Only update a feature's lastUsed time every ten seconds

Author: joegallo

x-pack/plugin/core/src/main/java/org/elasticsearch/license/XPackLicenseState.java

@@ -33,6 +33,12 @@
  */
 public class XPackLicenseState {
 
+    /**
+     * For features that are used at high frequency (e.g. per-search or per-document, etc.), we don't want to bother updating
+     * the 'last used' timestamp more often than some minimum frequency.
+     */
+    private static final long FEATURE_USAGE_MINIMUM_ELAPSED_TIME_MILLIS = TimeValue.timeValueSeconds(10).getMillis();
+
     /** Messages for each feature which are printed when the license expires. */
     static final Map<String, String[]> EXPIRATION_MESSAGES;
     static {
@@ -447,7 +453,13 @@ public String statusDescription() {
 
     void featureUsed(LicensedFeature feature) {
         checkExpiry();
-        usage.put(new FeatureUsage(feature, null), epochMillisProvider.getAsLong());
+        // if at least the minimum elapsed time has passed, then update the most recently used time for this feature
+        final FeatureUsage feat = new FeatureUsage(feature, null);
+        final long now = epochMillisProvider.getAsLong();
+        final Long mostRecent = usage.get(feat);
+        if (mostRecent == null || now - mostRecent >= FEATURE_USAGE_MINIMUM_ELAPSED_TIME_MILLIS) {
+            usage.put(feat, now);
+        }
     }
 
     void enableUsageTracking(LicensedFeature feature, String contextName) {

x-pack/plugin/core/src/test/java/org/elasticsearch/license/XPackLicenseStateTests.java

@@ -239,11 +239,18 @@ public void testLastUsedMomentaryFeature() {
         assertThat(usage.contextName(), nullValue());
         assertThat(lastUsed.get(usage), equalTo(100L));
 
-        currentTime.set(200);
+        // updates to the last used timestamp only happen if at least ten seconds have passed since the last update (*for this feature*)
+        currentTime.set(10099);
         goldFeature.check(licenseState);
         lastUsed = licenseState.getLastUsed();
         assertThat("feature.check updates usage", lastUsed.keySet(), containsInAnyOrder(usage));
-        assertThat(lastUsed.get(usage), equalTo(200L));
+        assertThat(lastUsed.get(usage), equalTo(100L));
+
+        currentTime.set(10100);
+        goldFeature.check(licenseState);
+        lastUsed = licenseState.getLastUsed();
+        assertThat("feature.check updates usage", lastUsed.keySet(), containsInAnyOrder(usage));
+        assertThat(lastUsed.get(usage), equalTo(10100L));
     }
 
     public void testLastUsedMomentaryFeatureWithSameNameDifferentFamily() {
@@ -270,7 +277,7 @@ public void testLastUsedMomentaryFeatureWithSameNameDifferentFamily() {
             )
         );
 
-        currentTime.set(200);
+        currentTime.set(10200);
         featureFamilyB.check(licenseState);
 
         lastUsed = licenseState.getLastUsed();
@@ -283,7 +290,7 @@ public void testLastUsedMomentaryFeatureWithSameNameDifferentFamily() {
             actualFeatures,
             containsInAnyOrder(
                 new FeatureInfoWithTimestamp("familyA", "goldFeature", 100L),
-                new FeatureInfoWithTimestamp("familyB", "goldFeature", 200L)
+                new FeatureInfoWithTimestamp("familyB", "goldFeature", 10200L)
             )
         );
     }