defs.go

package sub

import (
	"net"
	"time"
)

var (
	uNet = "udp4"

	// Maximum of 9 packets per message, so 16kb round is enough
	defaultBufferSize = 16384

	// FEC expands message by 150%, we don't split message chunks over more than one packet
	maxMessageSize = 3072

	// default channel buffer sizes for Base
	baseChanBufs = 128

	// latency maximum
	latencyMax = time.Millisecond * 250
)

// BaseInterface is the core functions required for a Base

type BaseInterface interface {
	SetupListener()
}

// BaseCfg is the configuration for a Base

type BaseCfg struct {
	Handler    func(message Message)
	Listener   string
	Password   []byte
	BufferSize int
}

// Base is the common structure between a worker and a node

type Base struct {
	cfg       BaseCfg
	listener  *net.UDPConn
	packets   chan Packet
	incoming  chan Bundle
	returning chan Bundle
	trash     chan Bundle
	doneRet   chan bool
	message   chan Message
	quit      chan bool
}

// A Node is a server with some number of subscribers

type Node struct {
	Base
	subscribers []*net.UDPAddr
}

// A Worker is a node that subscribes to a Node's messages

type Worker struct {
	Base
	node *net.UDPAddr
}

// Packet is the structure of individual encoded packets of the message. These are made from a 9/3 Reed Solomon code and 9 are sent in distinct packets and only 3 are required to guarantee retransmit-free delivery.

type Packet struct {
	sender string // address packet was received from
	bytes  []byte // raw FEC encoded bytes of packet
}

// A Bundle is a collection of the received packets received from the same sender with up to 9 pieces.

type Bundle struct {
	uuid     int32
	sender   string
	received time.Time
	packets  [][]byte
}

// Message is the data reconstructed from a complete Bundle, containing data in messagepack format

type Message struct {
	uuid      int32
	sender    string
	timestamp time.Time
	bytes     []byte
}

// Subscription is the message sent by a worker node to request updates from the node

type Subscription struct {
	address string
	pubKey  []byte
}

// Confirmation is the reply message for a subscription request

type Confirmation struct {
	subscriber string // confirming address of subscriber
	pubKey     []byte // public key of server for message verification
}