moonstream/nodes/node_balancer/cmd/nodebalancer/clients.go

package main

import (
	"errors"
	"reflect"
	"sync"
	"time"
)

var (
	ethereumClientPool ClientPool
	polygonClientPool  ClientPool
	xdaiClientPool     ClientPool
)

// Structure to define user access according with Brood resources
type ClientResourceData struct {
	UserID           string `json:"user_id"`
	AccessID         string `json:"access_id"`
	Name             string `json:"name"`
	Description      string `json:"description"`
	BlockchainAccess bool   `json:"blockchain_access"`
	ExtendedMethods  bool   `json:"extended_methods"`

	LastAccessTs int64 `json:"last_access_ts"`

	dataSource string
}

// Node - which one node client worked with
// LastCallTs - timestamp from last call
type Client struct {
	Node       *Node
	LastCallTs int64

	mux sync.RWMutex
}

// Where id is a key and equal to ClientResourceData -> AccessID
type ClientPool struct {
	Client map[string]*Client
}

// Generate pools for clients for different blockchains
func CreateClientPools() {
	ethereumClientPool.Client = make(map[string]*Client)
	polygonClientPool.Client = make(map[string]*Client)
	xdaiClientPool.Client = make(map[string]*Client)
}

// Return client pool corresponding to provided blockchain
func GetClientPool(blockchain string) (*ClientPool, error) {
	var cpool *ClientPool
	if blockchain == "ethereum" {
		cpool = &ethereumClientPool
	} else if blockchain == "polygon" {
		cpool = &polygonClientPool
	} else if blockchain == "xdai" {
		cpool = &xdaiClientPool
	} else {
		return nil, errors.New("Unsupported blockchain provided")
	}
	return cpool, nil
}

// Updates client last appeal to node
func (client *Client) UpdateClientLastCall() {
	ts := time.Now().Unix()

	client.mux.Lock()
	client.LastCallTs = ts
	client.mux.Unlock()
}

// Get number of seconds from current last call to client node
func (client *Client) GetClientLastCallDiff() (lastCallTs int64) {
	ts := time.Now().Unix()

	client.mux.RLock()
	lastCallTs = ts - client.LastCallTs
	client.mux.RUnlock()

	return lastCallTs
}

// Find clint with same ID and update timestamp or
// add new one if doesn't exist
func (cpool *ClientPool) AddClientNode(id string, node *Node) {
	if cpool.Client[id] != nil {
		if reflect.DeepEqual(cpool.Client[id].Node, node) {
			cpool.Client[id].UpdateClientLastCall()
			return
		}
	}
	cpool.Client[id] = &Client{
		Node:       node,
		LastCallTs: time.Now().Unix(),
	}
}

// Get client hot node if exists
func (cpool *ClientPool) GetClientNode(id string) *Node {
	if cpool.Client[id] != nil {
		lastCallTs := cpool.Client[id].GetClientLastCallDiff()
		if lastCallTs < NB_CLIENT_NODE_KEEP_ALIVE {
			cpool.Client[id].UpdateClientLastCall()
			return cpool.Client[id].Node
		}
		delete(cpool.Client, id)
	}

	return nil
}

// Clean client list of hot outdated nodes
func (cpool *ClientPool) CleanInactiveClientNodes() int {
	cnt := 0
	for id, client := range cpool.Client {
		lastCallTs := client.GetClientLastCallDiff()
		if lastCallTs >= NB_CLIENT_NODE_KEEP_ALIVE {
			delete(cpool.Client, id)
		} else {
			cnt += 1
		}
	}

	return cnt
}