From 09d20d105915450f8f7497662d26c8def54cf523 Mon Sep 17 00:00:00 2001
From: VilhoRaatikka <vilho.raatikka@skysql.com>
Date: Fri, 13 Jun 2014 14:52:04 +0300
Subject: [PATCH] Modified dcb_call_foreach so that it doesn't hold spinlock
 (dcbspin) continuously because it caused deadlock when new slaves were tried
 to connect with.

Fixed a few smallish things.
---
 server/core/dcb.c                             | 50 +++++++++++++++---
 server/modules/protocol/mysql_backend.c       | 51 ++++++++++++++++++-
 .../routing/readwritesplit/readwritesplit.c   |  3 +-
 3 files changed, 94 insertions(+), 10 deletions(-)

diff --git a/server/core/dcb.c b/server/core/dcb.c
index f19cfefb0..fe5b29590 100644
--- a/server/core/dcb.c
+++ b/server/core/dcb.c
@@ -83,6 +83,7 @@ static bool dcb_set_state_nomutex(
         const dcb_state_t new_state,
         dcb_state_t*      old_state);
 static void dcb_call_callback(DCB *dcb, DCB_REASON reason);
+static DCB* dcb_get_next (DCB* dcb);
 
 DCB* dcb_get_zombies(void)
 {
@@ -1728,6 +1729,41 @@ int	rval = 0;
 	return rval;
 }
 
+static DCB* dcb_get_next (
+        DCB* dcb)
+{
+        DCB* p;
+        
+        spinlock_acquire(&dcbspin);
+        
+        p = allDCBs;
+        
+        if (dcb == NULL || p == NULL)
+        {
+                dcb = p;
+                
+        }
+        else
+        {
+                while (p != NULL && dcb != p)
+                {
+                        p = p->next;
+                }
+                
+                if (p != NULL)
+                {
+                        dcb = p->next;
+                }
+                else
+                {
+                        dcb = NULL;
+                }
+        }
+        spinlock_release(&dcbspin);
+        
+        return dcb;
+}        
+
 void dcb_call_foreach (
         SERVER* srv,
         DCB_REASON reason)
@@ -1742,16 +1778,16 @@ void dcb_call_foreach (
                 case DCB_REASON_NOT_RESPONDING: 
                 {
                         DCB* dcb;
+                        dcb = dcb_get_next(NULL);
                         
-                        spinlock_acquire(&dcbspin);
-                        
-                        dcb = allDCBs;
-                        while (dcb)
+                        while (dcb != NULL)
                         {
-                                dcb_call_callback(dcb, DCB_REASON_NOT_RESPONDING);
-                                dcb = dcb->next;
+                                if (dcb->state == DCB_STATE_POLLING)
+                                {
+                                        dcb_call_callback(dcb, DCB_REASON_NOT_RESPONDING);
+                                }
+                                dcb = dcb_get_next(dcb);
                         }
-                        spinlock_release(&dcbspin);
                         break;
                 }
                         
diff --git a/server/modules/protocol/mysql_backend.c b/server/modules/protocol/mysql_backend.c
index 932886a6e..588443c63 100644
--- a/server/modules/protocol/mysql_backend.c
+++ b/server/modules/protocol/mysql_backend.c
@@ -887,7 +887,56 @@ return_fd:
 static int
 gw_backend_hangup(DCB *dcb)
 {
-        /*< vraa : errorHandle */
+        SESSION*       session;
+        void*          rsession;
+        ROUTER_OBJECT* router;
+        ROUTER*        router_instance;
+        int            rc = 0;
+        bool           succp;
+        
+        CHK_DCB(dcb);
+        session = dcb->session;
+        CHK_SESSION(session);
+        rsession = session->router_session;
+        router = session->service->router;
+        router_instance = session->service->router_instance;
+
+        mysql_send_custom_error(
+                dcb->session->client,
+                1,
+                0,
+                "Lost connection to backend server.");
+        
+        /**
+         *         errorHandle :
+         *      - sulje katkennut yhteys - miten?
+         *      - etsi riittävä määrä servereitä
+         *      - jos epäonnistui, sammuta sessio
+         *      - jos onnistui, jatka
+         * 
+         * Jos sammutetaan :
+         * - dcb_close - backend->func.close()
+         */
+        
+         /*< vraa : errorHandle */
+        /*
+         * 
+        - lähetä virheviesti clientille jos odottaa
+        errorHandle :
+        - etsi riittävä määrä servereitä
+        - jos epäonnistui, sammuta sessio
+        - jos onnistui, jatka
+        */
+        router->handleError(router_instance, 
+                            rsession, 
+                            "Lost connection to backend server", 
+                            dcb,
+                            ERRACT_NEW_CONNECTION,
+                            &succp);
+        
+        if (succp) {
+                dcb_close(dcb);
+        }
 	return 1;
 }
 
diff --git a/server/modules/routing/readwritesplit/readwritesplit.c b/server/modules/routing/readwritesplit/readwritesplit.c
index b116bda69..f18f0ac18 100644
--- a/server/modules/routing/readwritesplit/readwritesplit.c
+++ b/server/modules/routing/readwritesplit/readwritesplit.c
@@ -813,7 +813,7 @@ static bool get_dcb(
                 {
                         backend_ref = rses->rses_master_ref;
 
-                        if (BREF_IS_IN_USE((&backend_ref[i])))
+                        if (BREF_IS_IN_USE(backend_ref))
                         {
                                 *p_dcb = backend_ref->bref_dcb;
                                 succp = true;
@@ -2765,7 +2765,6 @@ static int router_handle_state_switch(
                 case DCB_REASON_NOT_RESPONDING:
                         if (BREF_IS_WAITING_RESULT(bref))
                         {
-                                printf("foo");
                                 dcb->func.hangup(dcb);
                         }
                         break;