378 lines
6.8 KiB
Go
378 lines
6.8 KiB
Go
package pool
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import (
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"errors"
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"net"
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"sync"
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"sync/atomic"
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"time"
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"github.com/go-redis/redis/internal"
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)
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var ErrClosed = errors.New("redis: client is closed")
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var ErrPoolTimeout = errors.New("redis: connection pool timeout")
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var timers = sync.Pool{
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New: func() interface{} {
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t := time.NewTimer(time.Hour)
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t.Stop()
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return t
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},
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}
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// Stats contains pool state information and accumulated stats.
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type Stats struct {
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Hits uint32 // number of times free connection was found in the pool
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Misses uint32 // number of times free connection was NOT found in the pool
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Timeouts uint32 // number of times a wait timeout occurred
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TotalConns uint32 // number of total connections in the pool
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FreeConns uint32 // number of free connections in the pool
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StaleConns uint32 // number of stale connections removed from the pool
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}
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type Pooler interface {
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NewConn() (*Conn, error)
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CloseConn(*Conn) error
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Get() (*Conn, bool, error)
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Put(*Conn) error
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Remove(*Conn) error
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Len() int
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FreeLen() int
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Stats() *Stats
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Close() error
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}
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type Options struct {
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Dialer func() (net.Conn, error)
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OnClose func(*Conn) error
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PoolSize int
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PoolTimeout time.Duration
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IdleTimeout time.Duration
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IdleCheckFrequency time.Duration
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}
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type ConnPool struct {
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opt *Options
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dialErrorsNum uint32 // atomic
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lastDialError error
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lastDialErrorMu sync.RWMutex
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queue chan struct{}
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connsMu sync.Mutex
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conns []*Conn
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freeConnsMu sync.Mutex
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freeConns []*Conn
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stats Stats
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_closed uint32 // atomic
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}
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var _ Pooler = (*ConnPool)(nil)
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func NewConnPool(opt *Options) *ConnPool {
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p := &ConnPool{
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opt: opt,
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queue: make(chan struct{}, opt.PoolSize),
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conns: make([]*Conn, 0, opt.PoolSize),
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freeConns: make([]*Conn, 0, opt.PoolSize),
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}
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if opt.IdleTimeout > 0 && opt.IdleCheckFrequency > 0 {
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go p.reaper(opt.IdleCheckFrequency)
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}
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return p
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}
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func (p *ConnPool) NewConn() (*Conn, error) {
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if p.closed() {
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return nil, ErrClosed
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}
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if atomic.LoadUint32(&p.dialErrorsNum) >= uint32(p.opt.PoolSize) {
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return nil, p.getLastDialError()
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}
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netConn, err := p.opt.Dialer()
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if err != nil {
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p.setLastDialError(err)
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if atomic.AddUint32(&p.dialErrorsNum, 1) == uint32(p.opt.PoolSize) {
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go p.tryDial()
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}
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return nil, err
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}
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cn := NewConn(netConn)
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p.connsMu.Lock()
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p.conns = append(p.conns, cn)
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p.connsMu.Unlock()
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return cn, nil
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}
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func (p *ConnPool) tryDial() {
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for {
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if p.closed() {
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return
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}
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conn, err := p.opt.Dialer()
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if err != nil {
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p.setLastDialError(err)
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time.Sleep(time.Second)
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continue
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}
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atomic.StoreUint32(&p.dialErrorsNum, 0)
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_ = conn.Close()
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return
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}
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}
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func (p *ConnPool) setLastDialError(err error) {
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p.lastDialErrorMu.Lock()
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p.lastDialError = err
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p.lastDialErrorMu.Unlock()
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}
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func (p *ConnPool) getLastDialError() error {
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p.lastDialErrorMu.RLock()
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err := p.lastDialError
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p.lastDialErrorMu.RUnlock()
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return err
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}
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// Get returns existed connection from the pool or creates a new one.
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func (p *ConnPool) Get() (*Conn, bool, error) {
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if p.closed() {
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return nil, false, ErrClosed
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}
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select {
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case p.queue <- struct{}{}:
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default:
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timer := timers.Get().(*time.Timer)
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timer.Reset(p.opt.PoolTimeout)
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select {
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case p.queue <- struct{}{}:
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if !timer.Stop() {
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<-timer.C
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}
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timers.Put(timer)
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case <-timer.C:
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timers.Put(timer)
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atomic.AddUint32(&p.stats.Timeouts, 1)
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return nil, false, ErrPoolTimeout
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}
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}
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for {
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p.freeConnsMu.Lock()
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cn := p.popFree()
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p.freeConnsMu.Unlock()
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if cn == nil {
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break
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}
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if cn.IsStale(p.opt.IdleTimeout) {
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p.CloseConn(cn)
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continue
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}
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atomic.AddUint32(&p.stats.Hits, 1)
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return cn, false, nil
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}
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atomic.AddUint32(&p.stats.Misses, 1)
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newcn, err := p.NewConn()
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if err != nil {
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<-p.queue
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return nil, false, err
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}
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return newcn, true, nil
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}
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func (p *ConnPool) popFree() *Conn {
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if len(p.freeConns) == 0 {
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return nil
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}
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idx := len(p.freeConns) - 1
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cn := p.freeConns[idx]
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p.freeConns = p.freeConns[:idx]
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return cn
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}
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func (p *ConnPool) Put(cn *Conn) error {
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if data := cn.Rd.PeekBuffered(); data != nil {
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internal.Logf("connection has unread data: %q", data)
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return p.Remove(cn)
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}
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p.freeConnsMu.Lock()
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p.freeConns = append(p.freeConns, cn)
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p.freeConnsMu.Unlock()
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<-p.queue
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return nil
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}
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func (p *ConnPool) Remove(cn *Conn) error {
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_ = p.CloseConn(cn)
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<-p.queue
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return nil
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}
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func (p *ConnPool) CloseConn(cn *Conn) error {
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p.connsMu.Lock()
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for i, c := range p.conns {
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if c == cn {
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p.conns = append(p.conns[:i], p.conns[i+1:]...)
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break
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}
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}
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p.connsMu.Unlock()
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return p.closeConn(cn)
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}
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func (p *ConnPool) closeConn(cn *Conn) error {
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if p.opt.OnClose != nil {
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_ = p.opt.OnClose(cn)
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}
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return cn.Close()
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}
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// Len returns total number of connections.
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func (p *ConnPool) Len() int {
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p.connsMu.Lock()
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l := len(p.conns)
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p.connsMu.Unlock()
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return l
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}
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// FreeLen returns number of free connections.
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func (p *ConnPool) FreeLen() int {
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p.freeConnsMu.Lock()
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l := len(p.freeConns)
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p.freeConnsMu.Unlock()
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return l
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}
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func (p *ConnPool) Stats() *Stats {
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return &Stats{
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Hits: atomic.LoadUint32(&p.stats.Hits),
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Misses: atomic.LoadUint32(&p.stats.Misses),
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Timeouts: atomic.LoadUint32(&p.stats.Timeouts),
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TotalConns: uint32(p.Len()),
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FreeConns: uint32(p.FreeLen()),
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StaleConns: atomic.LoadUint32(&p.stats.StaleConns),
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}
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}
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func (p *ConnPool) closed() bool {
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return atomic.LoadUint32(&p._closed) == 1
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}
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func (p *ConnPool) Filter(fn func(*Conn) bool) error {
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var firstErr error
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p.connsMu.Lock()
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for _, cn := range p.conns {
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if fn(cn) {
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if err := p.closeConn(cn); err != nil && firstErr == nil {
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firstErr = err
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}
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}
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}
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p.connsMu.Unlock()
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return firstErr
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}
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func (p *ConnPool) Close() error {
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if !atomic.CompareAndSwapUint32(&p._closed, 0, 1) {
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return ErrClosed
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}
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var firstErr error
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p.connsMu.Lock()
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for _, cn := range p.conns {
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if err := p.closeConn(cn); err != nil && firstErr == nil {
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firstErr = err
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}
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}
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p.conns = nil
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p.connsMu.Unlock()
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p.freeConnsMu.Lock()
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p.freeConns = nil
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p.freeConnsMu.Unlock()
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return firstErr
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}
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func (p *ConnPool) reapStaleConn() bool {
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if len(p.freeConns) == 0 {
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return false
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}
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cn := p.freeConns[0]
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if !cn.IsStale(p.opt.IdleTimeout) {
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return false
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}
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p.CloseConn(cn)
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p.freeConns = append(p.freeConns[:0], p.freeConns[1:]...)
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return true
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}
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func (p *ConnPool) ReapStaleConns() (int, error) {
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var n int
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for {
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p.queue <- struct{}{}
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p.freeConnsMu.Lock()
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reaped := p.reapStaleConn()
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p.freeConnsMu.Unlock()
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<-p.queue
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if reaped {
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n++
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} else {
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break
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}
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}
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return n, nil
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}
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func (p *ConnPool) reaper(frequency time.Duration) {
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ticker := time.NewTicker(frequency)
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defer ticker.Stop()
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for range ticker.C {
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if p.closed() {
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break
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}
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n, err := p.ReapStaleConns()
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if err != nil {
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internal.Logf("ReapStaleConns failed: %s", err)
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continue
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}
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atomic.AddUint32(&p.stats.StaleConns, uint32(n))
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}
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}
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