working as intended

backend/backend.go

@@ -5,11 +5,13 @@ import (
 	"errors"
 	"fmt"
 	"os"
+	"io/fs"
 	"os/exec"
 	"path/filepath"
 	"strings"
 	"time"
 	"git.noctra.dev/noctra/servtex/globals"
+	"github.com/fsnotify/fsnotify"
 )
 
 // Returns the current time in the timezone specified in the config file
@@ -111,15 +113,89 @@ func ConfigReader(configFileName string, configOptionStorage *globals.Config) er
 	return err 
 }
 
+// Contents copied from https://github.com/fsnotify/fsnotify/blob/main/cmd/fsnotify/watch.go
+func watchLoop(watcher *fsnotify.Watcher, callOnChange func() error) {
+	defer watcher.Close()
+	for {
+		select {
+			// Errors
+			case err, ok := <-watcher.Errors:
+				if !ok {
+					LogLine(fmt.Sprintf("Watcher crashed on error, manual compile only: %s", err), 4)
+					return
+				}
+				LogLine(fmt.Sprintf("Watcher Error: %s", err), 3)
+
+			// Events
+			case event, ok := <-watcher.Events:
+				if !ok {
+					LogLine(fmt.Sprintf("Watcher crashed on event, manual compile only: %s", event), 4)
+					return
+				}
+				LogLine(fmt.Sprintf("File change noticed: %s", event.Name), 2)
+
+				err := callOnChange()
+				if err != nil {
+					LogLine(fmt.Sprintf("Latex compilation failed: %s", err), 4)
+				}
+
+				if err = watcher.Add(event.Name); err != nil {
+					LogLine(fmt.Sprintf("File could not be re-added to watcher: %s", event.Name), 4)
+				}
+			}
+	}
+}
+
+
+func texFinder(path string) []string {
+	var texFiles []string
+	err := filepath.WalkDir(path, func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+		    return err
+		}
+		if !d.IsDir() && filepath.Ext(path) == ".tex" {
+		    texFiles = append(texFiles, path)
+		}
+		return nil
+	})
+	if err != nil {
+		LogLine("Some paths could not be traversed while search for .tex files", 3)
+	}
+	return texFiles
+}
+
 // Watches a specified directory and calls a function on change
 //
 // Optionally, a minimum time to wait for consecutive changes can be specified
-func ChangeWatch(path string, callOnChange func()) {
-	LogLine("File change noticed", 2)
+func ChangeWatch(path string, callOnChange func() error) {
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		LogLine("File system watcher could not be initialised, manual compile only", 4)
+		return
+	}
+
+	for _, file := range texFinder(path) {
+		if err = watcher.Add(file); err != nil {
+			LogLine(fmt.Sprintf("File could not be added to watcher: %s", err), 4)
+		}
+		LogLine(fmt.Sprintf("File added to watcher: %s", file), 1)
+	}
+
+	go watchLoop(watcher, callOnChange)
+
+	LogLine("Watcher initialised", 1)
+}
+
+
+func updateExecutionTimestamp(execution *globals.LatexExecution) {
+	execution.Timestamp = GetLocalTimePretty()
+	execution.TimestampRFC = GetLocalTimeRFC()
 }
 
 // Intended to be run as goroutine
-func LatexCompile(config globals.Config, execution *globals.LatexExecution) error {
+func LatexCompile() error {
+	execution := &globals.LatexExec
+	config := globals.AppConfig
 	if execution.ExecutionLock.TryLock() {
 		defer execution.ExecutionLock.Unlock()
 	} else {
@@ -143,7 +219,8 @@ func LatexCompile(config globals.Config, execution *globals.LatexExecution) erro
 		default:
 			execution.ExecutionState = "Unknown Latex Engine"
 			execution.Output = []byte{}
-			execution.Timestamp = GetLocalTimePretty()
+			updateExecutionTimestamp(execution)
+
 			LogLine("Unsupported LaTeX Engine", 4)
 			return errors.New("Unsupported LaTeX Engine")
 	}
@@ -156,8 +233,9 @@ func LatexCompile(config globals.Config, execution *globals.LatexExecution) erro
 	}
 
 	execution.Output = stdout
-	execution.Timestamp = GetLocalTimePretty()
 	execution.ExecutionState = "Done"
+	updateExecutionTimestamp(execution)
+
 	LogLine("LaTeX execution finished", 2)
 	return nil
 }

frontend/webserver.go

@@ -77,16 +77,17 @@ func SSEventHandler(writer http.ResponseWriter, request *http.Request) {
 	writer.Header().Set("Content-Type", "text/event-stream")
 	writer.Header().Set("Cache-Control", "no-cache")
 	writer.Header().Set("Connection", "keep-alive")
+	ssePing(&writer)
+
 	lastExecution := "startup"
 	for range time.Tick(time.Second) {
-		if lastExecution == globals.LatexExec.Timestamp {
+		if lastExecution == globals.LatexExec.TimestampRFC {
 			ssePing(&writer)
 		} else {
 			sseStatusSend(&writer)
 			ssePDFSend(&writer)
 			sseOutputSend(&writer)
-			// comment out for testing purposes
-			lastExecution = globals.LatexExec.Timestamp
+			lastExecution = globals.LatexExec.TimestampRFC
 		}
 	}
 }
@@ -114,6 +115,6 @@ func MainHandler(writer http.ResponseWriter, request *http.Request) {
 }
 
 func PDFCompile(writer http.ResponseWriter, request *http.Request) {
-	backend.LatexCompile(globals.AppConfig, &globals.LatexExec)
+	backend.LatexCompile()
 }
 

globals/memory.go

@@ -32,6 +32,7 @@ type LatexExecution struct {
 	ExecutionLock	sync.Mutex
 	ExecutionState	string
 	Timestamp	string
+	TimestampRFC	string
 	Output		[]byte
 }
 var LatexExec LatexExecution

main.go

@@ -1,14 +1,16 @@
 package main
 
 import (
-	"os"
-	"os/signal"
-	"syscall"
-	"io/fs"
 	"context"
 	"fmt"
-	"time"
+	"io/fs"
 	"net/http"
+	"os"
+	"os/signal"
+	"path/filepath"
+	"syscall"
+	"time"
+
 	"git.noctra.dev/noctra/servtex/backend"
 	"git.noctra.dev/noctra/servtex/frontend"
 	"git.noctra.dev/noctra/servtex/globals"
@@ -49,6 +51,15 @@ func main() {
 	if globals.AppConfig.WebserverSecure {
 		go serverSecure.ListenAndServeTLS(globals.AppConfig.CertificatePath, globals.AppConfig.CertificateKeyPath)
 	}
+
+	// file system change watch
+	absTexPath, err := filepath.Abs(globals.AppConfig.LatexSourceFilePath)
+	if err == nil {
+		backend.ChangeWatch(filepath.Dir(absTexPath), backend.LatexCompile)
+	} else {
+		backend.LogLine("Absolute TeX file path could not be gotten", 4)
+	}
+
 	backend.LogLine("Started", 2)
 	fmt.Println("Press CTRL-C to Exit ServTeX")
 
@@ -61,7 +72,7 @@ func main() {
 	fmt.Print("\r")
 
 	// shutdown
-	context, cancel := context.WithTimeout(context.Background(), 15*time.Second)
+	context, cancel := context.WithTimeout(context.Background(), 2*time.Second)
 	defer cancel()
 	if err = server.Shutdown(context); err != nil {
 		backend.LogLine("Graceful Shutdown failed", 4)

testfiles/Example.tex

@@ -1,4 +1,8 @@
 \documentclass{article}
 \begin{document}
 (This is an Example Document)
+Filewatcher Test Document
+Filewatcher Test Document
+Filewatcher Test Document
+Filewatcher Test Document
 \end{document}