package com.fasterxml.aalto.util;

This is a small utility class, whose main functionality is to allow
simple reuse of raw byte/char buffers. It is usually used through
ThreadLocal member of the owning class pointing to
instance of this class through a SoftReference. The
end result is a low-overhead GC-cleanable recycling: hopefully
ideal for use by stream readers.

Regarding implementation: the key design goal is simplicity; and to
that end, different types of buffers are handled separately. While
code may look inelegant as a result (would be cleaner to just
have generic char[]/byte[] buffer accessors), benefit is that
no data structures are needed, just simple references. As long
as usage pattern is well known (which it is, for stream readers)
this should be highly optimal and robust implementation.
/**
 * This is a small utility class, whose main functionality is to allow
 * simple reuse of raw byte/char buffers. It is usually used through
 * <code>ThreadLocal</code> member of the owning class pointing to
 * instance of this class through a <code>SoftReference</code>. The
 * end result is a low-overhead GC-cleanable recycling: hopefully
 * ideal for use by stream readers.
 *<p>
 * Regarding implementation: the key design goal is simplicity; and to
 * that end, different types of buffers are handled separately. While
 * code may look inelegant as a result (would be cleaner to just
 * have generic char[]/byte[] buffer accessors), benefit is that
 * no data structures are needed, just simple references. As long
 * as usage pattern is well known (which it is, for stream readers)
 * this should be highly optimal and robust implementation.
 */
public final class BufferRecycler
{
    private volatile char[] mSmallCBuffer = null; // temp buffers
    private volatile char[] mMediumCBuffer = null; // text collector
    private volatile char[] mFullCBuffer = null; // for actual parsing buffer

    private volatile byte[] mFullBBuffer = null;

    public BufferRecycler() { }

    // // // Char buffers:

    // // Small buffers, for temporary parsing

    public synchronized char[] getSmallCBuffer(int minSize)
    {
        char[] result = mSmallCBuffer;
        if (result != null && result.length >= minSize) {
            mSmallCBuffer = null;
            return result;
        }
        return null;
    }

    public synchronized void returnSmallCBuffer(char[] buffer)
    {
        mSmallCBuffer = buffer;
    }

    // // Medium buffers, for text output collection

    public synchronized char[] getMediumCBuffer(int minSize)
    {
        char[] result = mMediumCBuffer;
        if (result != null && result.length >= minSize) {
            mMediumCBuffer = null;
            return result;
        }
        return null;
    }

    public synchronized void returnMediumCBuffer(char[] buffer)
    {
        mMediumCBuffer = buffer;
    }

    // // Full buffers, for parser buffering

    public synchronized char[] getFullCBuffer(int minSize)
    {
        char[] result = mFullCBuffer;
        if (result != null && result.length >= minSize) {
            mFullCBuffer = null;
            return result;
        }
        return null;
    }

    public synchronized void returnFullCBuffer(char[] buffer)
    {
        mFullCBuffer = buffer;
    }

    // // // Byte buffers:

    // // Full byte buffers, for byte->char conversion (Readers)

    public synchronized byte[] getFullBBuffer(int minSize)
    {
        byte[] result = mFullBBuffer;
        if (result != null && result.length >= minSize) {
            mFullBBuffer = null;
            return result;
        }
        return null;
    }

    public synchronized void returnFullBBuffer(byte[] buffer)
    {
        mFullBBuffer = buffer;
    }
}