FastThreadLocal Class — netty Architecture

Source Code

common/src/main/java/io/netty/util/concurrent/FastThreadLocal.java lines 47–308

public class FastThreadLocal<V> {

    /**
     * Removes all {@link FastThreadLocal} variables bound to the current thread.  This operation is useful when you
     * are in a container environment, and you don't want to leave the thread local variables in the threads you do not
     * manage.
     */
    public static void removeAll() {
        InternalThreadLocalMap threadLocalMap = InternalThreadLocalMap.getIfSet();
        if (threadLocalMap == null) {
            return;
        }

        try {
            Object v = threadLocalMap.indexedVariable(VARIABLES_TO_REMOVE_INDEX);
            if (v != null && v != InternalThreadLocalMap.UNSET) {
                @SuppressWarnings("unchecked")
                Set<FastThreadLocal<?>> variablesToRemove = (Set<FastThreadLocal<?>>) v;
                FastThreadLocal<?>[] variablesToRemoveArray =
                        variablesToRemove.toArray(new FastThreadLocal[0]);
                for (FastThreadLocal<?> tlv: variablesToRemoveArray) {
                    tlv.remove(threadLocalMap);
                }
            }
        } finally {
            InternalThreadLocalMap.remove();
        }
    }

    /**
     * Returns the number of thread local variables bound to the current thread.
     */
    public static int size() {
        InternalThreadLocalMap threadLocalMap = InternalThreadLocalMap.getIfSet();
        if (threadLocalMap == null) {
            return 0;
        } else {
            return threadLocalMap.size();
        }
    }

    /**
     * Destroys the data structure that keeps all {@link FastThreadLocal} variables accessed from
     * non-{@link FastThreadLocalThread}s.  This operation is useful when you are in a container environment, and you
     * do not want to leave the thread local variables in the threads you do not manage.  Call this method when your
     * application is being unloaded from the container.
     */
    public static void destroy() {
        InternalThreadLocalMap.destroy();
    }

    @SuppressWarnings("unchecked")
    private static void addToVariablesToRemove(InternalThreadLocalMap threadLocalMap, FastThreadLocal<?> variable) {
        Object v = threadLocalMap.indexedVariable(VARIABLES_TO_REMOVE_INDEX);
        Set<FastThreadLocal<?>> variablesToRemove;
        if (v == InternalThreadLocalMap.UNSET || v == null) {
            variablesToRemove = Collections.newSetFromMap(new IdentityHashMap<FastThreadLocal<?>, Boolean>());
            threadLocalMap.setIndexedVariable(VARIABLES_TO_REMOVE_INDEX, variablesToRemove);
        } else {
            variablesToRemove = (Set<FastThreadLocal<?>>) v;
        }

        variablesToRemove.add(variable);
    }

    private static void removeFromVariablesToRemove(
            InternalThreadLocalMap threadLocalMap, FastThreadLocal<?> variable) {

        Object v = threadLocalMap.indexedVariable(VARIABLES_TO_REMOVE_INDEX);

        if (v == InternalThreadLocalMap.UNSET || v == null) {
            return;
        }

        @SuppressWarnings("unchecked")
        Set<FastThreadLocal<?>> variablesToRemove = (Set<FastThreadLocal<?>>) v;
        variablesToRemove.remove(variable);
    }

    private final int index;