rpc ppol example

rpc_pool.go

package client

import (
	"net/rpc"

	"github.com/go-playground/log"
)

// NewFunc is the type of function that is called to create a new Go rpc Client
type NewFunc func() *rpc.Client

type clientsChan chan *rpc.Client

// clientPool contains a contrained pool of *rpc.Client objects
type clientPool struct {
	pool      clientsChan
	newClient NewFunc
	max       uint
}

// newPool creates and returns new ClientPool
func newPool(max uint, fn NewFunc) *clientPool {

	if max == 0 {
		log.Warn("**** Warning invalid 'max' param, setting to 10 by default")
	}

	return &clientPool{
		pool:      make(clientsChan, max),
		newClient: fn,
		max:       max,
	}
}

func (p *clientPool) Get() (c *rpc.Client) {

	select {
	case c = <-p.pool:
	default:

		if uint(len(p.pool)) == p.max {
			// if reached max number of allowed connections, must
			// wait until another gets put back into the pool instead
			// of creating new ones beyond the capacity of the machine
			// to handle.
			c = <-p.pool
		} else {
			c = p.newClient()
		}
	}

	return
}

func (p *clientPool) Put(c *rpc.Client) {

	select {
	case p.pool <- c:
	default:
		// eventual garbage collection
	}
}