cache.go

package main

import (
	"bytes"
	"encoding/json"
	"goFactServView/cwlog"
	"os"
	"time"
)

const (
	CacheFile    = "data/cache.json"
	CacheVersion = 2
)

func ReadServerCache() {

	FetchLock.Lock()
	defer FetchLock.Unlock()

	_, err := os.Stat(CacheFile)
	notfound := os.IsNotExist(err)

	if notfound {
		return
	} else { /* Otherwise just read in the config */
		info, err := os.Stat(CacheFile)
		lastRefresh := time.Time{}
		if err == nil {
			lastRefresh = info.ModTime()
		}

		file, err := os.ReadFile(CacheFile)

		if file != nil && err == nil {

			tempServerList := CacheData{}
			err := json.Unmarshal([]byte(file), &tempServerList)
			if err != nil {
				cwlog.DoLog(true, "ReadServerList: Unmarshal failure")
				return
			}
			if tempServerList.Version < CacheVersion {
				cwlog.DoLog(false, "Cache data is incompatable, skipping.")
				return
			}

			if len(tempServerList.Servers) > MinValidCount {
				sParam.ServerList.Servers = sortServers(false, tempServerList.Servers, SORT_PLAYER)
				getVersions()
				sParam.LastRefresh = lastRefresh
				sParam.ServersCount = len(tempServerList.Servers)

				cwlog.DoLog(true, "Read cached server list.")
			}

			totalPlayers := 0
			for _, item := range tempServerList.Servers {
				totalPlayers = totalPlayers + len(item.Players)
			}
			sParam.PlayerCount = totalPlayers
			return
		} else {
			cwlog.DoLog(true, "ReadServerList: Read file failure")
			return
		}
	}

}

func WriteServerCache() {

	tempPath := CacheFile + ".tmp"

	outbuf := new(bytes.Buffer)
	enc := json.NewEncoder(outbuf)
	enc.SetIndent("", "\t")

	if len(sParam.ServerList.Servers) <= MinValidCount {
		return
	}

	sParam.ServerList.Version = CacheVersion
	if err := enc.Encode(sParam.ServerList); err != nil {
		cwlog.DoLog(true, "WriteServerList: enc.Encode failure")
		return
	}

	_, err := os.Create(tempPath)

	if err != nil {
		cwlog.DoLog(true, "WriteServerList: os.Create failure")
		return
	}

	err = os.WriteFile(tempPath, outbuf.Bytes(), 0644)

	if err != nil {
		cwlog.DoLog(true, "WriteServerList: Write file failure")
	}

	err = os.Rename(tempPath, CacheFile)

	if err != nil {
		cwlog.DoLog(true, "Couldn't rename cache file.")
		return
	}
}