arpadboda commented on a change in pull request #489: MINIFICPP-740: Add ability to run NiFi processors from Java and Python URL: https://github.com/apache/nifi-minifi-cpp/pull/489#discussion_r259919624
########## File path: extensions/jni/jvm/JVMLoader.h ########## @@ -0,0 +1,514 @@ +/** + * + * 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. + */ +#ifndef EXTENSIONS_JVMLOADER_H +#define EXTENSIONS_JVMLOADER_H + +#include <string> +#include <map> +#include <vector> +#include <sstream> +#include <iterator> +#include <algorithm> +#include "JavaClass.h" +#include "JavaServicer.h" +#include "../JavaException.h" +#include "core/Core.h" +#include <jni.h> +#ifndef WIN32 +#include <dlfcn.h> +#endif +#include "Core.h" + +namespace org { +namespace apache { +namespace nifi { +namespace minifi { +namespace jni { + +/** + * Purpose and Justification: Provides a mapping function for jfields. + * Note that jFieldIDs aren't local references, so we don't need to worry + * about keeping them around. Thus this class provides us a caching mechanism. + */ +class FieldMapping { + public: + jfieldID getField(const std::string &clazz, const std::string &fnArg) { + std::lock_guard<std::mutex> guard(mutex_); + auto group = map_.find(clazz); + if (group != map_.end()) { + auto match = group->second.find(fnArg); + if (match != group->second.end()) { + return match->second; + } + } + return nullptr; + } + + void putField(const std::string &clazz, const std::string &fnArg, jfieldID field) { + std::lock_guard<std::mutex> guard(mutex_); + map_[clazz].insert(std::make_pair(fnArg, field)); + } + + private: + std::mutex mutex_; + std::map<std::string, std::map<std::string, jfieldID>> map_; +}; + +typedef jint (*registerNatives_t)(JNIEnv* env, jclass clazz); + +jfieldID getPtrField(JNIEnv *env, jobject obj); + +template<typename T> +T *getPtr(JNIEnv *env, jobject obj); + +template<typename T> +void setPtr(JNIEnv *env, jobject obj, T *t); + +/** + * Purpose and Justification: Provides a singleton reference to a JVM. + * + * Since JVMs are singular in reference ( meaning that there cannot be more than one + * at any given time ), we need to create a singleton access pattern. + * + */ +class JVMLoader { + public: + + bool initialized() { + return initialized_; + } + + /** + * Attach the current thread + * @return JNIEnv reference. + */ + JNIEnv *attach(const std::string &name = "") { + JNIEnv* jenv; + jint ret = jvm_->GetEnv((void**) &jenv, JNI_VERSION_1_8); + if (ret == JNI_EDETACHED) { + ret = jvm_->AttachCurrentThread((void**) &jenv, NULL); + if (ret != JNI_OK || jenv == NULL) { + throw std::runtime_error("Could not find class"); + } + } + + return jenv; + } + + /** + * Returns a reference to an instantiated class loader + * @return class loader. + */ + jobject getClassLoader() { + return gClassLoader; + } + + /** + * Removes a class reference + * @param name class name + */ + void remove_class(const std::string &name) { + std::lock_guard<std::mutex> lock(internal_mutex_); + auto finder = objects_.find(name); + if (finder != objects_.end()) { + auto oldClzz = finder->second; + JavaClass clazz(oldClzz); + attach(name)->DeleteGlobalRef(clazz.getReference()); + } + objects_.erase(name); + } + + /** + * Loads a class, creating a global reference to the jclass + * @param class name. + * @return JavaClass + */ + JavaClass load_class(const std::string &clazz_name, JNIEnv *lenv = nullptr) { + // names should come with package/package/name, so we must normalize the name + + JNIEnv *env = lenv; + + std::string name = clazz_name; + name = utils::StringUtils::replaceAll(name, ".", "/"); + + if (env == nullptr) { + env = attach(name); + } + + std::lock_guard<std::mutex> lock(internal_mutex_); + auto finder = objects_.find(name); + if (finder != objects_.end()) { + auto oldClzz = finder->second; + JavaClass clazz(oldClzz); + return clazz; + } + + std::string modifiedName = name; + modifiedName = utils::StringUtils::replaceAll(modifiedName, "/", "."); + + auto jstringclass = env->NewStringUTF(modifiedName.c_str()); + + auto preclass = env->CallObjectMethod(gClassLoader, gFindClassMethod, jstringclass); + + minifi::jni::ThrowIf(env); + + auto obj = (jclass) env->NewGlobalRef(preclass); + + minifi::jni::ThrowIf(env); + + auto clazzobj = static_cast<jclass>(obj); + + JavaClass clazz(name, clazzobj, env); + objects_.insert(std::make_pair(name, clazz)); + return clazz; + } + + JavaClass getObjectClass(const std::string &name, jobject jobj) { + auto env = attach(); + auto jcls = (jclass) env->NewGlobalRef(env->GetObjectClass(jobj)); + return JavaClass(name, jcls, env); + } + + static JVMLoader *getInstance() { + static JVMLoader jvm; + return &jvm; + } + + JNIEnv *getEnv() { + return env_; + } + + /** + * Returns an instance to the JVMLoader + * @param pathVector vector of paths + * @param otherOptions jvm options. + */ + static JVMLoader *getInstance(const std::vector<std::string> &pathVector, const std::vector<std::string> &otherOptions = std::vector<std::string>()) { + JVMLoader *jvm = getInstance(); + if (!jvm->initialized()) { + std::stringstream str; + std::vector<std::string> options; + for (const auto &path : pathVector) { + if (str.str().length() > 0) { +#ifdef WIN32 Review comment: ``` #ifdef WIN32 const char * delimiter = ";"; #else const char * delimiter = ":"; #endif stringstream str; std::copy(pathVector.begin(), pathVector.end(), std::ostream_iterator<std::string>(str, delimiter)); ``` A bit Pythonic, but I guess easier to read. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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