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rocksdb/java/rocksjni/jnicallback.cc

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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
// This file implements the callback "bridge" between Java and C++ for
// JNI Callbacks from C++ to sub-classes or org.rocksdb.RocksCallbackObject
#include "rocksjni/jnicallback.h"
#include <assert.h>
#include "rocksjni/portal.h"
namespace ROCKSDB_NAMESPACE {
JniCallback::JniCallback(JNIEnv* env, jobject jcallback_obj) {
// Note: jcallback_obj may be accessed by multiple threads,
// so we ref the jvm not the env
const jint rs = env->GetJavaVM(&m_jvm);
if (rs != JNI_OK) {
// exception thrown
return;
}
// Note: we may want to access the Java callback object instance
// across multiple method calls, so we create a global ref
assert(jcallback_obj != nullptr);
m_jcallback_obj = env->NewGlobalRef(jcallback_obj);
if (jcallback_obj == nullptr) {
// exception thrown: OutOfMemoryError
return;
}
}
JNIEnv* JniCallback::getJniEnv(jboolean* attached) const {
return JniUtil::getJniEnv(m_jvm, attached);
}
void JniCallback::releaseJniEnv(jboolean& attached) const {
JniUtil::releaseJniEnv(m_jvm, attached);
}
JniCallback::~JniCallback() {
jboolean attached_thread = JNI_FALSE;
JNIEnv* env = getJniEnv(&attached_thread);
assert(env != nullptr);
if (m_jcallback_obj != nullptr) {
env->DeleteGlobalRef(m_jcallback_obj);
}
releaseJniEnv(attached_thread);
}
} // namespace ROCKSDB_NAMESPACE