DefaultHeaders Class — netty Architecture

Source Code

codec-base/src/main/java/io/netty/handler/codec/DefaultHeaders.java lines 44–1474

public class DefaultHeaders<K, V, T extends Headers<K, V, T>> implements Headers<K, V, T> {
    /**
     * Constant used to seed the hash code generation. Could be anything but this was borrowed from murmur3.
     */
    static final int HASH_CODE_SEED = 0xc2b2ae35;

    private final HeaderEntry<K, V>[] entries;
    protected final HeaderEntry<K, V> head;

    private final byte hashMask;
    private final ValueConverter<V> valueConverter;
    private final NameValidator<K> nameValidator;
    private final ValueValidator<V> valueValidator;
    private final HashingStrategy<K> hashingStrategy;
    int size;

    public interface NameValidator<K> {
        /**
         * Verify that {@code name} is valid.
         * @param name The name to validate.
         * @throws RuntimeException if {@code name} is not valid.
         */
        void validateName(K name);

        @SuppressWarnings("rawtypes")
        NameValidator NOT_NULL = new NameValidator() {
            @Override
            public void validateName(Object name) {
                checkNotNull(name, "name");
            }
        };
    }

    public interface ValueValidator<V> {
        /**
         * Validate the given value. If the validation fails, then an implementation specific runtime exception may be
         * thrown.
         *
         * @param value The value to validate.
         */
        void validate(V value);

        ValueValidator<?> NO_VALIDATION = new ValueValidator<Object>() {
            @Override
            public void validate(Object value) {
            }
        };
    }

    @SuppressWarnings("unchecked")
    public DefaultHeaders(ValueConverter<V> valueConverter) {
        this(JAVA_HASHER, valueConverter);
    }

    @SuppressWarnings("unchecked")
    public DefaultHeaders(ValueConverter<V> valueConverter, NameValidator<K> nameValidator) {
        this(JAVA_HASHER, valueConverter, nameValidator);
    }

    @SuppressWarnings("unchecked")
    public DefaultHeaders(HashingStrategy<K> nameHashingStrategy, ValueConverter<V> valueConverter) {
        this(nameHashingStrategy, valueConverter, NameValidator.NOT_NULL);
    }

    public DefaultHeaders(HashingStrategy<K> nameHashingStrategy,
            ValueConverter<V> valueConverter, NameValidator<K> nameValidator) {
        this(nameHashingStrategy, valueConverter, nameValidator, 16);
    }

    /**
     * Create a new instance.
     * @param nameHashingStrategy Used to hash and equality compare names.
     * @param valueConverter Used to convert values to/from native types.
     * @param nameValidator Used to validate name elements.
     * @param arraySizeHint A hint as to how large the hash data structure should be.
     * The next positive power of two will be used. An upper bound may be enforced.
     */
    @SuppressWarnings("unchecked")
    public DefaultHeaders(HashingStrategy<K> nameHashingStrategy,
                          ValueConverter<V> valueConverter, NameValidator<K> nameValidator, int arraySizeHint) {
        this(nameHashingStrategy, valueConverter, nameValidator, arraySizeHint,