org.springframework.context.support.DefaultLifecycleProcessor

/*
* Copyright 2002-2013 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
*
* 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 org.springframework.context.support;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.context.ApplicationContextException;
import org.springframework.context.Lifecycle;
import org.springframework.context.LifecycleProcessor;
import org.springframework.context.Phased;
import org.springframework.context.SmartLifecycle;
import org.springframework.util.Assert;

/**
* Default implementation of the {@link LifecycleProcessor} strategy.
*
* @author Mark Fisher
* @author Juergen Hoeller
* @since 3.0
*/
public class DefaultLifecycleProcessor implements LifecycleProcessor, BeanFactoryAware {

private final Log logger = LogFactory.getLog(getClass());

private volatile long timeoutPerShutdownPhase = 30000;

private volatile boolean running;

private volatile ConfigurableListableBeanFactory beanFactory;


/**
 * Specify the maximum time allotted in milliseconds for the shutdown of
 * any phase (group of SmartLifecycle beans with the same 'phase' value).
 * The default value is 30 seconds.
 */
public void setTimeoutPerShutdownPhase(long timeoutPerShutdownPhase) {
    this.timeoutPerShutdownPhase = timeoutPerShutdownPhase;
}

@Override
public void setBeanFactory(BeanFactory beanFactory) {
    Assert.isInstanceOf(ConfigurableListableBeanFactory.class, beanFactory);
    this.beanFactory = (ConfigurableListableBeanFactory) beanFactory;
}


// Lifecycle implementation

/**
 * Start all registered beans that implement Lifecycle and are
 * not already running. Any bean that implements SmartLifecycle
 * will be started within its 'phase', and all phases will be ordered
 * from lowest to highest value. All beans that do not implement
 * SmartLifecycle will be started in the default phase 0. A bean
 * declared as a dependency of another bean will be started before
 * the dependent bean regardless of the declared phase.
 */
@Override
public void start() {
    startBeans(false);
    this.running = true;
}

/**
 * Stop all registered beans that implement Lifecycle and are
 * currently running. Any bean that implements SmartLifecycle
 * will be stopped within its 'phase', and all phases will be ordered
 * from highest to lowest value. All beans that do not implement
 * SmartLifecycle will be stopped in the default phase 0. A bean
 * declared as dependent on another bean will be stopped before
 * the dependency bean regardless of the declared phase.
 */
@Override
public void stop() {
    stopBeans();
    this.running = false;
}

@Override
public void onRefresh() {
    startBeans(true);
    this.running = true;
}

@Override
public void onClose() {
    stopBeans();
    this.running = false;
}

@Override
public boolean isRunning() {
    return this.running;
}


// internal helpers

private void startBeans(boolean autoStartupOnly) {
    Map lifecycleBeans = getLifecycleBeans();
    Map phases = new HashMap();
    for (Map.Entry entry : lifecycleBeans.entrySet()) {
        Lifecycle bean = entry.getValue();
        if (!autoStartupOnly || (bean instanceof SmartLifecycle && ((SmartLifecycle) bean).isAutoStartup())) {
            int phase = getPhase(bean);
            LifecycleGroup group = phases.get(phase);
            if (group == null) {
                group = new LifecycleGroup(phase, this.timeoutPerShutdownPhase, lifecycleBeans, autoStartupOnly);
                phases.put(phase, group);
            }
            group.add(entry.getKey(), bean);
        }
    }
    if (phases.size() > 0) {
        List keys = new ArrayList(phases.keySet());
        Collections.sort(keys);
        for (Integer key : keys) {
            phases.get(key).start();
        }
    }
}

/**
 * Start the specified bean as part of the given set of Lifecycle beans,
 * making sure that any beans that it depends on are started first.
 * @param lifecycleBeans Map with bean name as key and Lifecycle instance as value
 * @param beanName the name of the bean to start
 */
private void doStart(Map lifecycleBeans, String beanName, boolean autoStartupOnly) {
    Lifecycle bean = lifecycleBeans.remove(beanName);
    if (bean != null && !this.equals(bean)) {
        String[] dependenciesForBean = this.beanFactory.getDependenciesForBean(beanName);
        for (String dependency : dependenciesForBean) {
            doStart(lifecycleBeans, dependency, autoStartupOnly);
        }
        if (!bean.isRunning() &&
                (!autoStartupOnly || !(bean instanceof SmartLifecycle) || ((SmartLifecycle) bean).isAutoStartup())) {
            if (logger.isDebugEnabled()) {
                logger.debug("Starting bean '" + beanName + "' of type [" + bean.getClass() + "]");
            }
            try {
                bean.start();
            }
            catch (Throwable ex) {
                throw new ApplicationContextException("Failed to start bean '" + beanName + "'", ex);
            }
            if (logger.isDebugEnabled()) {
                logger.debug("Successfully started bean '" + beanName + "'");
            }
        }
    }
}

private void stopBeans() {
    Map lifecycleBeans = getLifecycleBeans();
    Map phases = new HashMap();
    for (Map.Entry entry : lifecycleBeans.entrySet()) {
        Lifecycle bean = entry.getValue();
        int shutdownOrder = getPhase(bean);
        LifecycleGroup group = phases.get(shutdownOrder);
        if (group == null) {
            group = new LifecycleGroup(shutdownOrder, this.timeoutPerShutdownPhase, lifecycleBeans, false);
            phases.put(shutdownOrder, group);
        }
        group.add(entry.getKey(), bean);
    }
    if (phases.size() > 0) {
        List keys = new ArrayList(phases.keySet());
        Collections.sort(keys, Collections.reverseOrder());
        for (Integer key : keys) {
            phases.get(key).stop();
        }
    }
}

/**
 * Stop the specified bean as part of the given set of Lifecycle beans,
 * making sure that any beans that depends on it are stopped first.
 * @param lifecycleBeans Map with bean name as key and Lifecycle instance as value
 * @param beanName the name of the bean to stop
 */
private void doStop(Map lifecycleBeans, final String beanName,
        final CountDownLatch latch, final Set countDownBeanNames) {

    Lifecycle bean = lifecycleBeans.remove(beanName);
    if (bean != null) {
        String[] dependentBeans = this.beanFactory.getDependentBeans(beanName);
        for (String dependentBean : dependentBeans) {
            doStop(lifecycleBeans, dependentBean, latch, countDownBeanNames);
        }
        try {
            if (bean.isRunning()) {
                if (bean instanceof SmartLifecycle) {
                    if (logger.isDebugEnabled()) {
                        logger.debug("Asking bean '" + beanName + "' of type [" + bean.getClass() + "] to stop");
                    }
                    countDownBeanNames.add(beanName);
                    ((SmartLifecycle) bean).stop(new Runnable() {
                        @Override
                        public void run() {
                            latch.countDown();
                            countDownBeanNames.remove(beanName);
                            if (logger.isDebugEnabled()) {
                                logger.debug("Bean '" + beanName + "' completed its stop procedure");
                            }
                        }
                    });
                }
                else {
                    if (logger.isDebugEnabled()) {
                        logger.debug("Stopping bean '" + beanName + "' of type [" + bean.getClass() + "]");
                    }
                    bean.stop();
                    if (logger.isDebugEnabled()) {
                        logger.debug("Successfully stopped bean '" + beanName + "'");
                    }
                }
            }
            else if (bean instanceof SmartLifecycle) {
                // don't wait for beans that aren't running
                latch.countDown();
            }
        }
        catch (Throwable ex) {
            if (logger.isWarnEnabled()) {
                logger.warn("Failed to stop bean '" + beanName + "'", ex);
            }
        }
    }
}


// overridable hooks

/**
 * Retrieve all applicable Lifecycle beans: all singletons that have already been created,
 * as well as all SmartLifecycle beans (even if they are marked as lazy-init).
 * @return the Map of applicable beans, with bean names as keys and bean instances as values
 */
protected Map getLifecycleBeans() {
    Map beans = new LinkedHashMap();
    String[] beanNames = this.beanFactory.getBeanNamesForType(Lifecycle.class, false, false);
    for (String beanName : beanNames) {
        String beanNameToRegister = BeanFactoryUtils.transformedBeanName(beanName);
        boolean isFactoryBean = this.beanFactory.isFactoryBean(beanNameToRegister);
        String beanNameToCheck = (isFactoryBean ? BeanFactory.FACTORY_BEAN_PREFIX + beanName : beanName);
        if ((this.beanFactory.containsSingleton(beanNameToRegister) &&
                (!isFactoryBean || Lifecycle.class.isAssignableFrom(this.beanFactory.getType(beanNameToCheck)))) ||
                SmartLifecycle.class.isAssignableFrom(this.beanFactory.getType(beanNameToCheck))) {
            Lifecycle bean = this.beanFactory.getBean(beanNameToCheck, Lifecycle.class);
            if (bean != this) {
                beans.put(beanNameToRegister, bean);
            }
        }
    }
    return beans;
}

/**
 * Determine the lifecycle phase of the given bean.
 * 
The default implementation checks for the {@link Phased} interface.
 * Can be overridden to apply other/further policies.
 * @param bean the bean to introspect
 * @return the phase an an integer value. The suggested default is 0.
 * @see Phased
 * @see SmartLifecycle
 */
protected int getPhase(Lifecycle bean) {
    return (bean instanceof Phased ? ((Phased) bean).getPhase() : 0);
}


/**
 * Helper class for maintaining a group of Lifecycle beans that should be started
 * and stopped together based on their 'phase' value (or the default value of 0).
 */
private class LifecycleGroup {

    private final List members = new ArrayList();

    private final int phase;

    private final long timeout;

    private final Map lifecycleBeans;

    private final boolean autoStartupOnly;

    private volatile int smartMemberCount;

    public LifecycleGroup(int phase, long timeout, Map lifecycleBeans, boolean autoStartupOnly) {
        this.phase = phase;
        this.timeout = timeout;
        this.lifecycleBeans = lifecycleBeans;
        this.autoStartupOnly = autoStartupOnly;
    }

    public void add(String name, Lifecycle bean) {
        if (bean instanceof SmartLifecycle) {
            this.smartMemberCount++;
        }
        this.members.add(new LifecycleGroupMember(name, bean));
    }

    public void start() {
        if (this.members.isEmpty()) {
            return;
        }
        if (logger.isInfoEnabled()) {
            logger.info("Starting beans in phase " + this.phase);
        }
        Collections.sort(this.members);
        for (LifecycleGroupMember member : this.members) {
            if (this.lifecycleBeans.containsKey(member.name)) {
                doStart(this.lifecycleBeans, member.name, this.autoStartupOnly);
            }
        }
    }

    public void stop() {
        if (this.members.isEmpty()) {
            return;
        }
        if (logger.isInfoEnabled()) {
            logger.info("Stopping beans in phase " + this.phase);
        }
        Collections.sort(this.members, Collections.reverseOrder());
        CountDownLatch latch = new CountDownLatch(this.smartMemberCount);
        Set countDownBeanNames = Collections.synchronizedSet(new LinkedHashSet());
        for (LifecycleGroupMember member : this.members) {
            if (this.lifecycleBeans.containsKey(member.name)) {
                doStop(this.lifecycleBeans, member.name, latch, countDownBeanNames);
            }
            else if (member.bean instanceof SmartLifecycle) {
                // already removed, must have been a dependent
                latch.countDown();
            }
        }
        try {
            latch.await(this.timeout, TimeUnit.MILLISECONDS);
            if (latch.getCount() > 0 && !countDownBeanNames.isEmpty() && logger.isWarnEnabled()) {
                logger.warn("Failed to shut down " + countDownBeanNames.size() + " bean" +
                        (countDownBeanNames.size() > 1 ? "s" : "") + " with phase value " +
                        this.phase + " within timeout of " + this.timeout + ": " + countDownBeanNames);
            }
        }
        catch (InterruptedException ex) {
            Thread.currentThread().interrupt();
        }
    }
}


/**
 * Adapts the Comparable interface onto the lifecycle phase model.
 */
private class LifecycleGroupMember implements Comparable {

    private final String name;

    private final Lifecycle bean;

    LifecycleGroupMember(String name, Lifecycle bean) {
        this.name = name;
        this.bean = bean;
    }

    @Override
    public int compareTo(LifecycleGroupMember other) {
        int thisOrder = getPhase(this.bean);
        int otherOrder = getPhase(other.bean);
        return (thisOrder == otherOrder ? 0 : (thisOrder < otherOrder) ? -1 : 1);
    }
}

}