mutable

Documentation

Index

• type Content
  • func NewContent(initialContent lease.ReadProxy, clock timeutil.Clock) (mc Content)
• type StatResult

Types

type Content

type Content interface {
	// Panic if any internal invariants are violated.
	CheckInvariants()

	// Destroy any state used by the object, putting it into an indeterminate
	// state. The object must not be used again.
	Destroy()

	// If the content has been dirtied from its initial state, return a
	// read/write lease for the current content. Otherwise return nil.
	//
	// If this method returns a non-nil read/write lease, the Content is
	// implicitly destroyed and must not be used again.
	Release() (rwl lease.ReadWriteLease)

	// Read part of the content, with semantics equivalent to io.ReaderAt aside
	// from context support.
	ReadAt(ctx context.Context, buf []byte, offset int64) (n int, err error)

	// Return information about the current state of the content.
	Stat(ctx context.Context) (sr StatResult, err error)

	// Write into the content, with semantics equivalent to io.WriterAt aside from
	// context support.
	WriteAt(ctx context.Context, buf []byte, offset int64) (n int, err error)

	// Truncate our the content to the given number of bytes, extending if n is
	// greater than the current size.
	Truncate(ctx context.Context, n int64) (err error)
}

A mutable view on some content. Created with an initial read-only view, which then can be modified by the user and read back. Keeps track of which portion of the content has been dirtied.

External synchronization is required.

func NewContent

func NewContent(
	initialContent lease.ReadProxy,
	clock timeutil.Clock) (mc Content)

Create a mutable content object whose initial contents are given by the supplied read proxy.

type StatResult

type StatResult struct {
	// The current size in bytes of the content.
	Size int64

	// It is guaranteed that all bytes in the range [0, DirtyThreshold) are
	// unmodified from the original content with which the mutable content object
	// was created.
	DirtyThreshold int64

	// The time at which the content was last updated, or nil if we've never
	// changed it.
	Mtime *time.Time
}