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mumbledj/bot/cache.go

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2016-06-21 02:16:05 +02:00
/*
* MumbleDJ
* By Matthieu Grieger
* bot/cache.go
* Copyright (c) 2016 Matthieu Grieger (MIT License)
*/
package bot
import (
"errors"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"sort"
"time"
"github.com/Sirupsen/logrus"
"github.com/spf13/viper"
)
// SortFilesByAge is a type that holds file information for cached items for
// sorting.
type SortFilesByAge []os.FileInfo
// Len returns the length of the file slice.
func (a SortFilesByAge) Len() int {
return len(a)
}
// Swap swaps two elements in the file slice.
func (a SortFilesByAge) Swap(i, j int) {
a[i], a[j] = a[j], a[i]
}
// Less compares two file modification times to determine if one is less than
// the other. Returns true if the item in index i is older than the item in
// index j, false otherwise.
func (a SortFilesByAge) Less(i, j int) bool {
return time.Since(a[i].ModTime()) < time.Since(a[j].ModTime())
}
// Cache keeps track of the filesize of the audio cache and
// provides methods for pruning the cache.
type Cache struct {
NumAudioFiles int
TotalFileSize int64
}
// NewCache creates an empty Cache and returns it.
func NewCache() *Cache {
return &Cache{
NumAudioFiles: 0,
TotalFileSize: 0,
}
}
// CheckDirectorySize checks the cache directory to determine if the filesize
// of the files within exceed the user-specified size limit. If so, the oldest
// files are cleared until it is no longer exceeding the limit.
func (c *Cache) CheckDirectorySize() {
const bytesInMiB int = 1048576
c.UpdateStatistics()
for c.TotalFileSize > int64(viper.GetInt("cache.maximum_size")*bytesInMiB) {
if err := c.DeleteOldest(); err != nil {
break
}
}
}
// UpdateStatistics updates the statistics relevant to the cache (number of
// audio files cached, total current size of the cache).
func (c *Cache) UpdateStatistics() {
c.NumAudioFiles, c.TotalFileSize = c.getCurrentStatistics()
logrus.WithFields(logrus.Fields{
"num_audio_files": c.NumAudioFiles,
"total_file_size": c.TotalFileSize,
}).Infoln("Updated cache statistics.")
}
// CleanPeriodically loops forever, deleting expired cached audio files as necessary.
func (c *Cache) CleanPeriodically() {
for range time.Tick(time.Duration(viper.GetInt("cache.check_interval")) * time.Minute) {
logrus.Infoln("Checking cache for expired files...")
files, _ := ioutil.ReadDir(os.ExpandEnv(viper.GetString("cache.directory")))
for _, file := range files {
// It is safe to check the modification time because when audio files are
// played their modification time is updated. This ensures that audio
// files will not get deleted while they are playing, assuming a reasonable
// expiry time is set in the configuration.
hours := time.Since(file.ModTime()).Hours()
if hours >= viper.GetFloat64("cache.expire_time") {
logrus.WithFields(logrus.Fields{
"expired_file": file.Name(),
}).Infoln("Removing expired cache entry.")
os.Remove(fmt.Sprintf("%s/%s", os.ExpandEnv(viper.GetString("cache.directory")), file.Name()))
}
}
}
}
// DeleteOldest deletes the oldest file in the cache.
func (c *Cache) DeleteOldest() error {
files, _ := ioutil.ReadDir(os.ExpandEnv(viper.GetString("cache.directory")))
if len(files) > 0 {
sort.Sort(SortFilesByAge(files))
os.Remove(fmt.Sprintf("%s/%s", os.ExpandEnv(viper.GetString("cache.directory")), files[0].Name()))
return nil
}
return errors.New("There are no files currently cached")
}
// DeleteAll deletes all cached audio files.
func (c *Cache) DeleteAll() error {
dir, err := os.Open(os.ExpandEnv(viper.GetString("cache.directory")))
if err != nil {
return err
}
defer dir.Close()
names, err := dir.Readdirnames(-1)
if err != nil {
return err
}
logrus.Infoln("Deleting all cached audio files...")
for _, name := range names {
err = os.RemoveAll(filepath.Join(os.ExpandEnv(viper.GetString("cache.directory")), name))
if err != nil {
return err
}
}
return nil
}
func (c *Cache) getCurrentStatistics() (int, int64) {
var totalSize int64
files, _ := ioutil.ReadDir(os.ExpandEnv(viper.GetString("cache.directory")))
for _, file := range files {
totalSize += file.Size()
}
return len(files), totalSize
}