Documentation
¶
Overview ¶
Package blob defines types to refer to and retrieve low-level Perkeep blobs.
Index ¶
- Constants
- Variables
- func HashFuncs() []string
- func NewHash() hash.Hash
- func NewHashOfType(alg string) (hash.Hash, error)
- func ReaderAt(ctx context.Context, sf SubFetcher, br Ref) io.ReaderAt
- func ValidRefString(s string) bool
- type Blob
- type ByRef
- type ChanPeeker
- type DirFetcher
- type Fetcher
- type Ref
- func (r Ref) Digest() string
- func (r Ref) DigestPrefix(digits int) string
- func (r Ref) DomID() string
- func (r Ref) EqualString(s string) bool
- func (r Ref) HasPrefix(s string) bool
- func (r Ref) Hash() hash.Hash
- func (r Ref) HashMatches(h hash.Hash) bool
- func (r Ref) HashName() string
- func (r Ref) IsSupported() bool
- func (r Ref) Less(o Ref) bool
- func (r Ref) MarshalBinary() (data []byte, err error)
- func (r Ref) MarshalJSON() ([]byte, error)
- func (r Ref) String() string
- func (r Ref) StringMinusOne() string
- func (r Ref) Sum32() uint32
- func (r Ref) Sum64() uint64
- func (r *Ref) UnmarshalBinary(data []byte) error
- func (r *Ref) UnmarshalJSON(d []byte) error
- func (r Ref) Valid() bool
- type SizedByRef
- type SizedRef
- type SubFetcher
Constants ¶
const Pattern = `\b([a-z][a-z0-9]*)-([a-f0-9]+)\b`
Pattern is the regular expression which matches a blobref. It does not contain ^ or $.
Variables ¶
var ( ErrNegativeSubFetch = errors.New("invalid negative subfetch parameters") ErrOutOfRangeOffsetSubFetch = errors.New("subfetch offset greater than blob size") )
var ErrUnimplemented = errors.New("optional method not implemented")
ErrUnimplemented is returned by optional interfaces when their wrapped values don't implemented the optional interface.
Functions ¶
func HashFuncs ¶
func HashFuncs() []string
HashFuncs returns the names of the supported hash functions.
func NewHash ¶
NewHash returns a new hash.Hash of the currently recommended hash type. Currently this is SHA-224, but is subject to change over time.
func NewHashOfType ¶
NewHashOfType returns a new hash.Hash for the provided hash type. If alg is the empty string, it returns the default value (see NewHash). It returns an error if the alg is unknown.
func ReaderAt ¶
ReaderAt returns an io.ReaderAt of br, fetching against sf. The context is stored in and used by the returned ReaderAt.
func ValidRefString ¶
Types ¶
type Blob ¶
type Blob struct {
// contains filtered or unexported fields
}
Blob represents a blob. Use the methods Size, SizedRef and ReadAll to query and get data from Blob.
func FromFetcher ¶
FromFetcher fetches br from fetcher and slurps its contents to memory. It does not validate the blob's digest. Use the Blob.ValidContents method for that.
func FromReader ¶
FromReader slurps the given blob from r to memory. It does not validate the blob's digest. Use the Blob.ValidContents method for that.
func NewBlob ¶
NewBlob constructs a Blob from its Ref, size and a function that returns the contents of the blob. Any error in the function newReader when constructing the io.ReadCloser should be returned upon the first call to Read or Close.
func (*Blob) ReadAll ¶
ReadAll reads the blob completely to memory, using the provided context, and then returns a reader over it. The Reader will not have errors except EOF.
The provided is only ctx is used until ReadAll returns.
type ChanPeeker ¶
type ChanPeeker struct {
Ch <-chan SizedRef
// contains filtered or unexported fields
}
ChanPeeker wraps a channel receiving SizedRefs and adds a 1 element buffer on it, with Peek and Take methods.
func (*ChanPeeker) Closed ¶
func (cp *ChanPeeker) Closed() bool
Closed reports true if no more SizedRef values are available.
func (*ChanPeeker) ConsumeAll ¶
func (cp *ChanPeeker) ConsumeAll()
ConsumeAll drains the channel of all items.
func (*ChanPeeker) MustPeek ¶
func (cp *ChanPeeker) MustPeek() SizedRef
MustPeek returns the next SizedRef or panics if none is available.
func (*ChanPeeker) MustTake ¶
func (cp *ChanPeeker) MustTake() SizedRef
MustTake returns the next SizedRef, else panics if none is available.
func (*ChanPeeker) Peek ¶
func (cp *ChanPeeker) Peek() (sr SizedRef, ok bool)
Peek returns the next SizedRef and whether one was available.
func (*ChanPeeker) Take ¶
func (cp *ChanPeeker) Take() (sr SizedRef, ok bool)
Take returns the next SizedRef and whether one was available for the taking.
type DirFetcher ¶
type DirFetcher struct {
// contains filtered or unexported fields
}
func NewSimpleDirectoryFetcher ¶
func NewSimpleDirectoryFetcher(dir string) *DirFetcher
func (*DirFetcher) Fetch ¶
func (df *DirFetcher) Fetch(ctx context.Context, r Ref) (file io.ReadCloser, size uint32, err error)
type Fetcher ¶
type Fetcher interface {
// Fetch returns a blob. If the blob is not found then
// os.ErrNotExist should be returned for the error (not a wrapped
// error with a ErrNotExist inside)
//
// The contents are not guaranteed to match the digest of the
// provided Ref (e.g. when streamed over HTTP). Paranoid
// callers should verify them.
//
// The caller must close blob.
//
// The provided context is used until blob is closed and its
// cancellation should but may not necessarily cause reads from
// blob to fail with an error.
Fetch(context.Context, Ref) (blob io.ReadCloser, size uint32, err error)
}
Fetcher is the minimal interface for retrieving a blob from storage. The full storage interface is blobserver.Storage.
func NewSerialFetcher ¶
type Ref ¶
type Ref struct {
// contains filtered or unexported fields
}
Ref is a reference to a Perkeep blob. It is used as a value type and supports equality (with ==) and the ability to use it as a map key.
func ParseBytes ¶
ParseBytes is like Parse, but parses from a byte slice.
func ParseKnown ¶
ParseKnown is like Parse, but only parse blobrefs known to this server. It returns ok == false for well-formed but unsupported blobrefs.
func ParseOrZero ¶
ParseOrZero parses as a blobref. If s is invalid, a zero Ref is returned which can be tested with the Valid method.
func RefFromBytes ¶
RefFromBytes returns a blobref from the given string, for the currently recommended hash function.
func RefFromHash ¶
RefFromHash returns a blobref representing the given hash. It panics if the hash isn't of a known type.
func RefFromString ¶
RefFromString returns a blobref from the given string, for the currently recommended hash function.
func (Ref) Digest ¶
Digest returns the lower hex digest of the blobref, without the e.g. "sha224-" prefix. It panics if r is zero.
func (Ref) DigestPrefix ¶
func (Ref) EqualString ¶
EqualString reports whether r.String() is equal to s. It does not allocate.
func (Ref) HasPrefix ¶
HasPrefix reports whether s is a prefix of r.String(). It returns false if s does not contain at least the digest name prefix (e.g. "sha224-") and one byte of digest. It does not allocate.
func (Ref) Hash ¶
Hash returns a new hash.Hash of r's type.
It panics if r is zero (invalid).
It returns nil if Ref is valid, but of an unknown hash type.
func (Ref) HashName ¶
HashName returns the lowercase hash function name of the reference. It panics if r is invalid (the zero value).
func (Ref) IsSupported ¶
func (Ref) MarshalBinary ¶
MarshalBinary implements Go's encoding.BinaryMarshaler interface.
func (Ref) MarshalJSON ¶
func (Ref) StringMinusOne ¶
StringMinusOne returns the first string that's before String.
func (*Ref) UnmarshalBinary ¶
UnmarshalBinary implements Go's encoding.BinaryUnmarshaler interface.
func (*Ref) UnmarshalJSON ¶
type SizedByRef ¶
type SizedByRef []SizedRef
SizedByRef sorts SizedRefs by their blobref.
func (SizedByRef) Len ¶
func (s SizedByRef) Len() int
func (SizedByRef) Less ¶
func (s SizedByRef) Less(i, j int) bool
func (SizedByRef) Swap ¶
func (s SizedByRef) Swap(i, j int)
type SizedRef ¶
SizedRef is like a Ref but includes a size. It should also be used as a value type and supports equality.
type SubFetcher ¶
type SubFetcher interface {
// SubFetch returns part of a blob.
// The caller must close the returned io.ReadCloser.
// The Reader may return fewer than 'length' bytes. Callers should
// check. The returned error should be: ErrNegativeSubFetch if any of
// offset or length is negative, or os.ErrNotExist if the blob
// doesn't exist, or ErrOutOfRangeOffsetSubFetch if offset goes over
// the size of the blob. If the error is ErrUnimplemented, the caller should
// treat this Fetcher as if it doesn't implement SubFetcher.
SubFetch(ctx context.Context, ref Ref, offset, length int64) (io.ReadCloser, error)
}
A SubFetcher is a Fetcher that can retrieve part of a blob.
Source Files