net.openhft.chronicle.bytes.internal.ByteBuffers Maven / Gradle / Ivy
/*
* Copyright (c) 2016-2022 chronicle.software
*
* https://chronicle.software
*
* 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.
*/
package net.openhft.chronicle.bytes.internal;
import net.openhft.chronicle.core.Jvm;
import java.lang.reflect.Field;
import java.nio.ByteBuffer;
/**
* Utility class for working with {@link ByteBuffer} instances.
*
* Provides functionality to directly set the address and capacity of a ByteBuffer.
*/
public final class ByteBuffers {
private ByteBuffers() {
}
private static final Field ADDRESS;
private static final Field CAPACITY;
static {
ByteBuffer direct = ByteBuffer.allocateDirect(0);
ADDRESS = Jvm.getField(direct.getClass(), "address");
CAPACITY = Jvm.getField(direct.getClass(), "capacity");
}
/**
* Sets the memory address and capacity of a {@link ByteBuffer} instance directly.
*
* This method uses reflection to access and modify the address and capacity fields of the ByteBuffer.
* It should be used with caution as it bypasses the usual safety checks and can lead to undefined behavior
* if used improperly.
*
* @param buffer the ByteBuffer whose address and capacity are to be set
* @param address the memory address to be set
* @param capacity the capacity to be set
* @throws AssertionError if the operation fails due to IllegalAccessException or IllegalArgumentException
*/
public static void setAddressCapacity(ByteBuffer buffer, long address, long capacity) {
int cap = Math.toIntExact(capacity);
try {
ADDRESS.setLong(buffer, address);
CAPACITY.setInt(buffer, cap);
} catch (IllegalAccessException | IllegalArgumentException e) {
throw new AssertionError(e);
}
}
}