add rng-seed flag to set random seed

DataDog · Nov 10, 2023 · 5b0a2f1 · 5b0a2f1
1 parent b6ec32e
commit 5b0a2f1
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Showing 3 changed files with 17 additions and 4 deletions.
diff --git a/tools/misbehaving-jmx-server/src/main/java/org/datadog/misbehavingjmxserver/App.java b/tools/misbehaving-jmx-server/src/main/java/org/datadog/misbehavingjmxserver/App.java
@@ -45,6 +45,9 @@ class AppConfig {
     @Parameter(names = {"--rmi-host", "-rh"})
     public String rmiHost = Defaults.JMXSERVER_RMI_INTERFACE;
 
+    @Parameter(names = {"--rng-seed", "-rs"})
+    public long rngSeed = 1042849;
+
     // Can only be set via env var
     public int controlPort = Defaults.JMXSERVER_CONTROL_PORT;
 
@@ -71,6 +74,10 @@ public void overrideFromEnv() {
         if (val != null) {
             this.config_path = val;
         }
+        val = System.getenv("RNG_SEED");
+        if (val != null) {
+            this.rngSeed = Long.parseLong(val);
+        }
     }
 
     public void readConfigFileOnDisk () {
@@ -168,7 +175,7 @@ public static void main( String[] args ) throws IOException, MalformedObjectName
         MetricDAO mDao = new MetricDAO();
         mDao.runTickLoop();
 
-        BeanManager bm = new BeanManager(mbs, mDao);
+        BeanManager bm = new BeanManager(mbs, mDao, config.rngSeed);
 
         // Set up test domain
         BeanSpec testDomainBeanSpec = new BeanSpec(1, 1, 0, 0);

diff --git a/tools/misbehaving-jmx-server/src/main/java/org/datadog/misbehavingjmxserver/BeanManager.java b/tools/misbehaving-jmx-server/src/main/java/org/datadog/misbehavingjmxserver/BeanManager.java
@@ -13,6 +13,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.Random;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.Executors;
@@ -25,13 +26,15 @@ public class BeanManager {
     private final MBeanServer mBeanServer;
     private final Map<String, List<DynamicMBeanMetrics>> registeredBeans;
     private final MetricDAO mDao;
+    private final RandomIdentifier idGen;
     static final long ATTRIBUTE_REFRESH_INTERVAL = 10;
     private final ScheduledExecutorService executor;
 
-    public BeanManager(MBeanServer mBeanServer, MetricDAO mDao) {
+    public BeanManager(MBeanServer mBeanServer, MetricDAO mDao, long rngSeed) {
         this.mBeanServer = mBeanServer;
         this.registeredBeans = new HashMap<>();
         this.mDao = mDao;
+        this.idGen = new RandomIdentifier(rngSeed);
         this.executor = Executors.newSingleThreadScheduledExecutor();
         runAttributeUpdateLoop();
     }
@@ -60,7 +63,6 @@ public void clearDomainBeans(String beanDomain){
 
     public void setMBeanState(String beanDomain, BeanSpec domainSpec) {
         clearDomainBeans(beanDomain);
-        RandomIdentifier idGen = new RandomIdentifier();
         ArrayList<DynamicMBeanMetrics> beansList = new ArrayList<DynamicMBeanMetrics>();
 
         for (int i = 0; i < domainSpec.beanCount; i++) {

diff --git a/...sbehaving-jmx-server/src/main/java/org/datadog/misbehavingjmxserver/RandomIdentifier.java b/...sbehaving-jmx-server/src/main/java/org/datadog/misbehavingjmxserver/RandomIdentifier.java
@@ -14,7 +14,11 @@ public class RandomIdentifier {
     private static final List<String> VOWELS = List.of("a", "e", "i", "o", "u");
     private static final List<String> CONSONANTS = List.of("b", "c", "d", "f", "g", "h", "j", "k", "l", "m", "n", "p", "q", "r", "s", "t", "v", "w", "x", "y", "z");
     private static final List<String> RARE_SEQUENCES = Arrays.asList("qz", "qp", "qj", "qw", "qx", "qr", "qt", "qy", "qs", "qd", "qf", "qg", "qh", "qk", "ql", "qc", "qv", "qb", "qn", "qm", "wz", "wq", "wk", "wp", "wj", "wy", "wh", "wl");
-    private static final Random RANDOM = new Random();
+    private final Random RANDOM;
+
+    public RandomIdentifier(long seed) {
+        this.RANDOM = new Random(seed);
+    }
 
     private String generateWord(int minLength, int maxLength) {
         int wordLength = minLength + RANDOM.nextInt(maxLength - minLength + 1);