Support standard maxPoolSize URL option.

Author: niemeyer

cluster_test.go

@@ -1152,41 +1152,40 @@ func (s *S) TestRemovalOfClusterMember(c *C) {
 }
 
 func (s *S) TestPoolLimitSimple(c *C) {
-	session, err := mgo.Dial("localhost:40001")
-	c.Assert(err, IsNil)
-	defer session.Close()
-
-	stats := mgo.GetStats()
-	for stats.MasterConns+stats.SlaveConns != 1 {
-		stats = mgo.GetStats()
-		c.Log("Waiting for connection to be established...")
-		time.Sleep(100 * time.Millisecond)
-	}
-
-	c.Assert(stats.SocketsAlive, Equals, 1)
-	c.Assert(stats.SocketsInUse, Equals, 0)
+	for test := 0; test < 2; test++ {
+		var session *mgo.Session
+		var err error
+		if test == 0 {
+			session, err = mgo.Dial("localhost:40001")
+			c.Assert(err, IsNil)
+			session.SetPoolLimit(1)
+		} else {
+			session, err = mgo.Dial("localhost:40001?maxPoolSize=1")
+			c.Assert(err, IsNil)
+		}
+		defer session.Close()
 
-	// Put one socket in use.
-	c.Assert(session.Ping(), IsNil)
+		// Put one socket in use.
+		c.Assert(session.Ping(), IsNil)
 
-	done := make(chan time.Duration)
+		done := make(chan time.Duration)
 
-	// Now block trying to get another one due to the pool limit.
-	go func() {
-		copy := session.Copy()
-		defer copy.Close()
-		copy.SetPoolLimit(1)
-		started := time.Now()
-		c.Check(copy.Ping(), IsNil)
-		done <- time.Now().Sub(started)
-	}()
+		// Now block trying to get another one due to the pool limit.
+		go func() {
+			copy := session.Copy()
+			defer copy.Close()
+			started := time.Now()
+			c.Check(copy.Ping(), IsNil)
+			done <- time.Now().Sub(started)
+		}()
 
-	time.Sleep(500 * time.Millisecond)
+		time.Sleep(300 * time.Millisecond)
 
-	// Put the one socket back in the pool, freeing it for the copy.
-	session.Refresh()
-	delay := <-done
-	c.Assert(delay > 500 * time.Millisecond, Equals, true, Commentf("Delay: %s", delay))
+		// Put the one socket back in the pool, freeing it for the copy.
+		session.Refresh()
+		delay := <-done
+		c.Assert(delay > 300 * time.Millisecond, Equals, true, Commentf("Delay: %s", delay))
+	}
 }
 
 func (s *S) TestPoolLimitMany(c *C) {

session.go

@@ -186,8 +186,13 @@ const defaultPrefetch = 0.25
 //
 //     gssapiServiceName=<name>
 //
-//           Defines the service name to use when authenticating with the GSSAPI
-//           mechanism. Defaults to "mongodb".
+//        Defines the service name to use when authenticating with the GSSAPI
+//        mechanism. Defaults to "mongodb".
+//
+//     maxPoolSize=<limit>
+//
+//        Defines the per-server socket pool limit. Defaults to 4096.
+//        See Session.SetPoolLimit for details.
 //
 //
 // Relevant documentation:
@@ -218,6 +223,7 @@ func DialWithTimeout(url string, timeout time.Duration) (*Session, error) {
 	mechanism := ""
 	service := ""
 	source := ""
+	poolLimit := 0
 	for k, v := range uinfo.options {
 		switch k {
 		case "authSource":
@@ -226,6 +232,11 @@ func DialWithTimeout(url string, timeout time.Duration) (*Session, error) {
 			mechanism = v
 		case "gssapiServiceName":
 			service = v
+		case "maxPoolSize":
+			poolLimit, err = strconv.Atoi(v)
+			if err != nil {
+				return nil, errors.New("bad value for maxPoolSize: " + v)
+			}
 		case "connect":
 			if v == "direct" {
 				direct = true
@@ -249,6 +260,7 @@ func DialWithTimeout(url string, timeout time.Duration) (*Session, error) {
 		Mechanism: mechanism,
 		Service:   service,
 		Source:    source,
+		PoolLimit: poolLimit,
 	}
 	return DialWithInfo(&info)
 }
@@ -300,6 +312,10 @@ type DialInfo struct {
 	Username string
 	Password string
 
+	// PoolLimit defines the per-server socket pool limit. Defaults to 4096.
+	// See Session.SetPoolLimit for details.
+	PoolLimit int
+
 	// DialServer optionally specifies the dial function for establishing
 	// connections with the MongoDB servers.
 	DialServer func(addr *ServerAddr) (net.Conn, error)
@@ -363,6 +379,9 @@ func DialWithInfo(info *DialInfo) (*Session, error) {
 		}
 		session.creds = []Credential{*session.dialCred}
 	}
+	if info.PoolLimit > 0 {
+		session.poolLimit = info.PoolLimit
+	}
 	cluster.Release()
 
 	// People get confused when we return a session that is not actually