diff options
Diffstat (limited to 'internal/feed/cache.go')
-rw-r--r-- | internal/feed/cache.go | 172 |
1 files changed, 0 insertions, 172 deletions
diff --git a/internal/feed/cache.go b/internal/feed/cache.go deleted file mode 100644 index 5f5c394..0000000 --- a/internal/feed/cache.go +++ /dev/null @@ -1,172 +0,0 @@ -package feed - -import ( - "bufio" - "encoding/gob" - "errors" - "fmt" - "os" - "path/filepath" - "time" - - "github.com/nightlyone/lockfile" - - "github.com/Necoro/feed2imap-go/pkg/log" -) - -type Version byte - -const ( - currentVersion Version = 1 -) - -type CacheImpl interface { - findItem(*Feed) CachedFeed - Version() Version - Info() string - SpecificInfo(interface{}) string - transformToCurrent() (CacheImpl, error) -} - -type Cache struct { - CacheImpl - lock lockfile.Lockfile - locked bool -} - -type CachedFeed interface { - Checked(withFailure bool) - Failures() int - Last() time.Time - ID() string - filterItems(items []item, ignoreHash bool, alwaysNew bool) []item - Commit() -} - -func cacheForVersion(version Version) (CacheImpl, error) { - switch version { - case v1Version: - return newV1Cache(), nil - default: - return nil, fmt.Errorf("unknown cache version '%d'", version) - } -} - -func lockName(fileName string) (string, error) { - return filepath.Abs(fileName + ".lck") -} - -func lock(fileName string) (lock lockfile.Lockfile, err error) { - var lockFile string - - if lockFile, err = lockName(fileName); err != nil { - return - } - log.Debugf("Handling lock file '%s'", lockFile) - - if lock, err = lockfile.New(lockFile); err != nil { - err = fmt.Errorf("Creating lock file: %w", err) - return - } - - if err = lock.TryLock(); err != nil { - err = fmt.Errorf("Locking cache: %w", err) - return - } - - return -} - -func (cache *Cache) store(fileName string) error { - if cache.CacheImpl == nil { - return fmt.Errorf("trying to store nil cache") - } - if cache.Version() != currentVersion { - return fmt.Errorf("trying to store cache with unsupported version '%d' (current: '%d')", cache.Version(), currentVersion) - } - - f, err := os.Create(fileName) - if err != nil { - return fmt.Errorf("trying to store cache to '%s': %w", fileName, err) - } - defer f.Close() - - writer := bufio.NewWriter(f) - if err = writer.WriteByte(byte(currentVersion)); err != nil { - return fmt.Errorf("writing to '%s': %w", fileName, err) - } - - encoder := gob.NewEncoder(writer) - if err = encoder.Encode(cache.CacheImpl); err != nil { - return fmt.Errorf("encoding cache: %w", err) - } - - writer.Flush() - log.Printf("Stored cache to '%s'.", fileName) - - return cache.Unlock() -} - -func (cache *Cache) Unlock() error { - if cache.locked { - if err := cache.lock.Unlock(); err != nil { - return fmt.Errorf("Unlocking cache: %w", err) - } - } - cache.locked = false - return nil -} - -func newCache() (Cache, error) { - cache, err := cacheForVersion(currentVersion) - if err != nil { - return Cache{}, err - } - return Cache{ - CacheImpl: cache, - locked: false, - }, nil -} - -func LoadCache(fileName string) (Cache, error) { - f, err := os.Open(fileName) - if err != nil { - if errors.Is(err, os.ErrNotExist) { - // no cache there yet -- make new - return newCache() - } - return Cache{}, fmt.Errorf("opening cache at '%s': %w", fileName, err) - } - defer f.Close() - - lock, err := lock(fileName) - if err != nil { - return Cache{}, err - } - - log.Printf("Loading cache from '%s'", fileName) - - reader := bufio.NewReader(f) - version, err := reader.ReadByte() - if err != nil { - return Cache{}, fmt.Errorf("reading from '%s': %w", fileName, err) - } - - cache, err := cacheForVersion(Version(version)) - if err != nil { - return Cache{}, err - } - - decoder := gob.NewDecoder(reader) - if err = decoder.Decode(cache); err != nil { - return Cache{}, fmt.Errorf("decoding for version '%d' from '%s': %w", version, fileName, err) - } - - if cache, err = cache.transformToCurrent(); err != nil { - return Cache{}, fmt.Errorf("cannot transform from version %d to %d: %w", version, currentVersion, err) - } - - log.Printf("Loaded cache (version %d), transformed to version %d.", version, currentVersion) - - return Cache{cache, lock, true}, nil -} |