gearman-go/client/pool.go
2015-12-10 11:19:04 -08:00

168 lines
3.2 KiB
Go

package client
import (
"errors"
"math/rand"
"sync"
)
const (
poolSize = 10
)
var (
ErrNotFound = errors.New("Server Not Found")
SelectWithRate = selectWithRate
SelectRandom = selectRandom
)
type PoolClient struct {
*Client
Rate int
mutex sync.Mutex
}
type SelectionHandler func(map[string]*PoolClient, string) string
func selectWithRate(pool map[string]*PoolClient,
last string) (addr string) {
total := 0
for _, item := range pool {
total += item.Rate
if rand.Intn(total) < item.Rate {
return item.addr
}
}
return last
}
func selectRandom(pool map[string]*PoolClient,
last string) (addr string) {
r := rand.Intn(len(pool))
i := 0
for k, _ := range pool {
if r == i {
return k
}
i++
}
return last
}
type Pool struct {
SelectionHandler SelectionHandler
ErrorHandler ErrorHandler
clients map[string]*PoolClient
last string
mutex sync.Mutex
}
// Return a new pool.
func NewPool() (pool *Pool) {
return &Pool{
clients: make(map[string]*PoolClient, poolSize),
SelectionHandler: SelectWithRate,
}
}
// Add a server with rate.
func (pool *Pool) Add(net, addr string, rate int) (err error) {
pool.mutex.Lock()
defer pool.mutex.Unlock()
var item *PoolClient
var ok bool
if item, ok = pool.clients[addr]; ok {
item.Rate = rate
} else {
var client *Client
client, err = New(net, addr)
if err == nil {
item = &PoolClient{Client: client, Rate: rate}
pool.clients[addr] = item
}
}
return
}
// Remove a server.
func (pool *Pool) Remove(addr string) {
pool.mutex.Lock()
defer pool.mutex.Unlock()
delete(pool.clients, addr)
}
func (pool *Pool) Do(funcname string, data []byte,
flag byte, h ResponseHandler) (addr, handle string, err error) {
client := pool.selectServer()
client.Lock()
defer client.Unlock()
handle, err = client.Do(funcname, data, flag, h)
addr = client.addr
return
}
func (pool *Pool) DoBg(funcname string, data []byte,
flag byte) (addr, handle string, err error) {
client := pool.selectServer()
client.Lock()
defer client.Unlock()
handle, err = client.DoBg(funcname, data, flag)
addr = client.addr
return
}
// Get job status from job server.
// !!!Not fully tested.!!!
func (pool *Pool) Status(addr, handle string) (status *Status, err error) {
if client, ok := pool.clients[addr]; ok {
client.Lock()
defer client.Unlock()
status, err = client.Status(handle)
} else {
err = ErrNotFound
}
return
}
// Send a something out, get the samething back.
func (pool *Pool) Echo(addr string, data []byte) (echo []byte, err error) {
var client *PoolClient
if addr == "" {
client = pool.selectServer()
} else {
var ok bool
if client, ok = pool.clients[addr]; !ok {
err = ErrNotFound
return
}
}
client.Lock()
defer client.Unlock()
echo, err = client.Echo(data)
return
}
// Close
func (pool *Pool) Close() (err map[string]error) {
err = make(map[string]error)
for _, c := range pool.clients {
err[c.addr] = c.Close()
}
return
}
// selecting server
func (pool *Pool) selectServer() (client *PoolClient) {
for client == nil {
addr := pool.SelectionHandler(pool.clients, pool.last)
var ok bool
if client, ok = pool.clients[addr]; ok {
pool.last = addr
break
}
}
return
}