text: /*
   * fdbJNI.cpp
   *
   * This source file is part of the FoundationDB open source project
   *
   * Copyright 2013-2022 Apple Inc. and the FoundationDB project authors
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #include <jni.h>
  #include <string.h>
  #include <functional>
  
  #include "com_apple_foundationdb_FDB.h"
  #include "com_apple_foundationdb_FDBDatabase.h"
  #include "com_apple_foundationdb_FDBTransaction.h"
  #include "com_apple_foundationdb_FutureInt64.h"
  #include "com_apple_foundationdb_FutureKey.h"
  #include "com_apple_foundationdb_FutureKeyArray.h"
  #include "com_apple_foundationdb_FutureResult.h"
  #include "com_apple_foundationdb_FutureResults.h"
  #include "com_apple_foundationdb_FutureStrings.h"
  #include "com_apple_foundationdb_NativeFuture.h"
  
  #define FDB_API_VERSION 710
  
  #include <foundationdb/fdb_c.h>
  
  #define JNI_NULL nullptr
  
  #if defined(__GNUG__)
  #undef JNIEXPORT
  #define JNIEXPORT __attribute__((visibility("default")))
  #endif
  
  static JavaVM* g_jvm = nullptr;
  static thread_local JNIEnv* g_thread_jenv =
      nullptr; // Defined for the network thread once it is running, and for any thread that has called registerCallback
  static thread_local jmethodID g_IFutureCallback_call_methodID = JNI_NULL;
  static thread_local bool is_external = false;
  static jclass range_result_summary_class;
  static jclass range_result_class;
  static jclass mapped_range_result_class;
  static jclass mapped_key_value_class;
  static jclass string_class;
  static jclass key_array_result_class;
  static jmethodID key_array_result_init;
  static jmethodID range_result_init;
  static jmethodID mapped_range_result_init;
  static jmethodID mapped_key_value_from_bytes;
  static jmethodID range_result_summary_init;
  
  void detachIfExternalThread(void* ignore) {
  	if (is_external && g_thread_jenv != nullptr) {
  		g_thread_jenv = nullptr;
  		g_IFutureCallback_call_methodID = JNI_NULL;
  		g_jvm->DetachCurrentThread();
  	}
  }
  
  void throwOutOfMem(JNIEnv* jenv) {
  	const char* className = "java/lang/OutOfMemoryError";
  	jclass illegalArgClass = jenv->FindClass(className);
  
  	if (jenv->ExceptionOccurred())
  		return;
  
  	if (jenv->ThrowNew(illegalArgClass, nullptr) != 0) {
  		if (!jenv->ExceptionOccurred()) {
  			jenv->FatalError("Could not throw OutOfMemoryError");
  		} else {
  			// This means that an exception is pending. We do not know what it is, but are sure
  			//  that control flow will include throwing that exception into the calling Java code.
  		}
  	}
  }
  
  static jthrowable getThrowable(JNIEnv* jenv, fdb_error_t e, const char* msg = nullptr) {
  	jclass excepClass = jenv->FindClass("com/apple/foundationdb/FDBException");
  	if (jenv->ExceptionOccurred())
  		return JNI_NULL;
  
  	jmethodID excepCtor = jenv->GetMethodID(excepClass, "<init>", "(Ljava/lang/String;I)V");
  	if (jenv->ExceptionOccurred())
  		return JNI_NULL;
  
  	const char* fdb_message = msg ? msg : fdb_get_error(e);
  	jstring m = jenv->NewStringUTF(fdb_message);
  	if (jenv->ExceptionOccurred())
  		return JNI_NULL;
  
  	jthrowable t = (jthrowable)jenv->NewObject(excepClass, excepCtor, m, e);
  	if (jenv->ExceptionOccurred())
  		return JNI_NULL;
  
  	return t;
  }
  
  void throwNamedException(JNIEnv* jenv, const char* class_full_name, const char* message) {
  	jclass exceptionClass = jenv->FindClass(class_full_name);
  	if (jenv->ExceptionOccurred())
  		return;
  
  	if (jenv->ThrowNew(exceptionClass, message) != 0) {
  		if (jenv->ExceptionOccurred())
  			return;
  		jenv->FatalError("FDB: Error throwing exception");
  	}
  }
  
  void throwRuntimeEx(JNIEnv* jenv, const char* message) {
  	throwNamedException(jenv, "java/lang/RuntimeException", message);
  }
  
  void throwParamNotNull(JNIEnv* jenv) {
  	throwNamedException(jenv, "java/lang/IllegalArgumentException", "Argument cannot be null");
  }
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  // If the methods are not found, exceptions are thrown and this will return false.
  //  Returns TRUE on success, false otherwise.
  static bool findCallbackMethods(JNIEnv* jenv) {
  	jclass cls = jenv->FindClass("java/lang/Runnable");
  	if (jenv->ExceptionOccurred())
  		return false;
  
  	g_IFutureCallback_call_methodID = jenv->GetMethodID(cls, "run", "()V");
  	if (jenv->ExceptionOccurred())
  		return false;
  
  	return true;
  }
  
  static void callCallback(FDBFuture* f, void* data) {
  	if (g_thread_jenv == nullptr) {
  		// We are on an external thread and must attach to the JVM.
  		// The shutdown hook will later detach this thread.
  		is_external = true;
  		if (g_jvm != nullptr && g_jvm->AttachCurrentThreadAsDaemon((void**)&g_thread_jenv, nullptr) == JNI_OK) {
  			if (!findCallbackMethods(g_thread_jenv)) {
  				g_thread_jenv->FatalError("FDB: Could not find callback method.\n");
  			}
  		} else {
  			// Can't call FatalError, because we don't have a pointer to the jenv...
  			// There will be a segmentation fault from the attempt to call the callback method.
  			fprintf(stderr, "FDB: Could not attach external client thread to the JVM as daemon.\n");
  		}
  	}
  
  	jobject callback = (jobject)data;
  	g_thread_jenv->CallVoidMethod(callback, g_IFutureCallback_call_methodID);
  	g_thread_jenv->DeleteGlobalRef(callback);
  }
  
  // Attempts to throw 't', attempts to shut down the JVM if this fails.
  void safeThrow(JNIEnv* jenv, jthrowable t) {
  	if (jenv->Throw(t) != 0) {
  		jenv->FatalError("FDB: Unable to throw exception");
  	}
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_NativeFuture_Future_1registerCallback(JNIEnv* jenv,
                                                                                           jobject cls,
                                                                                           jlong future,
                                                                                           jobject callback) {
  	// SOMEDAY: Do this on module load instead. Can we cache method ids across threads?
  	if (!g_IFutureCallback_call_methodID) {
  		if (!findCallbackMethods(jenv)) {
  			return;
  		}
  	}
  
  	if (!future || !callback) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	FDBFuture* f = (FDBFuture*)future;
  
  	// This is documented as not throwing, but simply returning null on OOM.
  	//  As belt and suspenders, we will check for pending exceptions and then,
  	//  if there are none and the result is null, we'll throw our own OOM.
  	callback = jenv->NewGlobalRef(callback);
  	if (!callback) {
  		if (!jenv->ExceptionOccurred())
  			throwOutOfMem(jenv);
  		return;
  	}
  
  	// Here we cache a thread-local reference to jenv
  	g_thread_jenv = jenv;
  	fdb_error_t err = fdb_future_set_callback(f, &callCallback, callback);
  	if (err) {
  		jenv->DeleteGlobalRef(callback);
  		safeThrow(jenv, getThrowable(jenv, err));
  	}
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_NativeFuture_Future_1blockUntilReady(JNIEnv* jenv,
                                                                                          jobject,
                                                                                          jlong future) {
  	if (!future) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	FDBFuture* sav = (FDBFuture*)future;
  
  	fdb_error_t err = fdb_future_block_until_ready(sav);
  	if (err)
  		safeThrow(jenv, getThrowable(jenv, err));
  }
  
  JNIEXPORT jthrowable JNICALL Java_com_apple_foundationdb_NativeFuture_Future_1getError(JNIEnv* jenv,
                                                                                         jobject,
                                                                                         jlong future) {
  	if (!future) {
  		throwParamNotNull(jenv);
  		return JNI_NULL;
  	}
  	FDBFuture* sav = (FDBFuture*)future;
  	fdb_error_t err = fdb_future_get_error(sav);
  	if (err)
  		return getThrowable(jenv, err);
  	else
  		return JNI_NULL;
  }
  
  JNIEXPORT jboolean JNICALL Java_com_apple_foundationdb_NativeFuture_Future_1isReady(JNIEnv* jenv,
                                                                                      jobject,
                                                                                      jlong future) {
  	if (!future) {
  		throwParamNotNull(jenv);
  		return JNI_FALSE;
  	}
  	FDBFuture* var = (FDBFuture*)future;
  	return (jboolean)fdb_future_is_ready(var);
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_NativeFuture_Future_1dispose(JNIEnv* jenv, jobject, jlong future) {
  	if (!future) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	FDBFuture* var = (FDBFuture*)future;
  	fdb_future_destroy(var);
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_NativeFuture_Future_1cancel(JNIEnv* jenv, jobject, jlong future) {
  	if (!future) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	FDBFuture* var = (FDBFuture*)future;
  	fdb_future_cancel(var);
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_NativeFuture_Future_1releaseMemory(JNIEnv* jenv,
                                                                                        jobject,
                                                                                        jlong future) {
  	if (!future) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	FDBFuture* var = (FDBFuture*)future;
  	fdb_future_release_memory(var);
  }
  
  JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FutureInt64_FutureInt64_1get(JNIEnv* jenv, jobject, jlong future) {
  	if (!future) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBFuture* f = (FDBFuture*)future;
  
  	int64_t value = 0;
  	fdb_error_t err = fdb_future_get_int64(f, &value);
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  		return 0;
  	}
  
  	return (jlong)value;
  }
  
  JNIEXPORT jobjectArray JNICALL Java_com_apple_foundationdb_FutureStrings_FutureStrings_1get(JNIEnv* jenv,
                                                                                              jobject,
                                                                                              jlong future) {
  	if (!future) {
  		throwParamNotNull(jenv);
  		return JNI_NULL;
  	}
  	FDBFuture* f = (FDBFuture*)future;
  
  	const char** strings;
  	int count;
  	fdb_error_t err = fdb_future_get_string_array(f, &strings, &count);
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  		return JNI_NULL;
  	}
  
  	if (jenv->ExceptionOccurred())
  		return JNI_NULL;
  	jobjectArray arr = jenv->NewObjectArray(count, string_class, JNI_NULL);
  	if (!arr) {
  		if (!jenv->ExceptionOccurred())
  			throwOutOfMem(jenv);
  		return JNI_NULL;
  	}
  
  	for (int i = 0; i < count; i++) {
  		jstring str = jenv->NewStringUTF(strings[i]);
  		if (!str) {
  			if (!jenv->ExceptionOccurred())
  				throwOutOfMem(jenv);
  			return JNI_NULL;
  		}
  
  		jenv->SetObjectArrayElement(arr, i, str);
  		if (jenv->ExceptionOccurred())
  			return JNI_NULL;
  	}
  
  	return arr;
  }
  
  JNIEXPORT jobject JNICALL Java_com_apple_foundationdb_FutureKeyArray_FutureKeyArray_1get(JNIEnv* jenv,
                                                                                           jobject,
                                                                                           jlong future) {
  	if (!future) {
  		throwParamNotNull(jenv);
  		return JNI_NULL;
  	}
  
  	FDBFuture* f = (FDBFuture*)future;
  
  	const FDBKey* ks;
  	int count;
  	fdb_error_t err = fdb_future_get_key_array(f, &ks, &count);
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  		return JNI_NULL;
  	}
  
  	int totalKeySize = 0;
  	for (int i = 0; i < count; i++) {
  		totalKeySize += ks[i].key_length;
  	}
  
  	jbyteArray keyArray = jenv->NewByteArray(totalKeySize);
  	if (!keyArray) {
  		if (!jenv->ExceptionOccurred())
  			throwOutOfMem(jenv);
  		return JNI_NULL;
  	}
  	uint8_t* keys_barr = (uint8_t*)jenv->GetByteArrayElements(keyArray, JNI_NULL);
  	if (!keys_barr) {
  		throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return JNI_NULL;
  	}
  
  	jintArray lengthArray = jenv->NewIntArray(count);
  	if (!lengthArray) {
  		if (!jenv->ExceptionOccurred())
  			throwOutOfMem(jenv);
  
  		jenv->ReleaseByteArrayElements(keyArray, (jbyte*)keys_barr, 0);
  		return JNI_NULL;
  	}
  
  	jint* length_barr = jenv->GetIntArrayElements(lengthArray, JNI_NULL);
  	if (!length_barr) {
  		if (!jenv->ExceptionOccurred())
  			throwOutOfMem(jenv);
  
  		jenv->ReleaseByteArrayElements(keyArray, (jbyte*)keys_barr, 0);
  		return JNI_NULL;
  	}
  
  	int offset = 0;
  	for (int i = 0; i < count; i++) {
  		memcpy(keys_barr + offset, ks[i].key, ks[i].key_length);
  		length_barr[i] = ks[i].key_length;
  		offset += ks[i].key_length;
  	}
  
  	jenv->ReleaseByteArrayElements(keyArray, (jbyte*)keys_barr, 0);
  	jenv->ReleaseIntArrayElements(lengthArray, length_barr, 0);
  
  	jobject result = jenv->NewObject(key_array_result_class, key_array_result_init, keyArray, lengthArray);
  	if (jenv->ExceptionOccurred())
  		return JNI_NULL;
  
  	return result;
  }
  
  // SOMEDAY: explore doing this more efficiently with Direct ByteBuffers
  JNIEXPORT jobject JNICALL Java_com_apple_foundationdb_FutureResults_FutureResults_1get(JNIEnv* jenv,
                                                                                         jobject,
                                                                                         jlong future) {
  	if (!future) {
  		throwParamNotNull(jenv);
  		return JNI_NULL;
  	}
  
  	FDBFuture* f = (FDBFuture*)future;
  
  	const FDBKeyValue* kvs;
  	int count;
  	fdb_bool_t more;
  	fdb_error_t err = fdb_future_get_keyvalue_array(f, &kvs, &count, &more);
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  		return JNI_NULL;
  	}
  
  	int totalKeyValueSize = 0;
  	for (int i = 0; i < count; i++) {
  		totalKeyValueSize += kvs[i].key_length + kvs[i].value_length;
  	}
  
  	jbyteArray keyValueArray = jenv->NewByteArray(totalKeyValueSize);
  	if (!keyValueArray) {
  		if (!jenv->ExceptionOccurred())
  			throwOutOfMem(jenv);
  		return JNI_NULL;
  	}
  	uint8_t* keyvalues_barr = (uint8_t*)jenv->GetByteArrayElements(keyValueArray, JNI_NULL);
  	if (!keyvalues_barr) {
  		throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return JNI_NULL;
  	}
  
  	jintArray lengthArray = jenv->NewIntArray(count * 2);
  	if (!lengthArray) {
  		if (!jenv->ExceptionOccurred())
  			throwOutOfMem(jenv);
  
  		jenv->ReleaseByteArrayElements(keyValueArray, (jbyte*)keyvalues_barr, 0);
  		return JNI_NULL;
  	}
  
  	jint* length_barr = jenv->GetIntArrayElements(lengthArray, JNI_NULL);
  	if (!length_barr) {
  		if (!jenv->ExceptionOccurred())
  			throwOutOfMem(jenv);
  
  		jenv->ReleaseByteArrayElements(keyValueArray, (jbyte*)keyvalues_barr, 0);
  		return JNI_NULL;
  	}
  
  	int offset = 0;
  	for (int i = 0; i < count; i++) {
  		memcpy(keyvalues_barr + offset, kvs[i].key, kvs[i].key_length);
  		length_barr[i * 2] = kvs[i].key_length;
  		offset += kvs[i].key_length;
  
  		memcpy(keyvalues_barr + offset, kvs[i].value, kvs[i].value_length);
  		length_barr[(i * 2) + 1] = kvs[i].value_length;
  		offset += kvs[i].value_length;
  	}
  
  	jenv->ReleaseByteArrayElements(keyValueArray, (jbyte*)keyvalues_barr, 0);
  	jenv->ReleaseIntArrayElements(lengthArray, length_barr, 0);
  
  	jobject result = jenv->NewObject(range_result_class, range_result_init, keyValueArray, lengthArray, (jboolean)more);
  	if (jenv->ExceptionOccurred())
  		return JNI_NULL;
  
  	return result;
  }
  
  class ExecuteOnLeave {
  	std::function<void()> func;
  
  public:
  	explicit ExecuteOnLeave(std::function<void()> func) : func(func) {}
  	~ExecuteOnLeave() { func(); }
  };
  
  void cpBytesAndLengthInner(uint8_t*& pByte, jint*& pLength, const uint8_t* data, const int& length) {
  	*pLength = length;
  	pLength++;
  
  	memcpy(pByte, data, length);
  	pByte += length;
  }
  
  void cpBytesAndLength(uint8_t*& pByte, jint*& pLength, const FDBKey& key) {
  	cpBytesAndLengthInner(pByte, pLength, key.key, key.key_length);
  }
  
  JNIEXPORT jobject JNICALL Java_com_apple_foundationdb_FutureMappedResults_FutureMappedResults_1get(JNIEnv* jenv,
                                                                                                     jobject,
                                                                                                     jlong future) {
  	if (!future) {
  		throwParamNotNull(jenv);
  		return JNI_NULL;
  	}
  
  	FDBFuture* f = (FDBFuture*)future;
  
  	const FDBMappedKeyValue* kvms;
  	int count;
  	fdb_bool_t more;
  	fdb_error_t err = fdb_future_get_mappedkeyvalue_array(f, &kvms, &count, &more);
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  		return JNI_NULL;
  	}
  
  	jobjectArray mrr_values = jenv->NewObjectArray(count, mapped_key_value_class, NULL);
  	if (!mrr_values) {
  		if (!jenv->ExceptionOccurred())
  			throwOutOfMem(jenv);
  		return JNI_NULL;
  	}
  
  	for (int i = 0; i < count; i++) {
  		FDBMappedKeyValue kvm = kvms[i];
  		int kvm_count = kvm.getRange.m_size;
  
  		const int totalLengths = 4 + kvm_count * 2;
  
  		int totalBytes = kvm.key.key_length + kvm.value.key_length + kvm.getRange.begin.key.key_length +
  		                 kvm.getRange.end.key.key_length;
  		for (int i = 0; i < kvm_count; i++) {
  			auto kv = kvm.getRange.data[i];
  			totalBytes += kv.key_length + kv.value_length;
  		}
  
  		jbyteArray bytesArray = jenv->NewByteArray(totalBytes);
  		if (!bytesArray) {
  			if (!jenv->ExceptionOccurred())
  				throwOutOfMem(jenv);
  			return JNI_NULL;
  		}
  
  		jintArray lengthArray = jenv->NewIntArray(totalLengths);
  		if (!lengthArray) {
  			if (!jenv->ExceptionOccurred())
  				throwOutOfMem(jenv);
  			return JNI_NULL;
  		}
  
  		uint8_t* bytes_barr = (uint8_t*)jenv->GetByteArrayElements(bytesArray, JNI_NULL);
  		if (!bytes_barr) {
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  			return JNI_NULL;
  		}
  		{
  			ExecuteOnLeave e([&]() { jenv->ReleaseByteArrayElements(bytesArray, (jbyte*)bytes_barr, 0); });
  
  			jint* length_barr = jenv->GetIntArrayElements(lengthArray, JNI_NULL);
  			if (!length_barr) {
  				if (!jenv->ExceptionOccurred())
  					throwOutOfMem(jenv);
  				return JNI_NULL;
  			}
  			{
  				ExecuteOnLeave e([&]() { jenv->ReleaseIntArrayElements(lengthArray, length_barr, 0); });
  
  				uint8_t* pByte = bytes_barr;
  				jint* pLength = length_barr;
  
  				cpBytesAndLength(pByte, pLength, kvm.key);
  				cpBytesAndLength(pByte, pLength, kvm.value);
  				cpBytesAndLength(pByte, pLength, kvm.getRange.begin.key);
  				cpBytesAndLength(pByte, pLength, kvm.getRange.end.key);
  				for (int kvm_i = 0; kvm_i < kvm_count; kvm_i++) {
  					auto kv = kvm.getRange.data[kvm_i];
  					cpBytesAndLengthInner(pByte, pLength, kv.key, kv.key_length);
  					cpBytesAndLengthInner(pByte, pLength, kv.value, kv.value_length);
  				}
  			}
  		}
  		// After native arrays are released
  		jobject mkv = jenv->CallStaticObjectMethod(
  		    mapped_key_value_class, mapped_key_value_from_bytes, (jbyteArray)bytesArray, (jintArray)lengthArray);
  		if (jenv->ExceptionOccurred())
  			return JNI_NULL;
  		jenv->SetObjectArrayElement(mrr_values, i, mkv);
  		if (jenv->ExceptionOccurred())
  			return JNI_NULL;
  	}
  
  	jobject mrr = jenv->NewObject(mapped_range_result_class, mapped_range_result_init, mrr_values, (jboolean)more);
  	if (jenv->ExceptionOccurred())
  		return JNI_NULL;
  
  	return mrr;
  }
  
  // SOMEDAY: explore doing this more efficiently with Direct ByteBuffers
  JNIEXPORT jbyteArray JNICALL Java_com_apple_foundationdb_FutureResult_FutureResult_1get(JNIEnv* jenv,
                                                                                          jobject,
                                                                                          jlong future) {
  	if (!future) {
  		throwParamNotNull(jenv);
  		return JNI_NULL;
  	}
  	FDBFuture* f = (FDBFuture*)future;
  
  	fdb_bool_t present;
  	const uint8_t* value;
  	int length;
  	fdb_error_t err = fdb_future_get_value(f, &present, &value, &length);
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  		return JNI_NULL;
  	}
  
  	if (!present)
  		return JNI_NULL;
  
  	jbyteArray result = jenv->NewByteArray(length);
  	if (!result) {
  		if (!jenv->ExceptionOccurred())
  			throwOutOfMem(jenv);
  		return JNI_NULL;
  	}
  
  	jenv->SetByteArrayRegion(result, 0, length, (const jbyte*)value);
  	return result;
  }
  
  JNIEXPORT jbyteArray JNICALL Java_com_apple_foundationdb_FutureKey_FutureKey_1get(JNIEnv* jenv, jobject, jlong future) {
  	if (!future) {
  		throwParamNotNull(jenv);
  		return JNI_NULL;
  	}
  	FDBFuture* f = (FDBFuture*)future;
  
  	const uint8_t* value;
  	int length;
  	fdb_error_t err = fdb_future_get_key(f, &value, &length);
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  		return JNI_NULL;
  	}
  
  	jbyteArray result = jenv->NewByteArray(length);
  	if (!result) {
  		if (!jenv->ExceptionOccurred())
  			throwOutOfMem(jenv);
  		return JNI_NULL;
  	}
  
  	jenv->SetByteArrayRegion(result, 0, length, (const jbyte*)value);
  	return result;
  }
  
  JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDBDatabase_Database_1createTransaction(JNIEnv* jenv,
                                                                                              jobject,
                                                                                              jlong dbPtr) {
  	if (!dbPtr) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBDatabase* database = (FDBDatabase*)dbPtr;
  	FDBTransaction* tr;
  	fdb_error_t err = fdb_database_create_transaction(database, &tr);
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  		return 0;
  	}
  	return (jlong)tr;
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDBDatabase_Database_1dispose(JNIEnv* jenv, jobject, jlong dPtr) {
  	if (!dPtr) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	fdb_database_destroy((FDBDatabase*)dPtr);
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDBDatabase_Database_1setOption(JNIEnv* jenv,
                                                                                     jobject,
                                                                                     jlong dPtr,
                                                                                     jint code,
                                                                                     jbyteArray value) {
  	if (!dPtr) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	FDBDatabase* c = (FDBDatabase*)dPtr;
  	uint8_t* barr = nullptr;
  	int size = 0;
  
  	if (value != JNI_NULL) {
  		barr = (uint8_t*)jenv->GetByteArrayElements(value, JNI_NULL);
  		if (!barr) {
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  			return;
  		}
  		size = jenv->GetArrayLength(value);
  	}
  	fdb_error_t err = fdb_database_set_option(c, (FDBDatabaseOption)code, barr, size);
  	if (value != JNI_NULL)
  		jenv->ReleaseByteArrayElements(value, (jbyte*)barr, JNI_ABORT);
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  	}
  }
  
  // Get network thread busyness (updated every 1s)
  // A value of 0 indicates that the client is more or less idle
  // A value of 1 (or more) indicates that the client is saturated
  JNIEXPORT jdouble JNICALL Java_com_apple_foundationdb_FDBDatabase_Database_1getMainThreadBusyness(JNIEnv* jenv,
                                                                                                    jobject,
                                                                                                    jlong dbPtr) {
  	if (!dbPtr) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBDatabase* database = (FDBDatabase*)dbPtr;
  	return (jdouble)fdb_database_get_main_thread_busyness(database);
  }
  
  JNIEXPORT jboolean JNICALL Java_com_apple_foundationdb_FDB_Error_1predicate(JNIEnv* jenv,
                                                                              jobject,
                                                                              jint predicate,
                                                                              jint code) {
  	return (jboolean)fdb_error_predicate(predicate, code);
  }
  
  JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDB_Database_1create(JNIEnv* jenv,
                                                                           jobject,
                                                                           jstring clusterFileName) {
  	const char* fileName = nullptr;
  	if (clusterFileName != JNI_NULL) {
  		fileName = jenv->GetStringUTFChars(clusterFileName, JNI_NULL);
  		if (jenv->ExceptionOccurred()) {
  			return 0;
  		}
  	}
  
  	FDBDatabase* db;
  	fdb_error_t err = fdb_create_database(fileName, &db);
  
  	if (clusterFileName != JNI_NULL) {
  		jenv->ReleaseStringUTFChars(clusterFileName, fileName);
  	}
  
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  		return 0;
  	}
  
  	return (jlong)db;
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1setVersion(JNIEnv* jenv,
                                                                                            jobject,
                                                                                            jlong tPtr,
                                                                                            jlong version) {
  	if (!tPtr) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  	fdb_transaction_set_read_version(tr, version);
  }
  
  JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1getReadVersion(JNIEnv* jenv,
                                                                                                 jobject,
                                                                                                 jlong tPtr) {
  	if (!tPtr) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  	FDBFuture* f = fdb_transaction_get_read_version(tr);
  	return (jlong)f;
  }
  
  JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1get(JNIEnv* jenv,
                                                                                      jobject,
                                                                                      jlong tPtr,
                                                                                      jbyteArray keyBytes,
                                                                                      jboolean snapshot) {
  	if (!tPtr || !keyBytes) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  
  	uint8_t* barr = (uint8_t*)jenv->GetByteArrayElements(keyBytes, JNI_NULL);
  	if (!barr) {
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return 0;
  	}
  
  	FDBFuture* f = fdb_transaction_get(tr, barr, jenv->GetArrayLength(keyBytes), (fdb_bool_t)snapshot);
  	jenv->ReleaseByteArrayElements(keyBytes, (jbyte*)barr, JNI_ABORT);
  	return (jlong)f;
  }
  
  JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1getKey(JNIEnv* jenv,
                                                                                         jobject,
                                                                                         jlong tPtr,
                                                                                         jbyteArray keyBytes,
                                                                                         jboolean orEqual,
                                                                                         jint offset,
                                                                                         jboolean snapshot) {
  	if (!tPtr || !keyBytes) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  
  	uint8_t* barr = (uint8_t*)jenv->GetByteArrayElements(keyBytes, JNI_NULL);
  	if (!barr) {
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return 0;
  	}
  
  	FDBFuture* f =
  	    fdb_transaction_get_key(tr, barr, jenv->GetArrayLength(keyBytes), orEqual, offset, (fdb_bool_t)snapshot);
  	jenv->ReleaseByteArrayElements(keyBytes, (jbyte*)barr, JNI_ABORT);
  	return (jlong)f;
  }
  
  JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1getRange(JNIEnv* jenv,
                                                                                           jobject,
                                                                                           jlong tPtr,
                                                                                           jbyteArray keyBeginBytes,
                                                                                           jboolean orEqualBegin,
                                                                                           jint offsetBegin,
                                                                                           jbyteArray keyEndBytes,
                                                                                           jboolean orEqualEnd,
                                                                                           jint offsetEnd,
                                                                                           jint rowLimit,
                                                                                           jint targetBytes,
                                                                                           jint streamingMode,
                                                                                           jint iteration,
                                                                                           jboolean snapshot,
                                                                                           jboolean reverse) {
  	if (!tPtr || !keyBeginBytes || !keyEndBytes) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  
  	uint8_t* barrBegin = (uint8_t*)jenv->GetByteArrayElements(keyBeginBytes, JNI_NULL);
  	if (!barrBegin) {
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return 0;
  	}
  
  	uint8_t* barrEnd = (uint8_t*)jenv->GetByteArrayElements(keyEndBytes, JNI_NULL);
  	if (!barrEnd) {
  		jenv->ReleaseByteArrayElements(keyBeginBytes, (jbyte*)barrBegin, JNI_ABORT);
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return 0;
  	}
  
  	FDBFuture* f = fdb_transaction_get_range(tr,
  	                                         barrBegin,
  	                                         jenv->GetArrayLength(keyBeginBytes),
  	                                         orEqualBegin,
  	                                         offsetBegin,
  	                                         barrEnd,
  	                                         jenv->GetArrayLength(keyEndBytes),
  	                                         orEqualEnd,
  	                                         offsetEnd,
  	                                         rowLimit,
  	                                         targetBytes,
  	                                         (FDBStreamingMode)streamingMode,
  	                                         iteration,
  	                                         snapshot,
  	                                         reverse);
  	jenv->ReleaseByteArrayElements(keyBeginBytes, (jbyte*)barrBegin, JNI_ABORT);
  	jenv->ReleaseByteArrayElements(keyEndBytes, (jbyte*)barrEnd, JNI_ABORT);
  	return (jlong)f;
  }
  
  JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1getMappedRange(JNIEnv* jenv,
                                                                                                 jobject,
                                                                                                 jlong tPtr,
                                                                                                 jbyteArray keyBeginBytes,
                                                                                                 jboolean orEqualBegin,
                                                                                                 jint offsetBegin,
                                                                                                 jbyteArray keyEndBytes,
                                                                                                 jboolean orEqualEnd,
                                                                                                 jint offsetEnd,
                                                                                                 jbyteArray mapperBytes,
                                                                                                 jint rowLimit,
                                                                                                 jint targetBytes,
                                                                                                 jint streamingMode,
                                                                                                 jint iteration,
                                                                                                 jboolean snapshot,
                                                                                                 jboolean reverse) {
  	if (!tPtr || !keyBeginBytes || !keyEndBytes || !mapperBytes) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  
  	uint8_t* barrBegin = (uint8_t*)jenv->GetByteArrayElements(keyBeginBytes, JNI_NULL);
  	if (!barrBegin) {
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return 0;
  	}
  
  	uint8_t* barrEnd = (uint8_t*)jenv->GetByteArrayElements(keyEndBytes, JNI_NULL);
  	if (!barrEnd) {
  		jenv->ReleaseByteArrayElements(keyBeginBytes, (jbyte*)barrBegin, JNI_ABORT);
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return 0;
  	}
  
  	uint8_t* barrMapper = (uint8_t*)jenv->GetByteArrayElements(mapperBytes, JNI_NULL);
  	if (!barrMapper) {
  		jenv->ReleaseByteArrayElements(keyBeginBytes, (jbyte*)barrBegin, JNI_ABORT);
  		jenv->ReleaseByteArrayElements(keyEndBytes, (jbyte*)barrEnd, JNI_ABORT);
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return 0;
  	}
  
  	FDBFuture* f = fdb_transaction_get_mapped_range(tr,
  	                                                barrBegin,
  	                                                jenv->GetArrayLength(keyBeginBytes),
  	                                                orEqualBegin,
  	                                                offsetBegin,
  	                                                barrEnd,
  	                                                jenv->GetArrayLength(keyEndBytes),
  	                                                orEqualEnd,
  	                                                offsetEnd,
  	                                                barrMapper,
  	                                                jenv->GetArrayLength(mapperBytes),
  	                                                rowLimit,
  	                                                targetBytes,
  	                                                (FDBStreamingMode)streamingMode,
  	                                                iteration,
  	                                                snapshot,
  	                                                reverse);
  	jenv->ReleaseByteArrayElements(keyBeginBytes, (jbyte*)barrBegin, JNI_ABORT);
  	jenv->ReleaseByteArrayElements(keyEndBytes, (jbyte*)barrEnd, JNI_ABORT);
  	jenv->ReleaseByteArrayElements(mapperBytes, (jbyte*)barrMapper, JNI_ABORT);
  	return (jlong)f;
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FutureResults_FutureResults_1getDirect(JNIEnv* jenv,
                                                                                            jobject,
                                                                                            jlong future,
                                                                                            jobject jbuffer,
                                                                                            jint bufferCapacity) {
  	if (!future) {
  		throwParamNotNull(jenv);
  		return;
  	}
  
  	uint8_t* buffer = (uint8_t*)jenv->GetDirectBufferAddress(jbuffer);
  	if (!buffer) {
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return;
  	}
  
  	FDBFuture* f = (FDBFuture*)future;
  	const FDBKeyValue* kvs;
  	int count;
  	fdb_bool_t more;
  	fdb_error_t err = fdb_future_get_keyvalue_array(f, &kvs, &count, &more);
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  		return;
  	}
  
  	// Capacity for Metadata+Keys+Values
  	//  => sizeof(jint) for total key/value pairs
  	//  => sizeof(jint) to store more flag
  	//  => sizeof(jint) to store key length per KV pair
  	//  => sizeof(jint) to store value length per KV pair
  	int totalCapacityNeeded = 2 * sizeof(jint);
  	for (int i = 0; i < count; i++) {
  		totalCapacityNeeded += kvs[i].key_length + kvs[i].value_length + 2 * sizeof(jint);
  		if (bufferCapacity < totalCapacityNeeded) {
  			count = i; /* Only fit first `i` K/V pairs */
  			more = true;
  			break;
  		}
  	}
  
  	int offset = 0;
  
  	// First copy RangeResultSummary, i.e. [keyCount, more]
  	memcpy(buffer + offset, &count, sizeof(jint));
  	offset += sizeof(jint);
  
  	memcpy(buffer + offset, &more, sizeof(jint));
  	offset += sizeof(jint);
  
  	for (int i = 0; i < count; i++) {
  		memcpy(buffer + offset, &kvs[i].key_length, sizeof(jint));
  		memcpy(buffer + offset + sizeof(jint), &kvs[i].value_length, sizeof(jint));
  		offset += 2 * sizeof(jint);
  
  		memcpy(buffer + offset, kvs[i].key, kvs[i].key_length);
  		offset += kvs[i].key_length;
  
  		memcpy(buffer + offset, kvs[i].value, kvs[i].value_length);
  		offset += kvs[i].value_length;
  	}
  }
  
  void memcpyStringInner(uint8_t* buffer, int& offset, const uint8_t* data, const int& length) {
  	memcpy(buffer + offset, &length, sizeof(jint));
  	offset += sizeof(jint);
  	memcpy(buffer + offset, data, length);
  	offset += length;
  }
  
  void memcpyString(uint8_t* buffer, int& offset, const FDBKey& key) {
  	memcpyStringInner(buffer, offset, key.key, key.key_length);
  }
  
  JNIEXPORT void JNICALL
  Java_com_apple_foundationdb_FutureMappedResults_FutureMappedResults_1getDirect(JNIEnv* jenv,
                                                                                 jobject,
                                                                                 jlong future,
                                                                                 jobject jbuffer,
                                                                                 jint bufferCapacity) {
  
  	if (!future) {
  		throwParamNotNull(jenv);
  		return;
  	}
  
  	uint8_t* buffer = (uint8_t*)jenv->GetDirectBufferAddress(jbuffer);
  	if (!buffer) {
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return;
  	}
  
  	FDBFuture* f = (FDBFuture*)future;
  	const FDBMappedKeyValue* kvms;
  	int count;
  	fdb_bool_t more;
  	fdb_error_t err = fdb_future_get_mappedkeyvalue_array(f, &kvms, &count, &more);
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  		return;
  	}
  
  	int totalCapacityNeeded = 2 * sizeof(jint);
  	for (int i = 0; i < count; i++) {
  		const FDBMappedKeyValue& kvm = kvms[i];
  		totalCapacityNeeded += kvm.key.key_length + kvm.value.key_length + kvm.getRange.begin.key.key_length +
  		                       kvm.getRange.end.key.key_length +
  		                       5 * sizeof(jint); // Besides the 4 lengths above, also one for kvm_count.
  		int kvm_count = kvm.getRange.m_size;
  		for (int i = 0; i < kvm_count; i++) {
  			auto kv = kvm.getRange.data[i];
  			totalCapacityNeeded += kv.key_length + kv.value_length + 2 * sizeof(jint);
  		}
  		if (bufferCapacity < totalCapacityNeeded) {
  			count = i; /* Only fit first `i` K/V pairs */
  			more = true;
  			break;
  		}
  	}
  
  	int offset = 0;
  
  	// First copy RangeResultSummary, i.e. [keyCount, more]
  	memcpy(buffer + offset, &count, sizeof(jint));
  	offset += sizeof(jint);
  
  	memcpy(buffer + offset, &more, sizeof(jint));
  	offset += sizeof(jint);
  
  	for (int i = 0; i < count; i++) {
  		const FDBMappedKeyValue& kvm = kvms[i];
  		memcpyString(buffer, offset, kvm.key);
  		memcpyString(buffer, offset, kvm.value);
  		memcpyString(buffer, offset, kvm.getRange.begin.key);
  		memcpyString(buffer, offset, kvm.getRange.end.key);
  
  		int kvm_count = kvm.getRange.m_size;
  		memcpy(buffer + offset, &kvm_count, sizeof(jint));
  		offset += sizeof(jint);
  
  		for (int i = 0; i < kvm_count; i++) {
  			auto kv = kvm.getRange.data[i];
  			memcpyStringInner(buffer, offset, kv.key, kv.key_length);
  			memcpyStringInner(buffer, offset, kv.value, kv.value_length);
  		}
  	}
  }
  
  JNIEXPORT jlong JNICALL
  Java_com_apple_foundationdb_FDBTransaction_Transaction_1getEstimatedRangeSizeBytes(JNIEnv* jenv,
                                                                                     jobject,
                                                                                     jlong tPtr,
                                                                                     jbyteArray beginKeyBytes,
                                                                                     jbyteArray endKeyBytes) {
  	if (!tPtr || !beginKeyBytes || !endKeyBytes) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  
  	uint8_t* startKey = (uint8_t*)jenv->GetByteArrayElements(beginKeyBytes, JNI_NULL);
  	if (!startKey) {
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return 0;
  	}
  
  	uint8_t* endKey = (uint8_t*)jenv->GetByteArrayElements(endKeyBytes, JNI_NULL);
  	if (!endKey) {
  		jenv->ReleaseByteArrayElements(beginKeyBytes, (jbyte*)startKey, JNI_ABORT);
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return 0;
  	}
  
  	FDBFuture* f = fdb_transaction_get_estimated_range_size_bytes(
  	    tr, startKey, jenv->GetArrayLength(beginKeyBytes), endKey, jenv->GetArrayLength(endKeyBytes));
  	jenv->ReleaseByteArrayElements(beginKeyBytes, (jbyte*)startKey, JNI_ABORT);
  	jenv->ReleaseByteArrayElements(endKeyBytes, (jbyte*)endKey, JNI_ABORT);
  	return (jlong)f;
  }
  
  JNIEXPORT jlong JNICALL
  Java_com_apple_foundationdb_FDBTransaction_Transaction_1getRangeSplitPoints(JNIEnv* jenv,
                                                                              jobject,
                                                                              jlong tPtr,
                                                                              jbyteArray beginKeyBytes,
                                                                              jbyteArray endKeyBytes,
                                                                              jlong chunkSize) {
  	if (!tPtr || !beginKeyBytes || !endKeyBytes) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  
  	uint8_t* startKey = (uint8_t*)jenv->GetByteArrayElements(beginKeyBytes, JNI_NULL);
  	if (!startKey) {
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return 0;
  	}
  
  	uint8_t* endKey = (uint8_t*)jenv->GetByteArrayElements(endKeyBytes, JNI_NULL);
  	if (!endKey) {
  		jenv->ReleaseByteArrayElements(beginKeyBytes, (jbyte*)startKey, JNI_ABORT);
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return 0;
  	}
  
  	FDBFuture* f = fdb_transaction_get_range_split_points(
  	    tr, startKey, jenv->GetArrayLength(beginKeyBytes), endKey, jenv->GetArrayLength(endKeyBytes), chunkSize);
  	jenv->ReleaseByteArrayElements(beginKeyBytes, (jbyte*)startKey, JNI_ABORT);
  	jenv->ReleaseByteArrayElements(endKeyBytes, (jbyte*)endKey, JNI_ABORT);
  	return (jlong)f;
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1set(JNIEnv* jenv,
                                                                                     jobject,
                                                                                     jlong tPtr,
                                                                                     jbyteArray keyBytes,
                                                                                     jbyteArray valueBytes) {
  	if (!tPtr || !keyBytes || !valueBytes) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  
  	uint8_t* barrKey = (uint8_t*)jenv->GetByteArrayElements(keyBytes, JNI_NULL);
  	if (!barrKey) {
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return;
  	}
  
  	uint8_t* barrValue = (uint8_t*)jenv->GetByteArrayElements(valueBytes, JNI_NULL);
  	if (!barrValue) {
  		jenv->ReleaseByteArrayElements(keyBytes, (jbyte*)barrKey, JNI_ABORT);
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return;
  	}
  
  	fdb_transaction_set(tr, barrKey, jenv->GetArrayLength(keyBytes), barrValue, jenv->GetArrayLength(valueBytes));
  	jenv->ReleaseByteArrayElements(keyBytes, (jbyte*)barrKey, JNI_ABORT);
  	jenv->ReleaseByteArrayElements(valueBytes, (jbyte*)barrValue, JNI_ABORT);
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1clear__J_3B(JNIEnv* jenv,
                                                                                             jobject,
                                                                                             jlong tPtr,
                                                                                             jbyteArray keyBytes) {
  	if (!tPtr || !keyBytes) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  
  	uint8_t* barr = (uint8_t*)jenv->GetByteArrayElements(keyBytes, JNI_NULL);
  	if (!barr) {
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return;
  	}
  
  	fdb_transaction_clear(tr, barr, jenv->GetArrayLength(keyBytes));
  	jenv->ReleaseByteArrayElements(keyBytes, (jbyte*)barr, JNI_ABORT);
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1clear__J_3B_3B(JNIEnv* jenv,
                                                                                                jobject,
                                                                                                jlong tPtr,
                                                                                                jbyteArray keyBeginBytes,
                                                                                                jbyteArray keyEndBytes) {
  	if (!tPtr || !keyBeginBytes || !keyEndBytes) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  
  	uint8_t* barrKeyBegin = (uint8_t*)jenv->GetByteArrayElements(keyBeginBytes, JNI_NULL);
  	if (!barrKeyBegin) {
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return;
  	}
  
  	uint8_t* barrKeyEnd = (uint8_t*)jenv->GetByteArrayElements(keyEndBytes, JNI_NULL);
  	if (!barrKeyEnd) {
  		jenv->ReleaseByteArrayElements(keyBeginBytes, (jbyte*)barrKeyBegin, JNI_ABORT);
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return;
  	}
  
  	fdb_transaction_clear_range(
  	    tr, barrKeyBegin, jenv->GetArrayLength(keyBeginBytes), barrKeyEnd, jenv->GetArrayLength(keyEndBytes));
  	jenv->ReleaseByteArrayElements(keyBeginBytes, (jbyte*)barrKeyBegin, JNI_ABORT);
  	jenv->ReleaseByteArrayElements(keyEndBytes, (jbyte*)barrKeyEnd, JNI_ABORT);
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1mutate(JNIEnv* jenv,
                                                                                        jobject,
                                                                                        jlong tPtr,
                                                                                        jint code,
                                                                                        jbyteArray key,
                                                                                        jbyteArray value) {
  	if (!tPtr || !key || !value) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  
  	uint8_t* barrKey = (uint8_t*)jenv->GetByteArrayElements(key, JNI_NULL);
  	if (!barrKey) {
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return;
  	}
  
  	uint8_t* barrValue = (uint8_t*)jenv->GetByteArrayElements(value, JNI_NULL);
  	if (!barrValue) {
  		jenv->ReleaseByteArrayElements(key, (jbyte*)barrKey, JNI_ABORT);
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return;
  	}
  
  	fdb_transaction_atomic_op(
  	    tr, barrKey, jenv->GetArrayLength(key), barrValue, jenv->GetArrayLength(value), (FDBMutationType)code);
  
  	jenv->ReleaseByteArrayElements(key, (jbyte*)barrKey, JNI_ABORT);
  	jenv->ReleaseByteArrayElements(value, (jbyte*)barrValue, JNI_ABORT);
  }
  
  JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1commit(JNIEnv* jenv,
                                                                                         jobject,
                                                                                         jlong tPtr) {
  	if (!tPtr) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  	FDBFuture* f = fdb_transaction_commit(tr);
  	return (jlong)f;
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1setOption(JNIEnv* jenv,
                                                                                           jobject,
                                                                                           jlong tPtr,
                                                                                           jint code,
                                                                                           jbyteArray value) {
  	if (!tPtr) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  	uint8_t* barr = nullptr;
  	int size = 0;
  
  	if (value != JNI_NULL) {
  		barr = (uint8_t*)jenv->GetByteArrayElements(value, JNI_NULL);
  		if (!barr) {
  			if (!jenv->ExceptionOccurred())
  				throwRuntimeEx(jenv, "Error getting handle to native resources");
  			return;
  		}
  		size = jenv->GetArrayLength(value);
  	}
  	fdb_error_t err = fdb_transaction_set_option(tr, (FDBTransactionOption)code, barr, size);
  	if (value != JNI_NULL)
  		jenv->ReleaseByteArrayElements(value, (jbyte*)barr, JNI_ABORT);
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  	}
  }
  
  JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1getCommittedVersion(JNIEnv* jenv,
                                                                                                      jobject,
                                                                                                      jlong tPtr) {
  	if (!tPtr) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  	int64_t version;
  	fdb_error_t err = fdb_transaction_get_committed_version(tr, &version);
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  		return 0;
  	}
  	return (jlong)version;
  }
  
  JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1getApproximateSize(JNIEnv* jenv,
                                                                                                     jobject,
                                                                                                     jlong tPtr) {
  	if (!tPtr) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBFuture* f = fdb_transaction_get_approximate_size((FDBTransaction*)tPtr);
  	return (jlong)f;
  }
  
  JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1getVersionstamp(JNIEnv* jenv,
                                                                                                  jobject,
                                                                                                  jlong tPtr) {
  	if (!tPtr) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  	FDBFuture* f = fdb_transaction_get_versionstamp(tr);
  	return (jlong)f;
  }
  
  JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1getKeyLocations(JNIEnv* jenv,
                                                                                                  jobject,
                                                                                                  jlong tPtr,
                                                                                                  jbyteArray key) {
  	if (!tPtr || !key) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  
  	uint8_t* barr = (uint8_t*)jenv->GetByteArrayElements(key, JNI_NULL);
  	if (!barr) {
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return 0;
  	}
  	int size = jenv->GetArrayLength(key);
  
  	FDBFuture* f = fdb_transaction_get_addresses_for_key(tr, barr, size);
  
  	jenv->ReleaseByteArrayElements(key, (jbyte*)barr, JNI_ABORT);
  	return (jlong)f;
  }
  
  JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1onError(JNIEnv* jenv,
                                                                                          jobject,
                                                                                          jlong tPtr,
                                                                                          jint errorCode) {
  	if (!tPtr) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  	FDBFuture* f = fdb_transaction_on_error(tr, (fdb_error_t)errorCode);
  	return (jlong)f;
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1dispose(JNIEnv* jenv,
                                                                                         jobject,
                                                                                         jlong tPtr) {
  	if (!tPtr) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	fdb_transaction_destroy((FDBTransaction*)tPtr);
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1reset(JNIEnv* jenv,
                                                                                       jobject,
                                                                                       jlong tPtr) {
  	if (!tPtr) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	fdb_transaction_reset((FDBTransaction*)tPtr);
  }
  
  JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1watch(JNIEnv* jenv,
                                                                                        jobject,
                                                                                        jlong tPtr,
                                                                                        jbyteArray key) {
  	if (!tPtr || !key) {
  		throwParamNotNull(jenv);
  		return 0;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  
  	uint8_t* barr = (uint8_t*)jenv->GetByteArrayElements(key, JNI_NULL);
  	if (!barr) {
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return 0;
  	}
  	int size = jenv->GetArrayLength(key);
  	FDBFuture* f = fdb_transaction_watch(tr, barr, size);
  
  	jenv->ReleaseByteArrayElements(key, (jbyte*)barr, JNI_ABORT);
  	return (jlong)f;
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1cancel(JNIEnv* jenv,
                                                                                        jobject,
                                                                                        jlong tPtr) {
  	if (!tPtr) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	fdb_transaction_cancel((FDBTransaction*)tPtr);
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1addConflictRange(JNIEnv* jenv,
                                                                                                  jobject,
                                                                                                  jlong tPtr,
                                                                                                  jbyteArray keyBegin,
                                                                                                  jbyteArray keyEnd,
                                                                                                  jint conflictType) {
  	if (!tPtr || !keyBegin || !keyEnd) {
  		throwParamNotNull(jenv);
  		return;
  	}
  	FDBTransaction* tr = (FDBTransaction*)tPtr;
  
  	uint8_t* begin_barr = (uint8_t*)jenv->GetByteArrayElements(keyBegin, JNI_NULL);
  	if (!begin_barr) {
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return;
  	}
  	int begin_size = jenv->GetArrayLength(keyBegin);
  
  	uint8_t* end_barr = (uint8_t*)jenv->GetByteArrayElements(keyEnd, JNI_NULL);
  	if (!end_barr) {
  		jenv->ReleaseByteArrayElements(keyBegin, (jbyte*)begin_barr, JNI_ABORT);
  		if (!jenv->ExceptionOccurred())
  			throwRuntimeEx(jenv, "Error getting handle to native resources");
  		return;
  	}
  	int end_size = jenv->GetArrayLength(keyEnd);
  
  	fdb_error_t err = fdb_transaction_add_conflict_range(
  	    tr, begin_barr, begin_size, end_barr, end_size, (FDBConflictRangeType)conflictType);
  
  	jenv->ReleaseByteArrayElements(keyBegin, (jbyte*)begin_barr, JNI_ABORT);
  	jenv->ReleaseByteArrayElements(keyEnd, (jbyte*)end_barr, JNI_ABORT);
  
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  	}
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDB_Select_1API_1version(JNIEnv* jenv, jclass, jint version) {
  	fdb_error_t err = fdb_select_api_version((int)version);
  	if (err) {
  		if (err == 2203) {
  			int maxSupportedVersion = fdb_get_max_api_version();
  
  			char errorStr[1024];
  			if (FDB_API_VERSION > maxSupportedVersion) {
  				snprintf(errorStr,
  				         sizeof(errorStr),
  				         "This version of the FoundationDB Java binding is not supported by the installed "
  				         "FoundationDB C library. The binding requires a library that supports API version "
  				         "%d, but the installed library supports a maximum version of %d.",
  				         FDB_API_VERSION,
  				         maxSupportedVersion);
  			} else {
  				snprintf(errorStr,
  				         sizeof(errorStr),
  				         "API version %d is not supported by the installed FoundationDB C library.",
  				         version);
  			}
  
  			safeThrow(jenv, getThrowable(jenv, err, errorStr));
  		} else {
  			safeThrow(jenv, getThrowable(jenv, err));
  		}
  	}
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDB_Network_1setOption(JNIEnv* jenv,
                                                                            jobject,
                                                                            jint code,
                                                                            jbyteArray value) {
  	uint8_t* barr = nullptr;
  	int size = 0;
  	if (value != JNI_NULL) {
  		barr = (uint8_t*)jenv->GetByteArrayElements(value, JNI_NULL);
  		if (!barr) {
  			if (!jenv->ExceptionOccurred())
  				throwRuntimeEx(jenv, "Error getting handle to native resources");
  			return;
  		}
  		size = jenv->GetArrayLength(value);
  	}
  	fdb_error_t err = fdb_network_set_option((FDBNetworkOption)code, barr, size);
  	if (value != JNI_NULL)
  		jenv->ReleaseByteArrayElements(value, (jbyte*)barr, JNI_ABORT);
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  	}
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDB_Network_1setup(JNIEnv* jenv, jobject) {
  	fdb_error_t err = fdb_setup_network();
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  	}
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDB_Network_1run(JNIEnv* jenv, jobject) {
  	// initialize things for the callbacks on the network thread
  	g_thread_jenv = jenv;
  	if (!g_IFutureCallback_call_methodID) {
  		if (!findCallbackMethods(jenv))
  			return;
  	}
  
  	fdb_error_t hookErr = fdb_add_network_thread_completion_hook(&detachIfExternalThread, nullptr);
  	if (hookErr) {
  		safeThrow(jenv, getThrowable(jenv, hookErr));
  	}
  
  	fdb_error_t err = fdb_run_network();
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  	}
  }
  
  JNIEXPORT void JNICALL Java_com_apple_foundationdb_FDB_Network_1stop(JNIEnv* jenv, jobject) {
  	fdb_error_t err = fdb_stop_network();
  	if (err) {
  		safeThrow(jenv, getThrowable(jenv, err));
  	}
  }
  
  jint JNI_OnLoad(JavaVM* vm, void* reserved) {
  	JNIEnv* env;
  	g_jvm = vm;
  	if (vm->GetEnv((void**)&env, JNI_VERSION_1_6) != JNI_OK) {
  		return JNI_ERR;
  	} else {
  		jclass local_range_result_class = env->FindClass("com/apple/foundationdb/RangeResult");
  		range_result_init = env->GetMethodID(local_range_result_class, "<init>", "([B[IZ)V");
  		range_result_class = (jclass)(env)->NewGlobalRef(local_range_result_class);
  
  		jclass local_mapped_range_result_class = env->FindClass("com/apple/foundationdb/MappedRangeResult");
  		mapped_range_result_init =
  		    env->GetMethodID(local_mapped_range_result_class, "<init>", "([Lcom/apple/foundationdb/MappedKeyValue;Z)V");
  		mapped_range_result_class = (jclass)(env)->NewGlobalRef(local_mapped_range_result_class);
  
  		jclass local_mapped_key_value_class = env->FindClass("com/apple/foundationdb/MappedKeyValue");
  		mapped_key_value_from_bytes = env->GetStaticMethodID(
  		    local_mapped_key_value_class, "fromBytes", "([B[I)Lcom/apple/foundationdb/MappedKeyValue;");
  		mapped_key_value_class = (jclass)(env)->NewGlobalRef(local_mapped_key_value_class);
  
  		jclass local_key_array_result_class = env->FindClass("com/apple/foundationdb/KeyArrayResult");
  		key_array_result_init = env->GetMethodID(local_key_array_result_class, "<init>", "([B[I)V");
  		key_array_result_class = (jclass)(env)->NewGlobalRef(local_key_array_result_class);
  
  		jclass local_range_result_summary_class = env->FindClass("com/apple/foundationdb/RangeResultSummary");
  		range_result_summary_init = env->GetMethodID(local_range_result_summary_class, "<init>", "([BIZ)V");
  		range_result_summary_class = (jclass)(env)->NewGlobalRef(local_range_result_summary_class);
  
  		jclass local_string_class = env->FindClass("java/lang/String");
  		string_class = (jclass)(env)->NewGlobalRef(local_string_class);
  
  		return JNI_VERSION_1_6;
  	}
  }
  
  // Is automatically called once the Classloader is destroyed
  void JNI_OnUnload(JavaVM* vm, void* reserved) {
  	JNIEnv* env;
  	if (vm->GetEnv((void**)&env, JNI_VERSION_1_6) != JNI_OK) {
  		return;
  	} else {
  		// delete global references so the GC can collect them
  		if (range_result_summary_class != JNI_NULL) {
  			env->DeleteGlobalRef(range_result_summary_class);
  		}
  		if (range_result_class != JNI_NULL) {
  			env->DeleteGlobalRef(range_result_class);
  		}
  		if (mapped_range_result_class != JNI_NULL) {
  			env->DeleteGlobalRef(mapped_range_result_class);
  		}
  		if (mapped_key_value_class != JNI_NULL) {
  			env->DeleteGlobalRef(mapped_key_value_class);
  		}
  		if (string_class != JNI_NULL) {
  			env->DeleteGlobalRef(string_class);
  		}
  	}
  }
  
  #ifdef __cplusplus
  }
  #endif
  