Optimize ObjId2FullSidMap::extractObjectId

src/main/java/com/microsoft/jenkins/azuread/ObjId2FullSidMap.java

@@ -1,14 +1,9 @@
 package com.microsoft.jenkins.azuread;
 
 import java.util.HashMap;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 
 public class ObjId2FullSidMap extends HashMap<String, String> {
 
-    // full sid should be in the form of "<username> (<object_id>)".
-    private static final Pattern FULL_SID_PATTERN = Pattern.compile("(.*) \\((.*)\\)");
-
     public void putFullSid(String fullSid) {
         String objectId = extractObjectId(fullSid);
         if (objectId != null) {
@@ -34,13 +29,25 @@ public String getOrOriginal(String objectId) {
     }
 
     static String extractObjectId(String fullSid) {
-        Matcher matcher = FULL_SID_PATTERN.matcher(fullSid);
-        if (matcher.matches()) {
-            String objectId = matcher.group(2);
-            return objectId;
-        } else {
+        // full sid should be in the form of "<username> (<object_id>)".
+
+        // this code previously used regex: (.*) \((.*)\), which was shown to be a CPU hotspot in certain
+        // Jenkins installations
+
+        if (fullSid.isEmpty()) {
+            return null;
+        }
+        if (fullSid.charAt(fullSid.length() - 1) != ')') {
+            return null;
+        }
+        int openingParenthesesPosition = fullSid.lastIndexOf('(');
+        if (openingParenthesesPosition <= 0) {
+            return null;
+        }
+        if (fullSid.charAt(openingParenthesesPosition - 1) != ' ') {
             return null;
         }
+        return fullSid.substring(openingParenthesesPosition + 1, fullSid.length() - 1);
     }
 
     static String generateFullSid(final String displayName, final String objectId) {

src/test/java/com/microsoft/jenkins/azuread/ObjId2FullSidMapTest.java

@@ -1,8 +1,12 @@
 package com.microsoft.jenkins.azuread;
 
 import org.junit.Assert;
+import org.junit.Ignore;
 import org.junit.Test;
 
+import java.util.ArrayList;
+import java.util.List;
+
 public class ObjId2FullSidMapTest {
 
     public static final String FULL_SID_1 = "Smith@test (00000000-00000000-00000000-00000000)";
@@ -29,4 +33,49 @@ public void testPutAndGet() {
         Assert.assertEquals(FULL_SID_1, map.getOrOriginal(ObjId2FullSidMap.generateFullSid(NAME_1, OBJECT_ID_1)));
         Assert.assertEquals("some string", map.getOrOriginal("some string"));
     }
+
+    @Test
+    public void testExtractObjectId() {
+        Assert.assertNull(ObjId2FullSidMap.extractObjectId(""));
+        Assert.assertNull(ObjId2FullSidMap.extractObjectId("some string"));
+        Assert.assertNull(ObjId2FullSidMap.extractObjectId("email (id) "));
+        Assert.assertNull(ObjId2FullSidMap.extractObjectId("email (id"));
+        Assert.assertNull(ObjId2FullSidMap.extractObjectId("email id)"));
+        Assert.assertNull(ObjId2FullSidMap.extractObjectId("email(id)"));
+        Assert.assertEquals("id", ObjId2FullSidMap.extractObjectId("email (id)"));
+        Assert.assertEquals("", ObjId2FullSidMap.extractObjectId("email ()"));
+        Assert.assertEquals("id", ObjId2FullSidMap.extractObjectId(" (id)"));
+    }
+
+    @Ignore
+    @Test
+    public void testExtractObjectIdPerformance() throws Exception {
+        final int numWarmupIterations = 1_000_000;
+        final int numExperiments = 1000;
+        final int numIterations = 10000;
+
+        final String fullSid = ObjId2FullSidMap.generateFullSid(EMAIL_1, OBJECT_ID_1);
+
+        // warmup
+        for (int i = 0; i < numWarmupIterations; i++) {
+            ObjId2FullSidMap.extractObjectId(fullSid);
+        }
+        // allow async JIT compilation to catch up
+        Thread.sleep(100);
+
+        List<Long> durationsNanos = new ArrayList<>();
+        for (int r = 0; r < numExperiments; r++) {
+            long start = System.nanoTime();
+            for (int i = 0; i < numIterations; i++) {
+                ObjId2FullSidMap.extractObjectId(fullSid);
+            }
+            long durationNanos = (System.nanoTime() - start) / numIterations;
+            durationsNanos.add(durationNanos);
+        }
+        durationsNanos.sort(null);
+        long median = durationsNanos.get(durationsNanos.size() / 2);
+
+        System.out.println("Median duration per call (nanos): " + median);
+    }
+
 }