WriteLoadConstraintDecider: Have separate rate limiting for canRemain and canAllocate decisions (#138067)

Author: nicktindall

server/src/main/java/org/elasticsearch/cluster/routing/allocation/decider/WriteLoadConstraintDecider.java

@@ -33,16 +33,18 @@ public class WriteLoadConstraintDecider extends AllocationDecider {
 
     public static final String NAME = "write_load";
 
-    private final FrequencyCappedAction logInterventionMessage;
+    private final FrequencyCappedAction logCanRemainMessage;
+    private final FrequencyCappedAction logCanAllocateMessage;
     private final WriteLoadConstraintSettings writeLoadConstraintSettings;
 
     public WriteLoadConstraintDecider(ClusterSettings clusterSettings) {
         this.writeLoadConstraintSettings = new WriteLoadConstraintSettings(clusterSettings);
-        logInterventionMessage = new FrequencyCappedAction(System::currentTimeMillis, TimeValue.ZERO);
-        clusterSettings.initializeAndWatch(
-            WriteLoadConstraintSettings.WRITE_LOAD_DECIDER_MINIMUM_LOGGING_INTERVAL,
-            logInterventionMessage::setMinInterval
-        );
+        logCanRemainMessage = new FrequencyCappedAction(System::currentTimeMillis, TimeValue.ZERO);
+        logCanAllocateMessage = new FrequencyCappedAction(System::currentTimeMillis, TimeValue.ZERO);
+        clusterSettings.initializeAndWatch(WriteLoadConstraintSettings.WRITE_LOAD_DECIDER_MINIMUM_LOGGING_INTERVAL, timeValue -> {
+            logCanRemainMessage.setMinInterval(timeValue);
+            logCanAllocateMessage.setMinInterval(timeValue);
+        });
     }
 
     @Override
@@ -87,7 +89,7 @@ public Decision canAllocate(ShardRouting shardRouting, RoutingNode node, Routing
                     shardRouting.shardId()
                 );
                 if (logger.isDebugEnabled()) {
-                    logInterventionMessage.maybeExecute(() -> logger.debug(explain));
+                    logCanAllocateMessage.maybeExecute(() -> logger.debug(explain));
                 }
                 return allocation.decision(Decision.NOT_PREFERRED, NAME, explain);
             } else {
@@ -113,7 +115,7 @@ public Decision canAllocate(ShardRouting shardRouting, RoutingNode node, Routing
                     nodeWriteThreadPoolStats.totalThreadPoolThreads()
                 );
                 if (logger.isDebugEnabled()) {
-                    logInterventionMessage.maybeExecute(() -> logger.debug(explain));
+                    logCanAllocateMessage.maybeExecute(() -> logger.debug(explain));
                 }
                 return allocation.decision(Decision.NOT_PREFERRED, NAME, explain);
             } else {
@@ -162,7 +164,7 @@ public Decision canRemain(IndexMetadata indexMetadata, ShardRouting shardRouting
                     nodeWriteThreadPoolStats.averageThreadPoolUtilization()
                 );
                 if (logger.isDebugEnabled()) {
-                    logInterventionMessage.maybeExecute(() -> logger.debug(explain));
+                    logCanRemainMessage.maybeExecute(() -> logger.debug(explain));
                 }
                 return allocation.decision(Decision.NOT_PREFERRED, NAME, explain);
             } else {