Method Get

cache/filesystem_cache.go:92–134

(key *Key)

}

func (f *fileSystemCache) Get(key *Key) (*CachedData, error) {
	fp := key.filePath(f.dir)
	file, err := os.Open(fp)
	if err != nil {
		return nil, ErrMissing
	}

	// the file will be closed once it's read as an io.ReaderCloser
	// This  ReaderCloser is stored in the returned CachedData
	fi, err := file.Stat()
	if err != nil {
		return nil, fmt.Errorf("cache %q: cannot stat %q: %w", f.Name(), fp, err)
	}
	mt := fi.ModTime()
	age := time.Since(mt)
	if age > f.expire {
		// check if file exceeded expiration time + grace time
		if age > f.expire+f.grace {
			file.Close()
			return nil, ErrMissing
		}
		// Serve expired file in the hope it will be substituted
		// with the fresh file during deadline.
	}

	if err != nil {
		file.Close()
		return nil, fmt.Errorf("failed to read file content from %q: %w", f.Name(), err)
	}

	metadata, err := decodeHeader(file)
	if err != nil {
		return nil, err
	}

	value := &CachedData{
		ContentMetadata: *metadata,
		Data:            file,
		Ttl:             f.expire - age,
	}

	return value, nil
}

// decodeHeader decodes header from raw byte stream. Data is encoded as follows:
// length(contentType)|contentType|length(contentEncoding)|contentEncoding|length(contentLength)|contentLength|cachedData