extend api with transaction reset capabilities, bump minor, extend tests

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>com.tidesdb</groupId>
     <artifactId>tidesdb-java</artifactId>
-    <version>0.5.0</version>
+    <version>0.6.0</version>
     <packaging>jar</packaging>
 
     <name>TidesDB Java</name>

src/main/c/com_tidesdb_TidesDB.c

@@ -724,6 +724,18 @@ JNIEXPORT jlong JNICALL Java_com_tidesdb_Transaction_nativeNewIterator(JNIEnv *e
     return (jlong)(uintptr_t)iter;
 }
 
+JNIEXPORT void JNICALL Java_com_tidesdb_Transaction_nativeReset(JNIEnv *env, jclass cls,
+                                                                jlong handle, jint isolationLevel)
+{
+    tidesdb_txn_t *txn = (tidesdb_txn_t *)(uintptr_t)handle;
+    int result = tidesdb_txn_reset(txn, (tidesdb_isolation_level_t)isolationLevel);
+
+    if (result != TDB_SUCCESS)
+    {
+        throwTidesDBException(env, result, getErrorMessage(result));
+    }
+}
+
 JNIEXPORT void JNICALL Java_com_tidesdb_Transaction_nativeFree(JNIEnv *env, jclass cls,
                                                                jlong handle)
 {

src/main/java/com/tidesdb/Transaction.java

@@ -187,6 +187,21 @@ public TidesDBIterator newIterator(ColumnFamily cf) throws TidesDBException {
         return new TidesDBIterator(iterHandle);
     }
 
+    /**
+     * Resets a committed or aborted transaction for reuse with a new isolation level.
+     * This avoids the overhead of freeing and reallocating transaction resources in hot loops.
+     *
+     * @param isolation the new isolation level for the reset transaction
+     * @throws TidesDBException if the reset fails (e.g., transaction is still active)
+     */
+    public void reset(IsolationLevel isolation) throws TidesDBException {
+        checkNotFreed();
+        if (isolation == null) {
+            throw new IllegalArgumentException("Isolation level cannot be null");
+        }
+        nativeReset(nativeHandle, isolation.getValue());
+    }
+
     /**
      * Frees the transaction resources.
      */
@@ -225,5 +240,6 @@ long getNativeHandle() {
     private static native void nativeRollbackToSavepoint(long handle, String name) throws TidesDBException;
     private static native void nativeReleaseSavepoint(long handle, String name) throws TidesDBException;
     private static native long nativeNewIterator(long handle, long cfHandle) throws TidesDBException;
+    private static native void nativeReset(long handle, int isolationLevel) throws TidesDBException;
     private static native void nativeFree(long handle);
 }

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

@@ -654,4 +654,122 @@ void testTransactionPutGetDeleteBadKey() throws TidesDBException {
             });
         }
     }
+
+    @Test
+    @Order(17)
+    void testTransactionReset() throws TidesDBException {
+        Config config = Config.builder(tempDir.resolve("testdb17").toString())
+            .numFlushThreads(2)
+            .numCompactionThreads(2)
+            .logLevel(LogLevel.INFO)
+            .blockCacheSize(64 * 1024 * 1024)
+            .maxOpenSSTables(256)
+            .build();
+
+        try (TidesDB db = TidesDB.open(config)) {
+            ColumnFamilyConfig cfConfig = ColumnFamilyConfig.defaultConfig();
+            db.createColumnFamily("test_cf", cfConfig);
+
+            ColumnFamily cf = db.getColumnFamily("test_cf");
+
+            // Begin transaction and do first batch of work
+            Transaction txn = db.beginTransaction();
+            txn.put(cf, "key1".getBytes(), "value1".getBytes());
+            txn.commit();
+
+            // Reset instead of free + begin
+            txn.reset(IsolationLevel.READ_COMMITTED);
+
+            // Second batch of work using the same transaction
+            txn.put(cf, "key2".getBytes(), "value2".getBytes());
+            txn.commit();
+
+            // Free once when done
+            txn.free();
+
+            // Verify both keys exist
+            try (Transaction readTxn = db.beginTransaction()) {
+                byte[] result1 = readTxn.get(cf, "key1".getBytes());
+                assertNotNull(result1);
+                assertArrayEquals("value1".getBytes(), result1);
+
+                byte[] result2 = readTxn.get(cf, "key2".getBytes());
+                assertNotNull(result2);
+                assertArrayEquals("value2".getBytes(), result2);
+            }
+        }
+    }
+
+    @Test
+    @Order(18)
+    void testTransactionResetWithDifferentIsolation() throws TidesDBException {
+        Config config = Config.builder(tempDir.resolve("testdb18").toString())
+            .numFlushThreads(2)
+            .numCompactionThreads(2)
+            .logLevel(LogLevel.INFO)
+            .blockCacheSize(64 * 1024 * 1024)
+            .maxOpenSSTables(256)
+            .build();
+
+        try (TidesDB db = TidesDB.open(config)) {
+            ColumnFamilyConfig cfConfig = ColumnFamilyConfig.defaultConfig();
+            db.createColumnFamily("test_cf", cfConfig);
+
+            ColumnFamily cf = db.getColumnFamily("test_cf");
+
+            // Begin with READ_COMMITTED
+            Transaction txn = db.beginTransaction(IsolationLevel.READ_COMMITTED);
+            txn.put(cf, "key1".getBytes(), "value1".getBytes());
+            txn.commit();
+
+            // Reset with different isolation level (REPEATABLE_READ)
+            txn.reset(IsolationLevel.REPEATABLE_READ);
+            txn.put(cf, "key2".getBytes(), "value2".getBytes());
+            txn.commit();
+
+            // Reset again with SERIALIZABLE
+            txn.reset(IsolationLevel.SERIALIZABLE);
+            txn.put(cf, "key3".getBytes(), "value3".getBytes());
+            txn.commit();
+
+            txn.free();
+
+            // Verify all keys exist
+            try (Transaction readTxn = db.beginTransaction()) {
+                for (int i = 1; i <= 3; i++) {
+                    byte[] result = readTxn.get(cf, ("key" + i).getBytes());
+                    assertNotNull(result);
+                    assertArrayEquals(("value" + i).getBytes(), result);
+                }
+            }
+        }
+    }
+
+    @Test
+    @Order(19)
+    void testTransactionResetNullIsolation() throws TidesDBException {
+        Config config = Config.builder(tempDir.resolve("testdb19").toString())
+            .numFlushThreads(2)
+            .numCompactionThreads(2)
+            .logLevel(LogLevel.INFO)
+            .blockCacheSize(64 * 1024 * 1024)
+            .maxOpenSSTables(256)
+            .build();
+
+        try (TidesDB db = TidesDB.open(config)) {
+            ColumnFamilyConfig cfConfig = ColumnFamilyConfig.defaultConfig();
+            db.createColumnFamily("test_cf", cfConfig);
+
+            ColumnFamily cf = db.getColumnFamily("test_cf");
+
+            Transaction txn = db.beginTransaction();
+            txn.put(cf, "key1".getBytes(), "value1".getBytes());
+            txn.commit();
+
+            // Null isolation level should throw IllegalArgumentException
+            assertThrows(IllegalArgumentException.class, () -> txn.reset(null));
+
+            txn.free();
+        }
+    }
 }