Do not rely on timeout when testing smap entry cache (#9265)

Author: jbachorik

dd-java-agent/agent-profiling/profiling-controller-openjdk/src/main/java/com/datadog/profiling/controller/openjdk/events/SmapEntryCache.java

@@ -62,6 +62,11 @@ static class AnnotatedRegion {
     this.smapsPath = smapsPath;
   }
 
+  // @VisibleForTesting
+  void invalidate() {
+    UPDATER.getAndSet(this, System.nanoTime() - (2 * ttl));
+  }
+
   @SuppressWarnings("unchecked")
   public List<SmapEntryEvent> getEvents() {
     long prevTimestamp = lastTimestamp;
@@ -296,9 +301,9 @@ private static Map<Long, String> getAnnotatedRegions() {
     return Collections.emptyMap();
   }
 
-  private static void collectEvents(List<SmapEntryEvent> events) {
+  private void collectEvents(List<SmapEntryEvent> events) {
     try (BufferedReader br =
-        new BufferedReader(new InputStreamReader(Files.newInputStream(SMAPS_PATH)), 64 * 1024)) {
+        new BufferedReader(new InputStreamReader(Files.newInputStream(smapsPath)), 64 * 1024)) {
       readEvents(br, events);
       Map<Long, String> regions = getAnnotatedRegions();
       for (SmapEntryEvent e : events) {

dd-java-agent/agent-profiling/profiling-controller-openjdk/src/test/java/com/datadog/profiling/controller/openjdk/events/SmapEntryCacheTest.java

@@ -18,16 +18,14 @@ void getEvents() throws Exception {
     assumeTrue(OperatingSystem.isLinux());
     // We need at least Java 22 for the annotated regions
     assumeTrue(JavaVirtualMachine.isJavaVersionAtLeast(22));
-    SmapEntryCache smapEntryCache = new SmapEntryCache(Duration.ofMillis(100));
+    SmapEntryCache smapEntryCache =
+        new SmapEntryCache(Duration.ofHours(1)); // set up a really long expiration duration
     List<SmapEntryEvent> events1 = smapEntryCache.getEvents();
     List<SmapEntryEvent> events2 = smapEntryCache.getEvents();
     // the cache is using double buffered event list so we can use identity comparison
     assertSame(events1, events2);
 
-    long ts = System.nanoTime();
-    while (System.nanoTime() - ts < 150_000_000L) { // make sure the cache is expired
-      Thread.sleep(200);
-    }
+    smapEntryCache.invalidate(); // pretend expiring the cache
     events1 = smapEntryCache.getEvents();
     assertNotSame(events1, events2);
   }