zeroshade commented on code in PR #4441:
URL: https://github.com/apache/arrow-adbc/pull/4441#discussion_r3476051156
##########
java/driver/jni/src/main/java/org/apache/arrow/adbc/driver/jni/JniDatabase.java:
##########
@@ -21,27 +21,37 @@
import org.apache.arrow.adbc.core.AdbcDatabase;
import org.apache.arrow.adbc.core.AdbcException;
import org.apache.arrow.adbc.core.TypedKey;
+import org.apache.arrow.adbc.driver.jni.impl.ChildReferences;
+import org.apache.arrow.adbc.driver.jni.impl.HasChildReferences;
import org.apache.arrow.adbc.driver.jni.impl.JniLoader;
import org.apache.arrow.adbc.driver.jni.impl.NativeDatabaseHandle;
import org.apache.arrow.memory.BufferAllocator;
+import org.apache.arrow.util.AutoCloseables;
-public class JniDatabase implements AdbcDatabase {
+public class JniDatabase implements AdbcDatabase, HasChildReferences {
private final BufferAllocator allocator;
private final NativeDatabaseHandle handle;
+ private final ChildReferences childReferences;
public JniDatabase(BufferAllocator allocator, NativeDatabaseHandle handle) {
this.allocator = allocator;
this.handle = handle;
+ this.childReferences = new ChildReferences();
+ }
+
+ @Override
+ public ChildReferences getChildReferences() {
+ return childReferences;
}
@Override
public AdbcConnection connect() throws AdbcException {
- return new JniConnection(allocator,
JniLoader.INSTANCE.openConnection(handle));
+ return new JniConnection(allocator, this,
JniLoader.INSTANCE.openConnection(handle));
}
@Override
- public void close() {
- handle.close();
+ public void close() throws Exception {
+ AutoCloseables.close(childReferences, handle);
}
Review Comment:
`JniConnection.close()` and `JniStatement.close()` wrap failures with
`AdbcException.internal(...)` but here we're just declaring `throws exception`
and letting it propagate. Any reason for the difference? Should we wrap here
also for consistency?
##########
java/driver/jni/src/test/java/org/apache/arrow/adbc/driver/jni/impl/ImplTest.java:
##########
@@ -119,4 +121,43 @@ void offsetSlow() throws Exception {
assertThat(buf.remaining()).isEqualTo(3);
assertThat(JniLoader.INSTANCE.internalGetByteBuffer(buf)).isEqualTo(new
byte[] {1, 2, 3});
}
+
+ @Test
+ void childReferencesCloses() throws Exception {
+ ChildReferences refs = new ChildReferences();
+ var flag = new Closeable();
+ refs.addReference(flag);
+ refs.close();
+ assertThat(flag.closed).isTrue();
+ }
+
+ @Test
+ void childReferencesIsWeak() throws Exception {
+ ChildReferences refs = new ChildReferences();
+ var flag = new Closeable();
+ refs.addReference(flag);
+ var ref = new WeakReference<>(flag);
+ //noinspection UnusedAssignment
+ flag = null;
+
+ for (int i = 0; i < 50; i++) {
+ System.gc();
+ if (ref.get() == null) {
+ break;
+ }
+ Thread.sleep(100);
+ }
+
+ assertThat(ref.get()).isNull();
+ refs.close();
+ }
+
+ static final class Closeable implements AutoCloseable {
Review Comment:
this shadows the `java.io.Closeable` import which ends up being unused I
think. Should we drop the import?
##########
java/driver/jni/src/main/java/org/apache/arrow/adbc/driver/jni/impl/ChildReferences.java:
##########
@@ -0,0 +1,55 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.arrow.adbc.driver.jni.impl;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Set;
+import java.util.WeakHashMap;
+import org.apache.arrow.util.AutoCloseables;
+
+/**
+ * Track child resources for the ADBC FFI.
+ *
+ * <p>You are supposed to close statements before closing the connection
(etc.). This class helps
+ * track those references to prevent misuse at runtime.
+ */
+public final class ChildReferences implements AutoCloseable {
+ private final Set<AutoCloseable> openReferences;
+
+ public ChildReferences() {
+ this.openReferences = Collections.newSetFromMap(new WeakHashMap<>());
+ }
Review Comment:
Should we add a one-line comment just to point out that `WeakHashMap` isn't
thread-safe so that we don't overlook that in any future changes?
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