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142 lines (127 loc) · 4.51 KB
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/*-
* #%L
* LmdbJava
* %%
* Copyright (C) 2016 - 2017 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.
* #L%
*/
package org.lmdbjava;
import io.netty.buffer.ByteBuf;
import static io.netty.buffer.PooledByteBufAllocator.DEFAULT;
import static java.lang.Class.forName;
import static java.lang.ThreadLocal.withInitial;
import java.lang.reflect.Field;
import java.util.ArrayDeque;
import jnr.ffi.Pointer;
import static org.lmdbjava.UnsafeAccess.UNSAFE;
/**
* 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> {
private static final long ADDRESS_OFFSET;
/**
* A thread-safe pool for a given length. If the buffer found is bigger then
* the buffer in the pool creates a new buffer. If no buffer is found creates
* a new buffer.
*/
private static final ThreadLocal<ArrayDeque<ByteBuf>> BUFFERS = withInitial(()
-> new ArrayDeque<>(16));
private static final String FIELD_NAME_ADDRESS = "memoryAddress";
private static final String FIELD_NAME_LENGTH = "length";
private static final long LENGTH_OFFSET;
private static final String NAME = "io.netty.buffer.PooledUnsafeDirectByteBuf";
static {
try {
// create buffer (first is SimpleLeakAwareByteBuff but we need PooledUDBB)
DEFAULT.directBuffer(0);
final Field address = findField(NAME, FIELD_NAME_ADDRESS);
final Field length = findField(NAME, FIELD_NAME_LENGTH);
ADDRESS_OFFSET = UNSAFE.objectFieldOffset(address);
LENGTH_OFFSET = 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() {
final ArrayDeque<ByteBuf> queue = BUFFERS.get();
final ByteBuf buffer = queue.poll();
if (buffer != null && buffer.capacity() >= 0) {
return buffer;
} else {
return DEFAULT.directBuffer(0);
}
}
@Override
protected void deallocate(final ByteBuf buff) {
final ArrayDeque<ByteBuf> queue = BUFFERS.get();
if (!queue.offer(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 void in(final ByteBuf buffer, final Pointer ptr, final long ptrAddr) {
UNSAFE.putLong(ptrAddr + STRUCT_FIELD_OFFSET_SIZE,
buffer.writerIndex() - buffer.readerIndex());
UNSAFE.putLong(ptrAddr + STRUCT_FIELD_OFFSET_DATA,
buffer.memoryAddress() + buffer.readerIndex());
}
@Override
protected void in(final ByteBuf buffer, final int size, final Pointer ptr,
final long ptrAddr) {
UNSAFE.putLong(ptrAddr + STRUCT_FIELD_OFFSET_SIZE,
size);
UNSAFE.putLong(ptrAddr + STRUCT_FIELD_OFFSET_DATA,
buffer.memoryAddress() + buffer.readerIndex());
}
@Override
protected ByteBuf out(final ByteBuf buffer, final Pointer ptr,
final long ptrAddr) {
final long addr = UNSAFE.getLong(ptrAddr + STRUCT_FIELD_OFFSET_DATA);
final long size = UNSAFE.getLong(ptrAddr + STRUCT_FIELD_OFFSET_SIZE);
UNSAFE.putLong(buffer, ADDRESS_OFFSET, addr);
UNSAFE.putLong(buffer, LENGTH_OFFSET, (int) size);
buffer.readerIndex(0).writerIndex((int) size);
return buffer;
}
}