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

libadblockplus-android/jni/JniFilter.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 <AdblockPlus.h>
 #include "Utils.h"
 #include "JniJsValue.h"
+#include "JniFilter.h"
+
+// precached in JNI_OnLoad and released in JNI_OnUnload
+JniGlobalReference<jclass>* filterEnumClass;
+
+void JniFilter_OnLoad(JavaVM* vm, JNIEnv* env, void* reserved)
+{
+  filterEnumClass = new JniGlobalReference<jclass>(env, env->FindClass(PKG("Filter$Type")));
+}
+
+void JniFilter_OnUnload(JavaVM* vm, JNIEnv* env, void* reserved)
+{
+  if (filterEnumClass)
+  {
+    delete filterEnumClass;
+    filterEnumClass = NULL;
+  }
+}
 
 static AdblockPlus::Filter* GetFilterPtr(jlong ptr)
 {
   return JniLongToTypePtr<AdblockPlus::FilterPtr>(ptr)->get();
 }
 
 static jlong JNICALL JniCtor(JNIEnv* env, jclass clazz, jlong jsValue)
 {
   try
   {
@@ skipping 28 matching lines @@
     enumName = "ELEMHIDE_EXCEPTION";
     break;
   case AdblockPlus::Filter::TYPE_EXCEPTION:
     enumName = "EXCEPTION";
     break;
   default:
     enumName = "INVALID";
     break;
   }
 
-  JniLocalReference<jclass> enumClass(env, env->FindClass(PKG("Filter$Type")));
-  jfieldID enumField = env->GetStaticFieldID(*enumClass, enumName,
-      TYP("Filter$Type"));
-  return env->GetStaticObjectField(*enumClass, enumField);
+  jfieldID enumField = env->GetStaticFieldID(filterEnumClass->Get(), enumName, TYP("Filter$Type"));
+  return env->GetStaticObjectField(filterEnumClass->Get(), enumField);
 }
 
 static jboolean JNICALL JniIsListed(JNIEnv* env, jclass clazz, jlong ptr)
 {
   try
   {
     return GetFilterPtr(ptr)->IsListed() ? JNI_TRUE : JNI_FALSE;
   }
   CATCH_THROW_AND_RETURN(env, JNI_FALSE)
 }
@@ skipping 35 matching lines @@
   { (char*)"isListed", (char*)"(J)Z", (void*)JniIsListed },
   { (char*)"addToList", (char*)"(J)V", (void*)JniAddToList },
   { (char*)"removeFromList", (char*)"(J)V", (void*)JniRemoveFromList },
   { (char*)"operatorEquals", (char*)"(JJ)Z", (void*)JniOperatorEquals }
 };
 
 extern "C" JNIEXPORT void JNICALL Java_org_adblockplus_libadblockplus_Filter_registerNatives(JNIEnv *env, jclass clazz)
 {
   env->RegisterNatives(clazz, methods, sizeof(methods) / sizeof(methods[0]));
 }