[FIXED JENKINS-18660] Added dedicated denormalized counter function

core/src/main/java/hudson/model/Label.java

@@ -39,12 +39,15 @@ import hudson.model.labels.LabelExpressionLexer;
 import hudson.model.labels.LabelExpressionParser;
 import hudson.model.labels.LabelOperatorPrecedence;
 import hudson.model.labels.LabelVisitor;
+import hudson.security.ACL;
 import hudson.slaves.NodeProvisioner;
 import hudson.slaves.Cloud;
 import hudson.util.QuotedStringTokenizer;
 import hudson.util.VariableResolver;
 import jenkins.model.Jenkins;
 import jenkins.model.ModelObjectWithChildren;
+import org.acegisecurity.context.SecurityContext;
+import org.acegisecurity.context.SecurityContextHolder;
 import org.kohsuke.stapler.StaplerRequest;
 import org.kohsuke.stapler.StaplerResponse;
 import org.kohsuke.stapler.export.Exported;
@@ -57,6 +60,7 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 import java.util.Collection;
+import java.util.Stack;
 import java.util.TreeSet;
 
 import com.thoughtworks.xstream.converters.Converter;
@@ -345,6 +349,56 @@ public abstract class Label extends Actionable implements Comparable<Label>, Mod
         return r;
     }
 
+    /**
+     * Returns a count of projects that are tied on this node. In a system without security this should be the same
+     * as {@code getTiedJobs().size()} but significantly faster as it involves fewer temporary objects and avoids
+     * sorting the intermediary list. In a system with security, this will likely return a higher value as it counts
+     * all jobs (mostly) irrespective of access.
+     * @return a count of projects that are tied on this node.
+     */
+    public int getTiedJobCount() {
+        // denormalize for performance
+        // we don't need to respect security as much when returning a simple count
+        SecurityContext context = ACL.impersonate(ACL.SYSTEM);
+        try {
+            int result = 0;
+            // top level gives the map without checking security of items in the map
+            // therefore best performance
+            for (TopLevelItem topLevelItem : Jenkins.getInstance().getItemMap().values()) {
+                if (topLevelItem instanceof AbstractProject) {
+                    final AbstractProject project = (AbstractProject) topLevelItem;
+                    if (this.equals(project.getAssignedLabel())) {
+                        result++;
+                    }
+                }
+                if (topLevelItem instanceof ItemGroup) {
+                    Stack<ItemGroup> q = new Stack<ItemGroup>();
+                    q.push((ItemGroup) topLevelItem);
+
+                    while (!q.isEmpty()) {
+                        ItemGroup<?> parent = q.pop();
+                        // we run the risk of permissions checks in ItemGroup#getItems()
+                        // not much we can do here though
+                        for (Item i : parent.getItems()) {
+                            if (i instanceof AbstractProject) {
+                                final AbstractProject project = (AbstractProject) i;
+                                if (this.equals(project.getAssignedLabel())) {
+                                    result++;
+                                }
+                            }
+                            if (i instanceof ItemGroup) {
+                                q.push((ItemGroup) i);
+                            }
+                        }
+                    }
+                }
+            }
+            return result;
+        } finally {
+            SecurityContextHolder.setContext(context);
+        }
+    }
+
     public boolean contains(Node node) {
         return getNodes().contains(node);
     }

core/src/main/java/hudson/model/Node.java

@@ -225,7 +225,7 @@ public abstract class Node extends AbstractModelObject implements Reconfigurable
     public TagCloud<LabelAtom> getLabelCloud() {
         return new TagCloud<LabelAtom>(getAssignedLabels(),new WeightFunction<LabelAtom>() {
             public float weight(LabelAtom item) {
-                return item.getTiedJobs().size();
+                return item.getTiedJobCount();
             }
         });
     }