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pool.go
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pool.go
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//******************************************//
//****************** DEMO *****************//
//****************************************//
//func NewPool() *gobeanstalk.Pool {
// return &gobeanstalk.Pool{
// Dial: func() (*gobeanstalk.Conn, error) {
// conn, err := gobeanstalk.Dial(ADDR)
// if err != nil {
// log.Fatal(err)
// }
// if err != nil {
// return nil, err
// }
// return conn, nil
// },
// MaxIdle: 10,
// MaxActive: 100,
// IdleTimeout: 60 * time.Second,
// MaxLifetime: 180 * time.Second,
// Wait: true,
// }
//}
//main
//func main() {
// runtime.GOMAXPROCS(runtime.NumCPU())
// pool := NewPool()
// defer pool.Close()
//
// //Producer
// ch := make(chan int, 10)
// for i := 1; i <= 10; i++ {
// go Producer(pool, ch)
// }
//
// for i := 1; i <= 10; i++ {
// <-ch
// }
//
// fmt.Println("end...")
//}
//Producer
//func Producer(pool *gobeanstalk.Pool, ch chan int) {
// conn, err := pool.Get()
// if err != nil {
// log.Fatal(err)
// }
// defer pool.Release(conn)
//
// conn.Use(TEST_TUBE)
// for i := 0; i < 10000; i++ {
// id, err := conn.Put([]byte(fmt.Sprintf("%s:%d", "msg", i)), 1, 0, 120*time.Second)
// if err != nil {
// fmt.Println("[Producer] [", id, "] err:", err)
// } else {
// fmt.Println("[Producer]", id)
// }
// }
// ch <- 1
//}
package gobeanstalk
import (
"container/list"
"errors"
"sync"
"time"
)
var nowFunc = time.Now
// ErrPoolExhausted is returned from a pool connection method (Do, Send,
// Receive, Flush, Err) when the maximum number of database connections in the
// pool has been reached.
var ErrPoolExhausted = errors.New("gobeanstalk: connection pool exhausted")
var (
errPoolClosed = errors.New("gobeanstalk: connection pool closed")
)
type Pool struct {
// Dial is an application supplied function for creating and configuring a
// connection.
//
// The connection returned from Dial must not be in a special state
// (subscribed to pubsub channel, transaction started, ...).
Dial func() (*Conn, error)
// Maximum number of idle connections in the pool.
MaxIdle int
// Maximum number of connections allocated by the pool at a given time.
// When zero, there is no limit on the number of connections in the pool.
MaxActive int
// Close connections after remaining idle for this duration. If the value
// is zero, then idle connections are not closed. Applications should set
// the timeout to a value less than the server's timeout.
IdleTimeout time.Duration
// Close connections after MaxLifetime for this duration. If the value
// is zero, then connections are not closed.
MaxLifetime time.Duration
// If Wait is true and the pool is at the MaxActive limit, then Get() waits
// for a connection to be returned to the pool before returning.
Wait bool
// mu protects fields defined below.
mu sync.Mutex
cond *sync.Cond
closed bool
active int
// Stack of idleConn with most recently used at the front.
idle list.List
}
type idleConn struct {
c *Conn
t time.Time
}
// Get gets a connection. The application must close the returned connection.
// This method always returns a valid connection so that applications can defer
// error handling to the first use of the connection. If there is an error
// getting an underlying connection, then the connection Err, Do, Send, Flush
// and Receive methods return that error.
func (p *Pool) Get() (*Conn, error) {
c, err := p.get()
if err != nil {
return nil, err
}
return c, nil
}
// ActiveCount returns the number of active connections in the pool.
func (p *Pool) ActiveCount() int {
p.mu.Lock()
active := p.active
p.mu.Unlock()
return active
}
// Close releases the resources used by the pool.
func (p *Pool) Close() error {
p.mu.Lock()
idle := p.idle
p.idle.Init()
p.closed = true
p.active -= idle.Len()
if p.cond != nil {
p.cond.Broadcast()
}
p.mu.Unlock()
for e := idle.Front(); e != nil; e = e.Next() {
e.Value.(idleConn).c.Close()
}
return nil
}
// release decrements the active count and signals waiters. The caller must
// hold p.mu during the call.
func (p *Pool) release() {
p.active -= 1
if p.cond != nil {
p.cond.Signal()
}
}
// get prunes stale connections and returns a connection from the idle list or
// creates a new connection.
func (p *Pool) get() (*Conn, error) {
p.mu.Lock()
// Prune stale connections.
if timeout := p.IdleTimeout; timeout > 0 {
for i, n := 0, p.idle.Len(); i < n; i++ {
e := p.idle.Back()
if e == nil {
break
}
ic := e.Value.(idleConn)
if ic.t.Add(timeout).After(nowFunc()) {
break
}
p.idle.Remove(e)
p.release()
p.mu.Unlock()
ic.c.Close()
p.mu.Lock()
}
}
for {
// Get idle connection.
for i, n := 0, p.idle.Len(); i < n; i++ {
e := p.idle.Front()
if e == nil {
break
}
ic := e.Value.(idleConn)
//lifetime expired
if p.MaxLifetime > 0 && ic.c.createTime.Add(p.MaxLifetime).Before(nowFunc()) {
p.idle.Remove(e)
p.release()
p.mu.Unlock()
ic.c.Close()
p.mu.Lock()
continue
}
p.idle.Remove(e)
p.mu.Unlock()
return ic.c, nil
}
// Check for pool closed before dialing a new connection.
if p.closed {
p.mu.Unlock()
return nil, errPoolClosed
}
// Dial new connection if under limit.
if p.MaxActive == 0 || p.active < p.MaxActive {
dial := p.Dial
p.active += 1
p.mu.Unlock()
c, err := dial()
if err != nil {
p.mu.Lock()
p.release()
p.mu.Unlock()
c = nil
}
return c, err
}
if !p.Wait {
p.mu.Unlock()
return nil, ErrPoolExhausted
}
if p.cond == nil {
p.cond = sync.NewCond(&p.mu)
}
p.cond.Wait()
}
}
//Put back to idleList
func (p *Pool) put(c *Conn, forceClose bool) error {
p.mu.Lock()
if !p.closed && !forceClose {
p.idle.PushFront(idleConn{t: nowFunc(), c: c})
if p.idle.Len() > p.MaxIdle {
c = p.idle.Remove(p.idle.Back()).(idleConn).c
} else {
c = nil
}
}
if c == nil {
if p.cond != nil {
p.cond.Signal()
}
p.mu.Unlock()
return nil
}
p.release()
p.mu.Unlock()
err := c.Close()
//c = nil
return err
}
//Release a used connection, put back to idleList
func (p *Pool) Release(c *Conn, forceClose bool) error {
p.put(c, forceClose)
return nil
}