From a205c703748a76c85b9d2f787ccff4fd5d4f1048 Mon Sep 17 00:00:00 2001
From: Johan Wikman <johan.wikman@mariadb.com>
Date: Fri, 25 Jan 2019 14:28:39 +0200
Subject: [PATCH] MXS-2273 Allow the setting and clearing of BEING_DRAINED bit

Currently the bit is set so that is may be overwritten by the monitor
if the setting of the bit takes place while the monitor is performing
its monitor loop.
---
 server/core/server.cc | 50 ++++++++++++++++++++++++++++++++-----------
 1 file changed, 37 insertions(+), 13 deletions(-)

diff --git a/server/core/server.cc b/server/core/server.cc
index 17cd93fe9..de4980827 100644
--- a/server/core/server.cc
+++ b/server/core/server.cc
@@ -646,6 +646,7 @@ string SERVER::status_to_string(uint64_t flags)
     // should not change, but this is more dependant on the monitors and have already changed.
     // Also, system tests compare to these strings so the output must stay constant for now.
     const string maintenance = "Maintenance";
+    const string being_drained = "Being Drained";
     const string master = "Master";
     const string relay = "Relay Master";
     const string slave = "Slave";
@@ -657,8 +658,18 @@ string SERVER::status_to_string(uint64_t flags)
     const string running = "Running";
     const string down = "Down";
 
-    // Maintenance is usually set by user so is printed first.
-    concatenate_if(status_is_in_maint(flags), maintenance);
+    // Maintenance/Being Drained is usually set by user so is printed first.
+    // Being Drained in the presence of Maintenance has no effect, so we only
+    // print either one of those, with Maintenance taking precedence.
+    if (status_is_in_maint(flags))
+    {
+        concatenate_if(true, maintenance);
+    }
+    else if (status_is_being_drained(flags))
+    {
+        concatenate_if(true, being_drained);
+    }
+
     // Master cannot be a relay or a slave.
     if (status_is_master(flags))
     {
@@ -837,15 +848,16 @@ uint64_t SERVER::status_from_string(const char* str)
         uint64_t    bit;
     } ServerBits[] =
     {
-        {"running",     SERVER_RUNNING   },
-        {"master",      SERVER_MASTER    },
-        {"slave",       SERVER_SLAVE     },
-        {"synced",      SERVER_JOINED    },
-        {"ndb",         SERVER_NDB       },
-        {"maintenance", SERVER_MAINT     },
-        {"maint",       SERVER_MAINT     },
-        {"stale",       SERVER_WAS_MASTER},
-        {NULL,          0                }
+        {"running",     SERVER_RUNNING      },
+        {"master",      SERVER_MASTER       },
+        {"slave",       SERVER_SLAVE        },
+        {"synced",      SERVER_JOINED       },
+        {"ndb",         SERVER_NDB          },
+        {"maintenance", SERVER_MAINT        },
+        {"maint",       SERVER_MAINT        },
+        {"stale",       SERVER_WAS_MASTER   },
+        {"drain",       SERVER_BEING_DRAINED},
+        {NULL,          0                   }
     };
 
     for (int i = 0; ServerBits[i].str; i++)
@@ -960,7 +972,7 @@ bool mxs::server_set_status(SERVER* srv, int bit, string* errmsg_out)
     {
         /* This server is monitored, in which case modifying any other status bit than Maintenance is
          * disallowed. */
-        if (bit & ~SERVER_MAINT)
+        if (bit & ~(SERVER_MAINT | SERVER_BEING_DRAINED))
         {
             MXS_ERROR(ERR_CANNOT_MODIFY);
             if (errmsg_out)
@@ -982,6 +994,12 @@ bool mxs::server_set_status(SERVER* srv, int bit, string* errmsg_out)
             // Also set a flag so the next loop happens sooner.
             atomic_store_int(&mon->m_check_maintenance_flag, SERVER::MAINTENANCE_FLAG_CHECK);
         }
+        else
+        {
+            // TODO: This should be set the same way the maintenance bit is set.
+            srv->set_status(bit);
+            written = true;
+        }
     }
     else
     {
@@ -1000,7 +1018,7 @@ bool mxs::server_clear_status(SERVER* srv, int bit, string* errmsg_out)
     Monitor* mon = monitor_server_in_use(srv);
     if (mon && mon->m_state == MONITOR_STATE_RUNNING)
     {
-        if (bit & ~SERVER_MAINT)
+        if (bit & ~(SERVER_MAINT | SERVER_BEING_DRAINED))
         {
             MXS_ERROR(ERR_CANNOT_MODIFY);
             if (errmsg_out)
@@ -1019,6 +1037,12 @@ bool mxs::server_clear_status(SERVER* srv, int bit, string* errmsg_out)
             }
             atomic_store_int(&mon->m_check_maintenance_flag, SERVER::MAINTENANCE_FLAG_CHECK);
         }
+        else
+        {
+            // TODO: This should be set the same way the maintenance bit is set.
+            srv->clear_status(bit);
+            written = true;
+        }
     }
     else
     {