := len(subscribers)
+	start := time.Now()
+	delay := time.Millisecond * 100
+	timeout := time.Millisecond * 2000
+
+	for {
+		select {
+		case _ = <-done:
+			chanCount--
+			if chanCount == 0 {
+				log.Println("signalhandler: All boxes shut down successfully")
+				return
+			}
+		default:
+			time.Sleep(delay)
+		}
+		if time.Since(start) > timeout {
+			log.Println("signalhandler: Timouted while waiting for proper shutdown - " + strconv.Itoa(chanCount) + " boxes are up after " + timeout.String())
+			return
+		}
+	}
+}
+
+// Run catches and handles signals
+func Run(subscribers []chan os.Signal, done chan string, server *http.Server) {
+	signals := make(chan os.Signal, 1)
+
+	signal.Notify(signals, syscall.SIGINT, syscall.SIGTERM)
+
+	sig := <-signals
+	log.Println("signalhandler: Got signal " + sig.String())
+
+	log.Println("signalhandler: Sending signals to Subscribers")
+	sendSignals(sig, subscribers, done)
+
+	log.Println("signalhandler: Shutting down the server")
+	if err := server.Shutdown(context.Background()); err != nil {
+		log.Printf("HTTP server Shutdown: %v", err)
+	}
+}