From e452d455f4ba433d43844e01985288d9e6597779 Mon Sep 17 00:00:00 2001
From: DanB <danb@cgrates.org>
Date: Mon, 3 Apr 2017 13:18:13 +0200
Subject: [PATCH] SMG replication with session cloning to avoid concurrency on
 slow replication

---
 sessionmanager/smg_event_test.go |  3 ---
 sessionmanager/smg_session.go    |  3 ++-
 sessionmanager/smgeneric.go      | 13 ++++++++++++-
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/sessionmanager/smg_event_test.go b/sessionmanager/smg_event_test.go
index 2b2143d0b..249cd0235 100644
--- a/sessionmanager/smg_event_test.go
+++ b/sessionmanager/smg_event_test.go
@@ -18,7 +18,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>
 package sessionmanager
 
 import (
-	"fmt"
 	"reflect"
 	"testing"
 	"time"
@@ -148,8 +147,6 @@ func TestSMGenericEventGetSessionTTL(t *testing.T) {
 	sesTTLMaxDelay := time.Duration(10 * time.Second)
 	if sTTL := smGev.GetSessionTTL(time.Duration(5*time.Second), &sesTTLMaxDelay); sTTL == eSesTTL || sTTL > eSesTTL+sesTTLMaxDelay {
 		t.Errorf("Received: %v", sTTL)
-	} else {
-		fmt.Println(sTTL)
 	}
 }
 
diff --git a/sessionmanager/smg_session.go b/sessionmanager/smg_session.go
index 257ff9925..8645ee926 100644
--- a/sessionmanager/smg_session.go
+++ b/sessionmanager/smg_session.go
@@ -22,6 +22,7 @@ import (
 	"fmt"
 	"reflect"
 	"strconv"
+	"sync"
 	"time"
 
 	"github.com/cgrates/cgrates/engine"
@@ -31,6 +32,7 @@ import (
 
 // One session handled by SM
 type SMGSession struct {
+	mux           sync.RWMutex   // protects the SMGSession in places where is concurrently accessed
 	CGRID         string         // Unique identifier for this session
 	EventStart    SMGenericEvent // Event which started
 	stopDebit     chan struct{}  // Channel to communicate with debit loops when closing the session
@@ -142,7 +144,6 @@ func (self *SMGSession) debit(dur time.Duration, lastUsed *time.Duration) (time.
 
 // Attempts to refund a duration, error on failure
 func (self *SMGSession) refund(refundDuration time.Duration) error {
-
 	if refundDuration == 0 { // Nothing to refund
 		return nil
 	}
diff --git a/sessionmanager/smgeneric.go b/sessionmanager/smgeneric.go
index 733a93b69..76b46db77 100644
--- a/sessionmanager/smgeneric.go
+++ b/sessionmanager/smgeneric.go
@@ -471,7 +471,18 @@ func (smg *SMGeneric) replicateSessionsWithID(cgrID string, passiveSessions bool
 	}
 	ssMux.RLock()
 	ss := ssMp[cgrID]
+	if len(ss) != 0 {
+		ss[0].mux.RLock() // lock session so we can clone it after releasing the map lock
+	}
 	ssMux.RUnlock()
+	var ssCln []*SMGSession
+	err = utils.Clone(ss, &ssCln)
+	if len(ss) != 0 {
+		ss[0].mux.RUnlock()
+	}
+	if err != nil {
+		return
+	}
 	var wg sync.WaitGroup
 	for _, rplConn := range smgReplConns {
 		if rplConn.Synchronous {
@@ -484,7 +495,7 @@ func (smg *SMGeneric) replicateSessionsWithID(cgrID string, passiveSessions bool
 			if sync {
 				wg.Done()
 			}
-		}(rplConn.Connection, rplConn.Synchronous, ss)
+		}(rplConn.Connection, rplConn.Synchronous, ssCln)
 	}
 	wg.Wait() // wait for synchronous replication to finish
 	return