co.elastic.apm.agent.sdk.state.GlobalThreadLocal Maven / Gradle / Ivy

Go to download
/*-
 * #%L
 * Elastic APM Java agent
 * %%
 * Copyright (C) 2018 - 2020 Elastic and contributors
 * %%
 * Licensed to Elasticsearch B.V. under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch B.V. licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * #L%
 */
package co.elastic.apm.agent.sdk.state;

import co.elastic.apm.agent.sdk.weakmap.NullCheck;
import co.elastic.apm.agent.shaded.weaklockfree.DetachedThreadLocal;

import javax.annotation.Nullable;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

/**
 * Allows registering a globally shared instance of a {@link DetachedThreadLocal} that optionally allows for removal on get.
 * Similar to {@link GlobalVariables} and {@link GlobalState},
 * this allows to get thread locals whose state is shared across plugin class loaders.
 *
 * @param 
 */
public class GlobalThreadLocal extends DetachedThreadLocal {

    private static final ConcurrentMap> registry = new ConcurrentHashMap<>();
    @Nullable
    private final T defaultValue;

    private GlobalThreadLocal(@Nullable T defaultValue) {
        super(Cleaner.INLINE);
        this.defaultValue = defaultValue;
    }

    public static  GlobalThreadLocal get(Class adviceClass, String key) {
        return get(adviceClass.getName() + "." + key, null);
    }

    public static  GlobalThreadLocal get(Class adviceClass, String key, @Nullable T defaultValue) {
        return get(adviceClass.getName() + "." + key, defaultValue);
    }

    static  GlobalThreadLocal get(String key, @Nullable T defaultValue) {
        GlobalThreadLocal threadLocal = registry.get(key);
        if (threadLocal == null) {
            registry.putIfAbsent(key, new GlobalThreadLocal(defaultValue));
            threadLocal = registry.get(key);
        }
        return (GlobalThreadLocal) threadLocal;
    }

    @Nullable
    public T getAndRemove() {
        T value = get();
        if (value != null) {
            clear();
        }
        return value;
    }

    public T get(T defaultValue) {
        T value = get();
        if (value != null) {
            return value;
        }
        return defaultValue;
    }

    @Override
    public void set(@Nullable T value) {
        if (NullCheck.isNullKey(value)) {
            return;
        }
        super.set(value);
    }

    @Override
    @Nullable
    protected T initialValue(Thread thread) {
        return defaultValue;
    }

}