packetcache

Documentation

Overview

Package packetcache implement a packet cache that maintains a history of recently seen packets, the last keyframe, and a number of statistics that are needed for sending receiver reports.

Index

• Constants
• func ToBitmap(seqnos []uint16) (first uint16, bitmap uint16, remain []uint16)
• type Cache
  • func New(capacity int) *Cache
  • func (cache *Cache) BitmapGet(next uint16) (bool, uint16, uint16)
  • func (cache *Cache) Expect(n int)
  • func (cache *Cache) Get(seqno uint16, result []byte) uint16
  • func (cache *Cache) GetAt(seqno uint16, index uint16, result []byte) uint16
  • func (cache *Cache) GetStats(reset bool) Stats
  • func (cache *Cache) Keyframe() (uint16, bool)
  • func (cache *Cache) Last() (uint16, bool)
  • func (cache *Cache) Resize(capacity int)
  • func (cache *Cache) ResizeCond(capacity int) bool
  • func (cache *Cache) Store(seqno uint16, timestamp uint32, keyframe bool, marker bool, buf []byte) (uint16, uint16)
• type Stats

Constants

const BufSize = 1504

The maximum size of packets stored in the cache. Chosen to be a multiple of 8.

Functions

func ToBitmap

func ToBitmap(seqnos []uint16) (first uint16, bitmap uint16, remain []uint16)

ToBitmap takes a non-empty sorted list of seqnos, and computes a bitmap covering a prefix of the list. It returns the part of the list that couldn't be covered.

Types

type Cache

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

func New

func New(capacity int) *Cache

New creates a cache with the given capacity.

func (*Cache) BitmapGet

func (cache *Cache) BitmapGet(next uint16) (bool, uint16, uint16)

BitmapGet shifts up to 17 bits out of the bitmap. It returns a boolean indicating if any were 0, the index of the first 0 bit, and a bitmap indicating any 0 bits after the first one.

func (*Cache) Expect

func (cache *Cache) Expect(n int)

Expect records that we expect n additional packets.

func (*Cache) Get

func (cache *Cache) Get(seqno uint16, result []byte) uint16

Get retrieves a packet from the cache, returns the number of bytes copied. If result is of length 0, returns the size of the packet.

func (*Cache) GetAt

func (cache *Cache) GetAt(seqno uint16, index uint16, result []byte) uint16

GetAt retrieves a packet from the cache assuming it is at the given index.

func (*Cache) GetStats

func (cache *Cache) GetStats(reset bool) Stats

GetStats returns statistics about received packets. If reset is true, the statistics are reset.

func (*Cache) Keyframe

func (cache *Cache) Keyframe() (uint16, bool)

Keyframe returns the seqno of the last seen keyframe

func (*Cache) Last

func (cache *Cache) Last() (uint16, bool)

func (*Cache) Resize

func (cache *Cache) Resize(capacity int)

Resize resizes the cache to the given capacity. This might invalidate indices of recently stored packets.

func (*Cache) ResizeCond

func (cache *Cache) ResizeCond(capacity int) bool

ResizeCond is like Resize, but avoids invalidating recent indices.

func (*Cache) Store

func (cache *Cache) Store(seqno uint16, timestamp uint32, keyframe bool, marker bool, buf []byte) (uint16, uint16)

Store stores a packet in the cache. It returns the first seqno in the bitmap, and the index at which the packet was stored.

type Stats

type Stats struct {
	Received, TotalReceived uint32
	Expected, TotalExpected uint32
	ESeqno                  uint32
}

Stats contains cache statistics