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// Copyright 2014 Canonical Ltd.
// Licensed under the LGPLv3, see LICENCE file for details.
package filestorage
import (
"io"
"time"
)
// FileStorage is an abstraction that can be used for the storage of files.
type FileStorage interface {
io.Closer
// Metadata returns a file's metadata.
Metadata(id string) (Metadata, error)
// Get returns a file and its metadata.
Get(id string) (Metadata, io.ReadCloser, error)
// List returns the metadata for each stored file.
List() ([]Metadata, error)
// Add stores a file and its metadata.
Add(meta Metadata, archive io.Reader) (string, error)
// SetFile stores a file for an existing metadata entry.
SetFile(id string, file io.Reader) error
// Remove removes a file from storage.
Remove(id string) error
}
// Document represents a document that can be identified uniquely
// by a string.
type Document interface {
// ID returns the unique ID of the document.
ID() string
// SetID sets the ID of the document. If the ID is already set,
// SetID() should return true (false otherwise).
SetID(id string) (alreadySet bool)
}
// Metadata is the meta information for a stored file.
type Metadata interface {
Document
// Size is the size of the file (in bytes).
Size() int64
// Checksum is the checksum for the file.
Checksum() string
// ChecksumFormat is the kind (and encoding) of checksum.
ChecksumFormat() string
// Stored returns when the file was last stored. If it has not been
// stored yet, nil is returned. If it has been stored but the
// timestamp is not available, a zero value is returned
// (see Time.IsZero).
Stored() *time.Time
// SetFileInfo sets the file info on the metadata.
SetFileInfo(size int64, checksum, checksumFormat string) error
// SetStored records when the file was last stored. If the previous
// value matters, be sure to call Stored() first.
SetStored(timestamp *time.Time)
}
// DocStorage is an abstraction for a system that can store docs (structs).
// The system is expected to generate its own unique ID for each doc.
type DocStorage interface {
io.Closer
// Doc returns the doc that matches the ID. If there is no match,
// an error is returned (see errors.IsNotFound). Any other problem
// also results in an error.
Doc(id string) (Document, error)
// ListDocs returns a list of all the docs in the storage.
ListDocs() ([]Document, error)
// AddDoc adds the doc to the storage. If successful, the storage-
// generated ID for the doc is returned. Otherwise an error is
// returned.
AddDoc(doc Document) (string, error)
// RemoveDoc removes the matching doc from the storage. If there
// is no match an error is returned (see errors.IsNotFound). Any
// other problem also results in an error.
RemoveDoc(id string) error
}
// RawFileStorage is an abstraction around a system that can store files.
// The system is expected to rely on the user for unique IDs.
type RawFileStorage interface {
io.Closer
// File returns the matching file. If there is no match an error is
// returned (see errors.IsNotFound). Any other problem also results
// in an error.
File(id string) (io.ReadCloser, error)
// AddFile adds the file to the storage. If it fails to do so,
// it returns an error. If a file is already stored for the ID,
// AddFile() fails (see errors.IsAlreadyExists).
AddFile(id string, file io.Reader, size int64) error
// RemoveFile removes the matching file from the storage. It fails
// if there is no such file (see errors.IsNotFound). Any other problem
// also results in an error.
RemoveFile(id string) error
}
// MetadataStorage is an extension of DocStorage adapted to file metadata.
type MetadataStorage interface {
io.Closer
// Metadata returns the matching Metadata. It fails if there is no
// match (see errors.IsNotFound). Any other problems likewise
// results in an error.
Metadata(id string) (Metadata, error)
// ListMetadata returns a list of all metadata in the storage.
ListMetadata() ([]Metadata, error)
// AddMetadata adds the metadata to the storage. If successful, the
// storage-generated ID for the metadata is returned. Otherwise an
// error is returned.
AddMetadata(meta Metadata) (string, error)
// RemoveMetadata removes the matching metadata from the storage.
// If there is no match an error is returned (see errors.IsNotFound).
// Any other problem also results in an error.
RemoveMetadata(id string) error
// SetStored updates the stored metadata to indicate that the
// associated file has been successfully stored in a RawFileStorage
// system. If it does not find a stored metadata with the matching
// ID, it will return an error (see errors.IsNotFound). It also
// returns an error if it fails to update the stored metadata.
SetStored(id string) error
}
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