159 lines
3.3 KiB
Go
159 lines
3.3 KiB
Go
package cache
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import (
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"encoding/json"
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"errors"
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"fmt"
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"io"
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"os"
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"path/filepath"
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"strings"
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"time"
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)
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type Cache[T any] struct {
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Path string
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}
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// New Cache where default path is os.TempDir()
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func New[T any](path string) *Cache[T] {
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if path == "" {
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path = os.TempDir()
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}
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return &Cache[T]{path}
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}
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var (
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ErrorUnableToMarshalJSON = errors.New("unable to marshal as JSON")
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ErrorUnableToEnsureCacheDir = errors.New("unable to ensure cache-dir is present")
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ErrorUnableToWriteCache = errors.New("unable to write data to cache file")
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ErrorUnableToOpenCacheFile = errors.New("unable to open cache")
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ErrorUnableToReadCacheFile = errors.New("unable to read cache")
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ErrorUnableToUnmarshalCacheFile = errors.New("unable to unmarshal JSON from cache-file")
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ErrorUnableToReadCachePath = errors.New("unable to read from cache path")
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)
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// Add data as JSON-file into cache-dir, returns nil if success
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func (c *Cache[T]) Add(name string, data any) error {
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j, err := json.MarshalIndent(data, "", " ")
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if err != nil {
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return ErrorUnableToMarshalJSON
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}
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err = os.MkdirAll(c.Path, 0646)
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if err != nil {
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return ErrorUnableToEnsureCacheDir
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}
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filePath := filepath.Join(c.Path, filename(name))
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d := []byte(j)
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err = os.WriteFile(filePath, d, 0646)
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if err != nil {
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return ErrorUnableToWriteCache
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}
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return nil
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}
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// Get data from JSON-file from cache-dir, returns nil if no result
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func (c *Cache[T]) Get(name string) (*T, error) {
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filePath := filepath.Join(c.Path, filename(name))
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if _, err := os.Stat(filePath); errors.Is(err, os.ErrNotExist) {
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return nil, nil
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}
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rawFile, err := os.Open(filePath)
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if err != nil {
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return nil, ErrorUnableToOpenCacheFile
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}
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var result T
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bytes, err := io.ReadAll(rawFile)
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if err != nil {
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return nil, ErrorUnableToReadCacheFile
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}
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err = json.Unmarshal(bytes, &result)
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if err != nil {
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return nil, ErrorUnableToUnmarshalCacheFile
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}
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return &result, nil
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}
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type Saved[T any] struct {
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Filename string
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Item T
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}
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func (c *Cache[T]) List() ([]Saved[T], error) {
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var result []Saved[T]
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filenames, err := list(c.Path)
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if err != nil {
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return nil, ErrorUnableToReadCachePath
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}
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if len(filenames) == 0 {
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return result, nil
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}
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for _, f := range filenames {
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cached, err := c.Get(f)
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if err != nil {
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return nil, err
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}
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result = append(result, Saved[T]{Filename: f, Item: *(cached)})
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}
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return result, nil
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}
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func list(path string) ([]string, error) {
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dir, err := os.ReadDir(path)
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if err != nil {
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return nil, ErrorUnableToReadCachePath
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}
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var filenames []string
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for _, item := range dir {
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if !item.IsDir() && strings.Contains(item.Name(), prefix) {
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tmp := strings.ReplaceAll(strings.ReplaceAll(item.Name(), ".json", ""), prefix, "")
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filenames = append(filenames, tmp)
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}
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}
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return filenames, nil
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}
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func (c *Cache[T]) Clear() error {
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files, err := list(c.Path)
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if err != nil {
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return err
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}
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for _, f := range files {
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filePath := filepath.Join(c.Path, filename(f))
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err = os.Remove(filePath)
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if err != nil {
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return err
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}
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}
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return nil
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}
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var prefix = "yr-"
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func filename(name string) string {
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return fmt.Sprintf("%s%s.json", prefix, name)
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}
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// Returns if t is expired
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func IsExpired(expire time.Time, now *time.Time) bool {
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if now == nil {
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tmp := time.Now()
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now = &tmp
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}
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return now.After(expire)
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}
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