sparse

package

v1.9.0 Latest Latest Go to latest Published: Oct 27, 2026 License: MIT Imports: 2 Imported by: 0

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Valid go.mod file
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Repository

github.com/blackbirdworks/gopherstack

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Documentation ¶

Overview ¶

Package sparse implements sparse byte Extents: written runs of a file that otherwise reads back as zeroes, with copy-on-write sharing of the backing bytes.

Index ¶

type Extent
type Extents
type Range
type Reader
- func NewReader(x Extents, off, end int64) *Reader
- func (r *Reader) Read(p []byte) (int, error)

Constants ¶

This section is empty.

Variables ¶

This section is empty.

Functions ¶

This section is empty.

Types ¶

type Extent ¶

type Extent struct {
	Data []byte `json:"data"`
	Off  int64  `json:"off"`
}

Extent is one contiguous run of written bytes.

type Extents ¶

type Extents []Extent

Extents is a sorted, non-overlapping, non-adjacent list of written runs. Backing byte slices are never mutated after creation, so clones share them.

func (Extents) Clear ¶

func (x Extents) Clear(off, n int64) Extents

Clear removes [off, off+n) so it reads back as zeroes.

func (Extents) Clone ¶

func (x Extents) Clone() Extents

Clone copies the run list; the backing bytes are shared.

func (Extents) Diff ¶

func (x Extents) Diff(prev Extents, size int64) ([]Range, []Range)

Diff returns ranges of x that differ from prev (changed) and ranges written in prev but absent from x (cleared), clipped to [0, size).

func (Extents) Presence ¶

func (x Extents) Presence(off, n int64) []bool

Presence marks which of the n bytes from off lie inside a written run.

func (Extents) Ranges ¶

func (x Extents) Ranges(from, to int64) []Range

Ranges lists written runs clipped to [from, to] (inclusive).

func (Extents) Read ¶

func (x Extents) Read(off, n int64) []byte

Read returns n bytes starting at off, zero-filled where nothing was written.

func (Extents) Truncate ¶

func (x Extents) Truncate(size int64) Extents

Truncate drops everything at or beyond size.

func (Extents) Write ¶

func (x Extents) Write(off int64, data []byte) Extents

Write stores data at off, replacing anything it overlaps.

type Range ¶

type Range struct{ Start, End int64 }

Range is an inclusive byte range.

type Reader ¶

type Reader struct {
	// contains filtered or unexported fields
}

Reader streams [off, end] of a sparse file, zero-filling gaps. Reader streams a byte range of Extents, zero-filling gaps.

func NewReader ¶

func NewReader(x Extents, off, end int64) *Reader

NewReader streams bytes [off, end] (inclusive) of x.

func (*Reader) Read ¶

func (r *Reader) Read(p []byte) (int, error)

Source Files ¶

View all Source files

sparse.go

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