org.springframework.batch.core.scope.context.StepSynchronizationManager.java Source code

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Here is the source code for org.springframework.batch.core.scope.context.StepSynchronizationManager.java

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/*
 * Copyright 2006-2018 the original author or authors.
 *
 * 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
 *
 *      https://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 org.springframework.batch.core.scope.context;

import org.springframework.batch.core.Step;
import org.springframework.batch.core.StepExecution;
import org.springframework.batch.core.jsr.configuration.support.BatchPropertyContext;
import org.springframework.lang.Nullable;

/**
 * Central convenience class for framework use in managing the step scope
 * context. Generally only to be used by implementations of {@link Step}. N.B.
 * it is the responsibility of every {@link Step} implementation to ensure that
 * a {@link StepContext} is available on every thread that might be involved in
 * a step execution, including worker threads from a pool.
 *
 * @author Dave Syer
 * @author Michael Minella
 * @author Mahmoud Ben Hassine
 *
 */
public class StepSynchronizationManager {

    private static final SynchronizationManagerSupport<StepExecution, StepContext> manager = new SynchronizationManagerSupport<StepExecution, StepContext>() {

        @Override
        protected StepContext createNewContext(StepExecution execution, BatchPropertyContext propertyContext) {
            StepContext context;

            if (propertyContext != null) {
                context = new StepContext(execution, propertyContext);
            } else {
                context = new StepContext(execution);
            }

            return context;
        }

        @Override
        protected void close(StepContext context) {
            context.close();
        }
    };

    /**
     * Getter for the current context if there is one, otherwise returns {@code null}.
     *
     * @return the current {@link StepContext} or {@code null} if there is none (if one
     * has not been registered for this thread).
     */
    @Nullable
    public static StepContext getContext() {
        return manager.getContext();
    }

    /**
     * Register a context with the current thread - always put a matching
     * {@link #close()} call in a finally block to ensure that the correct
     * context is available in the enclosing block.
     *
     * @param stepExecution the step context to register
     * @return a new {@link StepContext} or the current one if it has the same
     * {@link StepExecution}
     */
    public static StepContext register(StepExecution stepExecution) {
        return manager.register(stepExecution);
    }

    /**
     * Register a context with the current thread - always put a matching
     * {@link #close()} call in a finally block to ensure that the correct
     * context is available in the enclosing block.
     *
     * @param stepExecution the step context to register
     * @param propertyContext an instance of {@link BatchPropertyContext} to be
     * used by the StepSynchronizationManager.
     * @return a new {@link StepContext} or the current one if it has the same
     * {@link StepExecution}
     */
    public static StepContext register(StepExecution stepExecution, BatchPropertyContext propertyContext) {
        return manager.register(stepExecution, propertyContext);
    }

    /**
     * Method for unregistering the current context - should always and only be
     * used by in conjunction with a matching {@link #register(StepExecution)}
     * to ensure that {@link #getContext()} always returns the correct value.
     * Does not call {@link StepContext#close()} - that is left up to the caller
     * because he has a reference to the context (having registered it) and only
     * he has knowledge of when the step actually ended.
     */
    public static void close() {
        manager.close();
    }

    /**
     * A convenient "deep" close operation. Call this instead of
     * {@link #close()} if the step execution for the current context is ending.
     * Delegates to {@link StepContext#close()} and then ensures that
     * {@link #close()} is also called in a finally block.
     */
    public static void release() {
        manager.release();
    }
}