Naive implementation for issue alphazero#2. Added a simple connection…

… pool using channels for concurrency

connection.go

@@ -21,12 +21,13 @@ import (
 	"log"
 	"net"
 	//	"os"
+	"sync"
 	"time"
 )
 
 const (
 	TCP       = "tcp"
-	UNIX       = "unix"
+	UNIX      = "unix"
 	LOCALHOST = "127.0.0.1"
 	//	ns1MSec   = 1000000
 	////	ns1Sec    = ns1MSec * 1000
@@ -148,6 +149,7 @@ type connHdl struct {
 	spec   *ConnectionSpec
 	conn   net.Conn // may want to change this to TCPConn
 	reader *bufio.Reader
+	m      sync.Mutex
 }
 
 func (chdl *connHdl) String() string {
@@ -165,19 +167,19 @@ func newConnHdl(spec *ConnectionSpec) (hdl *connHdl, err Error) {
 		return nil, NewError(SYSTEM_ERR, fmt.Sprintf("%s(): failed to allocate connHdl", here))
 	}
 
-    var mode, addr string
-	if (spec.port == 0) {
-    	mode = UNIX
-    	addr = spec.host
-    } else {
-    	mode = TCP
-    	addr = fmt.Sprintf("%s:%d", spec.host, spec.port)
-        _, e := net.ResolveTCPAddr(TCP, addr)
-        if e != nil {
-            msg := fmt.Sprintf("%s(): failed to resolve remote address %s", here, addr)
-            return nil, NewErrorWithCause(SYSTEM_ERR, msg, e)
-        }
-    }
+	var mode, addr string
+	if spec.port == 0 {
+		mode = UNIX
+		addr = spec.host
+	} else {
+		mode = TCP
+		addr = fmt.Sprintf("%s:%d", spec.host, spec.port)
+		_, e := net.ResolveTCPAddr(TCP, addr)
+		if e != nil {
+			msg := fmt.Sprintf("%s(): failed to resolve remote address %s", here, addr)
+			return nil, NewErrorWithCause(SYSTEM_ERR, msg, e)
+		}
+	}
 
 	conn, e := net.Dial(mode, addr)
 	switch {
@@ -195,6 +197,7 @@ func newConnHdl(spec *ConnectionSpec) (hdl *connHdl, err Error) {
 		hdl.reader = bufio.NewReaderSize(conn, bufsize)
 		log.Printf("<INFO> Connected to %s", hdl)
 	}
+	hdl.m = sync.Mutex{}
 	return hdl, nil
 }
 
@@ -204,12 +207,12 @@ func configureConn(conn net.Conn, spec *ConnectionSpec) {
 	// but we absolutely need to be able to use timeouts.
 	//			conn.SetReadTimeout(spec.rTimeout);
 	//			conn.SetWriteTimeout(spec.wTimeout);
-    if tcp, ok := conn.(*net.TCPConn); ok {
-        tcp.SetLinger(spec.lingerspec)
-        tcp.SetKeepAlive(spec.keepalive)
-        tcp.SetReadBuffer(spec.rBufSize)
-        tcp.SetWriteBuffer(spec.wBufSize)
-    }
+	if tcp, ok := conn.(*net.TCPConn); ok {
+		tcp.SetLinger(spec.lingerspec)
+		tcp.SetKeepAlive(spec.keepalive)
+		tcp.SetReadBuffer(spec.rBufSize)
+		tcp.SetWriteBuffer(spec.wBufSize)
+	}
 }
 
 // onConnect event handler will issue AUTH/SELECT on new connection
@@ -259,15 +262,62 @@ type SyncConnection interface {
 	Close() error
 }
 
+type connPool struct {
+	active int
+	count  int
+	pool   []*connHdl       // Connection pool
+	conn   chan *connHdl    // To handle concurrency
+}
+
+func (p *connPool) Close() error {
+	var err error
+
+	for i := 0; i < p.count; i++ {
+		err = p.pool[i].Close()
+		// XXX handle err
+	}
+
+	return err
+}
+
+func (p *connPool) AddConnection(conn *connHdl) {
+    // Put the connection in the pool, and add it to the channel
+	p.pool[p.active] = conn
+	p.active = p.active + 1
+	p.conn <- conn
+}
+
+func (p *connPool) ServiceRequest(cmd *Command, args [][]byte) (Response, Error) {
+    // Wait for a connection to become available
+	var conn = <-p.conn
+	res, err := conn.ServiceRequest(cmd, args)
+
+    // Return our connection to the pool
+	p.conn <- conn
+	return res, err
+}
+
+func newConnPool(count int) *connPool {
+	return &connPool{0, count, make([]*connHdl, count), make(chan *connHdl, count)}
+}
+
 // Creates a new SyncConnection using the provided ConnectionSpec
 func NewSyncConnection(spec *ConnectionSpec) (c SyncConnection, err Error) {
-	connHdl, e := newConnHdl(spec)
-	if e != nil {
-		return nil, e
-	}
+	var e Error
+
+    // XXX In order to allow backwards compatability
+    // the pool size is hardcoded for now.
+	pool := newConnPool(4)
+	for i := 0; i < 4; i++ {
+		connHdl, e := newConnHdl(spec)
+		if e != nil {
+			return nil, e
+		}
 
-	e = connHdl.onConnect()
-	return connHdl, e
+		e = connHdl.onConnect()
+		pool.AddConnection(connHdl)
+	}
+	return pool, e
 }
 
 // Implementation of SyncConnection.ServiceRequest.

synchclient.go

@@ -51,11 +51,10 @@ func NewSynchClient() (c Client, err Error) {
 //
 func NewSynchClientWithSpec(spec *ConnectionSpec) (c Client, err Error) {
 	_c := new(syncClient)
-	_c.conn, err = NewSyncConnection(spec)
+    _c.conn, err = NewSyncConnection(spec)
 	if err != nil {
-		return nil, withError (err)
-	}
-//	_c.conn = conn
+	   return nil, withError (err)
+    }
 	return _c, nil
 }