Go Load Balancing

It's just a naive package realizing some load balancing Algorithm, but in reality developer can use this package with the real tcp/udp/http servers. The example will show you how to do it.

这只实现了一些经典负载均衡算法的package。实际情况下，开发者可以使用此package来实现服务的负载均衡。Example会教你使用此package

Design

We can design some strategies like nginx to combine the different load balancing algorithms to get the final remote. We can also get the status of the remote server to add or delete the addresses and update weights of the addresses.

Interface And Type

Balancer

This interface Balanceris the core of the package. Every load balancing algorithm should realize it,and it defined two interfaces.

• init initialize the balancer, assigns the variables which DoBalance needs.
• DoBalance load balance the full node addresses according to the current situation.

package balance

type  Balancer interface {
    init(NodeAddrs)
    DoBalance(NodeAddrs) (*NodeAddr,int,error)
}

NodeAddr

• host: ip address
• port: the number of port
• weight: the weight of this full node address,default:1

This NodeAddr is the base struct of the address.

type NodeAddr struct{
    host string
    port int
    weight int
}

func (p *NodeAddr) GetHost() string

func (p *NodeAddr) GetPort() int

func (p *NodeAddr) GetWeight() int

func (p *NodeAddr) updateWeight(weight int)

The weight is the important factor that schedules which full node the LCD calls. The weight can be changed by the information from the full node. So we have the function updateWegiht.

NodeAddrs

in balance/types.go

NodeAddrs is the list of the full node address. This is the member variable in the BalanceManager(BalancerMgr).

type NodeAddrs []*NodeAddr

Load Balancing Algorithm

Random

in balance/random.go

Random algorithm selects a remote address randomly to process the request. The probability of them being selected is the same.

RandomWeight

in balance/random.go

RandomWeight Algorithm also selects a remote address randomly to process the request. But the higher the weight, the greater the probability.

RoundRobin

in balance/roundrobin.go

RoundRobin Algorithm selects a remote address orderly. Every remote address have the same probability to be selected.

RoundRobinWeight

in balance/roundrobin.go

RoundRobinWeight Algorthm selects a remote address orderly. But every remote address have different probability to be selected which are determined by their weight.

Hash

//TODO

Load Balancing Manager

BalanceMgr

in balance/manager.go

• addrs: the set of the remote full node addresses
• balancers: map the string of balancer name to the specific balancer
• change: record whether the machine reinitialize after the addrs changes

BalanceMgr is the manager of many balancer. It is the access of load balancing. Its main function is to maintain the NodeAddrs and to call the specific load balancing algorithm above.

type BalanceMgr struct{
    addrs NodeAddrs
    balancers map[string]Balancer
    change map[string]bool
}

func (p *BalanceMgr) RegisterBalancer(name string,balancer Balancer)

func (p *BalanceMgr) updateBalancer(name string)

func (p *BalanceMgr) AddNodeAddr(addr *NodeAddr)

func (p *BalanceMgr) DeleteNodeAddr(i int)

func (p *BalanceMgr) UpdateWeightNodeAddr(i int,weight int)

func (p *BalanceMgr) GetAddr(name string)(*NodeAddr,int,error) {
    // if addrs change,update the balancer which we use.
    if p.change[name]{
        p.updateBalancer(name)
    }

    // get the balancer by name
    balancer := p.balancers[name]

    // use the load balancing algorithm
    addr,index,err := balancer.DoBalance(p.addrs)

    return addr,index,err
}

• RegisterBalancer: register the basic balancer implementing the Balancer interface and initialize them.
• updateBalancer: update the specific balancer after the addrs change.
• AddNodeAddr: add the remote address and set all the values of the change to true.
• DeleteNodeAddr: delete the remote address and set all the values of the change to true.
• UpdateWeightNodeAddr: update the weight of the remote address and set all the values of the change to true.
• GetAddr:select the address by the balancer the name decides.