circular

README

Circular Buffer

A circular buffer, cyclic buffer or ring buffer is a data structure that uses a single, fixed-size buffer as if it were connected end-to-end.

A circular buffer first starts empty and of some predefined length. For example, this is a 7-element buffer:

[ ][ ][ ][ ][ ][ ][ ]

Assume that a 1 is written into the middle of the buffer (exact starting location does not matter in a circular buffer):

[ ][ ][ ][1][ ][ ][ ]

Then assume that two more elements are added — 2 & 3 — which get appended after the 1:

[ ][ ][ ][1][2][3][ ]

If two elements are then removed from the buffer, the oldest values inside the buffer are removed. The two elements removed, in this case, are 1 & 2, leaving the buffer with just a 3:

[ ][ ][ ][ ][ ][3][ ]

If the buffer has 7 elements then it is completely full:

[6][7][8][9][3][4][5]

When the buffer is full an error will be raised, alerting the client that further writes are blocked until a slot becomes free.

The client can opt to overwrite the oldest data with a forced write. In this case, two more elements — A & B — are added and they overwrite the 3 & 4:

[6][7][8][9][A][B][5]

Finally, if two elements are now removed then what would be returned is not 3 & 4 but 5 & 6 because A & B overwrote the 3 & the 4 yielding the buffer with:

[ ][7][8][9][A][B][ ]

Running the tests

To run the tests run the command go test from within the exercise directory.

If the test suite contains benchmarks, you can run these with the -bench flag:

go test -bench .

Keep in mind that each reviewer will run benchmarks on a different machine, with different specs, so the results from these benchmark tests may vary.

Further information

For more detailed information about the Go track, including how to get help if you're having trouble, please visit the exercism.io Go language page.

Source

Wikipedia http://en.wikipedia.org/wiki/Circular_buffer

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

Documentation

Index

• type Buffer
  • func NewBuffer(size int) *Buffer
  • func (b *Buffer) Overwrite(c byte)
  • func (b *Buffer) ReadByte() (byte, error)
  • func (b *Buffer) Reset()
  • func (b *Buffer) WriteByte(c byte) error

Types

type Buffer

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

Buffer implements a circular buffer supporting both overflow-checked writes and unconditional, possibly overwriting, writes.

func NewBuffer

func NewBuffer(size int) *Buffer

NewBuffer constructs a new empty circular buffer.

func (*Buffer) Overwrite

func (b *Buffer) Overwrite(c byte)

Overwrite unconditionally puts byte c in the buffer. If the buffer was already full, c overwrites the oldest byte in the buffer.

func (*Buffer) ReadByte

func (b *Buffer) ReadByte() (byte, error)

ReadByte removes one byte from the buffer and returns it. ReadByte returns an error if the buffer is empty.

func (*Buffer) Reset

func (b *Buffer) Reset()

Reset puts the buffer in an empty state.

func (*Buffer) WriteByte

func (b *Buffer) WriteByte(c byte) error

WriteByte puts byte c in the buffer there is room. WriteByte returns an error if the buffer is full.