com.almworks.sqlite4java.DirectBuffer Maven / Gradle / Ivy
/*
* Copyright 2010 ALM Works Ltd
*
* 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 com.almworks.sqlite4java;
import java.io.IOException;
import java.nio.ByteBuffer;
final class DirectBuffer {
static final int CONTROL_BYTES = 2;
private final int mySize;
private SWIGTYPE_p_direct_buffer myHandle;
private ByteBuffer myControlBuffer;
private ByteBuffer myDataBuffer;
DirectBuffer(SWIGTYPE_p_direct_buffer handle, ByteBuffer controlBuffer, ByteBuffer dataBuffer, int size) {
assert size == controlBuffer.capacity() + dataBuffer.capacity() : size + " " + controlBuffer.capacity() + " " + dataBuffer.capacity();
assert controlBuffer.capacity() == CONTROL_BYTES : controlBuffer.capacity();
assert size > CONTROL_BYTES : size;
myHandle = handle;
myControlBuffer = controlBuffer;
myDataBuffer = dataBuffer;
mySize = size;
}
public ByteBuffer data() throws IOException {
if (!isValid())
throw new IOException("buffer disposed");
return myDataBuffer;
}
public int getCapacity() {
return mySize - CONTROL_BYTES;
}
public int getPosition() {
ByteBuffer buffer = myDataBuffer;
return buffer == null ? 0 : buffer.position();
}
public SWIGTYPE_p_direct_buffer getHandle() {
return myHandle;
}
public boolean isValid() {
ByteBuffer controlBuffer = myControlBuffer;
if (controlBuffer == null || myDataBuffer == null || myHandle == null)
return false;
byte pendingRemove = controlBuffer.get(1);
return pendingRemove == 0;
}
public boolean isUsed() {
ByteBuffer controlBuffer = myControlBuffer;
if (controlBuffer == null)
return false;
return controlBuffer.get(0) != 0;
}
public void incUsed() {
ByteBuffer controlBuffer = myControlBuffer;
if (controlBuffer != null) {
controlBuffer.put(0, (byte) (controlBuffer.get(0) + 1));
}
}
public void decUsed() {
ByteBuffer controlBuffer = myControlBuffer;
if (controlBuffer != null) {
byte usage = controlBuffer.get(0);
if (usage > 0)
controlBuffer.put(0, (byte) (usage - 1));
}
}
void invalidate() {
myControlBuffer = null;
myDataBuffer = null;
myHandle = null;
}
}