feat(java/adbc/drivermgr): support loading AdbcDrivers from the Servi…

…ceLoader

Support loading AdbcDriver classes using the ServiceLoader
instead of require explicit registration.

An AdbcDriver can add a file in META-INF/services named
org.apache.arrow.adbc.core.AdbcDriver that contains the
fully-qualified class names of any AdbcDriver implementations.

This change requires that AdbcDriver implementations provide
a public, no argument constructor.

Change memory management such that the BufferAllocator is
supplied to the AdbcDatabase instance rather than held in
the AdbcDriver.

Update the FlightSQL and JDBC drivers to match above changes.

java/core/src/main/java/org/apache/arrow/adbc/core/AdbcDriverFactory.java

@@ -0,0 +1,31 @@
+/*
+ * 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.core;
+
+import org.apache.arrow.memory.BufferAllocator;
+
+/** A factory for instantiating new AdbcDrivers. */
+public interface AdbcDriverFactory {
+  /**
+   * Gets a new AdbcDriver.
+   *
+   * @param allocator The allocator to associate with the AdbcDriver.
+   * @return a new AdbcDriver.
+   */
+  AdbcDriver getDriver(BufferAllocator allocator);
+}

java/driver-manager/pom.xml

@@ -39,5 +39,11 @@
       <artifactId>junit-jupiter</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.apache.arrow</groupId>
+      <artifactId>arrow-memory-unsafe</artifactId>
+      <version>${dep.arrow.version}</version>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 </project>

java/driver-manager/src/main/java/org/apache/arrow/adbc/drivermanager/AdbcDriverManager.java

@@ -18,64 +18,78 @@
 package org.apache.arrow.adbc.drivermanager;
 
 import java.util.Map;
+import java.util.ServiceLoader;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 import java.util.function.Function;
 import org.apache.arrow.adbc.core.AdbcDatabase;
 import org.apache.arrow.adbc.core.AdbcDriver;
+import org.apache.arrow.adbc.core.AdbcDriverFactory;
 import org.apache.arrow.adbc.core.AdbcException;
 import org.apache.arrow.adbc.core.AdbcStatusCode;
 import org.apache.arrow.memory.BufferAllocator;
 
-/**
- * Load an ADBC driver based on name.
- *
- * <p>This class is EXPERIMENTAL. It will be rewritten before 1.0.0 (see <a
- * href="https://github.com/apache/arrow-adbc/issues/48">issue #48</a>).
- */
+/** Instantiate connections to ABDC databases generically based on driver name. */
 public final class AdbcDriverManager {
   private static final AdbcDriverManager INSTANCE = new AdbcDriverManager();
 
-  private final ConcurrentMap<String, Function<BufferAllocator, AdbcDriver>> drivers;
+  private final ConcurrentMap<String, Function<BufferAllocator, AdbcDriver>> driverFactoryFunctions;
 
-  public AdbcDriverManager() {
-    drivers = new ConcurrentHashMap<>();
+  private AdbcDriverManager() {
+    driverFactoryFunctions = new ConcurrentHashMap<>();
+    final ServiceLoader<AdbcDriverFactory> serviceLoader =
+        ServiceLoader.load(AdbcDriverFactory.class);
+    serviceLoader.forEach(
+        driverFactory ->
+            driverFactoryFunctions.putIfAbsent(
+                driverFactory.getClass().getCanonicalName(), driverFactory::getDriver));
   }
 
   /**
    * Connect to a database.
    *
-   * @param driverName The driver to use.
+   * @param driverFactoryName The driver to use.
    * @param allocator The allocator to use.
    * @param parameters Parameters for the driver.
    * @return The AdbcDatabase instance.
    * @throws AdbcException if the driver was not found or if connection fails.
    */
   public AdbcDatabase connect(
-      String driverName, BufferAllocator allocator, Map<String, Object> parameters)
+      String driverFactoryName, BufferAllocator allocator, Map<String, Object> parameters)
       throws AdbcException {
-    final Function<BufferAllocator, AdbcDriver> driver = lookupDriver(driverName);
-    if (driver == null) {
+    final Function<BufferAllocator, AdbcDriver> driverFactoryFunction = lookupDriver(driverFactoryName);
+    if (driverFactoryFunction == null) {
       throw new AdbcException(
-          "Driver not found for '" + driverName + "'", null, AdbcStatusCode.NOT_FOUND, null, 0);
+          "AdbcDriverFactory not found for '" + driverFactoryName + "'", null, AdbcStatusCode.NOT_FOUND, null, 0);
     }
-    return driver.apply(allocator).open(parameters);
+
+    return driverFactoryFunction.apply(allocator).open(parameters);
   }
 
   /**
    * Lookup a registered driver.
    *
-   * @param driverName The driver to lookup.
-   * @return The driver instance, or null if not found.
+   * @param driverFactoryName The driver factory function to lookup.
+   *                          This is usually the fully-qualified class name of an
+   *                          AdbcDriverFactory class.
+   * @return A function to construct an AdbcDriver from a BufferAllocator, or null
+   *    if not found.
    */
-  public Function<BufferAllocator, AdbcDriver> lookupDriver(String driverName) {
-    return drivers.get(driverName);
+  Function<BufferAllocator, AdbcDriver> lookupDriver(String driverFactoryName) {
+    return driverFactoryFunctions.get(driverName);
   }
 
-  public void registerDriver(String driverName, Function<BufferAllocator, AdbcDriver> driver) {
-    if (drivers.putIfAbsent(driverName, driver) != null) {
+  /**
+   * Register a driver manually.
+   *
+   * @param driverFactoryName The name of the driver to associate with the construction function.
+   * @param driverFactory The function to use to instantiate the driver.
+   */
+  public void registerDriver(
+      String driverFactoryName, Function<BufferAllocator, AdbcDriver> driverFactory) {
+    if (driverFactoryFunctions.putIfAbsent(driverFactoryName, driverFactory) != null) {
       throw new IllegalStateException(
-          "[DriverManager] Driver already registered for '" + driverName + "'");
+          "[DriverManager] Driver factory already registered for '" + driverFactoryName + "'");
     }
   }
 

java/driver-manager/src/test/java/org/apache/arrow/adbc/drivermanager/AdbcDriverManagerTest.java

@@ -0,0 +1,42 @@
+/*
+ * 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.drivermanager;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.function.Function;
+import org.apache.arrow.adbc.core.AdbcDriver;
+import org.apache.arrow.adbc.test.TestDriver;
+import org.apache.arrow.adbc.test.TestDriverFactory;
+import org.apache.arrow.memory.BufferAllocator;
+import org.apache.arrow.memory.RootAllocator;
+import org.junit.jupiter.api.Test;
+
+/** Test cases for {@link AdbcDriverManager}. */
+public class AdbcDriverManagerTest {
+  @Test
+  public void testDriverFromServiceLoader() {
+    final Function<BufferAllocator, AdbcDriver> driverFactoryFunction =
+        AdbcDriverManager.getInstance().lookupDriver(TestDriverFactory.class.getCanonicalName());
+
+    try (BufferAllocator allocator = new RootAllocator()) {
+      final AdbcDriver driverInstance = driverFactoryFunction.apply(allocator);
+      assertThat(driverInstance.getClass()).isEqualTo(TestDriver.class);
+    }
+  }
+}

java/driver-manager/src/test/java/org/apache/arrow/adbc/test/TestDriver.java

@@ -0,0 +1,32 @@
+/*
+ * 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.test;
+
+import java.util.Map;
+import org.apache.arrow.adbc.core.AdbcDatabase;
+import org.apache.arrow.adbc.core.AdbcDriver;
+
+/** A dummy {@link AdbcDriver} implementation for testing purposes. */
+public class TestDriver implements AdbcDriver {
+  public TestDriver() {}
+
+  @Override
+  public AdbcDatabase open(Map<String, Object> parameters) {
+    return null;
+  }
+}

java/driver-manager/src/test/java/org/apache/arrow/adbc/test/TestDriverFactory.java

@@ -0,0 +1,31 @@
+/*
+ * 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.test;
+
+import org.apache.arrow.adbc.core.AdbcDriver;
+import org.apache.arrow.adbc.core.AdbcDriverFactory;
+import org.apache.arrow.memory.BufferAllocator;
+
+/** Dummy AdbcDriverFactory used for testing. */
+public class TestDriverFactory implements AdbcDriverFactory {
+  @Override
+  public AdbcDriver getDriver(BufferAllocator allocator) {
+    // This dummy driver doesn't need to use its allocator.
+    return new TestDriver();
+  }
+}

java/driver-manager/src/test/resources/META-INF/services/org.apache.arrow.adbc.core.AdbcDriverFactory

@@ -0,0 +1,18 @@
+# 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.
+
+org.apache.arrow.adbc.test.TestDriverFactory

java/driver/flight-sql/src/main/java/org/apache/arrow/adbc/driver/flightsql/FlightSqlDriver.java

@@ -19,25 +19,20 @@
 import java.net.URISyntaxException;
 import java.util.Map;
 import java.util.Objects;
+
 import org.apache.arrow.adbc.core.AdbcDatabase;
 import org.apache.arrow.adbc.core.AdbcDriver;
 import org.apache.arrow.adbc.core.AdbcException;
-import org.apache.arrow.adbc.drivermanager.AdbcDriverManager;
 import org.apache.arrow.adbc.sql.SqlQuirks;
 import org.apache.arrow.flight.Location;
 import org.apache.arrow.memory.BufferAllocator;
 import org.apache.arrow.util.Preconditions;
 
 /** An ADBC driver wrapping Arrow Flight SQL. */
 public class FlightSqlDriver implements AdbcDriver {
-  static {
-    AdbcDriverManager.getInstance()
-        .registerDriver("org.apache.arrow.adbc.driver.flightsql", FlightSqlDriver::new);
-  }
-
   private final BufferAllocator allocator;
 
-  FlightSqlDriver(BufferAllocator allocator) {
+  public FlightSqlDriver(BufferAllocator allocator) {
     this.allocator = Objects.requireNonNull(allocator);
   }
 

java/driver/flight-sql/src/main/java/org/apache/arrow/adbc/driver/flightsql/FlightSqlDriverFactory.java

@@ -0,0 +1,30 @@
+/*
+ * 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.flightsql;
+
+import org.apache.arrow.adbc.core.AdbcDriver;
+import org.apache.arrow.adbc.core.AdbcDriverFactory;
+import org.apache.arrow.memory.BufferAllocator;
+
+/** Constructs new FlightSqlDriver instances. */
+public class FlightSqlDriverFactory implements AdbcDriverFactory {
+  @Override
+  public AdbcDriver getDriver(BufferAllocator allocator) {
+    return new FlightSqlDriver(allocator);
+  }
+}

java/driver/flight-sql/src/main/resources/META-INF/services/org.apache.arrow.adbc.core.AdbcDriverFactory

@@ -0,0 +1,18 @@
+# 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.
+
+org.apache.arrow.adbc.driver.flightsql.FlightSqlDriverFactory

java/driver/jdbc/src/main/java/org/apache/arrow/adbc/driver/jdbc/JdbcDriver.java

@@ -19,11 +19,11 @@
 import java.util.Arrays;
 import java.util.Map;
 import java.util.Objects;
+
 import javax.sql.DataSource;
 import org.apache.arrow.adbc.core.AdbcDatabase;
 import org.apache.arrow.adbc.core.AdbcDriver;
 import org.apache.arrow.adbc.core.AdbcException;
-import org.apache.arrow.adbc.drivermanager.AdbcDriverManager;
 import org.apache.arrow.adbc.sql.SqlQuirks;
 import org.apache.arrow.memory.BufferAllocator;
 
@@ -40,11 +40,6 @@ public class JdbcDriver implements AdbcDriver {
    */
   public static final String PARAM_URI = "uri";
 
-  static {
-    AdbcDriverManager.getInstance()
-        .registerDriver("org.apache.arrow.adbc.driver.jdbc", JdbcDriver::new);
-  }
-
   private final BufferAllocator allocator;
 
   public JdbcDriver(BufferAllocator allocator) {