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author | René 'Necoro' Neumann <necoro@necoro.eu> | 2020-04-25 11:27:34 +0200 |
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committer | René 'Necoro' Neumann <necoro@necoro.eu> | 2020-04-25 11:27:34 +0200 |
commit | d21881150c09986571a563eaf30bc1687787e63f (patch) | |
tree | a5da8a3fdb91a3dcf806b704e20b16616a934801 /internal/cache/cache.go | |
parent | c08aff21cd67cc27926a4cb1ca72ffe67e015ebf (diff) | |
download | feed2imap-go-d21881150c09986571a563eaf30bc1687787e63f.tar.gz feed2imap-go-d21881150c09986571a563eaf30bc1687787e63f.tar.bz2 feed2imap-go-d21881150c09986571a563eaf30bc1687787e63f.zip |
Improved caching
Diffstat (limited to 'internal/cache/cache.go')
-rw-r--r-- | internal/cache/cache.go | 120 |
1 files changed, 0 insertions, 120 deletions
diff --git a/internal/cache/cache.go b/internal/cache/cache.go deleted file mode 100644 index 979d661..0000000 --- a/internal/cache/cache.go +++ /dev/null @@ -1,120 +0,0 @@ -package cache - -import ( - "bufio" - "encoding/gob" - "errors" - "fmt" - "os" - - "github.com/Necoro/feed2imap-go/internal/log" -) - -const currentVersion byte = 1 - -type Cache interface { - Version() byte - transformToCurrent() (Cache, error) -} - -type feedId struct { - Name string - Url string -} - -type v1Cache struct { - version byte - Ids map[feedId]uint64 - NextId uint64 -} - -func (cache *v1Cache) Version() byte { - return cache.version -} - -func New() Cache { - cache := v1Cache{Ids: map[feedId]uint64{}} - cache.version = currentVersion - return &cache -} - -func cacheForVersion(version byte) (Cache, error) { - switch version { - case 1: - return New(), nil - default: - return nil, fmt.Errorf("unknown cache version '%d'", version) - } -} - -func (cache *v1Cache) transformToCurrent() (Cache, error) { - return cache, nil -} - -func Store(fileName string, cache Cache) error { - if cache == 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(currentVersion); err != nil { - return fmt.Errorf("writing to '%s': %w", fileName, err) - } - - encoder := gob.NewEncoder(writer) - if err = encoder.Encode(cache); err != nil { - return fmt.Errorf("encoding cache: %w", err) - } - - writer.Flush() - log.Printf("Stored cache to '%s'.", fileName) - - return nil -} - -func Read(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 New(), nil - } - return nil, fmt.Errorf("opening cache at '%s': %w", fileName, err) - } - defer f.Close() - - log.Printf("Loading cache from '%s'", fileName) - - reader := bufio.NewReader(f) - version, err := reader.ReadByte() - if err != nil { - return nil, fmt.Errorf("reading from '%s': %w", fileName, err) - } - - cache, err := cacheForVersion(version) - if err != nil { - return nil, err - } - - decoder := gob.NewDecoder(reader) - if err = decoder.Decode(cache); err != nil { - return nil, fmt.Errorf("decoding for version '%d' from '%s': %w", version, fileName, err) - } - - if cache, err = cache.transformToCurrent(); err != nil { - return nil, 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, nil -} |