gearman-go/client/pool.go

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// Copyright 2011 Xing Xing <mikespook@gmail.com>.
// All rights reserved.
// Use of this source code is governed by a MIT
// license that can be found in the LICENSE file.
package client
import (
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"sync"
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"errors"
"math/rand"
"github.com/mikespook/gearman-go/common"
)
const (
PoolSize = 10
)
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var (
ErrNotFound = errors.New("Server Not Found")
)
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type poolClient struct {
*Client
Rate int
}
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type SelectionHandler func(map[string]*poolClient, string) string
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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 {
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return item.addr
}
}
return last
}
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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
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}
type Pool struct {
SelectionHandler SelectionHandler
ErrHandler common.ErrorHandler
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clients map[string]*poolClient
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last string
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mutex sync.Mutex
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}
// Create a new pool.
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func NewPool() (pool *Pool) {
return &Pool{
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clients: make(map[string]*poolClient, PoolSize),
SelectionHandler: SelectWithRate,
}
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}
// Add a server with rate.
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func (pool *Pool) Add(addr string, rate int) (err error) {
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pool.mutex.Lock()
defer pool.mutex.Unlock()
var item *poolClient
var ok bool
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if item, ok = pool.clients[addr]; ok {
item.Rate = rate
} else {
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var client *Client
client, err = New(addr)
item = &poolClient{Client: client, Rate: rate}
err = item.connect()
pool.clients[addr] = item
}
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return
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}
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// 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,
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flag byte, h JobHandler) (addr, handle string) {
client := pool.selectServer()
handle = client.Do(funcname, data, flag, h)
addr = client.addr
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return
}
func (pool *Pool) DoBg(funcname string, data []byte,
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flag byte) (addr, handle string) {
client := pool.selectServer()
handle = client.DoBg(funcname, data, flag)
addr = client.addr
return
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}
// Get job status from job server.
// !!!Not fully tested.!!!
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func (pool *Pool) Status(addr, handle string) (status *Status, err error) {
if client, ok := pool.clients[addr]; ok {
status = client.Status(handle)
} else {
err = ErrNotFound
}
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return
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}
// Send a something out, get the samething back.
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func (pool *Pool) Echo(addr string, data []byte) (r []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
}
}
r = client.Echo(data)
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return
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}
// Close
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func (pool *Pool) Close() (err map[string]error) {
err = make(map[string]error)
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for _, c := range pool.clients {
err[c.addr] = c.Close()
}
return
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}
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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
}