SimpleStringMap Class — netty Architecture

Source Code

microbench/src/main/java/io/netty/handler/codec/http/HttpMethodMapBenchmark.java lines 114–152

    private static final class SimpleStringMap<T> {
        private final SimpleStringMap.Node<T>[] values;
        private final int valuesMask;

        SimpleStringMap(SimpleStringMap.Node<T>... nodes) {
            values = (SimpleStringMap.Node<T>[]) new SimpleStringMap.Node[findNextPositivePowerOfTwo(nodes.length)];
            valuesMask = values.length - 1;
            for (SimpleStringMap.Node<T> node : nodes) {
                int i = hashCode(node.key) & valuesMask;
                if (values[i] != null) {
                    throw new IllegalArgumentException("index " + i + " collision between values: [" +
                            values[i].key + ", " + node.key + "]");
                }
                values[i] = node;
            }
        }

        T get(String name) {
            SimpleStringMap.Node<T> node = values[hashCode(name) & valuesMask];
            return node == null || !node.key.equals(name) ? null : node.value;
        }

        private static int hashCode(String name) {
            // This hash code needs to produce a unique index for each HttpMethod. If new methods are added this
            // algorithm will need to be adjusted. The goal is to have each enum name's hash value correlate to a unique
            // index in the values array.
            return name.hashCode() >>> 6;
        }

        private static final class Node<T> {
            final String key;
            final T value;

            Node(String key, T value) {
                this.key = key;
                this.value = value;
            }
        }
    }