[bindings] Expose Engine.clone() to JS and add explicit Engine.prepare() warm-up API across bindings

bindings/cpp/regorus.hpp

@@ -80,6 +80,10 @@ namespace regorus {
 	    return std::unique_ptr<Engine>(new Engine(regorus_engine_clone(engine)));
 	}
 
+	Result prepare() {
+	    return Result(regorus_engine_prepare(engine));
+	}
+
 	Result set_rego_v0(bool enable) {
 		return Result(regorus_engine_set_rego_v0(engine, enable));
 	}

bindings/csharp/Regorus/Engine.cs

@@ -68,6 +68,18 @@ public Engine Clone()
             });
         }
 
+        /// <summary>
+        /// Prepare internal evaluation structures without executing a query.
+        /// This is optional: if skipped, the first evaluation pays this setup cost.
+        /// </summary>
+        public void Prepare()
+        {
+            UseHandle(enginePtr =>
+            {
+                CheckAndDropResult(Regorus.Internal.API.regorus_engine_prepare((Regorus.Internal.RegorusEngine*)enginePtr));
+            });
+        }
+
         public void SetStrictBuiltinErrors(bool strict)
         {
             UseHandle(enginePtr =>

bindings/csharp/Regorus/NativeMethods.cs

@@ -92,6 +92,12 @@ internal static unsafe partial class API
         [DllImport(LibraryName, EntryPoint = "regorus_engine_clone", CallingConvention = CallingConvention.Cdecl, ExactSpelling = true)]
         internal static extern RegorusEngine* regorus_engine_clone(RegorusEngine* engine);
 
+        /// <summary>
+        /// Prepare a RegorusEngine for evaluation without executing a query.
+        /// </summary>
+        [DllImport(LibraryName, EntryPoint = "regorus_engine_prepare", CallingConvention = CallingConvention.Cdecl, ExactSpelling = true)]
+        internal static extern RegorusResult regorus_engine_prepare(RegorusEngine* engine);
+
         /// <summary>
         /// Compile an RVM program from the engine state with entry points.
         /// </summary>

bindings/ffi/src/engine.rs

@@ -199,6 +199,21 @@ pub extern "C" fn regorus_engine_clone(engine: *mut RegorusEngine) -> *mut Regor
     }
 }
 
+/// Prepare a [`RegorusEngine`] for evaluation without executing a query.
+///
+/// This is optional. If not called, first eval performs the same setup.
+/// If policy/data changes after preparation, setup is invalidated.
+#[no_mangle]
+pub extern "C" fn regorus_engine_prepare(engine: *mut RegorusEngine) -> RegorusResult {
+    with_unwind_guard(|| {
+        to_regorus_result(|| -> Result<()> {
+            let engine = to_ref(engine)?;
+            let mut guard = engine.try_write()?;
+            guard.prepare()
+        }())
+    })
+}
+
 #[no_mangle]
 pub extern "C" fn regorus_engine_drop(engine: *mut RegorusEngine) {
     if let Ok(e) = to_ref(engine) {

bindings/go/pkg/regorus/mod.go

@@ -28,6 +28,17 @@ func (e *Engine) Clone() *Engine {
 	return c
 }
 
+func (e *Engine) Prepare() error {
+	result := C.regorus_engine_prepare(e.e)
+	defer C.regorus_result_drop(result)
+
+	if result.status != C.Ok {
+		return fmt.Errorf("%s", C.GoString(result.error_message))
+	}
+
+	return nil
+}
+
 func (e *Engine) SetRegoV0(enable bool) error {
 	result := C.regorus_engine_set_rego_v0(e.e, C.bool(enable))
 	defer C.regorus_result_drop(result)

bindings/java/src/lib.rs

@@ -27,13 +27,30 @@ pub extern "system" fn Java_com_microsoft_regorus_Engine_nativeNewEngine(
 
 #[no_mangle]
 pub extern "system" fn Java_com_microsoft_regorus_Engine_nativeClone(
-    _env: EnvUnowned,
+    env: EnvUnowned,
     _class: JClass,
     engine_ptr: jlong,
 ) -> jlong {
-    let engine = unsafe { &mut *(engine_ptr as *mut Engine) };
-    let c = engine.clone();
-    Box::into_raw(Box::new(c)) as jlong
+    let res = throw_err(env, |_env| {
+        let engine = unsafe { &mut *get_engine_ptr(engine_ptr)? };
+        let c = engine.clone();
+        Ok(Box::into_raw(Box::new(c)) as jlong)
+    });
+
+    res.unwrap_or_default()
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_nativePrepare(
+    env: EnvUnowned,
+    _class: JClass,
+    engine_ptr: jlong,
+) {
+    let _ = throw_err(env, |_env| {
+        let engine = unsafe { &mut *get_engine_ptr(engine_ptr)? };
+        engine.prepare()?;
+        Ok(())
+    });
 }
 
 #[no_mangle]
@@ -437,6 +454,9 @@ pub extern "system" fn Java_com_microsoft_regorus_Engine_nativeDestroyEngine(
     _class: JClass,
     engine_ptr: jlong,
 ) {
+    if engine_ptr == 0 {
+        return;
+    }
     unsafe {
         let _engine = Box::from_raw(engine_ptr as *mut Engine);
     }
@@ -816,6 +836,13 @@ fn throw_err<T>(mut env: EnvUnowned, f: impl FnOnce(&mut Env) -> Result<T>) -> R
     }
 }
 
+fn get_engine_ptr(engine_ptr: jlong) -> Result<*mut Engine> {
+    if engine_ptr == 0 {
+        return Err(anyhow::anyhow!("Engine is closed"));
+    }
+    Ok(engine_ptr as *mut Engine)
+}
+
 fn get_string_array(env: &mut Env, array: jobjectArray) -> Result<Vec<String>> {
     if array.is_null() {
         return Ok(Vec::new());

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

@@ -21,6 +21,7 @@ public class Engine implements AutoCloseable, Cloneable {
     // if you update the native API.
     private static native long nativeNewEngine();
     private static native long nativeClone(long enginePtr);
+    private static native void nativePrepare(long enginePtr);
     private static native void nativeSetRegoV0(long enginePtr, boolean enable);
     private static native String nativeAddPolicy(long enginePtr, String path, String rego);
     private static native String nativeAddPolicyFromFile(long enginePtr, String path);
@@ -45,7 +46,7 @@ public class Engine implements AutoCloseable, Cloneable {
 
     // 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;
+    private long enginePtr;
 
     /**
      * Creates a new Regorus Engine.
@@ -63,7 +64,15 @@ public Engine() {
      * Efficiently clones an Engine.
      */
     public Engine clone() {
-	return new Engine(nativeClone(enginePtr));
+	return new Engine(nativeClone(requireOpen()));
+    }
+
+    /**
+     * Prepares internal evaluation structures without executing a query.
+     * Optional: if skipped, first evaluation performs the same setup.
+     */
+    public void prepare() {
+        nativePrepare(requireOpen());
     }
 
      /**
@@ -73,7 +82,7 @@ public Engine clone() {
      * 
      */
     public void setRegoV0(boolean enable) {
-        nativeSetRegoV0(enginePtr, enable);
+        nativeSetRegoV0(requireOpen(), enable);
     }
 
     /**
@@ -85,7 +94,7 @@ public void setRegoV0(boolean enable) {
      * @return Rego package defined in the policy.
      */
     public String addPolicy(String filename, String rego) {
-        return nativeAddPolicy(enginePtr, filename, rego);
+        return nativeAddPolicy(requireOpen(), filename, rego);
     }
 
     /**
@@ -96,7 +105,7 @@ public String addPolicy(String filename, String rego) {
      * @return Rego package defined in the policy.
      */
     public String addPolicyFromFile(String path) {
-        return nativeAddPolicyFromFile(enginePtr, path);
+        return nativeAddPolicyFromFile(requireOpen(), path);
     }
 
     /**
@@ -105,7 +114,7 @@ public String addPolicyFromFile(String path) {
      * @return List of Rego packages as a JSON array of strings.
      */
     public String getPackages() {
-        return nativeGetPackages(enginePtr);
+        return nativeGetPackages(requireOpen());
     }
 
     /**
@@ -114,14 +123,14 @@ public String getPackages() {
      * @return List of Rego policies as a JSON array of sources.
      */
     public String getPolicies() {
-        return nativeGetPolicies(enginePtr);
+        return nativeGetPolicies(requireOpen());
     }
 
     /**
      * Clears the data  document.
      */
     public void clearData() {
-        nativeClearData(enginePtr);
+        nativeClearData(requireOpen());
     }
 
     /**
@@ -143,7 +152,7 @@ public void clearData() {
      * @param data Inline data document.
      */
     public void addDataJson(String data) throws RuntimeException {
-        nativeAddDataJson(enginePtr, data);
+        nativeAddDataJson(requireOpen(), data);
     }
 
     /**
@@ -160,7 +169,7 @@ public void addDataJson(String data) throws RuntimeException {
      * @param path Path to JSON data document.
      */
     public void addDataJsonFromFile(String path) throws RuntimeException {
-        nativeAddDataJsonFromFile(enginePtr, path);
+        nativeAddDataJsonFromFile(requireOpen(), path);
     }
 
     /**
@@ -169,7 +178,7 @@ public void addDataJsonFromFile(String path) throws RuntimeException {
      * @param input inline JSON input.
      */
     public void setInputJson(String input) {
-        nativeSetInputJson(enginePtr, input);
+        nativeSetInputJson(requireOpen(), input);
     }
 
     /**
@@ -178,7 +187,7 @@ public void setInputJson(String input) {
      * @param path Path to JSON input.
      */
     public void setInputJsonFromFile(String path) {
-        nativeSetInputJsonFromFile(enginePtr, path);
+        nativeSetInputJsonFromFile(requireOpen(), path);
     }
 
     /**
@@ -189,7 +198,7 @@ public void setInputJsonFromFile(String path) {
      * @return Query results as a JSON string.
      */
     public String evalQuery(String query) {
-        return nativeEvalQuery(enginePtr, query);
+        return nativeEvalQuery(requireOpen(), query);
     }
 
     /**
@@ -200,7 +209,7 @@ public String evalQuery(String query) {
      * @return Value of the rule as a JSON string.
      */
     public String evalRule(String rule) {
-        return nativeEvalRule(enginePtr, rule);
+        return nativeEvalRule(requireOpen(), rule);
     }
 
     /**
@@ -210,15 +219,15 @@ public String evalRule(String rule) {
      * 
      */
     public void setEnableCoverage(boolean enable) {
-        nativeSetEnableCoverage(enginePtr, enable);
+        nativeSetEnableCoverage(requireOpen(), enable);
     }
 
     /**
      * Clear coverage data.
      * 
      */
     public void clearCoverageData() {
-        nativeClearCoverageData(enginePtr);
+        nativeClearCoverageData(requireOpen());
     }
 
     /**
@@ -228,7 +237,7 @@ public void clearCoverageData() {
      * 
      */
     public String getCoverageReport() {
-        return nativeGetCoverageReport(enginePtr);
+        return nativeGetCoverageReport(requireOpen());
     }
 
     /**
@@ -238,7 +247,7 @@ public String getCoverageReport() {
      * 
      */
     public String getCoverageReportPretty() {
-        return nativeGetCoverageReportPretty(enginePtr);
+        return nativeGetCoverageReportPretty(requireOpen());
     }
 
     /**
@@ -248,7 +257,7 @@ public String getCoverageReportPretty() {
      * 
      */
     public void setGatherPrints(boolean b) {
-        nativeSetGatherPrints(enginePtr, b);
+        nativeSetGatherPrints(requireOpen(), b);
     }
 
     /**
@@ -258,7 +267,7 @@ public void setGatherPrints(boolean b) {
      * 
      */
     public String takePrints() {
-        return nativeTakePrints(enginePtr);
+        return nativeTakePrints(requireOpen());
     }
 
     /**
@@ -267,24 +276,34 @@ public String takePrints() {
      * @param config Policy length configuration.
      */
     public void setPolicyLengthConfig(PolicyLengthConfig config) {
-        nativeSetPolicyLengthConfig(enginePtr, config.maxCol, config.maxFileBytes, config.maxLines);
+        nativeSetPolicyLengthConfig(requireOpen(), config.maxCol, config.maxFileBytes, config.maxLines);
     }
 
     /**
      * Clear the policy length configuration, reverting to defaults.
      */
     public void clearPolicyLengthConfig() {
-        nativeClearPolicyLengthConfig(enginePtr);
+        nativeClearPolicyLengthConfig(requireOpen());
     }
 
     long getPtr() {
+        return requireOpen();
+    }
+
+    private long requireOpen() {
+        if (enginePtr == 0) {
+            throw new IllegalStateException("Engine is closed");
+        }
         return enginePtr;
     }
 
 
     @Override
     public void close() {
-        nativeDestroyEngine(enginePtr);
+        if (enginePtr != 0) {
+            nativeDestroyEngine(enginePtr);
+            enginePtr = 0;
+        }
     }
 
     // Loading native library from JAR is adapted from: