extend stats and error codes

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>com.tidesdb</groupId>
     <artifactId>tidesdb-java</artifactId>
-    <version>0.8.2</version>
+    <version>0.8.3</version>
     <packaging>jar</packaging>
 
     <name>TidesDB Java</name>

src/main/c/com_tidesdb_TidesDB.c

@@ -1423,10 +1423,12 @@ JNIEXPORT jobject JNICALL Java_com_tidesdb_TidesDB_nativeGetDbStats(JNIEnv *env,
     /* Constructor signature:
        int, long, long, long, int, int, long, int, int, long, int, long, long, long, long,
        boolean, long, int, boolean, int, long,
-       boolean, String, long, long, int, long, long, long, long, boolean */
+       boolean, String, long, long, int, long, long, long, long, boolean,
+       long (primaryEpoch), long (seenEpoch),
+       long, long, long, long, long, long, long, long */
     jmethodID constructor = (*env)->GetMethodID(
         env, dbStatsClass, "<init>",
-        "(IJJJIIJIIJIJJJJZJIZIJZLjava/lang/String;JJIJJJJZJJJJJJJJ)V");
+        "(IJJJIIJIIJIJJJJZJIZIJZLjava/lang/String;JJIJJJJZJJJJJJJJJJ)V");
 
     jstring connectorStr = NULL;
     if (db_stats.object_store_connector != NULL)
@@ -1466,6 +1468,8 @@ JNIEXPORT jobject JNICALL Java_com_tidesdb_TidesDB_nativeGetDbStats(JNIEnv *env,
                              (jlong)db_stats.total_uploads,
                              (jlong)db_stats.total_upload_failures,
                              db_stats.replica_mode != 0,
+                             (jlong)db_stats.primary_epoch,
+                             (jlong)db_stats.seen_epoch,
                              (jlong)db_stats.uwal_bytes_written,
                              (jlong)db_stats.wal_bytes_written,
                              (jlong)db_stats.flush_bytes_written,

src/main/java/com/tidesdb/DbStats.java

@@ -54,6 +54,8 @@ public class DbStats {
     private final long totalUploads;
     private final long totalUploadFailures;
     private final boolean replicaMode;
+    private final long primaryEpoch;
+    private final long seenEpoch;
     private final long uwalBytesWritten;
     private final long walBytesWritten;
     private final long flushBytesWritten;
@@ -75,6 +77,7 @@ public DbStats(int numColumnFamilies, long totalMemory, long availableMemory,
                    long localCacheBytesUsed, long localCacheBytesMax, int localCacheNumFiles,
                    long lastUploadedGeneration, long uploadQueueDepth,
                    long totalUploads, long totalUploadFailures, boolean replicaMode,
+                   long primaryEpoch, long seenEpoch,
                    long uwalBytesWritten, long walBytesWritten, long flushBytesWritten,
                    long compactionBytesWritten, long compactionBytesRead, long userBytesWritten,
                    long flushCount, long compactionCount) {
@@ -109,6 +112,8 @@ public DbStats(int numColumnFamilies, long totalMemory, long availableMemory,
         this.totalUploads = totalUploads;
         this.totalUploadFailures = totalUploadFailures;
         this.replicaMode = replicaMode;
+        this.primaryEpoch = primaryEpoch;
+        this.seenEpoch = seenEpoch;
         this.uwalBytesWritten = uwalBytesWritten;
         this.walBytesWritten = walBytesWritten;
         this.flushBytesWritten = flushBytesWritten;
@@ -243,6 +248,27 @@ public boolean isReplicaMode() {
         return replicaMode;
     }
 
+    /**
+     * Gets the lease epoch this primary currently holds (object-store single-writer fencing).
+     * Returns 0 when this node is not a primary or holds no lease. A promotion that takes
+     * effect bumps this value.
+     *
+     * @return the current primary lease epoch, or 0 if not a primary
+     */
+    public long getPrimaryEpoch() {
+        return primaryEpoch;
+    }
+
+    /**
+     * Gets the highest lease epoch this node has observed (object-store single-writer fencing).
+     * A fenced primary sees {@link #isReplicaMode()} flip back to true once a newer epoch is seen.
+     *
+     * @return the highest observed lease epoch
+     */
+    public long getSeenEpoch() {
+        return seenEpoch;
+    }
+
     /**
      * Gets the framed bytes appended to the shared unified WAL (lifetime since open).
      * Returns 0 when unified memtable mode is off.
@@ -355,6 +381,8 @@ public String toString() {
             ", totalUploads=" + totalUploads +
             ", totalUploadFailures=" + totalUploadFailures +
             ", replicaMode=" + replicaMode +
+            ", primaryEpoch=" + primaryEpoch +
+            ", seenEpoch=" + seenEpoch +
             ", uwalBytesWritten=" + uwalBytesWritten +
             ", walBytesWritten=" + walBytesWritten +
             ", flushBytesWritten=" + flushBytesWritten +

src/test/java/com/tidesdb/TidesDBTest.java

@@ -1480,11 +1480,17 @@ void testDbStatsUnifiedFields() throws TidesDBException {
             assertTrue(dbStats.getTotalUploads() >= 0);
             assertTrue(dbStats.getTotalUploadFailures() >= 0);
 
+            // Single-writer fencing epochs default to 0 outside object-store primary mode
+            assertEquals(0, dbStats.getPrimaryEpoch());
+            assertTrue(dbStats.getSeenEpoch() >= 0);
+
             // Verify toString includes new fields
             String str = dbStats.toString();
             assertTrue(str.contains("unifiedMemtableEnabled="));
             assertTrue(str.contains("objectStoreEnabled="));
             assertTrue(str.contains("replicaMode="));
+            assertTrue(str.contains("primaryEpoch="));
+            assertTrue(str.contains("seenEpoch="));
         }
     }