OAK-11452 : added metric for fullGcGeneration as well

Author: Rishabh Kumar

oak-store-document/src/main/java/org/apache/jackrabbit/oak/plugins/document/FullGCStatsCollector.java

@@ -166,4 +166,15 @@ public interface FullGCStatsCollector {
      * @param maxAge the maximum age to set for the FullGC process
      */
     void maxAge(long maxAge);
+
+    /**
+     * Sets the full garbage collection generation value.
+     * <p>
+     * This method is called to update the current full GC generation being tracked.
+     * The generation value is used to reset the full GC process when incremented,
+     * allowing it to run from the beginning with fresh state.
+     *
+     * @param generation the full GC generation value to set
+     */
+    void fullGCGeneration(long generation);
 }

oak-store-document/src/main/java/org/apache/jackrabbit/oak/plugins/document/FullGCStatsCollectorImpl.java

@@ -68,6 +68,7 @@ class FullGCStatsCollectorImpl implements FullGCStatsCollector {
     static final String PROGRESS_SIZE = "PROGRESS_SIZE";
     static final String EMBEDDED_VERIFICATION_ENABLED = "EMBEDDED_VERIFICATION_ENABLED";
     static final String MAX_AGE = "MAX_AGE";
+    static final String FULL_GC_GENERATION = "FULL_GC_GENERATION";
 
     private final StatisticsProvider provider;
 
@@ -104,6 +105,7 @@ class FullGCStatsCollectorImpl implements FullGCStatsCollector {
     private GaugeStats<Integer> progressSize;
     private GaugeStats<Boolean> embeddedVerificationEnabled;
     private GaugeStats<Long> maxAge;
+    private GaugeStats<Long> fullGCGeneration;
 
     FullGCStatsCollectorImpl(StatisticsProvider provider) {
         this(provider, false);
@@ -245,6 +247,11 @@ public void maxAge(long maxAge) {
         this.maxAge = gauge(provider, MAX_AGE, () -> maxAge);
     }
 
+    @Override
+    public void fullGCGeneration(long generation) {
+        this.fullGCGeneration = gauge(provider, FULL_GC_GENERATION, () -> generation);
+    }
+
     @Override
     public String toString() {
         return "FullGCStatsCollectorImpl{" +
@@ -255,6 +262,7 @@ public String toString() {
                 ", progressSize=" + getValue(progressSize, "0") +
                 ", embeddedVerificationEnabled=" + getValue(embeddedVerificationEnabled, "false") +
                 ", maxAge=" + getValue(maxAge, "0") +
+                ", fullGCGeneration=" + getValue(fullGCGeneration, "0") +
                 ", readDoc=" + readDoc.getCount() +
                 ", candidateRevisions=" + mapToString(candidateRevisions) +
                 ", candidateInternalRevisions=" + mapToString(candidateInternalRevisions) +

oak-store-document/src/main/java/org/apache/jackrabbit/oak/plugins/document/VersionGarbageCollector.java

@@ -167,6 +167,7 @@ public class VersionGarbageCollector {
     static final String SETTINGS_COLLECTION_FULL_GC_DRY_RUN_DOCUMENT_ID_PROP = "fullGCDryRunId";
 
     private static FullGCMode fullGcMode = GAP_ORPHANS_EMPTYPROPS;
+    private final long fullGcGen;
 
     static FullGCMode getFullGcMode() {
         return fullGcMode;
@@ -306,7 +307,7 @@ private void persistFullGcGen(long fullGcGeneration) {
         this.options = new VersionGCOptions();
 
         setFullGcMode(fullGCMode);
-        long fullGcGen = fullGCEnabled ? resetFullGcIfGenChange(fullGcGeneration) : fullGcGeneration;
+        this.fullGcGen = fullGCEnabled ? resetFullGcIfGenChange(fullGcGeneration) : fullGcGeneration;
         AUDIT_LOG.info("<init> VersionGarbageCollector created with fullGcMode: {}, maxFullGcAgeInMillis: {}, batchSize: {}, progressSize: {}, delayFactor: {}, fullGcGeneration: {}",
                 fullGcMode, fullGcMaxAgeInMillis, fullGCBatchSize, fullGCProgressSize, fullGCDelayFactor, fullGcGen);
     }
@@ -345,6 +346,7 @@ public void setStatisticsProvider(StatisticsProvider provider, boolean pushMetri
         this.fullGCStats.progressSize(fullGCProgressSize);
         this.fullGCStats.maxAge(fullGcMaxAgeInMillis);
         this.fullGCStats.verificationEnabled(this.embeddedVerification);
+        this.fullGCStats.fullGCGeneration(this.fullGcGen);
     }
 
     public void setFullGCMetricsExporter(FullGCMetricsExporter exporter) {

oak-store-document/src/test/java/org/apache/jackrabbit/oak/plugins/document/FullGCStatsCollectorImplTest.java

@@ -52,6 +52,7 @@
 import static org.apache.jackrabbit.oak.plugins.document.FullGCStatsCollectorImpl.ENABLED;
 import static org.apache.jackrabbit.oak.plugins.document.FullGCStatsCollectorImpl.FULL_GC;
 import static org.apache.jackrabbit.oak.plugins.document.FullGCStatsCollectorImpl.FULL_GC_ACTIVE_TIMER;
+import static org.apache.jackrabbit.oak.plugins.document.FullGCStatsCollectorImpl.FULL_GC_GENERATION;
 import static org.apache.jackrabbit.oak.plugins.document.FullGCStatsCollectorImpl.FULL_GC_TIMER;
 import static org.apache.jackrabbit.oak.plugins.document.FullGCStatsCollectorImpl.FAILURE_COUNTER;
 import static org.apache.jackrabbit.oak.plugins.document.FullGCStatsCollectorImpl.MAX_AGE;
@@ -273,6 +274,20 @@ public void getMaxAge() throws IllegalAccessException {
         assertEquals(86400L, (long)updated.getValue());
     }
 
+    @Test
+    @SuppressWarnings("unchecked")
+    public void getFullGCGeneration() throws IllegalAccessException {
+        stats.fullGCGeneration(3);
+        final Gauge<Long> gauge = getGauge(FULL_GC_GENERATION);
+        assertEquals(3L, (long)gauge.getValue());
+        assertEquals(3L, (long)((GaugeStats<Long>) readField(stats, "fullGCGeneration", true)).getValue());
+
+        // update the value
+        stats.fullGCGeneration(5);
+        final Gauge<Long> updated = getGauge(FULL_GC_GENERATION);
+        assertEquals(3L, (long)updated.getValue());
+    }
+
     @Test
     public void getFullGcOsgiConfigs() {
         stats.maxAge(86400);
@@ -282,6 +297,7 @@ public void getFullGcOsgiConfigs() {
         stats.batchSize(500);
         stats.delayFactor(5.0);
         stats.mode(4);
+        stats.fullGCGeneration(2);
 
         // update the value
         assertTrue(stats.toString().contains("maxAge=86400"));
@@ -291,6 +307,7 @@ public void getFullGcOsgiConfigs() {
         assertTrue(stats.toString().contains("batchSize=500"));
         assertTrue(stats.toString().contains("delayFactor=5.0"));
         assertTrue(stats.toString().contains("mode=4"));
+        assertTrue(stats.toString().contains("fullGCGeneration=2"));
     }
 
     @Test