Additional trace logging for desired balance computer (#105910)

Author: idegtiarenko

server/src/internalClusterTest/java/org/elasticsearch/cluster/routing/allocation/decider/DiskThresholdDeciderIT.java

@@ -162,7 +162,8 @@ public void testRestoreSnapshotAllocationDoesNotExceedWatermark() throws Excepti
     }
 
     @TestIssueLogging(
-        value = "org.elasticsearch.cluster.routing.allocation.allocator.DesiredBalanceReconciler:DEBUG,"
+        value = "org.elasticsearch.cluster.routing.allocation.allocator.DesiredBalanceComputer:TRACE,"
+            + "org.elasticsearch.cluster.routing.allocation.allocator.DesiredBalanceReconciler:DEBUG,"
             + "org.elasticsearch.cluster.routing.allocation.allocator.DesiredBalanceShardsAllocator:TRACE",
         issueUrl = "https://github.com/elastic/elasticsearch/issues/105331"
     )

server/src/main/java/org/elasticsearch/cluster/routing/allocation/allocator/DesiredBalanceComputer.java

@@ -77,7 +77,18 @@ public DesiredBalance compute(
         Predicate<DesiredBalanceInput> isFresh
     ) {
 
-        logger.debug("Recomputing desired balance for [{}]", desiredBalanceInput.index());
+        if (logger.isTraceEnabled()) {
+            logger.trace(
+                "Recomputing desired balance for [{}]: {}, {}, {}, {}",
+                desiredBalanceInput.index(),
+                previousDesiredBalance,
+                desiredBalanceInput.routingAllocation().routingNodes().toString(),
+                desiredBalanceInput.routingAllocation().clusterInfo().toString(),
+                desiredBalanceInput.routingAllocation().snapshotShardSizeInfo().toString()
+            );
+        } else {
+            logger.debug("Recomputing desired balance for [{}]", desiredBalanceInput.index());
+        }
 
         final var routingAllocation = desiredBalanceInput.routingAllocation().mutableCloneForSimulation();
         final var routingNodes = routingAllocation.routingNodes();
@@ -283,7 +294,6 @@ public DesiredBalance compute(
                         hasChanges = true;
                         clusterInfoSimulator.simulateShardStarted(shardRouting);
                         routingNodes.startShard(logger, shardRouting, changes, 0L);
-                        logger.trace("starting shard {}", shardRouting);
                     }
                 }
             }

server/src/main/java/org/elasticsearch/snapshots/SnapshotShardSizeInfo.java

@@ -46,4 +46,9 @@ public long getShardSize(ShardRouting shardRouting, long fallback) {
         }
         return shardSize;
     }
+
+    @Override
+    public String toString() {
+        return "SnapshotShardSizeInfo{snapshotShardSizes=" + snapshotShardSizes + '}';
+    }
 }