Add support for autoeviction of slow nodes.

Partial-Bug: 1815196

Change-Id: Ia3084c2a7eb8c4dc9b4eb7c6372369a5996f87b5

config.yaml

@@ -358,3 +358,16 @@ options:
       control message will be sent.  The fc_limit defaults to 16 transactions.
       This effectively means that this is as far as a given node can be behind
       committing transactions from the cluster.
+  autoevict:
+    type: int
+    default: 0
+    description: |
+      Number of entries allowed on delayed list until auto eviction takes place.
+      Setting value to 0 disables auto eviction. This setting enables autoeviction
+      of slow nodes. Implies 'evs.version=1'.
+      Related STATUS variables:
+      .
+      'wsrep_evs_delayed': Comma separated list of nodes that are considered delayed.
+                           The node format is <uuid>:<address>:<count>, where <count>
+                           is the number of entries on delayed list for that node.
+      'wsrep_evs_evict_list': List of UUIDs of the evicted nodes.

hooks/percona_utils.py

@@ -1071,6 +1071,11 @@ def get_wsrep_provider_options():
     if config('gcs-fc-limit') is not None:
         wsrep_provider_options.append(
             'gcs.fc_limit={}'.format(config('gcs-fc-limit')))
+    if config('autoevict') is not None:
+        wsrep_provider_options.append(
+            'evs.auto_evict={}'.format(config('autoevict')))
+        wsrep_provider_options.append(
+            'evs.version=1')
 
     peer_timeout = config('peer-timeout')
     if peer_timeout and(not peer_timeout.startswith('PT') or