cgrates/cmd/inquirer/balancer.go

package main

import (
	"net/rpc"
	"sync"
)

type RaterList struct {
	clientAddresses []string
	clientConnections []*rpc.Client
	balancerIndex int
	mu sync.RWMutex
}

/*
Constructor for RateList holding one slice for addreses and one slice for connections.
*/
func NewRaterList() *RaterList {
	r:= &RaterList{balancerIndex: 0} // leaving both slices to nil
	return r
}

/*
Adds a client to the two  internal slices.
*/
func (rl *RaterList) AddClient(address string, client *rpc.Client){
	rl.clientAddresses = append(rl.clientAddresses, address)
	rl.clientConnections = append(rl.clientConnections, client)
	return
}

/*
Removes a client from the slices locking the readers and reseting the balancer index.
*/
func (rl *RaterList) RemoveClient(address string){
	index := -1
	for i, v := range rl.clientAddresses {
		if v == address {
			index = i
			break
		}
	}
	if index == -1 {
		return
	}
	rl.mu.RLock()
	defer rl.mu.RUnlock()
	rl.clientAddresses = append(rl.clientAddresses[:index], rl.clientAddresses[index+1:]...)
	rl.clientConnections = append(rl.clientConnections[:index], rl.clientConnections[index+1:]...)
	rl.balancerIndex = 0
}

/*
Returns a client for the specifed address.
*/
func (rl *RaterList) GetClient(address string) (*rpc.Client, bool){
	for i, v := range rl.clientAddresses {
		if v == address {
			return rl.clientConnections[i], true
		}
	}
	return nil, false
}

/*
Returns the next available connection at each call looping at the end of connections.
*/
func (rl *RaterList) Balance() (result *rpc.Client) {
	rl.mu.Lock()
	defer rl.mu.Unlock()
	if rl.balancerIndex >= len(rl.clientAddresses) {
		rl.balancerIndex = 0
	}
	if len(rl.clientAddresses) > 0 {
		result = rl.clientConnections[rl.balancerIndex]
		rl.balancerIndex++
	} 
	
	return 
}