distribution/storagedriver/storagedriver.go

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package storagedriver
import (
"fmt"
"io"
)
// Defines methods that a Storage Driver must implement for a filesystem-like key/value object storage
type StorageDriver interface {
// Retrieve the content stored at "path" as a []byte
// Should primarily be used for small objects
GetContent(path string) ([]byte, error)
// Store the []byte content at a location designated by "path"
// Should primarily be used for small objects
PutContent(path string, content []byte) error
// Retrieve an io.ReadCloser for the content stored at "path" with a given byte offset
// May be used to resume reading a stream by providing a nonzero offset
ReadStream(path string, offset uint64) (io.ReadCloser, error)
// Store the contents of the provided io.ReadCloser at a location designated by "path"
// The driver will know it has received the full contents when it has read "size" bytes
// May be used to resume writing a stream by providing a nonzero offset
// The offset must be no larger than the number of bytes already written to this path
WriteStream(path string, offset, size uint64, readCloser io.ReadCloser) error
// Retrieve the byte offset at which it is safe to continue writing at "path"
ResumeWritePosition(path string) (uint64, error)
// Recursively lists the objects stored at a subpath of the given prefix
List(prefix string) ([]string, error)
// Moves an object stored at sourcePath to destPath, removing the original object
// Note: This may be no more efficient than a copy followed by a delete for many implementations
Move(sourcePath string, destPath string) error
// Recursively deletes all objects stored at "path" and its subpaths
Delete(path string) error
}
// Error returned when operating on a nonexistent path
type PathNotFoundError struct {
Path string
}
func (err PathNotFoundError) Error() string {
return fmt.Sprintf("Path not found: %s", err.Path)
}
// Error returned when attempting to read or write from an invalid offset
type InvalidOffsetError struct {
Path string
Offset uint64
}
func (err InvalidOffsetError) Error() string {
return fmt.Sprintf("Invalid offset: %d for path: %s", err.Offset, err.Path)
}