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/**
 * Copyright (C) 2000-2023 Atomikos 
 *
 * LICENSE CONDITIONS
 *
 * See http://www.atomikos.com/Main/WhichLicenseApplies for details.
 */


package com.atomikos.icatch.config;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.List;
import java.util.ServiceLoader;
import java.util.Vector;

import com.atomikos.datasource.RecoverableResource;
import com.atomikos.datasource.ResourceException;
import com.atomikos.icatch.CompositeTransactionManager;
import com.atomikos.icatch.RecoveryService;
import com.atomikos.icatch.SysException;
import com.atomikos.icatch.TransactionService;
import com.atomikos.icatch.TransactionServicePlugin;
import com.atomikos.icatch.provider.Assembler;
import com.atomikos.icatch.provider.ConfigProperties;
import com.atomikos.icatch.provider.TransactionServiceProvider;
import com.atomikos.recovery.RecoveryLog;

/**
 * Configuration is a facade for the transaction management core.
 * Allows the application code to find the transaction manager, even if
 * the actual implementation varies over time.
 */

@SuppressWarnings("all")
public final class Configuration
{
	

    private static CompositeTransactionManager ctxmgr_ = null;
    // the tm for the virtual machine instance

    private static Hashtable resources_ = new Hashtable ();
    // filled on startup, contains all resources managed by the
    // transaction manager.

    private static Vector resourceList_ = new Vector ();
    // keep resources in a list, to enable ordered search of XAResource
    // this way, an AcceptAllXATransactionalResource can be added at the end


    private static RecoveryService recoveryService_;
    // needed for addResource to do recovery

    private static TransactionServiceProvider service_;
    // the transaction service for this VM.

    private static Vector tsListenersList_ = new Vector ();

    private static List shutdownHooks_ = new ArrayList();

	private static Assembler assembler;

	private static ConfigProperties configProperties;


	private static void purgeResources ()
    {
        Collection resources = getResources ();
        for(RecoverableResource res : resources) {
            if (res.isClosed()) {
                removeResource(res.getName());
            }
        }
    }

    /**
     * Construction not allowed.
     *
     */
    private Configuration ()
    {
    }

    private static void addAllTransactionServicePluginServicesFromClasspath() {
        ServiceLoader loader = ServiceLoader.load(TransactionServicePlugin.class,Configuration.class.getClassLoader());
        for (TransactionServicePlugin l : loader ) {
			registerTransactionServicePlugin(l);
		}
	}
    
	/**
     * Adds a shutdown hook to the configuration.
     * Shutdown hooks are managed here, since regular shutdown
     * of the transaction core should remove hooks
     * (cf case 21519).
     *
     * @param hook
     */
    private static synchronized void addShutdownHook ( Thread hook )
    {
    	if ( shutdownHooks_.contains ( hook ) ) return;

    	shutdownHooks_.add ( hook );
    	try {
    		Runtime.getRuntime().addShutdownHook ( hook );
    	}
    	catch ( IllegalStateException alreadyShuttingDownVm ) {
			//ignore: this happens when the VM exits and this method
			//is called as part of one of the shutdown hooks executing
		}
    }


    /**
     * Removes all shutdown hooks from the system.
     * This method should be called on shutdown of the core.
     */

    private static synchronized void removeShutdownHooks()
    {
    	Iterator it = shutdownHooks_.iterator();

    	//first check if we are not already doing a VM exit;
    	//don't remove the hooks if so
    	boolean vmShutdown = false;
    	while ( it.hasNext() ) {
    		Thread t = ( Thread ) it.next();
    		if ( t.equals ( Thread.currentThread() ) ) vmShutdown = true;
    	}

    	it = shutdownHooks_.iterator();
    	while ( !vmShutdown && it.hasNext() ) {
    		Thread hook = ( Thread ) it.next();
    		it.remove();
    		try {
    			Runtime.getRuntime().removeShutdownHook ( hook );
    		}
    		catch ( IllegalStateException alreadyShuttingDownVm ) {
    			//ignore: this happens when the VM exits and this method
    			//is called as part of one of the shutdown hooks executing
    		}
    	}
    }

    /**
     * Retrieves the transaction service being used.
     *
     * @return TransactionService The transaction service.
     */

    public static TransactionService getTransactionService ()
    {
        return service_;
    }

    /**
     * Add a transaction service listener.
     *
     * @param l
     *            The listener.
     */
    public static synchronized void registerTransactionServicePlugin ( TransactionServicePlugin l )
    {

        if ( service_ != null ) {
            service_.addTSListener ( l );
        }
        tsListenersList_.add ( l );
    }

    /**
     * Remove a transaction service listener.
     *
     * @param l
     *            The listener.
     */
    public static synchronized void unregisterTransactionServicePlugin ( TransactionServicePlugin l )
    {
        if ( service_ != null ) {
            service_.removeTSListener ( l );
        }
        tsListenersList_.remove ( l );
    }

    /**
     * Installs a composite transaction manager as a Singleton.
     *
     * @param compositeTransactionManager
     *            The instance to install.
     */

    public static synchronized void installCompositeTransactionManager (
            CompositeTransactionManager compositeTransactionManager )
    {

        ctxmgr_ = compositeTransactionManager;
    }

    /**
     * Get the composite transaction manager.
     *
     * @return CompositeTransactionManager The instance, or null if none.
     */

    public static CompositeTransactionManager getCompositeTransactionManager ()
    {
        return ctxmgr_;
    }



    /**
     * Add a resource to the transaction manager domain. Should be called for
     * all resources that have to be recovered, BEFORE initializing the
     * transaction manager! The purpose of registering resources is mainly to be
     * able the recovery the ResourceTransaction context for each prepared
     * ResourceTransction. This is needed for those ResourceTransaction
     * instances that do not encapsulate the full state themselves, as in the
     * XAResource case.
     *
     * @param resource
     *            The resource to add.
     *
     * @exception IllegalStateException
     *                If the name of the resource is already in use.
     */

    public static synchronized void addResource ( RecoverableResource resource )
            throws IllegalStateException
    {
        // ADDED with new recovery: temporary resources:
        // memory overflow can only happen upon addition of resources
        // so before each add, first purge closed resources to make room
        purgeResources ();

        if ( resources_.containsKey ( resource.getName () ) )
            throw new IllegalStateException ( "Another resource already exists with name " + resource.getName() + " - pick a different name");


        //FIRST add init resource, only then add it - cf case 142795
        resource.setRecoveryService ( recoveryService_ );
        resources_.put ( resource.getName (), resource );
        resourceList_.add ( resource );
    }

    /**
     * Removes a resource from the config.
     *
     * @param name
     *            The resource's name.
     * @return RecoverableResource The removed object.
     */

    public static RecoverableResource removeResource ( String name )
    {
        RecoverableResource ret = null;
        if ( name != null ) {
        	ret = (RecoverableResource) resources_.remove ( name );
        	if ( ret != null ) resourceList_.remove ( ret );

        }
        return ret;
    }

    /**
     * Get the resource with the given name.
     *
     * @return RecoverableResource The resource.
     * @param name
     *            The name to find.
     */

    public static RecoverableResource getResource ( String name )
    {
        RecoverableResource res = null;
        if ( name != null ) res = (RecoverableResource) resources_.get ( name );
        return res;
    }

    /**
     * Get all resources added so far, in the order that they were added.
     *
     */

    public static Collection getResources ()
    {
        // clone to avoid concurrency problems with
        // add/removeResource (new recovery makes this possible)
        Vector ret = (Vector) resourceList_.clone ();
        return ret;
    }

	protected static synchronized Assembler getAssembler() {
		if (assembler == null) loadAssembler();
		return assembler;
	}

	private static void loadAssembler() {
        ServiceLoader loader = ServiceLoader.load(Assembler.class,Configuration.class.getClassLoader());
		Iterator it = loader.iterator();
		if (it.hasNext()) {
			assembler = it.next();
		} else {
			throw new SysException("No Assembler service found - please make sure that the right jars are in your classpath");
		}
	}

	public static synchronized ConfigProperties getConfigProperties() {
		if (configProperties == null) {
			configProperties = getAssembler().initializeProperties();
		}
		return configProperties;
	}

	static synchronized void resetConfigProperties() {
		configProperties = null;
	}
	
	public static synchronized void shutdown(boolean force) {
		if (service_ != null) {
			service_.shutdown(force);
			notifyAfterShutdown();
			removeShutdownHooks();
			removeAndCloseResources(force);
			clearSystemComponents();
		}
	}	
	
	private static void clearSystemComponents() {
		service_ = null;
		recoveryService_ = null;
		ctxmgr_ = null;
		tsListenersList_.clear();
		resetConfigProperties();
		assembler = null;
	}

	private static void notifyAfterShutdown() {
		for (TransactionServicePlugin p : tsListenersList_) {
			p.afterShutdown();
		}
	}

	private static void removeAndCloseResources(boolean force) {
		Collection resources = Configuration.getResources();
		for (RecoverableResource res : resources) {
		    Configuration.removeResource ( res.getName () );
            try {
                res.close ();
            } catch ( ResourceException re ) {
               //Issue 10038:
               //Ignore errors in force mode: force is most likely
               //during VM exit; in that case interleaving of shutdown hooks
               //means that resource connectors may have closed already
               //by the time the TM hook runs. We don't want useless
               //reports in that case.
               //NOTE: any invalid states will be detected during the next
               //(re)init so they can be ignored here (if force mode)

                if ( !force ) {
                    re.printStackTrace();
                }
            }
        }
	}

	/**
	 * 
	 * @return False if already running.
	 */
	public static synchronized boolean init() {
		boolean startupInitiated = false;
		if (service_ == null) {
			startupInitiated = true;
			addAllTransactionServicePluginServicesFromClasspath();
			ConfigProperties configProperties = getConfigProperties();
			notifyBeforeInit(configProperties);
			assembleSystemComponents(configProperties);
			initializeSystemComponents(configProperties);
			notifyAfterInit();
			if (configProperties.getForceShutdownOnVmExit()) {
				addShutdownHook(new ForceShutdownHook());
			}
		}
		return startupInitiated;
	}

	private static void notifyAfterInit() {
		for (TransactionServicePlugin p : tsListenersList_) {
			p.afterInit();
		}
		for (RecoverableResource r : resourceList_ ) {
			r.setRecoveryService(recoveryService_);
		}
		
	}

	private static void initializeSystemComponents(
			ConfigProperties configProperties) {
		service_.init(configProperties.getCompletedProperties());
	}

	private static void notifyBeforeInit(ConfigProperties configProperties) {
		for (TransactionServicePlugin p : tsListenersList_) {
			p.beforeInit();
		}
	}

	private static void assembleSystemComponents(
			ConfigProperties configProperties) {
		Assembler assembler = getAssembler();
		service_ = assembler.assembleTransactionService(configProperties);
		recoveryService_ = service_.getRecoveryService();
		ctxmgr_ = assembler.assembleCompositeTransactionManager();
	}
	
	public static RecoveryLog getRecoveryLog() {
		return recoveryService_.getRecoveryLog();
	}
	
	public static RecoveryService getRecoveryService() {
		return recoveryService_;
	}
	
	private static class ForceShutdownHook extends Thread
    {
        

        private ForceShutdownHook()
        {
            super();
        }

        public void run() {
            Configuration.shutdown(true);
        }
    }


}




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