[CONJ-1124] ensure not having OOM when setting huge fetch size

src/main/java/org/mariadb/jdbc/client/result/StreamingResult.java

@@ -38,9 +38,10 @@
  * execute the next query. This can lead to OutOfMemoryError if not handled.
  */
 public class StreamingResult extends Result {
-
+  private static final int MAX_FETCH_SIZE = 16384;
   private final ReentrantLock lock;
   private int dataFetchTime;
+  private int requestedFetchSize;
 
   /**
    * Constructor
@@ -87,8 +88,8 @@ public StreamingResult(
         fetchSize);
     this.lock = lock;
     this.dataFetchTime = 0;
-    this.data = new byte[Math.max(fetchSize, 10)][];
-
+    this.requestedFetchSize = fetchSize;
+    this.data = new byte[Math.min(MAX_FETCH_SIZE, Math.max(fetchSize, 10))][];
     addStreamingValue();
   }
 
@@ -384,16 +385,22 @@ public boolean previous() throws SQLException {
   @Override
   public int getFetchSize() throws SQLException {
     checkClose();
-    return super.getFetchSize();
+    return requestedFetchSize;
   }
 
   @Override
   public void setFetchSize(int fetchSize) throws SQLException {
-    super.setFetchSize(fetchSize);
+    // ensure huge fetch size won't create OOM because of array size exceeding VM limit
+    // when using fetchSize with value different from 0, value must be small because goal is to
+    // ensure not having too
+    // much data in memory
+    // so fetch size when explicitly different from 0 is limited to 16K rows
+    super.setFetchSize(Math.min(MAX_FETCH_SIZE, fetchSize));
+    this.requestedFetchSize = fetchSize;
     checkClose();
     if (fetchSize == 0) {
       // fetch all results
-      while (!loaded) {
+      while (!this.loaded) {
         addStreamingValue();
       }
     }

src/test/java/org/mariadb/jdbc/integration/StatementTest.java

@@ -482,13 +482,30 @@ public void testNegativeFetchSize() throws SQLException {
       stmt.executeBatch();
       try (ResultSet rs = stmt.getGeneratedKeys()) {
         assertThrowsContains(
-            SQLSyntaxErrorException.class,
-            () -> rs.setFetchSize(-2),
-            "invalid fetch size -2");
+            SQLSyntaxErrorException.class, () -> rs.setFetchSize(-2), "invalid fetch size -2");
       }
     }
   }
 
+  @Test
+  public void testHugeFetchSize() throws SQLException {
+    Assumptions.assumeTrue(isMariaDBServer());
+    try (PreparedStatement stmt =
+        sharedConn.prepareStatement(
+            "SELECT seq from seq_1_to_20000",
+            ResultSet.TYPE_SCROLL_SENSITIVE,
+            ResultSet.CONCUR_READ_ONLY,
+            ResultSet.CLOSE_CURSORS_AT_COMMIT)) {
+      stmt.setFetchSize(Integer.MAX_VALUE);
+      int i = 0;
+      try (ResultSet rs = stmt.executeQuery()) {
+        rs.setFetchSize(Integer.MAX_VALUE);
+        while (rs.next()) i++;
+      }
+      assertEquals(20000, i);
+    }
+  }
+
   @Test
   public void largeMaxRows() throws SQLException {
     Statement stmt = sharedConn.createStatement();