org.glassfish.grizzly.nio.DirectByteBufferRecord Maven / Gradle / Ivy

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package org.glassfish.grizzly.nio;

import java.lang.ref.SoftReference;
import java.nio.ByteBuffer;
import java.util.Arrays;
import org.glassfish.grizzly.ThreadCache;
import org.glassfish.grizzly.memory.Buffers;

/**
 * Thread-local Direct {@link ByteBuffer} storage.
 *
 * @author Alexey Stashok
 */
public final class DirectByteBufferRecord {

    private static final ThreadCache.CachedTypeIndex CACHE_IDX =
            ThreadCache.obtainIndex("direct-buffer-cache", DirectByteBufferRecord.class, 1);

    public static DirectByteBufferRecord get() {
        final DirectByteBufferRecord record =
                ThreadCache.getFromCache(CACHE_IDX);
        if (record != null) {
            return record;
        }
        final DirectByteBufferRecord recordLocal = new DirectByteBufferRecord();
        ThreadCache.putToCache(CACHE_IDX, recordLocal);
        return recordLocal;
    }
    
    
    private ByteBuffer directBuffer;
    private int sliceOffset;
    private ByteBuffer directBufferSlice;
    private SoftReference softRef;
    private ByteBuffer array[];
    private int arraySize;

    DirectByteBufferRecord() {
        array = new ByteBuffer[8];
    }

    public ByteBuffer getDirectBuffer() {
        return directBuffer;
    }

    public ByteBuffer getDirectBufferSlice() {
        return directBufferSlice;
    }

    public ByteBuffer allocate(final int size) {
        ByteBuffer byteBuffer;
        if ((byteBuffer = switchToStrong()) != null && byteBuffer.remaining() >= size) {
            return byteBuffer;
        } else {
            byteBuffer = ByteBuffer.allocateDirect(size);
            reset(byteBuffer);
            return byteBuffer;
        }
    }
        
    public ByteBuffer sliceBuffer() {
        int oldLim = directBuffer.limit();
        Buffers.setPositionLimit(directBuffer, sliceOffset, directBuffer.capacity());
        directBufferSlice = directBuffer.slice();
        Buffers.setPositionLimit(directBuffer, 0, oldLim);
        return directBufferSlice;
    }

    public void finishBufferSlice() {
        if (directBufferSlice != null) {
            directBufferSlice.flip();
            sliceOffset += directBufferSlice.remaining();
            directBufferSlice = null;
        }
    }

    public ByteBuffer[] getArray() {
        return array;
    }

    public int getArraySize() {
        return arraySize;
    }

    public void putToArray(ByteBuffer byteBuffer) {
        ensureArraySize();
        array[arraySize++] = byteBuffer;
    }

    public void release() {
        if (directBuffer != null) {
            directBuffer.clear();
            switchToSoft();
        }
        
        Arrays.fill(array, 0, arraySize, null);
        arraySize = 0;
        directBufferSlice = null;
        sliceOffset = 0;
    }

    ByteBuffer switchToStrong() {
        if (directBuffer == null && softRef != null) {
            directBuffer = directBufferSlice = softRef.get();
        }
        return directBuffer;
    }

    void switchToSoft() {
        if (directBuffer != null && softRef == null) {
            softRef = new SoftReference(directBuffer);
        }
        directBuffer = null;
    }

    void reset(ByteBuffer byteBuffer) {
        directBuffer = directBufferSlice = byteBuffer;
        softRef = null;
    }

    private void ensureArraySize() {
        if (arraySize == array.length) {
            array = Arrays.copyOf(array, (arraySize * 3) / 2 + 1);
        }
    }
}