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rocksdb/java/rocksjni/portal.h

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// Copyright (c) 2014, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
// This file is designed for caching those frequently used IDs and provide
// efficient portal (i.e, a set of static functions) to access java code
// from c++.
#ifndef JAVA_ROCKSJNI_PORTAL_H_
#define JAVA_ROCKSJNI_PORTAL_H_
#include <jni.h>
#include "rocksdb/db.h"
namespace rocksdb {
// The portal class for org.rocksdb.RocksDB
class RocksDBJni {
public:
// Get the java class id of org.rocksdb.RocksDB.
static jclass getJClass(JNIEnv* env) {
static jclass jclazz = env->FindClass("org/rocksdb/RocksDB");
assert(jclazz != nullptr);
return jclazz;
}
// Get the field id of the member variable of org.rocksdb.RocksDB
// that stores the pointer to rocksdb::DB.
static jfieldID getHandleFieldID(JNIEnv* env) {
static jfieldID fid = env->GetFieldID(
getJClass(env), "nativeHandle_", "J");
assert(fid != nullptr);
return fid;
}
// Get the pointer to rocksdb::DB of the specified org.rocksdb.RocksDB.
static rocksdb::DB* getHandle(JNIEnv* env, jobject jdb) {
return reinterpret_cast<rocksdb::DB*>(
env->GetLongField(jdb, getHandleFieldID(env)));
}
// Pass the rocksdb::DB pointer to the java side.
static void setHandle(JNIEnv* env, jobject jdb, rocksdb::DB* db) {
env->SetLongField(
jdb, getHandleFieldID(env),
reinterpret_cast<jlong>(db));
}
};
// The portal class for org.rocksdb.RocksDBException
class RocksDBExceptionJni {
public:
// Get the jclass of org.rocksdb.RocksDBException
static jclass getJClass(JNIEnv* env) {
static jclass jclazz = env->FindClass("org/rocksdb/RocksDBException");
assert(jclazz != nullptr);
return jclazz;
}
// Create and throw a java exception by converting the input
// Status to an RocksDBException.
//
// In case s.ok() is true, then this function will not throw any
// exception.
static void ThrowNew(JNIEnv* env, Status s) {
if (s.ok()) {
return;
}
jstring msg = env->NewStringUTF(s.ToString().c_str());
// get the constructor id of org.rocksdb.RocksDBException
static jmethodID mid = env->GetMethodID(
getJClass(env), "<init>", "(Ljava/lang/String;)V");
assert(mid != nullptr);
env->Throw((jthrowable)env->NewObject(getJClass(env), mid, msg));
}
};
} // namespace rocksdb
#endif // JAVA_ROCKSJNI_PORTAL_H_