feat(bindings/java): support get enabled services

bindings/java/src/lib.rs

@@ -41,6 +41,7 @@ use tokio::runtime::Runtime;
 mod blocking_operator;
 mod error;
 mod operator;
+mod utility;
 
 pub(crate) type Result<T> = std::result::Result<T, error::Error>;
 

bindings/java/src/main/java/org/apache/opendal/NativeLibrary.java

@@ -0,0 +1,103 @@
+/*
+ * 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.opendal;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.UncheckedIOException;
+import java.nio.file.Files;
+import java.nio.file.StandardCopyOption;
+import java.util.concurrent.atomic.AtomicReference;
+import lombok.experimental.UtilityClass;
+
+/**
+ * Utility for loading the native library.
+ */
+@UtilityClass
+public class NativeLibrary {
+    private enum LibraryState {
+        NOT_LOADED,
+        LOADING,
+        LOADED
+    }
+
+    private static final AtomicReference<LibraryState> libraryLoaded = new AtomicReference<>(LibraryState.NOT_LOADED);
+
+    static {
+        NativeLibrary.loadLibrary();
+    }
+
+    public static void loadLibrary() {
+        if (libraryLoaded.get() == LibraryState.LOADED) {
+            return;
+        }
+
+        if (libraryLoaded.compareAndSet(LibraryState.NOT_LOADED, LibraryState.LOADING)) {
+            try {
+                doLoadLibrary();
+            } catch (IOException e) {
+                libraryLoaded.set(LibraryState.NOT_LOADED);
+                throw new UncheckedIOException("Unable to load the OpenDAL shared library", e);
+            }
+            libraryLoaded.set(LibraryState.LOADED);
+            return;
+        }
+
+        while (libraryLoaded.get() == LibraryState.LOADING) {
+            try {
+                Thread.sleep(10);
+            } catch (InterruptedException ignore) {
+            }
+        }
+    }
+
+    private static void doLoadLibrary() throws IOException {
+        try {
+            // try dynamic library - the search path can be configured via "-Djava.library.path"
+            System.loadLibrary("opendal_java");
+            return;
+        } catch (UnsatisfiedLinkError ignore) {
+            // ignore - try from classpath
+        }
+
+        doLoadBundledLibrary();
+    }
+
+    private static void doLoadBundledLibrary() throws IOException {
+        final String libraryPath = bundledLibraryPath();
+        try (final InputStream is = NativeObject.class.getResourceAsStream(libraryPath)) {
+            if (is == null) {
+                throw new IOException("cannot find " + libraryPath);
+            }
+            final int dot = libraryPath.indexOf('.');
+            final File tmpFile = File.createTempFile(libraryPath.substring(0, dot), libraryPath.substring(dot));
+            tmpFile.deleteOnExit();
+            Files.copy(is, tmpFile.toPath(), StandardCopyOption.REPLACE_EXISTING);
+            System.load(tmpFile.getAbsolutePath());
+        }
+    }
+
+    private static String bundledLibraryPath() {
+        final String classifier = Environment.getClassifier();
+        final String libraryName = System.mapLibraryName("opendal_java");
+        return "/native/" + classifier + "/" + libraryName;
+    }
+}

bindings/java/src/main/java/org/apache/opendal/NativeObject.java

@@ -19,14 +19,6 @@
 
 package org.apache.opendal;
 
-import java.io.File;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.UncheckedIOException;
-import java.nio.file.Files;
-import java.nio.file.StandardCopyOption;
-import java.util.concurrent.atomic.AtomicReference;
-
 /**
  * NativeObject is the base-class of all OpenDAL classes that have
  * a pointer to a native object.
@@ -58,73 +50,8 @@
  * for discussion and alternatives.
  */
 public abstract class NativeObject implements AutoCloseable {
-
-    private enum LibraryState {
-        NOT_LOADED,
-        LOADING,
-        LOADED
-    }
-
-    private static final AtomicReference<LibraryState> libraryLoaded = new AtomicReference<>(LibraryState.NOT_LOADED);
-
     static {
-        NativeObject.loadLibrary();
-    }
-
-    public static void loadLibrary() {
-        if (libraryLoaded.get() == LibraryState.LOADED) {
-            return;
-        }
-
-        if (libraryLoaded.compareAndSet(LibraryState.NOT_LOADED, LibraryState.LOADING)) {
-            try {
-                doLoadLibrary();
-            } catch (IOException e) {
-                libraryLoaded.set(LibraryState.NOT_LOADED);
-                throw new UncheckedIOException("Unable to load the OpenDAL shared library", e);
-            }
-            libraryLoaded.set(LibraryState.LOADED);
-            return;
-        }
-
-        while (libraryLoaded.get() == LibraryState.LOADING) {
-            try {
-                Thread.sleep(10);
-            } catch (InterruptedException ignore) {
-            }
-        }
-    }
-
-    private static void doLoadLibrary() throws IOException {
-        try {
-            // try dynamic library - the search path can be configured via "-Djava.library.path"
-            System.loadLibrary("opendal_java");
-            return;
-        } catch (UnsatisfiedLinkError ignore) {
-            // ignore - try from classpath
-        }
-
-        doLoadBundledLibrary();
-    }
-
-    private static void doLoadBundledLibrary() throws IOException {
-        final String libraryPath = bundledLibraryPath();
-        try (final InputStream is = NativeObject.class.getResourceAsStream(libraryPath)) {
-            if (is == null) {
-                throw new IOException("cannot find " + libraryPath);
-            }
-            final int dot = libraryPath.indexOf('.');
-            final File tmpFile = File.createTempFile(libraryPath.substring(0, dot), libraryPath.substring(dot));
-            tmpFile.deleteOnExit();
-            Files.copy(is, tmpFile.toPath(), StandardCopyOption.REPLACE_EXISTING);
-            System.load(tmpFile.getAbsolutePath());
-        }
-    }
-
-    private static String bundledLibraryPath() {
-        final String classifier = Environment.getClassifier();
-        final String libraryName = System.mapLibraryName("opendal_java");
-        return "/native/" + classifier + "/" + libraryName;
+        NativeLibrary.loadLibrary();
     }
 
     /**

bindings/java/src/main/java/org/apache/opendal/OpenDAL.java

@@ -0,0 +1,47 @@
+/*
+ * 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.opendal;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+import lombok.experimental.UtilityClass;
+
+/**
+ * Utility facade for top-level functions.
+ */
+@UtilityClass
+public class OpenDAL {
+    static {
+        NativeLibrary.loadLibrary();
+        final Set<String> enabledServices = new HashSet<>(Arrays.asList(loadEnabledServices()));
+        ENABLED_SERVICES = Collections.unmodifiableSet(enabledServices);
+    }
+
+    private static final Set<String> ENABLED_SERVICES;
+
+    public static Collection<String> enabledServices() {
+        return ENABLED_SERVICES;
+    }
+
+    private static native String[] loadEnabledServices();
+}

bindings/java/src/test/java/org/apache/opendal/test/UtilityTest.java

@@ -0,0 +1,33 @@
+/*
+ * 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.opendal.test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import java.util.Collection;
+import org.apache.opendal.OpenDAL;
+import org.junit.jupiter.api.Test;
+
+public class UtilityTest {
+    @Test
+    public void testLoadEnabledServices() {
+        final Collection<String> enabledServices = OpenDAL.enabledServices();
+        assertThat(enabledServices).isNotEmpty();
+    }
+}

bindings/java/src/utility.rs

@@ -0,0 +1,49 @@
+// 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.
+
+use jni::objects::{JClass, JObject};
+use jni::sys::{jobjectArray, jsize};
+use jni::JNIEnv;
+use opendal::Scheme;
+
+use crate::{string_to_jstring, Result};
+
+/// # Safety
+///
+/// This function should not be called before the Operator are ready.
+#[no_mangle]
+pub unsafe extern "system" fn Java_org_apache_opendal_OpenDAL_loadEnabledServices(
+    mut env: JNIEnv,
+    _: JClass,
+) -> jobjectArray {
+    intern_load_enabled_services(&mut env).unwrap_or_else(|e| {
+        e.throw(&mut env);
+        JObject::default().into_raw()
+    })
+}
+
+fn intern_load_enabled_services(env: &mut JNIEnv) -> Result<jobjectArray> {
+    let services = Scheme::enabled();
+    let res = env.new_object_array(services.len() as jsize, "java/lang/String", JObject::null())?;
+
+    for (idx, service) in services.iter().enumerate() {
+        let srv = string_to_jstring(env, Some(&service.to_string()))?;
+        env.set_object_array_element(&res, idx as jsize, srv)?;
+    }
+
+    Ok(res.into_raw())
+}