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

libadblockplus-android/jni/JniWebRequest.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 "Utils.h"
+#include "JniWebRequest.h"
+
+// precached in JNI_OnLoad and released in JNI_OnUnload
+JniGlobalReference<jclass>* headerEntryClass;
+JniGlobalReference<jclass>* serverResponseClass;
+
+void JniWebRequest_OnLoad(JavaVM* vm, JNIEnv* env, void* reserved)
+{
+  headerEntryClass = new JniGlobalReference<jclass>(env, env->FindClass(PKG("HeaderEntry")));
+  serverResponseClass = new JniGlobalReference<jclass>(env, env->FindClass(PKG("ServerResponse")));
+}
+
+void JniWebRequest_OnUnload(JavaVM* vm, JNIEnv* env, void* reserved)
+{
+  if (headerEntryClass)
+  {
+    delete headerEntryClass;
+    headerEntryClass = NULL;
+  }
+
+  if (serverResponseClass)
+  {
+    delete serverResponseClass;
+    serverResponseClass = NULL;
+  }
+}
 
 static jlong JNICALL JniCtor(JNIEnv* env, jclass clazz, jobject callbackObject)
 {
   try
   {
     return JniPtrToLong(new AdblockPlus::WebRequestPtr(new JniWebRequest(env, callbackObject)));
   }
   CATCH_THROW_AND_RETURN(env, 0)
 }
 
 static void JNICALL JniDtor(JNIEnv* env, jclass clazz, jlong ptr)
 {
   delete JniLongToTypePtr<AdblockPlus::WebRequestPtr>(ptr);
 }
 
 JniWebRequest::JniWebRequest(JNIEnv* env, jobject callbackObject)
-  : JniCallbackBase(env, callbackObject), AdblockPlus::WebRequest(),
-    tupleClass(new JniGlobalReference<jclass>(env, env->FindClass(PKG("HeaderEntry")))),
-    serverResponseClass(new JniGlobalReference<jclass>(env, env->FindClass(PKG("ServerResponse"))))
+  : JniCallbackBase(env, callbackObject), AdblockPlus::WebRequest()
 {
 }
 
 AdblockPlus::ServerResponse JniWebRequest::GET(const std::string& url,
     const AdblockPlus::HeaderList& requestHeaders) const
 {
   JNIEnvAcquire env(GetJavaVM());
 
   jmethodID method = env->GetMethodID(
       *JniLocalReference<jclass>(*env,
           env->GetObjectClass(GetCallbackObject())),
       "httpGET",
       "(Ljava/lang/String;Ljava/util/List;)" TYP("ServerResponse"));
 
   AdblockPlus::ServerResponse sResponse;
   sResponse.status = AdblockPlus::WebRequest::NS_ERROR_FAILURE;
 
   if (method)
   {
     JniLocalReference<jobject> arrayList(*env, NewJniArrayList(*env));
+    jmethodID addMethod = JniGetAddToListMethod(*env, *arrayList);
 
     for (AdblockPlus::HeaderList::const_iterator it = requestHeaders.begin(),
         end = requestHeaders.end(); it != end; it++)
     {
-      JniLocalReference<jobject> tuple(*env,
-          NewTuple(*env, it->first, it->second));
-      JniAddObjectToList(*env, *arrayList, *tuple);
+      JniLocalReference<jobject> headerEntry(*env, NewTuple(*env, it->first, it->second));
+      JniAddObjectToList(*env, *arrayList, addMethod, *headerEntry);
     }
 
     JniLocalReference<jobject> response(*env,
         env->CallObjectMethod(GetCallbackObject(), method,
             *JniLocalReference<jstring>(*env, env->NewStringUTF(url.c_str())),
             *arrayList));
 
     if (!env->ExceptionCheck())
     {
       sResponse.status = JniGetLongField(*env, serverResponseClass->Get(),
           *response, "status");
       sResponse.responseStatus = JniGetIntField(*env,
-          serverResponseClass->Get(), *response, "responseStatus");
+                                                serverResponseClass->Get(),
+                                                *response,
+                                                "responseStatus");
       sResponse.responseText = JniGetStringField(*env,
-          serverResponseClass->Get(), *response, "response");
+                                                 serverResponseClass->Get(),
+                                                 *response,
+                                                 "response");
 
       // map headers
       jobjectArray responseHeadersArray = JniGetStringArrayField(*env,
-        serverResponseClass->Get(), *response, "headers");
+                                                                 serverResponseClass->Get(),
+                                                                 *response,
+                                                                 "headers");
 
       if (responseHeadersArray)
       {
         int itemsCount = env->GetArrayLength(responseHeadersArray) / 2;
         for (int i = 0; i < itemsCount; i++)
         {
           jstring jKey = (jstring)env->GetObjectArrayElement(responseHeadersArray, i * 2);
           std::string stdKey = JniJavaToStdString(*env, jKey);
           
           jstring jValue = (jstring)env->GetObjectArrayElement(responseHeadersArray, i * 2 + 1);
           std::string stdValue = JniJavaToStdString(*env, jValue);
           
           std::pair<std::string,std::string>  keyValue(stdKey, stdValue);
           sResponse.responseHeaders.push_back(keyValue);
         }
       }
     }
   }
 
   CheckAndLogJavaException(*env);
 
   return sResponse;
 }
 
 jobject JniWebRequest::NewTuple(JNIEnv* env, const std::string& a,
     const std::string& b) const
 {
-  jmethodID factory = env->GetMethodID(tupleClass->Get(), "<init>",
+  jmethodID factory = env->GetMethodID(headerEntryClass->Get(), "<init>",
       "(Ljava/lang/String;Ljava/lang/String;)V");
 
   JniLocalReference<jstring> strA(env, env->NewStringUTF(a.c_str()));
   JniLocalReference<jstring> strB(env, env->NewStringUTF(b.c_str()));
 
-  return env->NewObject(tupleClass->Get(), factory, *strA, *strB);
+  return env->NewObject(headerEntryClass->Get(), factory, *strA, *strB);
 }
 
 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_WebRequest_registerNatives(JNIEnv *env, jclass clazz)
 {
   env->RegisterNatives(clazz, methods, sizeof(methods) / sizeof(methods[0]));
 }