From 6aac86bebcc00ad3caa22f8260545a154f875c17 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ren=C3=A9=20Canna=C3=B2?= <rene.cannao@gmail.com>
Date: Fri, 22 Mar 2019 00:23:50 +1100
Subject: [PATCH] Changed the way max_lag_ms in query is computed

It now remembers if the query is waiting for long time
---
 include/query_processor.h |  2 +-
 lib/MySQL_Session.cpp     | 28 +++++++++++++++++++++++++---
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/include/query_processor.h b/include/query_processor.h
index 3940f224b..a2748c322 100644
--- a/include/query_processor.h
+++ b/include/query_processor.h
@@ -72,7 +72,7 @@ class Query_Processor_Output {
 	int sticky_conn;
 	int multiplex;
 	int gtid_from_hostgroup;
-	int max_lag_ms;
+	long long max_lag_ms;
 	int log;
 	char *comment; // #643
 	std::string *new_query;
diff --git a/lib/MySQL_Session.cpp b/lib/MySQL_Session.cpp
index acb9032d7..adbed28ef 100644
--- a/lib/MySQL_Session.cpp
+++ b/lib/MySQL_Session.cpp
@@ -4491,6 +4491,19 @@ void MySQL_Session::handler___client_DSS_QUERY_SENT___server_DSS_NOT_INITIALIZED
 		MySQL_Backend * _gtid_from_backend = NULL;
 		char uuid[64];
 		uint64_t trxid = 0;
+		unsigned long long now_us = 0;
+		if (qpo->max_lag_ms >= 0) {
+			if (qpo->max_lag_ms > 360000) { // this is an absolute time, we convert it to relative
+				if (now_us == 0) {
+					now_us = realtime_time();
+				}
+				long long now_ms = now_us/1000;
+				qpo->max_lag_ms -= now_ms;
+				if (qpo->max_lag_ms < 0) {
+					qpo->max_lag_ms = -1; // time expired
+				}
+			}
+		}
 		if (session_fast_forward == false) {
 			if (qpo->gtid_from_hostgroup >= 0) {
 				_gtid_from_backend = find_backend(qpo->gtid_from_hostgroup);
@@ -4514,14 +4527,14 @@ void MySQL_Session::handler___client_DSS_QUERY_SENT___server_DSS_NOT_INITIALIZED
 				uuid[n]='\0';
 				mc=thread->get_MyConn_local(mybe->hostgroup_id, this, uuid, trxid, -1);
 			} else {
-				mc=thread->get_MyConn_local(mybe->hostgroup_id, this, NULL, 0, qpo->max_lag_ms);
+				mc=thread->get_MyConn_local(mybe->hostgroup_id, this, NULL, 0, (int)qpo->max_lag_ms);
 			}
 		}
 		if (mc==NULL) {
 			if (trxid) {
-				mc=MyHGM->get_MyConn_from_pool(mybe->hostgroup_id, this, session_fast_forward, uuid, trxid, qpo->max_lag_ms);
+				mc=MyHGM->get_MyConn_from_pool(mybe->hostgroup_id, this, session_fast_forward, uuid, trxid, -1);
 			} else {
-				mc=MyHGM->get_MyConn_from_pool(mybe->hostgroup_id, this, session_fast_forward, NULL, 0, qpo->max_lag_ms);
+				mc=MyHGM->get_MyConn_from_pool(mybe->hostgroup_id, this, session_fast_forward, NULL, 0, (int)qpo->max_lag_ms);
 			}
 		} else {
 			thread->status_variables.ConnPool_get_conn_immediate++;
@@ -4532,6 +4545,15 @@ void MySQL_Session::handler___client_DSS_QUERY_SENT___server_DSS_NOT_INITIALIZED
 		} else {
 			thread->status_variables.ConnPool_get_conn_failure++;
 		}
+		if (qpo->max_lag_ms >= 0) {
+			if (qpo->max_lag_ms <= 360000) { // this is a relative time , we convert it to absolute
+				if (now_us == 0) {
+					now_us = realtime_time();
+				}
+				long long now_ms = now_us/1000;
+				qpo->max_lag_ms += now_ms;
+			}
+		}
 	proxy_debug(PROXY_DEBUG_MYSQL_CONNECTION, 5, "Sess=%p -- server_myds=%p -- MySQL_Connection %p\n", this, mybe->server_myds,  mybe->server_myds->myconn);
 	if (mybe->server_myds->myconn==NULL) {
 		// we couldn't get a connection for whatever reason, ex: no backends, or too busy