From d559459f982c803de606e638f8ff897f4928fbc7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ren=C3=A9=20Canna=C3=B2?= <rene.cannao@gmail.com>
Date: Thu, 13 Jul 2017 20:33:29 +0200
Subject: [PATCH] Bug fix for #1085

Immediatelly kill all client connections using an OFFLINE node
---
 include/MySQL_Session.h    |  1 +
 include/MySQL_Thread.h     |  2 ++
 include/mysql_connection.h |  1 +
 lib/MySQL_Session.cpp      | 17 +++++++++++++++++
 lib/MySQL_Thread.cpp       | 12 ++++++++++++
 lib/mysql_connection.cpp   | 16 ++++++++++++++++
 6 files changed, 49 insertions(+)

diff --git a/include/MySQL_Session.h b/include/MySQL_Session.h
index 9f4f5ed49c..4972f3209f 100644
--- a/include/MySQL_Session.h
+++ b/include/MySQL_Session.h
@@ -195,6 +195,7 @@ class MySQL_Session
 	void MySQL_Result_to_MySQL_wire(MYSQL *mysql, MySQL_ResultSet *MyRS, MySQL_Data_Stream *_myds=NULL);
 	void MySQL_Stmt_Result_to_MySQL_wire(MYSQL_STMT *stmt, MySQL_Connection *myconn);
 	unsigned int NumActiveTransactions();
+	bool HasOfflineBackends();
 	int FindOneActiveTransaction();
 	unsigned long long IdleTime();
 
diff --git a/include/MySQL_Thread.h b/include/MySQL_Thread.h
index 3daef4e309..f589776109 100644
--- a/include/MySQL_Thread.h
+++ b/include/MySQL_Thread.h
@@ -155,6 +155,8 @@ class ProxySQL_Poll {
 class MySQL_Thread
 {
 	private:
+	unsigned int servers_table_version_previous;
+	unsigned int servers_table_version_current;
   unsigned long long last_processing_idles;
 	MySQL_Connection **my_idle_conns;
   bool processing_idles;
diff --git a/include/mysql_connection.h b/include/mysql_connection.h
index 56d2db4bd4..7ba984dc69 100644
--- a/include/mysql_connection.h
+++ b/include/mysql_connection.h
@@ -165,6 +165,7 @@ class MySQL_Connection {
 			}
 		return ret;
 	}
+	bool IsServerOffline();
 	bool IsAutoCommit();
 	bool MultiplexDisabled();
 	void ProcessQueryAndSetStatusFlags(char *query_digest_text);
diff --git a/lib/MySQL_Session.cpp b/lib/MySQL_Session.cpp
index e8f28c2467..3bd874c564 100644
--- a/lib/MySQL_Session.cpp
+++ b/lib/MySQL_Session.cpp
@@ -3755,6 +3755,23 @@ unsigned int MySQL_Session::NumActiveTransactions() {
 	return ret;
 }
 
+bool MySQL_Session::HasOfflineBackends() {
+	bool ret=false;
+	if (mybes==0) return ret;
+	MySQL_Backend *_mybe;
+	unsigned int i;
+	for (i=0; i < mybes->len; i++) {
+		_mybe=(MySQL_Backend *)mybes->index(i);
+		if (_mybe->server_myds)
+			if (_mybe->server_myds->myconn)
+				if (_mybe->server_myds->myconn->IsServerOffline()) {
+					ret=true;
+					return ret;
+				}
+	}
+	return ret;
+}
+
 int MySQL_Session::FindOneActiveTransaction() {
 	int ret=-1;
 	if (mybes==0) return ret;
diff --git a/lib/MySQL_Thread.cpp b/lib/MySQL_Thread.cpp
index 8b783d624d..e544f5f268 100644
--- a/lib/MySQL_Thread.cpp
+++ b/lib/MySQL_Thread.cpp
@@ -2474,6 +2474,8 @@ void MySQL_Thread::run() {
 		if (curtime > last_maintenance_time + maintenance_interval) {
 			last_maintenance_time=curtime;
 			maintenance_loop=true;
+			servers_table_version_previous = servers_table_version_current;
+			servers_table_version_current = MyHGM->get_servers_table_version();
 		} else {
 			maintenance_loop=false;
 		}
@@ -2907,6 +2909,12 @@ void MySQL_Thread::process_all_sessions() {
 						if (sess_time/1000 > (unsigned long long)mysql_thread___wait_timeout) sess->killed=true;
 					}
 				}
+				if (servers_table_version_current != servers_table_version_previous) { // bug fix for #1085
+					// Immediatelly kill all client connections using an OFFLINE node
+					if (sess->HasOfflineBackends()) {
+						sess->killed=true;
+					}
+				}
 			}
 #ifdef IDLE_THREADS
 				else
@@ -3104,6 +3112,10 @@ MySQL_Thread::MySQL_Thread() {
 	status_variables.frontend_stmt_prepare=0;
 	status_variables.frontend_stmt_execute=0;
 	status_variables.frontend_stmt_close=0;
+
+	servers_table_version_previous=0;
+	servers_table_version_current=0;
+
 	status_variables.queries=0;
 	status_variables.queries_slow=0;
 	status_variables.queries_backends_bytes_sent=0;
diff --git a/lib/mysql_connection.cpp b/lib/mysql_connection.cpp
index b5f1218268..5b65180233 100644
--- a/lib/mysql_connection.cpp
+++ b/lib/mysql_connection.cpp
@@ -1125,6 +1125,22 @@ int MySQL_Connection::async_connect(short event) {
 }
 
 
+bool MySQL_Connection::IsServerOffline() {
+	bool ret=false;
+	if (parent==NULL)
+		return ret;
+	server_status=parent->status; // we copy it here to avoid race condition. The caller will see this
+	if (
+		(server_status==MYSQL_SERVER_STATUS_OFFLINE_HARD) // the server is OFFLINE as specific by the user
+		||
+		(server_status==MYSQL_SERVER_STATUS_SHUNNED && parent->shunned_automatic==true && parent->shunned_and_kill_all_connections==true) // the server is SHUNNED due to a serious issue
+		||
+		(server_status==MYSQL_SERVER_STATUS_SHUNNED_REPLICATION_LAG) // slave is lagging! see #774
+	) {
+		ret=true;
+	}
+	return ret;
+}
 
 // Returns:
 // 0 when the query is completed