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/*
 * =========================================================================================
 * Copyright © 2013-2018 the kamon project 
 *
 * Licensed 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.
 * =========================================================================================
 */

package kanela.agent.bootstrap.context;

import java.util.concurrent.Callable;

/**
 * {@code ContextHandler} provides methods for accessing and manipulating the context from
 * instrumented bytecode.
 *
 * {@code ContextHandler} avoids tight coupling with the concrete implementation of the
 * context by accessing and manipulating the context through the {@link ContextProvider} interface.
 *
 * 
Both {@link ContextHandler} and {@link ContextProvider} are loaded by the bootstrap
 * classloader so that they can be used from classes loaded by the bootstrap classloader. A concrete
 * implementation of {@link ContextProvider} will be loaded by the system classloader. This allows
 * for using the same context implementation as the instrumented application.
 *
 * {@code ContextHandler} is implemented as a static class to allow for easy and fast use from
 * instrumented bytecode. We cannot use dependency injection for the instrumented bytecode.
 *
 * @since 0.10
 */

public final class ContextHandler {

    private static ContextProvider contextProvider = ContextProvider.NoOp.INSTANCE;

    private ContextHandler() {}

    public static void setContextProvider(ContextProvider contextProvider) {
        if(contextProvider != ContextProvider.NoOp.INSTANCE) {
            ContextHandler.contextProvider = contextProvider;
        }
    }

    public static Runnable wrapInContextAware(Runnable runnable) { return contextProvider.wrapInContextAware(runnable);}
    public static  Callable wrapInContextAware(Callable callable) { return contextProvider.wrapInContextAware(callable);}
}