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server.go
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server.go
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// Package server contains all logic related to the server.
package server
import (
"errors"
"fmt"
"io"
"net"
"os"
"os/signal"
"strings"
"syscall"
"time"
"github.com/lzambarda/hbt/internal"
)
func saveRoutines(g Graph, cachePath string) {
// Intercept termination signal to save the most recent knowledge
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt, syscall.SIGTERM)
go func() {
<-c
if internal.Debug {
fmt.Println("Saving graph at", cachePath)
}
err := g.Save(cachePath)
if err != nil {
fmt.Println(err)
os.Exit(1)
}
os.Exit(0)
}()
// Periodically save the file
go func() {
for {
time.Sleep(internal.SaveInterval)
if internal.Debug {
fmt.Println("Saving graph at", cachePath)
}
err := g.Save(cachePath)
if err != nil {
fmt.Println(err)
os.Exit(1)
}
}
}()
}
// Start the hbt server with the given graph and cache path.
func Start(g Graph, cachePath string) error {
saveRoutines(g, cachePath)
if internal.Debug {
fmt.Println("Starting server at", internal.Port)
}
l, err := net.Listen("tcp4", ":"+internal.Port)
if err != nil {
return err
}
defer l.Close() //nolint:errcheck // It is okay.
for {
c, err := l.Accept()
if err != nil {
return err
}
go handleConnection(c, g)
}
}
// Stop the server.
func Stop() error {
return nil
}
func handleConnection(c net.Conn, g Graph) {
defer c.Close() //nolint:errcheck // It is okay.
buf := make([]byte, 0, 4096) // arbitrary
tmp := make([]byte, 64) // arbitrary
for {
n, err := c.Read(tmp)
if err != nil {
if !errors.Is(err, io.EOF) {
fmt.Println(err)
return
}
break
}
buf = append(buf, tmp[:n]...)
}
args := strings.Split(string(buf), "\n")
if internal.Debug {
fmt.Println(args)
}
result, err := ProcessCommand(args, g)
if err != nil {
fmt.Println(err)
return
}
if result != "" {
_, err = c.Write([]byte(result))
if err != nil {
fmt.Println(err)
}
}
}
// ProcessCommand processes the arguments and runs a command on the given Graph.
func ProcessCommand(args []string, g Graph) (result string, err error) {
if len(args) == 0 {
return "", errors.New("missing command")
}
switch args[0] {
case "track":
if len(args) != 4 {
return "", fmt.Errorf("wrong number of arguments, expected 4, got %d", len(args))
}
g.Track(args[1], args[2], args[3])
case "hint":
if len(args) != 3 {
return "", fmt.Errorf("wrong number of arguments, expected 3, got %d", len(args))
}
// args[3] is unused for now
hint := g.Hint(args[1], args[2]) //nolint:errcheck,gosec // It is okay.
return hint, nil
case "end":
if len(args) != 2 {
return "", fmt.Errorf("wrong number of arguments, expected 2, got %d", len(args))
}
g.End(args[1])
case "del":
if len(args) != 4 {
return "", fmt.Errorf("wrong number of arguments, expected 4, got %d", len(args))
}
g.Delete(args[1], args[2], args[3])
default:
return "", fmt.Errorf("unknown command: %q", args[0])
}
return "", nil
}