Add connnection pool and improve API.

connpool.go

@@ -0,0 +1,95 @@
+package redis
+
+import (
+	"io"
+	"log"
+	"os"
+	"sync"
+
+	"github.com/vmihailenco/bufreader"
+)
+
+type Conn struct {
+	RW io.ReadWriter
+	Rd *bufreader.Reader
+}
+
+func NewConn(rw io.ReadWriter) *Conn {
+	return &Conn{
+		RW: rw,
+		Rd: bufreader.NewSizedReader(8024),
+	}
+}
+
+type ConnPool struct {
+	Logger      *log.Logger
+	cond        *sync.Cond
+	conns       []*Conn
+	OpenConn    OpenConnFunc
+	CloseConn   CloseConnFunc
+	cap, MaxCap int64
+}
+
+func NewConnPool(openConn OpenConnFunc, closeConn CloseConnFunc, maxCap int64) *ConnPool {
+	logger := log.New(
+		os.Stdout,
+		"redis.connpool: ",
+		log.Ldate|log.Ltime|log.Lshortfile,
+	)
+	return &ConnPool{
+		cond:      sync.NewCond(&sync.Mutex{}),
+		Logger:    logger,
+		conns:     make([]*Conn, 0),
+		OpenConn:  openConn,
+		CloseConn: closeConn,
+		MaxCap:    maxCap,
+	}
+}
+
+func (p *ConnPool) Get() (*Conn, bool, error) {
+	p.cond.L.Lock()
+	defer p.cond.L.Unlock()
+
+	for len(p.conns) == 0 && p.cap >= p.MaxCap {
+		p.cond.Wait()
+	}
+
+	if len(p.conns) == 0 {
+		rw, err := p.OpenConn()
+		if err != nil {
+			return nil, false, err
+		}
+
+		p.cap++
+		return NewConn(rw), true, nil
+	}
+
+	last := len(p.conns) - 1
+	conn := p.conns[last]
+	p.conns[last] = nil
+	p.conns = p.conns[:last]
+
+	return conn, false, nil
+}
+
+func (p *ConnPool) Add(conn *Conn) {
+	p.cond.L.Lock()
+	defer p.cond.L.Unlock()
+	p.conns = append(p.conns, conn)
+	p.cond.Signal()
+}
+
+func (p *ConnPool) Remove(conn *Conn) {
+	p.cond.L.Lock()
+	p.cap--
+	p.cond.Signal()
+	p.cond.L.Unlock()
+
+	if p.CloseConn != nil && conn != nil {
+		p.CloseConn(conn.RW)
+	}
+}
+
+func (p *ConnPool) Len() int {
+	return len(p.conns)
+}