codec

Documentation

Overview

Package codec provides support for serializing and deserializing file-hash information using channels.

Channel-based operation allows to stream file information, which becomes relevant when millions of files are supposed to be handled without any delay or noticeable memory overhead.

Index

• Constants
• func Names() []string
• type Codec
  • func NewByName(name string) Codec
  • func NewByPath(path string) Codec
• type DecodeError
  • func (d *DecodeError) Error() string
• type Gob
  • func (g *Gob) Deserialize(reader io.Reader, out chan<- api.FileInfo, predicate func(*api.FileInfo) bool) error
  • func (g *Gob) Extension() string
  • func (g *Gob) Serialize(in <-chan api.FileInfo, writer io.Writer) (err error)
• type MHL
  • func (m *MHL) Deserialize(reader io.Reader, out chan<- api.FileInfo, predicate func(*api.FileInfo) bool) error
  • func (m *MHL) Extension() string
  • func (m *MHL) Serialize(in <-chan api.FileInfo, writer io.Writer) (err error)
• type SignatureMismatchError
  • func (s *SignatureMismatchError) Error() string

Constants

const (
	GobName      = "gob"
	GobExtension = "gobz"
	Version      = 1
)

const (
	MHLName      = "mhl"
	MHLExtension = "mhl"
	MHLVersion   = "1.0"
)

Functions

func Names

func Names() []string

Types

type Codec

type Codec interface {
	// Write the file-info structures received from in channel to the given writer.
	// When the channel is closed, the read-operation naturally finishes.
	// The codec must protect the written data against modification, usually by hashing the contained information
	Serialize(in <-chan api.FileInfo, writer io.Writer) error

	// Stream a FileInfo obtained from the given reader.
	// An error must be returned if the data read could not be verified.
	// You must pass each read fileinfo structure to the given predicate - it might modify it before
	// sending it down the channel. It returns false in case you should stop reading and return without error
	// Check the done-channel and cancel the operation
	// This function doesn't close the stream
	// The only errors returned must of type DecodeError
	Deserialize(reader io.Reader, out chan<- api.FileInfo, predicate func(*api.FileInfo) bool) error

	// Extension returns the file extension of the codec, without the '.' prefix
	Extension() string
}

Represents a codec's standard capabilities. A codec is a specialized implementation able to read and write indices of file hash information NOTE: Even though it would be more idiomatic to have two interfaces for read and write respectively, we just don't need it here

func NewByName

func NewByName(name string) Codec

Find a codec matching the given name, and return it. Retuns nil otherwise

func NewByPath

func NewByPath(path string) Codec

Finds a codec which can decode the file at the given path. We work strictly by name.

type DecodeError

type DecodeError struct {
	Msg string
}

func (*DecodeError) Error

func (d *DecodeError) Error() string

type Gob

type Gob struct {
}

Reads and writes a file structured like so - version - numEntries - gobValue... - sha1 (hash of all hashes in prior map)

func (*Gob) Deserialize

func (g *Gob) Deserialize(reader io.Reader, out chan<- api.FileInfo, predicate func(*api.FileInfo) bool) error

func (*Gob) Extension

func (g *Gob) Extension() string

func (*Gob) Serialize

func (g *Gob) Serialize(in <-chan api.FileInfo, writer io.Writer) (err error)

type MHL

type MHL struct {
}

Empty type to implement the codec interface

func (*MHL) Deserialize

func (m *MHL) Deserialize(reader io.Reader, out chan<- api.FileInfo, predicate func(*api.FileInfo) bool) error

func (*MHL) Extension

func (m *MHL) Extension() string

func (*MHL) Serialize

func (m *MHL) Serialize(in <-chan api.FileInfo, writer io.Writer) (err error)

type SignatureMismatchError

type SignatureMismatchError struct {
	DecodeError
}

func (*SignatureMismatchError) Error

func (s *SignatureMismatchError) Error() string