LongLongHashMap Class — netty Architecture

Source Code

common/src/main/java/io/netty/util/internal/LongLongHashMap.java lines 20–135

public final class LongLongHashMap {
    private static final int MASK_TEMPLATE = ~1;
    private int mask;
    private long[] array;
    private int maxProbe;
    private long zeroVal;
    private final long emptyVal;

    public LongLongHashMap(long emptyVal) {
        this.emptyVal = emptyVal;
        zeroVal = emptyVal;
        int initialSize = 32;
        array = new long[initialSize];
        mask = initialSize - 1;
        computeMaskAndProbe();
    }

    public LongLongHashMap(LongLongHashMap other) {
        this.mask = other.mask;
        this.array = Arrays.copyOf(other.array, other.array.length);
        this.maxProbe = other.maxProbe;
        this.zeroVal = other.zeroVal;
        this.emptyVal = other.emptyVal;
    }

    public long put(long key, long value) {
        if (key == 0) {
            long prev = zeroVal;
            zeroVal = value;
            return prev;
        }

        for (;;) {
            int index = index(key);
            for (int i = 0; i < maxProbe; i++) {
                long existing = array[index];
                if (existing == key || existing == 0) {
                    long prev = existing == 0? emptyVal : array[index + 1];
                    array[index] = key;
                    array[index + 1] = value;
                    for (; i < maxProbe; i++) { // Nerf any existing misplaced entries.
                        index = index + 2 & mask;
                        if (array[index] == key) {
                            array[index] = 0;
                            prev = array[index + 1];
                            break;
                        }
                    }
                    return prev;
                }
                index = index + 2 & mask;
            }
            expand(); // Grow array and re-hash.
        }
    }

    public void remove(long key) {
        if (key == 0) {
            zeroVal = emptyVal;
            return;
        }
        int index = index(key);
        for (int i = 0; i < maxProbe; i++) {
            long existing = array[index];
            if (existing == key) {
                array[index] = 0;
                break;
            }
            index = index + 2 & mask;
        }
    }

    public long get(long key) {
        if (key == 0) {
            return zeroVal;
        }
        int index = index(key);
        for (int i = 0; i < maxProbe; i++) {
            long existing = array[index];
            if (existing == key) {
                return array[index + 1];