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161 lines (140 loc) · 5.14 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 java.lang.ThreadLocal.withInitial;
import static java.nio.ByteBuffer.allocateDirect;
import static java.nio.ByteOrder.BIG_ENDIAN;
import static java.util.Objects.requireNonNull;
import static org.lmdbjava.UnsafeAccess.UNSAFE;
import java.nio.ByteBuffer;
import java.util.ArrayDeque;
import java.util.Comparator;
import jnr.ffi.Pointer;
import org.agrona.DirectBuffer;
import org.agrona.MutableDirectBuffer;
import org.agrona.concurrent.UnsafeBuffer;
/**
* A buffer proxy backed by Agrona's {@link DirectBuffer}.
*
* <p>This class requires {@link UnsafeAccess} and Agrona must be in the classpath.
*/
public final class DirectBufferProxy extends BufferProxy<DirectBuffer> {
private static final Comparator<DirectBuffer> signedComparator =
(o1, o2) -> {
requireNonNull(o1);
requireNonNull(o2);
return o1.compareTo(o2);
};
private static final Comparator<DirectBuffer> unsignedComparator = DirectBufferProxy::compareBuff;
/**
* The {@link MutableDirectBuffer} proxy. Guaranteed to never be null, although a class
* initialization exception will occur if an attempt is made to access this field when unsafe or
* Agrona is unavailable.
*/
public static final BufferProxy<DirectBuffer> PROXY_DB = new DirectBufferProxy();
/**
* A thread-safe pool for a given length. If the buffer found is valid (ie not of a negative
* length) then that buffer is used. If no valid buffer is found, a new buffer is created.
*/
private static final ThreadLocal<ArrayDeque<DirectBuffer>> BUFFERS =
withInitial(() -> new ArrayDeque<>(16));
private DirectBufferProxy() {}
/**
* Lexicographically compare two buffers.
*
* @param o1 left operand (required)
* @param o2 right operand (required)
* @return as specified by {@link Comparable} interface
*/
public static int compareBuff(final DirectBuffer o1, final DirectBuffer o2) {
requireNonNull(o1);
requireNonNull(o2);
final int minLength = Math.min(o1.capacity(), o2.capacity());
final int minWords = minLength / Long.BYTES;
for (int i = 0; i < minWords * Long.BYTES; i += Long.BYTES) {
final long lw = o1.getLong(i, BIG_ENDIAN);
final long rw = o2.getLong(i, BIG_ENDIAN);
final int diff = Long.compareUnsigned(lw, rw);
if (diff != 0) {
return diff;
}
}
for (int i = minWords * Long.BYTES; i < minLength; i++) {
final int lw = Byte.toUnsignedInt(o1.getByte(i));
final int rw = Byte.toUnsignedInt(o2.getByte(i));
final int result = Integer.compareUnsigned(lw, rw);
if (result != 0) {
return result;
}
}
return o1.capacity() - o2.capacity();
}
@Override
protected DirectBuffer allocate() {
final ArrayDeque<DirectBuffer> q = BUFFERS.get();
final DirectBuffer buffer = q.poll();
if (buffer != null && buffer.capacity() >= 0) {
return buffer;
} else {
final ByteBuffer bb = allocateDirect(0);
return new UnsafeBuffer(bb);
}
}
@Override
protected Comparator<DirectBuffer> getSignedComparator() {
return signedComparator;
}
@Override
protected Comparator<DirectBuffer> getUnsignedComparator() {
return unsignedComparator;
}
@Override
protected void deallocate(final DirectBuffer buff) {
final ArrayDeque<DirectBuffer> q = BUFFERS.get();
q.offer(buff);
}
@Override
protected byte[] getBytes(final DirectBuffer buffer) {
final byte[] dest = new byte[buffer.capacity()];
buffer.getBytes(0, dest, 0, buffer.capacity());
return dest;
}
@Override
protected Pointer in(final DirectBuffer buffer, final Pointer ptr) {
final long ptrAddr = ptr.address();
final long addr = buffer.addressOffset();
final long size = buffer.capacity();
UNSAFE.putLong(ptrAddr + STRUCT_FIELD_OFFSET_DATA, addr);
UNSAFE.putLong(ptrAddr + STRUCT_FIELD_OFFSET_SIZE, size);
return null;
}
@Override
protected Pointer in(final DirectBuffer buffer, final int size, final Pointer ptr) {
final long ptrAddr = ptr.address();
final long addr = buffer.addressOffset();
UNSAFE.putLong(ptrAddr + STRUCT_FIELD_OFFSET_DATA, addr);
UNSAFE.putLong(ptrAddr + STRUCT_FIELD_OFFSET_SIZE, size);
return null;
}
@Override
protected DirectBuffer out(final DirectBuffer 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);
buffer.wrap(addr, (int) size);
return buffer;
}
}