com.b2international.snowowl.datastore.oplock.OperationLockRunner.java Source code

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Here is the source code for com.b2international.snowowl.datastore.oplock.OperationLockRunner.java

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/*
 * Copyright 2011-2015 B2i Healthcare Pte Ltd, http://b2i.sg
 * 
 * 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 com.b2international.snowowl.datastore.oplock;

import java.io.Serializable;
import java.lang.reflect.InvocationTargetException;

import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;

/**
 * Contains utility methods for executing a {@link Runnable} while holding one or more operation locks.
 *
 * @param <C> the lock context type (must implement {@link Serializable})
 */
public class OperationLockRunner<C extends Serializable> {

    private final IOperationLockManager<C> manager;

    /**
     * Creates a new instance with the specified operation lock manager.
     * 
     * @param manager the lock manager to use (may not be {@code null})
     */
    public static <T extends Serializable> OperationLockRunner<T> with(final IOperationLockManager<T> manager) {
        return new OperationLockRunner<T>(manager);
    }

    private OperationLockRunner(final IOperationLockManager<C> manager) {
        this.manager = Preconditions.checkNotNull(manager, "Lock manager reference may not be null.");
    }

    /**
     * Ensures that the specified locks are acquired for the given context while a {@link Runnable} is executing; cleans
     * up acquired locks if the runnable finishes or an exception is thrown from it.
     * 
     * @param runnable the runnable to call with the locks held (may not be {@code null})
     * @param context the lock context (may not be {@code null})
     * @param timeoutMillis the maximum allowed time in milliseconds in which this call may block (must be {@link #NO_TIMEOUT}, zero or positive)
     * @param firstTarget the first (or only) target to hold while running (may not be {@code null})
     * @param restTargets subsequent targets to hold while running (may not be {@code null}; individual elements may not be {@code null})
     * @throws OperationLockException when one or more locks for the given targets could not be acquired or released for some reason
     * @throws InterruptedException if waiting for the requested locks to be acquired is interrupted
     * @throws InvocationTargetException if the specified runnable throws an exception
     */
    public void run(final Runnable runnable, final C context, final long timeoutMillis,
            final IOperationLockTarget firstTarget, final IOperationLockTarget... restTargets)
            throws OperationLockException, InterruptedException, InvocationTargetException {

        run(runnable, context, timeoutMillis, Lists.asList(firstTarget, restTargets));
    }

    /**
     * Ensures that the specified locks are acquired for the given context while a {@link Runnable} is executing; cleans
     * up acquired locks if the runnable finishes or an exception is thrown from it.
     * 
     * @param runnable the runnable to call with the locks held (may not be {@code null})
     * @param context the lock context (may not be {@code null})
     * @param timeoutMillis the maximum allowed time in milliseconds in which this call may block (must be {@link #NO_TIMEOUT}, zero or positive)
     * @param targets the targets to hold while running (may not be {@code null}; can be empty)
     * @throws OperationLockException when one or more locks for the given targets could not be acquired or released for some reason
     * @throws InterruptedException if waiting for the requested locks to be acquired is interrupted
     * @throws InvocationTargetException if the specified runnable throws an exception
     */
    public void run(final Runnable runnable, final C context, final long timeoutMillis,
            final Iterable<IOperationLockTarget> targets)
            throws OperationLockException, InterruptedException, InvocationTargetException {

        Throwable caught = null;
        manager.lock(context, timeoutMillis, targets);

        try {
            runnable.run();
        } catch (final Throwable t) {
            caught = t;
            throw new InvocationTargetException(t);
        } finally {
            try {
                manager.unlock(context, targets);
            } catch (final OperationLockException e) {
                if (null != caught) {
                    caught.addSuppressed(e);
                } else {
                    throw e;
                }
            }
        }
    }
}