MB-14986: Increase connection pool size and provide API to change it on

the fly
CBSE-1762: Provide API to enable TCP Keepalive on memcached connections

Change-Id: I8d9ea0d347fc3da7f80631fddeff3d40b433e4dd
Reviewed-on: http://review.couchbase.org/51043
Reviewed-by: Manik Taneja <manik@couchbase.com>
Tested-by: Manik Taneja <manik@couchbase.com>

conn_pool.go

@@ -51,6 +51,11 @@ var ConnPoolCallback func(host string, source string, start time.Time, err error
 
 func defaultMkConn(host string, ah AuthHandler) (*memcached.Client, error) {
 	conn, err := memcached.Connect("tcp", host)
+
+	if TCPKeepalive == true {
+		conn.SetKeepAliveOptions(time.Duration(TCPKeepaliveInterval) * time.Second)
+	}
+
 	if err != nil {
 		return nil, err
 	}

examples/streaming/example.go

@@ -39,6 +39,9 @@ func main() {
 		return
 	}
 
+	couchbase.SetConnectionPoolParams(256, 16)
+	couchbase.SetTcpKeepalive(true, 30)
+
 	go performOp(cbbucket)
 
 	errCh := make(chan error)
@@ -58,13 +61,15 @@ func performOp(b *couchbase.Bucket) {
 	for {
 		key := fmt.Sprintf("k%d", i)
 		value := fmt.Sprintf("value%d", i)
+		log.Printf(" setting key %v", key)
 		err := b.Set(key, len(value), value)
 		if err != nil {
 			log.Printf("set failed error %v", err)
 			return
 		}
 		i++
-		<-time.After(1 * time.Second)
 
+		<-time.After(1 * time.Second)
 	}
+
 }

pools.go

@@ -27,11 +27,39 @@ var HTTPTransport = &http.Transport{MaxIdleConnsPerHost: MaxIdleConnsPerHost}
 var HTTPClient = &http.Client{Transport: HTTPTransport}
 
 // PoolSize is the size of each connection pool (per host).
-var PoolSize = 4
+var PoolSize = 64
 
 // PoolOverflow is the number of overflow connections allowed in a
 // pool.
-var PoolOverflow = PoolSize
+var PoolOverflow = 16
+
+// TCP KeepAlive enabled/disabled
+var TCPKeepalive = false
+
+// TCP keepalive interval in seconds. Default 30 minutes
+var TCPKeepaliveInterval = 30 * 60
+
+// Allow applications to speciify the Poolsize and Overflow
+func SetConnectionPoolParams(size, overflow int) {
+
+	if size > 0 {
+		PoolSize = size
+	}
+
+	if overflow > 0 {
+		PoolOverflow = overflow
+	}
+}
+
+// Allow TCP keepalive parameters to be set by the application
+func SetTcpKeepalive(enabled bool, interval int) {
+
+	TCPKeepalive = enabled
+
+	if interval > 0 {
+		TCPKeepaliveInterval = interval
+	}
+}
 
 // AuthHandler is a callback that gets the auth username and password
 // for the given bucket.