Issue 4442 - Cache class and ctors references in JNI_Load/UnLoad

libadblockplus-android/jni/JniLogSystem.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include "JniCallbacks.h"
+#include "JniLogSystem.h"
+
+// precached in JNI_OnLoad and released in JNI_OnUnload
+JniGlobalReference<jclass>* logLevelClass;
+
+void JniLogSystem_OnLoad(JavaVM* vm, JNIEnv* env, void* reserved)
+{
+  logLevelClass = new JniGlobalReference<jclass>(env, env->FindClass(PKG("LogSystem$LogLevel")));
+}
+
+void JniLogSystem_OnUnload(JavaVM* vm, JNIEnv* env, void* reserved)
+{
+  if (logLevelClass)
+  {
+    delete logLevelClass;
+    logLevelClass = NULL;
+  }
+}
 
 static jlong JNICALL JniCtor(JNIEnv* env, jclass clazz, jobject callbackObject)
 {
   try
   {
     return JniPtrToLong(new JniLogSystemCallback(env, callbackObject));
   }
   CATCH_THROW_AND_RETURN(env, 0)
 }
 
 static void JNICALL JniDtor(JNIEnv* env, jclass clazz, jlong ptr)
 {
   delete JniLongToTypePtr<JniLogSystemCallback>(ptr);
 }
 
 JniLogSystemCallback::JniLogSystemCallback(JNIEnv* env, jobject callbackObject)
-  : JniCallbackBase(env, callbackObject), AdblockPlus::LogSystem(), logLevelClass(new JniGlobalReference<jclass>(env, env->FindClass(PKG("LogSystem$LogLevel"))))
+  : JniCallbackBase(env, callbackObject), AdblockPlus::LogSystem()
 {
 }
 
 void JniLogSystemCallback::operator()(AdblockPlus::LogSystem::LogLevel logLevel,
     const std::string& message, const std::string& source)
 {
   JNIEnvAcquire env(GetJavaVM());
 
   jmethodID method = env->GetMethodID(
       *JniLocalReference<jclass>(*env,
@@ skipping 51 matching lines @@
 static JNINativeMethod methods[] =
 {
   { (char*)"ctor", (char*)"(Ljava/lang/Object;)J", (void*)JniCtor },
   { (char*)"dtor", (char*)"(J)V", (void*)JniDtor }
 };
 
 extern "C" JNIEXPORT void JNICALL Java_org_adblockplus_libadblockplus_LogSystem_registerNatives(JNIEnv *env, jclass clazz)
 {
   env->RegisterNatives(clazz, methods, sizeof(methods) / sizeof(methods[0]));
 }