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ByteBufProxy.java
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166 lines (147 loc) · 5.16 KB
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/*
* Copyright © 2016-2025 The LmdbJava Open Source Project
*
* 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 org.lmdbjava;
import static io.netty.buffer.PooledByteBufAllocator.DEFAULT;
import static java.lang.Class.forName;
import static java.util.Objects.requireNonNull;
import static org.lmdbjava.UnsafeAccess.UNSAFE;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.PooledByteBufAllocator;
import java.lang.reflect.Field;
import java.util.Comparator;
import jnr.ffi.Pointer;
/**
* A buffer proxy backed by Netty's {@link ByteBuf}.
*
* <p>This class requires {@link UnsafeAccess} and netty-buffer must be in the classpath.
*/
public final class ByteBufProxy extends BufferProxy<ByteBuf> {
/**
* A proxy for using Netty {@link ByteBuf}. Guaranteed to never be null, although a class
* initialization exception will occur if an attempt is made to access this field when Netty is
* unavailable.
*/
public static final BufferProxy<ByteBuf> PROXY_NETTY = new ByteBufProxy();
private static final int BUFFER_RETRIES = 10;
private static final String FIELD_NAME_ADDRESS = "memoryAddress";
private static final String FIELD_NAME_LENGTH = "length";
private static final String NAME = "io.netty.buffer.PooledUnsafeDirectByteBuf";
private static final Comparator<ByteBuf> comparator =
(o1, o2) -> {
requireNonNull(o1);
requireNonNull(o2);
return o1.compareTo(o2);
};
private final long lengthOffset;
private final long addressOffset;
private final PooledByteBufAllocator nettyAllocator;
private ByteBufProxy() {
this(DEFAULT);
}
/**
* Constructs a buffer proxy for use with Netty.
*
* @param allocator the Netty allocator to obtain the {@link ByteBuf} from
*/
public ByteBufProxy(final PooledByteBufAllocator allocator) {
super();
this.nettyAllocator = allocator;
try {
final ByteBuf initBuf = this.allocate();
initBuf.release();
final Field address = findField(NAME, FIELD_NAME_ADDRESS);
final Field length = findField(NAME, FIELD_NAME_LENGTH);
addressOffset = UNSAFE.objectFieldOffset(address);
lengthOffset = UNSAFE.objectFieldOffset(length);
} catch (final SecurityException e) {
throw new LmdbException("Field access error", e);
}
}
static Field findField(final String c, final String name) {
Class<?> clazz;
try {
clazz = forName(c);
} catch (final ClassNotFoundException e) {
throw new LmdbException(c + " class unavailable", e);
}
do {
try {
final Field field = clazz.getDeclaredField(name);
field.setAccessible(true);
return field;
} catch (final NoSuchFieldException e) {
clazz = clazz.getSuperclass();
}
} while (clazz != null);
throw new LmdbException(name + " not found");
}
@Override
protected ByteBuf allocate() {
for (int i = 0; i < BUFFER_RETRIES; i++) {
final ByteBuf bb = nettyAllocator.directBuffer();
if (NAME.equals(bb.getClass().getName())) {
return bb;
} else {
bb.release();
}
}
throw new IllegalStateException("Netty buffer must be " + NAME);
}
@Override
protected Comparator<ByteBuf> getSignedComparator() {
return comparator;
}
@Override
protected Comparator<ByteBuf> getUnsignedComparator() {
return comparator;
}
@Override
protected void deallocate(final ByteBuf buff) {
buff.release();
}
@Override
protected byte[] getBytes(final ByteBuf buffer) {
final byte[] dest = new byte[buffer.capacity()];
buffer.getBytes(0, dest);
return dest;
}
@Override
protected Pointer in(final ByteBuf buffer, final Pointer ptr) {
final long ptrAddr = ptr.address();
UNSAFE.putLong(ptrAddr + STRUCT_FIELD_OFFSET_SIZE, buffer.writerIndex() - buffer.readerIndex());
UNSAFE.putLong(
ptrAddr + STRUCT_FIELD_OFFSET_DATA, buffer.memoryAddress() + buffer.readerIndex());
return null;
}
@Override
protected Pointer in(final ByteBuf buffer, final int size, final Pointer ptr) {
final long ptrAddr = ptr.address();
UNSAFE.putLong(ptrAddr + STRUCT_FIELD_OFFSET_SIZE, size);
UNSAFE.putLong(
ptrAddr + STRUCT_FIELD_OFFSET_DATA, buffer.memoryAddress() + buffer.readerIndex());
return null;
}
@Override
protected ByteBuf out(final ByteBuf buffer, final Pointer ptr) {
final long ptrAddr = ptr.address();
final long addr = UNSAFE.getLong(ptrAddr + STRUCT_FIELD_OFFSET_DATA);
final long size = UNSAFE.getLong(ptrAddr + STRUCT_FIELD_OFFSET_SIZE);
UNSAFE.putLong(buffer, addressOffset, addr);
UNSAFE.putInt(buffer, lengthOffset, (int) size);
buffer.clear().writerIndex((int) size);
return buffer;
}
}