From aab1d784463d708426fa9218c1167586eccebf2a Mon Sep 17 00:00:00 2001
From: DanB <danb@cgrates.org>
Date: Mon, 18 Feb 2019 13:20:19 +0100
Subject: [PATCH] DispatcherS - new strategies for *random and *round_robin

---
 dispatchers/libdispatcher.go | 54 +++++++++++++++++++++++++++++++++++-
 utils/consts.go              | 33 +++++++++++-----------
 2 files changed, 70 insertions(+), 17 deletions(-)

diff --git a/dispatchers/libdispatcher.go b/dispatchers/libdispatcher.go
index 460d94591..657f1fc89 100644
--- a/dispatchers/libdispatcher.go
+++ b/dispatchers/libdispatcher.go
@@ -42,6 +42,10 @@ func newDispatcher(pfl *engine.DispatcherProfile) (d Dispatcher, err error) {
 	switch pfl.Strategy {
 	case utils.MetaWeight:
 		d = &WeightDispatcher{conns: pfl.Conns.Clone()}
+	case utils.MetaRandom:
+		d = &RandomDispatcher{conns: pfl.Conns.Clone()}
+	case utils.MetaRoundRobin:
+		d = &RoundRobinDispatcher{conns: pfl.Conns.Clone()}
 	default:
 		err = fmt.Errorf("unsupported dispatch strategy: <%s>", pfl.Strategy)
 	}
@@ -57,7 +61,7 @@ type WeightDispatcher struct {
 func (wd *WeightDispatcher) SetProfile(pfl *engine.DispatcherProfile) {
 	wd.Lock()
 	pfl.Conns.Sort()
-	wd.conns = pfl.Conns.Clone()
+	wd.conns = pfl.Conns.Clone() // avoid concurrency on profile
 	wd.Unlock()
 	return
 }
@@ -68,3 +72,51 @@ func (wd *WeightDispatcher) ConnIDs() (connIDs []string) {
 	wd.RUnlock()
 	return
 }
+
+// RandomDispatcher selects the next connection randomly
+// together with RouteID can serve as load-balancer
+type RandomDispatcher struct {
+	sync.RWMutex
+	conns engine.DispatcherConns
+}
+
+func (d *RandomDispatcher) SetProfile(pfl *engine.DispatcherProfile) {
+	d.Lock()
+	d.conns = pfl.Conns.Clone()
+	d.Unlock()
+	return
+}
+
+func (d *RandomDispatcher) ConnIDs() (connIDs []string) {
+	d.RLock()
+	conns := d.conns.Clone()
+	d.RUnlock()
+	conns.Shuffle() // randomize the connections
+	return conns.ConnIDs()
+}
+
+// RoundRobinDispatcher selects the next connection in round-robin fashion
+type RoundRobinDispatcher struct {
+	sync.RWMutex
+	conns   engine.DispatcherConns
+	connIdx int // used for the next connection
+}
+
+func (d *RoundRobinDispatcher) SetProfile(pfl *engine.DispatcherProfile) {
+	d.Lock()
+	d.conns = pfl.Conns.Clone()
+	d.Unlock()
+	return
+}
+
+func (d *RoundRobinDispatcher) ConnIDs() (connIDs []string) {
+	d.RLock()
+	conns := d.conns.Clone()
+	conns.ReorderFromIndex(d.connIdx)
+	d.connIdx++
+	if d.connIdx >= len(d.conns) {
+		d.connIdx = 0
+	}
+	d.RUnlock()
+	return conns.ConnIDs()
+}
diff --git a/utils/consts.go b/utils/consts.go
index f6faae712..d6095b515 100755
--- a/utils/consts.go
+++ b/utils/consts.go
@@ -671,22 +671,23 @@ const (
 
 // Dispatcher Const
 const (
-	MetaFirst     = "*first"
-	MetaRandom    = "*random"
-	MetaBroadcast = "*broadcast"
-	MetaNext      = "*next"
-	ThresholdSv1  = "ThresholdSv1"
-	StatSv1       = "StatSv1"
-	ResourceSv1   = "ResourceSv1"
-	SupplierSv1   = "SupplierSv1"
-	AttributeSv1  = "AttributeSv1"
-	SessionSv1    = "SessionSv1"
-	ChargerSv1    = "ChargerSv1"
-	MetaAuth      = "*auth"
-	APIKey        = "APIKey"
-	APIMethods    = "APIMethods"
-	APIMethod     = "APIMethod"
-	NestingSep    = "."
+	MetaFirst      = "*first"
+	MetaRandom     = "*random"
+	MetaBroadcast  = "*broadcast"
+	MetaNext       = "*next"
+	MetaRoundRobin = "*round_robin"
+	ThresholdSv1   = "ThresholdSv1"
+	StatSv1        = "StatSv1"
+	ResourceSv1    = "ResourceSv1"
+	SupplierSv1    = "SupplierSv1"
+	AttributeSv1   = "AttributeSv1"
+	SessionSv1     = "SessionSv1"
+	ChargerSv1     = "ChargerSv1"
+	MetaAuth       = "*auth"
+	APIKey         = "APIKey"
+	APIMethods     = "APIMethods"
+	APIMethod      = "APIMethod"
+	NestingSep     = "."
 )
 
 // ApierV1 APIs