Optimize Label parsing calls

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

@@ -592,10 +592,16 @@ public static Set<LabelAtom> parse(@CheckForNull String labels) {
         final Set<LabelAtom> r = new TreeSet<>();
         labels = fixNull(labels);
         if (labels.length() > 0) {
-            final QuotedStringTokenizer tokenizer = new QuotedStringTokenizer(labels);
-            while (tokenizer.hasMoreTokens())
-                r.add(Jenkins.get().getLabelAtom(tokenizer.nextToken()));
+            Jenkins j = Jenkins.get();
+            LabelAtom labelAtom = j.tryGetLabelAtom(labels);
+            if (labelAtom == null) {
+                final QuotedStringTokenizer tokenizer = new QuotedStringTokenizer(labels);
+                while (tokenizer.hasMoreTokens())
+                    r.add(j.getLabelAtom(tokenizer.nextToken()));
+            } else {
+                r.add(labelAtom);
             }
+        }
         return r;
     }
 

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

@@ -298,20 +298,30 @@ public OfflineCause getTemporaryOfflineCause() {
     public TagCloud<LabelAtom> getLabelCloud() {
         return new TagCloud<>(getAssignedLabels(), Label::getTiedJobCount);
     }
+
+    /**
+     * @return An immutable set of LabelAtom associated with the current node label.
+     */
+    @NonNull
+    protected Set<LabelAtom> getLabelAtomSet() {
+        // Default implementation doesn't cache, since we can't hook on label updates.
+        return Collections.unmodifiableSet(Label.parse(getLabelString()));
+    }
+
     /**
      * Returns the possibly empty set of labels that are assigned to this node,
      * including the automatic {@link #getSelfLabel() self label}, manually
      * assigned labels and dynamically assigned labels via the
      * {@link LabelFinder} extension point.
      *
      * This method has a side effect of updating the hudson-wide set of labels
-     * and should be called after events that will change that - e.g. a agent
+     * and should be called after events that will change that - e.g. an agent
      * connecting.
      */
 
     @Exported
     public Set<LabelAtom> getAssignedLabels() {
-        Set<LabelAtom> r = Label.parse(getLabelString());
+        Set<LabelAtom> r = new HashSet<>(getLabelAtomSet());
         r.add(getSelfLabel());
         r.addAll(getDynamicLabels());
         return Collections.unmodifiableSet(r);

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

@@ -36,6 +36,7 @@
 import hudson.Util;
 import hudson.cli.CLI;
 import hudson.model.Descriptor.FormException;
+import hudson.model.labels.LabelAtom;
 import hudson.remoting.Callable;
 import hudson.remoting.Channel;
 import hudson.remoting.Which;
@@ -60,6 +61,7 @@
 import java.net.URLConnection;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.Set;
 import java.util.jar.JarFile;
@@ -179,6 +181,7 @@ protected Slave(@NonNull String name, String remoteFS, ComputerLauncher launcher
         this.name = name;
         this.remoteFS = remoteFS;
         this.launcher = launcher;
+        this.labelAtomSet = Collections.unmodifiableSet(Label.parse(label));
     }
 
     /**
@@ -193,7 +196,7 @@ protected Slave(@NonNull String name, String nodeDescription, String remoteFS, i
         this.numExecutors = numExecutors;
         this.mode = mode;
         this.remoteFS = Util.fixNull(remoteFS).trim();
-        this.label = Util.fixNull(labelString).trim();
+        this.labelAtomSet = Collections.unmodifiableSet(Label.parse(labelString));
         this.launcher = launcher;
         this.retentionStrategy = retentionStrategy;
         getAssignedLabels();    // compute labels now
@@ -328,11 +331,24 @@ public String getLabelString() {
     @Override
     @DataBoundSetter
     public void setLabelString(String labelString) throws IOException {
-        this.label = Util.fixNull(labelString).trim();
+        _setLabelString(labelString);
         // Compute labels now.
         getAssignedLabels();
     }
 
+    private void _setLabelString(String labelString) {
+        this.label = Util.fixNull(labelString).trim();
+        this.labelAtomSet = Collections.unmodifiableSet(Label.parse(label));
+    }
+
+    @NonNull
+    private transient Set<LabelAtom> labelAtomSet;
+
+    @Override
+    protected Set<LabelAtom> getLabelAtomSet() {
+        return labelAtomSet;
+    }
+
     @Override
     public Callable<ClockDifference, IOException> getClockDifferenceCallable() {
         return new GetClockDifference1();
@@ -574,6 +590,7 @@ public int hashCode() {
     protected Object readResolve() {
         if (nodeProperties == null)
             nodeProperties = new DescribableList<>(this);
+        _setLabelString(label);
         return this;
     }
 

core/src/main/java/jenkins/model/Jenkins.java

@@ -930,7 +930,7 @@ protected Jenkins(File root, ServletContext context, PluginManager pluginManager
 
             Trigger.timer = new java.util.Timer("Jenkins cron thread");
             queue = new Queue(LoadBalancer.CONSISTENT_HASH);
-
+            labelAtomSet = Collections.unmodifiableSet(Label.parse(label));
             try {
                 dependencyGraph = DependencyGraph.EMPTY;
             } catch (InternalError e) {
@@ -1088,6 +1088,7 @@ protected Object readResolve() {
             /* deserializing without a value set means we need to migrate */
             nodeRenameMigrationNeeded = true;
         }
+        _setLabelString(label);
 
         return this;
     }
@@ -2114,6 +2115,20 @@ public Label getLabel(String expr) {
         }
     }
 
+    /**
+     * Returns the label atom of the given name, only if it already exists.
+     * @return non-null if the label atom already exists.
+     */
+    @Restricted(NoExternalUse.class)
+    public @Nullable LabelAtom tryGetLabelAtom(@NonNull String name) {
+        Label label = labels.get(name);
+        if (label instanceof LabelAtom) {
+            return (LabelAtom) label;
+        }
+        return null;
+    }
+
+
     /**
      * Gets all the active labels in the current system.
      */
@@ -2126,6 +2141,14 @@ public Set<Label> getLabels() {
         return r;
     }
 
+    @NonNull
+    private transient Set<LabelAtom> labelAtomSet;
+
+    @Override
+    protected Set<LabelAtom> getLabelAtomSet() {
+        return labelAtomSet;
+    }
+
     public Set<LabelAtom> getLabelAtoms() {
         Set<LabelAtom> r = new TreeSet<>();
         for (Label l : labels.values()) {
@@ -3291,10 +3314,17 @@ public String getLabelString() {
 
     @Override
     public void setLabelString(String label) throws IOException {
-        this.label = label;
+        _setLabelString(label);
         save();
     }
 
+    private void _setLabelString(String label) {
+        this.label = label;
+        if (Jenkins.getInstanceOrNull() != null) { // avoid on unit tests
+            this.labelAtomSet = Collections.unmodifiableSet(Label.parse(label));
+        }
+    }
+
     @NonNull
     @Override
     public LabelAtom getSelfLabel() {

test/src/test/java/hudson/model/labels/LabelBenchmarkTest.java

@@ -0,0 +1,82 @@
+package hudson.model.labels;
+
+import static org.junit.Assert.assertTrue;
+
+import hudson.model.Label;
+import hudson.slaves.DumbSlave;
+import hudson.slaves.JNLPLauncher;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.concurrent.TimeUnit;
+import jenkins.benchmark.jmh.JmhBenchmark;
+import jenkins.benchmark.jmh.JmhBenchmarkState;
+import org.junit.Test;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.infra.Blackhole;
+import org.openjdk.jmh.results.format.ResultFormatType;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.options.ChainedOptionsBuilder;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+public class LabelBenchmarkTest {
+    @Test
+    public void runBenchmark() throws Exception {
+        // run the minimum possible number of iterations
+        ChainedOptionsBuilder options = new OptionsBuilder()
+                .mode(Mode.AverageTime)
+                .forks(1)
+                .result("jmh-report.json")
+                .resultFormat(ResultFormatType.JSON)
+                .operationsPerInvocation(1)
+                .threads(1)
+                .warmupForks(0)
+                .warmupIterations(0)
+                .measurementBatchSize(1)
+                .measurementIterations(1)
+                .timeUnit(TimeUnit.NANOSECONDS)
+                .shouldFailOnError(true)
+                .include(LabelBenchmarkTest.class.getName() + ".*");
+        new Runner(options.build()).run();
+        assertTrue(Files.exists(Paths.get("jmh-report.json")));
+    }
+
+    @JmhBenchmark
+    public static class NodeLabelBenchmark {
+        public static class StateImpl extends JmhBenchmarkState {
+            @Override
+            public void setup() throws Exception {
+                DumbSlave test = new DumbSlave("test", "/tmp/slave", new JNLPLauncher());
+                test.setLabelString("a b c");
+                getJenkins().addNode(test);
+            }
+        }
+
+        @Benchmark
+        public void nodeGetAssignedLabels(StateImpl state, Blackhole blackhole) {
+            blackhole.consume(state.getJenkins().getNode("test").getAssignedLabels());
+        }
+    }
+
+
+    @JmhBenchmark
+    public static class LabelBenchmark {
+        public static class MyState extends JmhBenchmarkState {
+        }
+
+        @Benchmark
+        public void simpleLabel(MyState state, Blackhole blackhole) {
+            blackhole.consume(Label.parse("some-label"));
+        }
+
+        @Benchmark
+        public void complexLabel(MyState state, Blackhole blackhole) {
+            blackhole.consume(Label.parse("label1 && label2"));
+        }
+
+        @Benchmark
+        public void jenkinsGetAssignedLabels(MyState state, Blackhole blackhole) {
+            blackhole.consume(state.getJenkins().getAssignedLabels());
+        }
+    }
+}