Examples of com.alexkasko.unsafe.offheap.OffHeapMemory

com.alexkasko.unsafe.offheap.OffHeapMemory

Allocates an area of off-heap memory that is not a subject to GC. Default implementation uses {@code sun.misc.Unsafe}, with all operations guarded with {@code assert}boundary checks. With assert enabled in runtime ( {@code -ea} java switch) {@link AssertionError}will be thrown on illegal input. Without assertions illegal input will crash JVM.
Fallback implementation uses {@link java.nio.ByteBuffer#allocateDirect(int)} that may (OpenJDK)or may not (Dalvik) use {@code sun.misc.Unsafe} under the hood.Note: only unsafe implementation ( {@link #allocateMemoryUnsafe(long)}) may use memory areas longer than {@code Integer.MAX_VALUE}
Unsafe implementation uses native endianness (LE on most platforms). Fallback implementation uses Little Endian byte order.
Provides methods to access allocated memory. More complex data structures (off-heap quasi-objects) may be constructed wrapping this class, see {@link com.alexkasko.unsafe.offheaplong.OffHeapLongArray}.
Memory may be freed manually calling {@link #free()} (thread-safe and may be called safely more than one time),or it will be freed when {@link OffHeapMemory} instance itself will be garbage collected. @author alexkaskoDate: 1/14/13

     *
     * @param struct struct to add
     * @param structPos struct offset
     */
    public void add(byte[] struct, int structPos) {
        OffHeapMemory oh = ohm;
        long s = size;
        if (s == capacity) {
            long len = s + (s < (MIN_CAPACITY_INCREMENT / 2) ? MIN_CAPACITY_INCREMENT : s >> 1);
            OffHeapMemory newOhm = null == bt ? OffHeapMemory.allocateMemory(len * structLength)
                    : OffHeapMemory.allocateMemoryOnHeap(bt, len * structLength);
            // maybe it's better to use Unsafe#reallocateMemory here
            oh.copy(0, newOhm, 0, oh.length());
            oh.free();
            ohm = newOhm;

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    /**
     * Shrinks array list capacity to current size
     */
    public void shrinkToFit() {
        long byteslen = size * structLength;
        OffHeapMemory oh = ohm;
        OffHeapMemory newOhm = null == bt ? OffHeapMemory.allocateMemory(byteslen)
                : OffHeapMemory.allocateMemoryOnHeap(bt, byteslen);
        oh.copy(0, newOhm, 0, byteslen);
        oh.free();
        ohm = newOhm;
        capacity = size;

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    /**
     * {@inheritDoc}
     */
    @Override
    public OffHeapStructArray clone() {
        OffHeapMemory cloned = ohm.clone();
        return new OffHeapStructArray(cloned, structLength);
    }

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     * on capacity exceed.
     *
     * @param value value to add
     */
    public void add(long value) {
        OffHeapMemory oh = ohm;
        long s = size;
        if (s == capacity) {
            long len = s + (s < (MIN_CAPACITY_INCREMENT / 2) ? MIN_CAPACITY_INCREMENT : s >> 1);
            OffHeapMemory newOhm = OffHeapMemory.allocateMemory(len * ELEMENT_LENGTH);
            // maybe it's better to use Unsafe#reallocateMemory here
            oh.copy(0, newOhm, 0, oh.length());
            oh.free();
            ohm = newOhm;
            capacity = len;

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    /**
     * {@inheritDoc}
     */
    @Override
    public OffHeapLongArray clone() {
        OffHeapMemory cloned = ohm.clone();
        return new OffHeapLongArray(cloned);
    }

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     *
     * @param header header to add
     * @param payload payload to add
     */
    public void add(long header, long payload) {
        OffHeapMemory oh = ohm;
        long s = size;
        if (s == capacity()) {
            long len = s + (s < (MIN_CAPACITY_INCREMENT / 2) ? MIN_CAPACITY_INCREMENT : s >> 1);
            OffHeapMemory newOhm = OffHeapMemory.allocateMemory(len * ELEMENT_LENGTH);
            // maybe it's better to use Unsafe#reallocateMemory here
            oh.copy(0, newOhm, 0, ohm.length());
            oh.free();
            ohm = newOhm;
        }

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     *
     * @param struct struct to add
     * @param structPos struct offset
     */
    public void add(byte[] struct, int structPos) {
        OffHeapMemory oh = ohm;
        long s = size;
        if (s == capacity()) {
            long len = s + (s < (MIN_CAPACITY_INCREMENT / 2) ? MIN_CAPACITY_INCREMENT : s >> 1);
            OffHeapMemory newOhm = null == bt ? OffHeapMemory.allocateMemory(len * structLength)
                    : OffHeapMemory.allocateMemoryOnHeap(bt, len * structLength);
            // maybe it's better to use Unsafe#reallocateMemory here
            oh.copy(0, newOhm, 0, ohm.length());
            oh.free();
            ohm = newOhm;

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     *
     * @param header header to add
     * @param payload payload to add
     */
    public void add(long header, int payload) {
        OffHeapMemory oh = ohm;
        long s = size;
        if (s == capacity()) {
            long len = s + (s < (MIN_CAPACITY_INCREMENT / 2) ? MIN_CAPACITY_INCREMENT : s >> 1);
            OffHeapMemory newOhm = OffHeapMemory.allocateMemory(len * ELEMENT_LENGTH);
            // maybe it's better to use Unsafe#reallocateMemory here
            oh.copy(0, newOhm, 0, ohm.length());
            oh.free();
            ohm = newOhm;
        }

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     * @param header header to add
     * @param payload payload to add
     * @param payloadPos payload offset
     */
    public void add(long header, byte[] payload, int payloadPos) {
        OffHeapMemory oh = ohm;
        long s = size;
        if (s == capacity()) {
            long len = s + (s < (MIN_CAPACITY_INCREMENT / 2) ? MIN_CAPACITY_INCREMENT : s >> 1);
            OffHeapMemory newOhm = OffHeapMemory.allocateMemory(len * elementLength);
            // maybe it's better to use Unsafe#reallocateMemory here
            oh.copy(0, newOhm, 0, ohm.length());
            oh.free();
            ohm = newOhm;
        }

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     * on capacity exceed.
     *
     * @param value value to add
     */
    public void add(long value) {
        OffHeapMemory oh = ohm;
        long s = size;
        if (s == capacity()) {
            long len = s + (s < (MIN_CAPACITY_INCREMENT / 2) ? MIN_CAPACITY_INCREMENT : s >> 1);
            OffHeapMemory newOhm = OffHeapMemory.allocateMemory(len * ELEMENT_LENGTH);
            // maybe it's better to use Unsafe#reallocateMemory here
            oh.copy(0, newOhm, 0, ohm.length());
            oh.free();
            ohm = newOhm;
        }

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