Java bindings (#147)

bindings/java/src/lib.rs

@@ -0,0 +1,150 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+use anyhow::Result;
+use jni::objects::{JClass, JObject, JString};
+use jni::sys::{jlong, jstring};
+use jni::JNIEnv;
+
+use regorus::{Engine, Value};
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_newEngine(
+    _env: JNIEnv,
+    _class: JClass,
+) -> jlong {
+    let engine = Engine::new();
+    Box::into_raw(Box::new(engine)) as jlong
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_addPolicy(
+    env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+    path: JString,
+    rego: JString,
+) {
+    let _ = throw_err(env, |env| {
+        let engine = unsafe { &mut *(engine_ptr as *mut Engine) };
+        let path: String = env.get_string(&path)?.into();
+        let rego: String = env.get_string(&rego)?.into();
+        engine.add_policy(path, rego)?;
+        Ok(())
+    });
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_addPolicyFromFile(
+    env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+    path: JString,
+) {
+    let _ = throw_err(env, |env| {
+        let engine = unsafe { &mut *(engine_ptr as *mut Engine) };
+        let path: String = env.get_string(&path)?.into();
+        engine.add_policy_from_file(path)?;
+        Ok(())
+    });
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_addDataJson(
+    env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+    data: JString,
+) {
+    let _ = throw_err(env, |env| {
+        let engine = unsafe { &mut *(engine_ptr as *mut Engine) };
+        let data: String = env.get_string(&data)?.into();
+        engine.add_data_json(&data)?;
+        Ok(())
+    });
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_addDataJsonFromFile(
+    env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+    path: JString,
+) {
+    let _ = throw_err(env, |env| {
+        let engine = unsafe { &mut *(engine_ptr as *mut Engine) };
+        let path: String = env.get_string(&path)?.into();
+        engine.add_data(Value::from_json_file(path)?)?;
+        Ok(())
+    });
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_setInputJson(
+    env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+    input: JString,
+) {
+    let _ = throw_err(env, |env| {
+        let engine = unsafe { &mut *(engine_ptr as *mut Engine) };
+        let input: String = env.get_string(&input)?.into();
+        engine.set_input_json(&input)?;
+        Ok(())
+    });
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_setInputJsonFromFile(
+    env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+    path: JString,
+) {
+    let _ = throw_err(env, |env| {
+        let engine = unsafe { &mut *(engine_ptr as *mut Engine) };
+        let path: String = env.get_string(&path)?.into();
+        engine.set_input(Value::from_json_file(&path)?);
+        Ok(())
+    });
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_evalQuery(
+    env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+    query: JString,
+) -> jstring {
+    let res = throw_err(env, |env| {
+        let engine = unsafe { &mut *(engine_ptr as *mut Engine) };
+        let query: String = env.get_string(&query)?.into();
+        let results = engine.eval_query(query, false)?;
+        let output = env.new_string(serde_json::to_string(&results)?)?;
+        Ok(output.into_raw())
+    });
+
+    match res {
+        Ok(val) => val,
+        Err(_) => JObject::null().into_raw(),
+    }
+}
+
+#[no_mangle]
+pub unsafe extern "system" fn Java_com_microsoft_regorus_Engine_destroyEngine(
+    _env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+) {
+    let _engine = Box::from_raw(engine_ptr as *mut Engine);
+}
+
+fn throw_err<T>(mut env: JNIEnv, mut f: impl FnMut(&mut JNIEnv) -> Result<T>) -> Result<T> {
+    match f(&mut env) {
+        Ok(val) => Ok(val),
+        Err(err) => {
+            env.throw(err.to_string())?;
+            Err(err)
+        }
+    }
+}

bindings/java/src/main/java/com/microsoft/regorus/Engine.java

@@ -0,0 +1,114 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ * Licensed under the MIT License.
+ **/
+
+package com.microsoft.regorus;
+
+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;
+
+public class Engine implements AutoCloseable {
+    // Methods exposed from Rust side, you can run
+    // `javac -h . src/main/java/com/microsoft/regorus/Engine.java` to update
+    // expected native header at `bindings/java/com_microsoft_regorus_Engine.h`
+    // if you update the native API.
+    private static native long newEngine();
+    private static native void addPolicy(long enginePtr, String path, String rego);
+    private static native void addPolicyFromFile(long enginePtr, String path);
+    private static native void addDataJson(long enginePtr, String data);
+    private static native void addDataJsonFromFile(long enginePtr, String path);
+    private static native void setInputJson(long enginePtr, String input);
+    private static native void setInputJsonFromFile(long enginePtr, String path);
+    private static native String evalQuery(long enginePtr, String query);
+    private static native void destroyEngine(long enginePtr);
+
+    // Pointer to Engine allocated on Rust's heap, all native methods works on
+    // engine expects this pointer. It is free'd in `close` method.
+    private final long enginePtr;
+
+    public Engine() {
+        enginePtr = newEngine();
+    }
+
+    public void pubAddPolicy(String path, String rego) {
+        addPolicy(enginePtr, path, rego);
+    }
+
+    public void pubAddDataJson(String path) {
+        addDataJson(enginePtr, path);
+    }
+
+    public void pubSetInputJson(String path) {
+        setInputJson(enginePtr, path);
+    }
+
+    public String pubEvalQuery(String path) {
+        return evalQuery(enginePtr, path);
+    }
+    
+    @Override
+    public void close() {
+        destroyEngine(enginePtr);
+    }
+
+    // Loading native library from jar is adapted from:
+    // https://github.com/apache/opendal/blob/93e5f65bbf30df2fed4bdd95bb0685c73c6418c2/bindings/java/src/main/java/org/apache/opendal/NativeLibrary.java
+    // https://github.com/apache/opendal/blob/93e5f65bbf30df2fed4bdd95bb0685c73c6418c2/bindings/java/src/main/java/org/apache/opendal/Environment.java
+    private static final String classifier;
+    static {
+        final StringBuilder classifierBuilder = new StringBuilder();
+        final String os = System.getProperty("os.name").toLowerCase();
+        if (os.startsWith("windows")) {
+            classifierBuilder.append("windows");
+        } else if (os.startsWith("mac")) {
+            classifierBuilder.append("osx");
+        } else {
+            classifierBuilder.append("linux");
+        }
+        classifierBuilder.append("-");
+        final String arch = System.getProperty("os.arch").toLowerCase();
+        if (arch.equals("aarch64")) {
+            classifierBuilder.append("aarch_64");
+        } else {
+            classifierBuilder.append("x86_64");
+        }
+        classifier = classifierBuilder.toString();
+
+        loadNativeLibrary();
+    }
+
+    private static void loadNativeLibrary() {
+        try {
+            // try dynamic library - the search path can be configured via "-Djava.library.path"
+            System.loadLibrary("regorus_java");
+            return;
+        } catch (UnsatisfiedLinkError ignore) {
+            // ignore - try from classpath
+        }
+
+        final String libraryPath = bundledLibraryPath();
+        try (final InputStream is = Engine.class.getResourceAsStream(libraryPath)) {
+            if (is == null) {
+                throw new RuntimeException("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());
+        } catch (IOException exception) {
+            throw new RuntimeException(exception);
+        }
+    }
+
+    private static String bundledLibraryPath() {
+        final String libraryName = System.mapLibraryName("regorus_java");
+        return "/native/" + classifier + "/" + libraryName;
+    }
+}

bindings/java/src/test/java/com/microsoft/regorus/EngineTest.java

@@ -0,0 +1,36 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ * Licensed under the MIT License.
+ **/
+package com.microsoft.regorus;
+
+import java.util.Map;
+import java.util.ArrayList;
+import junit.framework.TestCase;
+import junit.framework.Assert;
+import com.google.gson.Gson;
+import com.google.gson.reflect.TypeToken;
+
+public class EngineTest extends TestCase
+{
+    public void test_engine()
+    {
+        String resJson;
+        try (Engine engine = new Engine()) {
+            engine.pubAddPolicy(
+                "hello.rego",
+                "package test\nmessage = concat(\", \", [input.message, data.message])"
+            );
+            engine.pubAddDataJson("{\"message\":\"World!\"}");
+            engine.pubSetInputJson("{\"message\":\"Hello\"}");
+            resJson = engine.pubEvalQuery("data.test.message");
+        }
+
+        Gson gson = new Gson();
+        Map res = gson.fromJson(resJson, Map.class);
+        ArrayList results = (ArrayList) res.get("result");
+        ArrayList expressions = (ArrayList) ((Map) results.get(0)).get("expressions");
+        Map expression = (Map) expressions.get(0);
+        Assert.assertEquals("Hello, World!", expression.get("value"));
+    }
+}