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Shaded version of DataStax Java Driver for Apache Cassandra
/*
* Copyright (C) 2009 Wayne Meissner
*
* This file is part of jffi.
*
* 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.
*
*
* Alternatively, you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This code 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 Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this work. If not, see .
*/
package com.kenai.jffi;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.WeakHashMap;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Utility class to register native methods on a class
*/
public final class NativeMethods {
/**
* Store a link from the class to the native method holder in a weak
* hash map, so as long as the class remains alive, the native memory for the
* structures remains alive.
*
* This doesn't seem to be necessary on sun's jvm, but best do it to be safe.
*/
private static final Map registeredMethods
= new WeakHashMap();
private final ResourceHolder memory;
private NativeMethods(ResourceHolder memory) {
this.memory = memory;
}
/**
* Registers the native methods for a class.
*
* @param clazz The java class to register the native methods for.
* @param methods The list of methods to attach to the class.
*/
public static synchronized final void register(Class clazz, List methods) {
//
// Calculate how much memory is needed for the function names + signatures
//
int stringSize = 0;
for (NativeMethod m : methods) {
stringSize += m.name.getBytes().length + 1;
stringSize += m.signature.getBytes().length + 1;
}
final int ptrSize = Platform.getPlatform().addressSize() / 8;
final MemoryIO mm = MemoryIO.getInstance();
//
// Each JNINativeMethod struct is 3 pointers
// i.e.
// typedef struct {
// char *name;
// char *signature;
// void *fnPtr;
// } JNINativeMethod;
int structSize = methods.size() * 3 * ptrSize;
long memory = mm.allocateMemory(structSize + stringSize, true);
if (memory == 0L) {
throw new OutOfMemoryError("could not allocate native memory");
}
NativeMethods nm = new NativeMethods(new ResourceHolder(mm, memory));
int off = 0;
int stringOff = structSize;
for (NativeMethod m : methods) {
byte[] name = m.name.getBytes();
long nameAddress = memory + stringOff;
stringOff += name.length + 1;
mm.putZeroTerminatedByteArray(nameAddress, name, 0, name.length);
byte[] sig = m.signature.getBytes();
long sigAddress = memory + stringOff;
stringOff += sig.length + 1;
mm.putZeroTerminatedByteArray(sigAddress, sig, 0, sig.length);
mm.putAddress(memory + off, nameAddress); off += ptrSize;
mm.putAddress(memory + off, sigAddress); off += ptrSize;
mm.putAddress(memory + off, m.function); off += ptrSize;
}
if (Foreign.getInstance().registerNatives(clazz, memory, methods.size()) != Foreign.JNI_OK) {
throw new RuntimeException("failed to register native methods");
}
registeredMethods.put(clazz, nm);
}
/**
* Removes all native method attachments for the specified class.
*
* @param clazz The class to unregister the native methods on.
*/
public static synchronized final void unregister(Class clazz) {
if (!registeredMethods.containsKey(clazz)) {
throw new IllegalArgumentException("methods were not registered on class via NativeMethods.register");
}
if (Foreign.getInstance().unregisterNatives(clazz) != Foreign.JNI_OK) {
throw new RuntimeException("failed to unregister native methods");
}
registeredMethods.remove(clazz);
}
private static final class ResourceHolder {
private final MemoryIO mm;
private final long memory;
public ResourceHolder(MemoryIO mm, long memory) {
this.mm = mm;
this.memory = memory;
}
@Override
protected void finalize() throws Throwable {
try {
mm.freeMemory(memory);
} catch (Throwable t) {
Logger.getLogger(getClass().getName()).log(Level.WARNING,
"Exception when freeing native method struct array: %s", t.getLocalizedMessage());
} finally {
super.finalize();
}
}
}
}
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