InternalThreadLocalMap Class — netty Architecture

Source Code

common/src/main/java/io/netty/util/internal/InternalThreadLocalMap.java lines 41–393

public final class InternalThreadLocalMap extends UnpaddedInternalThreadLocalMap {
    private static final ThreadLocal<InternalThreadLocalMap> slowThreadLocalMap =
            new ThreadLocal<InternalThreadLocalMap>();
    private static final AtomicInteger nextIndex = new AtomicInteger();
    // Internal use only.
    public static final int VARIABLES_TO_REMOVE_INDEX = nextVariableIndex();

    private static final int DEFAULT_ARRAY_LIST_INITIAL_CAPACITY = 8;
    private static final int ARRAY_LIST_CAPACITY_EXPAND_THRESHOLD = 1 << 30;
    // Reference: https://hg.openjdk.java.net/jdk8/jdk8/jdk/file/tip/src/share/classes/java/util/ArrayList.java#l229
    private static final int ARRAY_LIST_CAPACITY_MAX_SIZE = Integer.MAX_VALUE - 8;

    private static final int HANDLER_SHARABLE_CACHE_INITIAL_CAPACITY = 4;
    private static final int INDEXED_VARIABLE_TABLE_INITIAL_SIZE = 32;

    private static final int STRING_BUILDER_INITIAL_SIZE;
    private static final int STRING_BUILDER_MAX_SIZE;

    private static final InternalLogger logger;
    /** Internal use only. */
    public static final Object UNSET = new Object();

    /** Used by {@link FastThreadLocal} */
    private Object[] indexedVariables;

    // Core thread-locals
    private int futureListenerStackDepth;
    private int localChannelReaderStackDepth;
    private Map<Class<?>, Boolean> handlerSharableCache;
    private Map<Class<?>, TypeParameterMatcher> typeParameterMatcherGetCache;
    private Map<Class<?>, Map<String, TypeParameterMatcher>> typeParameterMatcherFindCache;

    // String-related thread-locals
    private StringBuilder stringBuilder;
    private Map<Charset, CharsetEncoder> charsetEncoderCache;
    private Map<Charset, CharsetDecoder> charsetDecoderCache;

    // ArrayList-related thread-locals
    private ArrayList<Object> arrayList;

    private BitSet cleanerFlags;

    /** @deprecated These padding fields will be removed in the future. */
    public long rp1, rp2, rp3, rp4, rp5, rp6, rp7, rp8;

    static {
        STRING_BUILDER_INITIAL_SIZE =
                SystemPropertyUtil.getInt("io.netty.threadLocalMap.stringBuilder.initialSize", 1024);
        STRING_BUILDER_MAX_SIZE =
                SystemPropertyUtil.getInt("io.netty.threadLocalMap.stringBuilder.maxSize", 1024 * 4);

        // Ensure the InternalLogger is initialized as last field in this class as InternalThreadLocalMap might be used
        // by the InternalLogger itself. For this its important that all the other static fields are correctly
        // initialized.
        //
        // See https://github.com/netty/netty/issues/12931.
        logger = InternalLoggerFactory.getInstance(InternalThreadLocalMap.class);
        logger.debug("-Dio.netty.threadLocalMap.stringBuilder.initialSize: {}", STRING_BUILDER_INITIAL_SIZE);
        logger.debug("-Dio.netty.threadLocalMap.stringBuilder.maxSize: {}", STRING_BUILDER_MAX_SIZE);
    }

    public static InternalThreadLocalMap getIfSet() {
        Thread thread = Thread.currentThread();
        if (thread instanceof FastThreadLocalThread) {
            return ((FastThreadLocalThread) thread).threadLocalMap();
        }
        return slowThreadLocalMap.get();
    }

    public static InternalThreadLocalMap get() {
        Thread thread = Thread.currentThread();
        if (thread instanceof FastThreadLocalThread) {
            return fastGet((FastThreadLocalThread) thread);
        } else {
            return slowGet();
        }
    }

    private static InternalThreadLocalMap fastGet(FastThreadLocalThread thread) {
        InternalThreadLocalMap threadLocalMap = thread.threadLocalMap();
        if (threadLocalMap == null) {