ceph/src/rocksdb/java/rocksjni/jnicallback.cc

   1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under both the GPLv2 (found in the
   3 //  COPYING file in the root directory) and Apache 2.0 License
   4 //  (found in the LICENSE.Apache file in the root directory).
   5 //
   6 // This file implements the callback "bridge" between Java and C++ for
   7 // JNI Callbacks from C++ to sub-classes or org.rocksdb.RocksCallbackObject
   8
   9 #include <assert.h>
  10 #include "rocksjni/jnicallback.h"
  11 #include "rocksjni/portal.h"
  12
  13 namespace ROCKSDB_NAMESPACE {
  14 JniCallback::JniCallback(JNIEnv* env, jobject jcallback_obj) {
  15   // Note: jcallback_obj may be accessed by multiple threads,
  16   // so we ref the jvm not the env
  17   const jint rs = env->GetJavaVM(&m_jvm);
  18   if(rs != JNI_OK) {
  19     // exception thrown
  20     return;
  21   }
  22
  23   // Note: we may want to access the Java callback object instance
  24   // across multiple method calls, so we create a global ref
  25   assert(jcallback_obj != nullptr);
  26   m_jcallback_obj = env->NewGlobalRef(jcallback_obj);
  27   if(jcallback_obj == nullptr) {
  28     // exception thrown: OutOfMemoryError
  29     return;
  30   }
  31 }
  32
  33 JNIEnv* JniCallback::getJniEnv(jboolean* attached) const {
  34   return JniUtil::getJniEnv(m_jvm, attached);
  35 }
  36
  37 void JniCallback::releaseJniEnv(jboolean& attached) const {
  38   JniUtil::releaseJniEnv(m_jvm, attached);
  39 }
  40
  41 JniCallback::~JniCallback() {
  42   jboolean attached_thread = JNI_FALSE;
  43   JNIEnv* env = getJniEnv(&attached_thread);
  44   assert(env != nullptr);
  45
  46   if(m_jcallback_obj != nullptr) {
  47     env->DeleteGlobalRef(m_jcallback_obj);
  48   }
  49
  50   releaseJniEnv(attached_thread);
  51 }
  52 // @lint-ignore TXT4 T25377293 Grandfathered in
  53 }  // namespace ROCKSDB_NAMESPACE