ambari-server/src/main/java/org/apache/ambari/server/controller/internal/AbstractResourceProvider.java - ambari - Git at Google

 /**
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you 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.apache.ambari.server.controller.internal;

 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.Map.Entry;
 import java.util.regex.Pattern;

 import org.apache.ambari.server.AmbariException;
 import org.apache.ambari.server.DuplicateResourceException;
 import org.apache.ambari.server.ObjectNotFoundException;
 import org.apache.ambari.server.ParentObjectNotFoundException;
 import org.apache.ambari.server.controller.ConfigurationRequest;
 import org.apache.ambari.server.controller.RequestStatusResponse;
 import org.apache.ambari.server.controller.predicate.ArrayPredicate;
 import org.apache.ambari.server.controller.predicate.EqualsPredicate;
 import org.apache.ambari.server.controller.spi.*;
 import org.apache.ambari.server.controller.utilities.PredicateHelper;
 import org.apache.ambari.server.controller.utilities.PropertyHelper;
 import org.apache.ambari.server.security.authorization.AuthorizationException;
 import org.apache.ambari.server.utils.RetryHelper;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

 /**
  * Abstract resource provider implementation that maps to an Ambari management controller.
  */
 public abstract class AbstractResourceProvider extends BaseProvider implements ResourceProvider, ObservableResourceProvider {

   /**
    * Key property mapping by resource type.
    */
   private final Map<Resource.Type, String> keyPropertyIds;

   /**
    * Observers of this observable resource provider.
    */
   private final Set<ResourceProviderObserver> observers = new HashSet<ResourceProviderObserver>();

   protected final static Logger LOG = LoggerFactory.getLogger(AbstractResourceProvider.class);
   protected final static String PROPERTIES_ATTRIBUTES_REGEX = "properties_attributes/[a-zA-Z][a-zA-Z._-]*$";
   public static Pattern propertiesAttributesPattern = Pattern.compile(".*/" + PROPERTIES_ATTRIBUTES_REGEX);


   // ----- Constructors ------------------------------------------------------

   /**
    * Create a  new resource provider.
    *
    * @param propertyIds     the property ids
    * @param keyPropertyIds  the key property ids
    */
   protected AbstractResourceProvider(Set<String> propertyIds,
                                      Map<Resource.Type, String> keyPropertyIds) {
     super(propertyIds);
     this.keyPropertyIds = keyPropertyIds;
   }


   // ----- ResourceProvider --------------------------------------------------

   @Override
   public Map<Resource.Type, String> getKeyPropertyIds() {
     return keyPropertyIds;
   }


   // ----- ObservableResourceProvider ----------------------------------------

   @Override
   public void updateObservers(ResourceProviderEvent event) {
     for (ResourceProviderObserver observer : observers) {
       observer.update(event);
     }
   }

   @Override
   public void addObserver(ResourceProviderObserver observer) {
     observers.add(observer);
   }


   // ----- utility methods ---------------------------------------------------

   /**
    * Get the set of property ids that uniquely identify the resources
    * of this provider.
    *
    * @return the set of primary key properties
    */
   protected abstract Set<String> getPKPropertyIds();

   /**
    * Notify all listeners of a creation event.
    *
    * @param type     the type of the resources being created
    * @param request  the request used to create the resources
    */
   protected void notifyCreate(Resource.Type type, Request request) {
     updateObservers(new ResourceProviderEvent(type, ResourceProviderEvent.Type.Create, request, null));
   }

   /**
    * Notify all listeners of a update event.
    *
    * @param type       the type of the resources being updated
    * @param request    the request used to update the resources
    * @param predicate  the predicate used to update the resources
    */
   protected void notifyUpdate(Resource.Type type, Request request, Predicate predicate) {
     updateObservers(new ResourceProviderEvent(type, ResourceProviderEvent.Type.Update, request, predicate));
   }

   /**
    * Notify all listeners of a delete event.
    *
    * @param type       the type of the resources being deleted
    * @param predicate  the predicate used to delete the resources
    */
   protected void notifyDelete(Resource.Type type, Predicate predicate) {
     updateObservers(new ResourceProviderEvent(type, ResourceProviderEvent.Type.Delete, null, predicate));
   }

   /**
    * Get a set of properties from the given predicate.  The returned set of
    * property/value mappings is required to generate delete or get requests
    * to the back end which does not deal with predicates.  Note that the
    * single predicate can result in multiple backend requests.
    *
    * @param givenPredicate           the predicate
    *
    * @return the set of properties used to build request objects
    */
   protected Set<Map<String, Object>> getPropertyMaps(Predicate givenPredicate) {

     SimplifyingPredicateVisitor visitor = new SimplifyingPredicateVisitor(this);
     PredicateHelper.visit(givenPredicate, visitor);
     List<Predicate> predicates = visitor.getSimplifiedPredicates();

     Set<Map<String, Object>> propertyMaps = new HashSet<Map<String, Object>>();

     for (Predicate predicate : predicates) {
       propertyMaps.add(PredicateHelper.getProperties(predicate));
     }
     return propertyMaps;
   }

   /**
    * Get a set of properties from the given property map and predicate.  The
    * returned set of property/value mappings is required to generate update
    * requests to the back end which does not deal with Predicates.  Note that
    * the single property map & predicate can result in multiple backend requests.
    *
    * @param requestPropertyMap  the request update properties; may not be null
    * @param givenPredicate      the predicate
    *
    * @return the set of properties used to build request objects
    */
   protected Set<Map<String, Object>> getPropertyMaps(Map<String, Object> requestPropertyMap, Predicate givenPredicate)
       throws UnsupportedPropertyException, SystemException, NoSuchResourceException, NoSuchParentResourceException {

     Set<Map<String, Object>> propertyMaps = new HashSet<Map<String, Object>>();

     // If the predicate specifies a unique resource then we can simply return a single
     // property map for the update.  Otherwise we need to do a get with the given predicate
     // to get the set of property maps for the resources that need to be updated.
     if (specifiesUniqueResource(givenPredicate)) {
       Map<String, Object> propertyMap = new HashMap<String, Object>(PredicateHelper.getProperties(givenPredicate));
       propertyMap.putAll(requestPropertyMap);
       propertyMaps.add(propertyMap);
     } else {
       for (Resource resource : getResources(givenPredicate)) {
         Map<String, Object> propertyMap = new HashMap<String, Object>(PropertyHelper.getProperties(resource));
         propertyMap.putAll(requestPropertyMap);
         propertyMaps.add(propertyMap);
       }
     }
     return propertyMaps;
   }

   /**
    * Get a request status
    *
    * @return the request status
    */
   protected RequestStatus getRequestStatus(RequestStatusResponse response, Set<Resource> associatedResources) {
     return getRequestStatus(response, associatedResources, null);
   }

   protected RequestStatus getRequestStatus(RequestStatusResponse response, Set<Resource> associatedResources, RequestStatusMetaData requestStatusMetaData) {
     if (response != null){
       Resource requestResource = new ResourceImpl(Resource.Type.Request);
       if (response.getMessage() != null){
         requestResource.setProperty(PropertyHelper.getPropertyId("Requests", "message"), response.getMessage());
       }
       requestResource.setProperty(PropertyHelper.getPropertyId("Requests", "id"), response.getRequestId());
       requestResource.setProperty(PropertyHelper.getPropertyId("Requests", "status"), "Accepted");
       return new RequestStatusImpl(requestResource, associatedResources, requestStatusMetaData);
     }
     return new RequestStatusImpl(null, associatedResources, requestStatusMetaData);
   }

   /**
    * Get a request status
    *
    * @return the request status
    */
   protected RequestStatus getRequestStatus(RequestStatusResponse response) {
     return getRequestStatus(response, null) ;
   }

   /**
    * Extracting given query_parameter value from the predicate
    * @param queryParameterId  query parameter id
    * @param predicate         predicate
    * @return the query parameter
    */
   protected static Object getQueryParameterValue(String queryParameterId, Predicate predicate) {

     Object result = null;

     if (predicate instanceof EqualsPredicate) {
       EqualsPredicate equalsPredicate = (EqualsPredicate) predicate;
       if (queryParameterId.equals(equalsPredicate.getPropertyId())) {
         return equalsPredicate.getValue();
       }
     } else if (predicate instanceof ArrayPredicate) {
       ArrayPredicate arrayPredicate  = (ArrayPredicate) predicate;
       for (Predicate predicateItem : arrayPredicate.getPredicates()) {
         result = getQueryParameterValue(queryParameterId, predicateItem);
         if (result != null) {
           return result;
         }
       }

     }
     return result;
   }

   /**
    * Invoke a command against the Ambari backend to create resources and map
    * any {@link AmbariException} to the types appropriate for the
    * {@link ResourceProvider} interface.
    *
    * @param command  the command to invoke
    * @param <T>      the type of the response
    *
    * @return the response
    *
    * @throws SystemException                thrown if a system exception occurred
    * @throws ResourceAlreadyExistsException thrown if a resource already exists
    * @throws NoSuchParentResourceException  thrown if a parent of a resource doesn't exist
    */
   protected <T> T createResources(Command<T> command)
       throws SystemException, ResourceAlreadyExistsException, NoSuchParentResourceException {
     try {
       return invokeWithRetry(command);
     } catch (ParentObjectNotFoundException e) {
       throw new NoSuchParentResourceException(e.getMessage(), e);
     } catch (DuplicateResourceException e) {
       throw new ResourceAlreadyExistsException(e.getMessage());
     } catch (AmbariException e) {
       if (LOG.isErrorEnabled()) {
         LOG.error("Caught AmbariException when creating a resource", e);
       }
       throw new SystemException("An internal system exception occurred: " + e.getMessage(), e);
     }
   }

   /**
    * Invoke a command against the Ambari backend to get resources and map
    * any {@link AmbariException} to the types appropriate for the
    * {@link ResourceProvider} interface.
    *
    * @param command  the command to invoke
    * @param <T>      the type of the response
    *
    * @return the response
    *
    * @throws SystemException                thrown if a system exception occurred
    * @throws NoSuchParentResourceException  thrown if a parent of a resource doesn't exist
    */
   protected <T> T getResources (Command<T> command)
       throws SystemException, NoSuchResourceException, NoSuchParentResourceException {
     try {
       return command.invoke();
     } catch (ParentObjectNotFoundException e) {
       throw new NoSuchParentResourceException(e.getMessage(), e);
     } catch (ObjectNotFoundException e) {
       throw new NoSuchResourceException("The requested resource doesn't exist: " + e.getMessage(), e);
     }  catch (AmbariException e) {
       if (LOG.isErrorEnabled()) {
         LOG.error("Caught AmbariException when getting a resource", e);
       }
       throw new SystemException("An internal system exception occurred: " + e.getMessage(), e);
     }
   }

   /**
    * Invoke a command against the Ambari backend to modify resources and map
    * any {@link AmbariException} to the types appropriate for the
    * {@link ResourceProvider} interface.
    *
    * @param command  the command to invoke
    * @param <T>      the type of the response
    *
    * @return the response
    *
    * @throws SystemException                thrown if a system exception occurred
    * @throws NoSuchParentResourceException  thrown if a parent of a resource doesn't exist
    */
   protected <T> T modifyResources (Command<T> command)
       throws SystemException, NoSuchResourceException, NoSuchParentResourceException {
     try {
       return invokeWithRetry(command);
     } catch (ParentObjectNotFoundException e) {
       throw new NoSuchParentResourceException(e.getMessage(), e);
     } catch (ObjectNotFoundException e) {
       throw new NoSuchResourceException("The specified resource doesn't exist: " + e.getMessage(), e);
     }  catch (AmbariException e) {
       if (LOG.isErrorEnabled()) {
         LOG.error("Caught AmbariException when modifying a resource", e);
       }
       throw new SystemException("An internal system exception occurred: " + e.getMessage(), e);
     }
   }

   /**
    * Helper method to get a configuration request, if one exists.
    * @param parentCategory  the parent category name.  Checks for a property
    *    whose category is the parent and marked as a desired config.
    * @param properties  the properties on the request.
    */
   public static List<ConfigurationRequest> getConfigurationRequests(String parentCategory, Map<String, Object> properties) {

     List<ConfigurationRequest> configs = new LinkedList<ConfigurationRequest>();

     String desiredConfigKey = parentCategory + "/desired_config";
     // Multiple configs to be updated
     if (properties.containsKey(desiredConfigKey)
       && properties.get(desiredConfigKey) instanceof Set) {

       Set<Map<String, Object>> configProperties =
         (Set<Map<String, Object>>) properties.get(desiredConfigKey);
       for (Map<String, Object> value: configProperties) {
         ConfigurationRequest newConfig = new ConfigurationRequest();

         for (Entry<String, Object> e : value.entrySet()) {
           String propName =
             PropertyHelper.getPropertyName(desiredConfigKey + '/' + e.getKey());
           String absCatategory =
             PropertyHelper.getPropertyCategory(desiredConfigKey + '/' + e.getKey());
           parseProperties(newConfig, absCatategory, propName, e.getValue() == null ? null : e.getValue().toString());
         }
         configs.add(newConfig);
       }
       return configs;
     }

     ConfigurationRequest config = null;
     // as a convenience, allow consumers to specify name/value overrides in this
     // call instead of forcing a cluster call to do that work
     for (Entry<String, Object> entry : properties.entrySet()) {
       String absCategory = PropertyHelper.getPropertyCategory(entry.getKey());
       String propName = PropertyHelper.getPropertyName(entry.getKey());

       if (absCategory != null && absCategory.startsWith(desiredConfigKey)) {
         config = (null == config) ? new ConfigurationRequest() : config;
         if(entry.getValue() != null) {
           parseProperties(config, absCategory, propName, entry.getValue().toString());
         }
       }
     }
     if (config != null) {
       configs.add(config);
     }
     return configs;
   }

   public static void parseProperties(ConfigurationRequest config, String absCategory, String propName, String propValue) {
     if (propName.equals("type"))
       config.setType(propValue);
     else if (propName.equals("tag"))
       config.setVersionTag(propValue);
     else if (propName.equals("selected")) {
       config.setSelected(Boolean.parseBoolean(propValue));
     }
     else if (propName.equals("service_config_version_note")) {
       config.setServiceConfigVersionNote(propValue);
     }
     else if (absCategory.endsWith("/properties")) {
       config.getProperties().put(propName, propValue);
     }
     else if (propertiesAttributesPattern.matcher(absCategory).matches()) {
       String attributeName = absCategory.substring(absCategory.lastIndexOf('/') + 1);
       Map<String, Map<String, String>> configAttributesMap = config.getPropertiesAttributes();
       if (null == configAttributesMap) {
         configAttributesMap = new HashMap<String, Map<String,String>>();
         config.setPropertiesAttributes(configAttributesMap);
       }
       Map<String, String> attributesMap = configAttributesMap.get(attributeName);
       if (null == attributesMap) {
         attributesMap = new HashMap<String, String>();
         configAttributesMap.put(attributeName, attributesMap);
       }
       attributesMap.put(propName, propValue);
     }
   }

   // get the resources (id fields only) for the given predicate.
   private Set<Resource> getResources(Predicate givenPredicate)
       throws SystemException, UnsupportedPropertyException, NoSuchResourceException, NoSuchParentResourceException {

     // TODO : Check for case where we should pass the request out to the cluster controller.
     return getResources(PropertyHelper.getReadRequest(getPKPropertyIds()), givenPredicate);
   }

   // determine whether or not the given predicate specifies a unique resource for this provider.
   private boolean specifiesUniqueResource(Predicate predicate) {
     SimplifyingPredicateVisitor visitor = new SimplifyingPredicateVisitor(this);
     PredicateHelper.visit(predicate, visitor);
     List<Predicate> predicates = visitor.getSimplifiedPredicates();

     return predicates.size() == 1 && PredicateHelper.getPropertyIds(predicate).containsAll(getPKPropertyIds());
   }

   //invoke command with retry support in case of database fail
   private <T> T invokeWithRetry(Command<T> command) throws AmbariException, AuthorizationException {
     RetryHelper.clearAffectedClusters();
     int retryAttempts = RetryHelper.getOperationsRetryAttempts();
     do {

       try {
         return command.invoke();
       } catch (Exception e) {
         if (RetryHelper.isDatabaseException(e)) {

           RetryHelper.invalidateAffectedClusters();

           if (retryAttempts > 0) {
             LOG.error("Ignoring database exception to perform operation retry, attempts remaining: " + retryAttempts, e);
             retryAttempts--;
           } else {
             RetryHelper.clearAffectedClusters();
             throw e;
           }
         } else {
           RetryHelper.clearAffectedClusters();
           throw e;
         }
       }

     } while (true);
   }


   // ----- Inner interface ---------------------------------------------------

   /**
    * Command to invoke against the Ambari backend.
    *
    * @param <T>  the response type
    */
   protected interface Command<T> {
     /**
      * Invoke this command.
      *
      * @return  the response
      *
      * @throws AmbariException thrown if a problem occurred during invocation
      */
     public T invoke() throws AmbariException, AuthorizationException;
   }
 }
	/**
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you 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.apache.ambari.server.controller.internal;

	import java.util.HashMap;
	import java.util.HashSet;
	import java.util.LinkedList;
	import java.util.List;
	import java.util.Map;
	import java.util.Set;
	import java.util.Map.Entry;
	import java.util.regex.Pattern;

	import org.apache.ambari.server.AmbariException;
	import org.apache.ambari.server.DuplicateResourceException;
	import org.apache.ambari.server.ObjectNotFoundException;
	import org.apache.ambari.server.ParentObjectNotFoundException;
	import org.apache.ambari.server.controller.ConfigurationRequest;
	import org.apache.ambari.server.controller.RequestStatusResponse;
	import org.apache.ambari.server.controller.predicate.ArrayPredicate;
	import org.apache.ambari.server.controller.predicate.EqualsPredicate;
	import org.apache.ambari.server.controller.spi.*;
	import org.apache.ambari.server.controller.utilities.PredicateHelper;
	import org.apache.ambari.server.controller.utilities.PropertyHelper;
	import org.apache.ambari.server.security.authorization.AuthorizationException;
	import org.apache.ambari.server.utils.RetryHelper;
	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;

	/**
	* Abstract resource provider implementation that maps to an Ambari management controller.
	*/
	public abstract class AbstractResourceProvider extends BaseProvider implements ResourceProvider, ObservableResourceProvider {

	/**
	* Key property mapping by resource type.
	*/
	private final Map<Resource.Type, String> keyPropertyIds;

	/**
	* Observers of this observable resource provider.
	*/
	private final Set<ResourceProviderObserver> observers = new HashSet<ResourceProviderObserver>();

	protected final static Logger LOG = LoggerFactory.getLogger(AbstractResourceProvider.class);
	protected final static String PROPERTIES_ATTRIBUTES_REGEX = "properties_attributes/[a-zA-Z][a-zA-Z._-]*$";
	public static Pattern propertiesAttributesPattern = Pattern.compile(".*/" + PROPERTIES_ATTRIBUTES_REGEX);


	// ----- Constructors ------------------------------------------------------

	/**
	* Create a new resource provider.
	*
	* @param propertyIds the property ids
	* @param keyPropertyIds the key property ids
	*/
	protected AbstractResourceProvider(Set<String> propertyIds,
	Map<Resource.Type, String> keyPropertyIds) {
	super(propertyIds);
	this.keyPropertyIds = keyPropertyIds;
	}


	// ----- ResourceProvider --------------------------------------------------

	@Override
	public Map<Resource.Type, String> getKeyPropertyIds() {
	return keyPropertyIds;
	}


	// ----- ObservableResourceProvider ----------------------------------------

	@Override
	public void updateObservers(ResourceProviderEvent event) {
	for (ResourceProviderObserver observer : observers) {
	observer.update(event);
	}
	}

	@Override
	public void addObserver(ResourceProviderObserver observer) {
	observers.add(observer);
	}


	// ----- utility methods ---------------------------------------------------

	/**
	* Get the set of property ids that uniquely identify the resources
	* of this provider.
	*
	* @return the set of primary key properties
	*/
	protected abstract Set<String> getPKPropertyIds();

	/**
	* Notify all listeners of a creation event.
	*
	* @param type the type of the resources being created
	* @param request the request used to create the resources
	*/
	protected void notifyCreate(Resource.Type type, Request request) {
	updateObservers(new ResourceProviderEvent(type, ResourceProviderEvent.Type.Create, request, null));
	}

	/**
	* Notify all listeners of a update event.
	*
	* @param type the type of the resources being updated
	* @param request the request used to update the resources
	* @param predicate the predicate used to update the resources
	*/
	protected void notifyUpdate(Resource.Type type, Request request, Predicate predicate) {
	updateObservers(new ResourceProviderEvent(type, ResourceProviderEvent.Type.Update, request, predicate));
	}

	/**
	* Notify all listeners of a delete event.
	*
	* @param type the type of the resources being deleted
	* @param predicate the predicate used to delete the resources
	*/
	protected void notifyDelete(Resource.Type type, Predicate predicate) {
	updateObservers(new ResourceProviderEvent(type, ResourceProviderEvent.Type.Delete, null, predicate));
	}

	/**
	* Get a set of properties from the given predicate. The returned set of
	* property/value mappings is required to generate delete or get requests
	* to the back end which does not deal with predicates. Note that the
	* single predicate can result in multiple backend requests.
	*
	* @param givenPredicate the predicate
	*
	* @return the set of properties used to build request objects
	*/
	protected Set<Map<String, Object>> getPropertyMaps(Predicate givenPredicate) {

	SimplifyingPredicateVisitor visitor = new SimplifyingPredicateVisitor(this);
	PredicateHelper.visit(givenPredicate, visitor);
	List<Predicate> predicates = visitor.getSimplifiedPredicates();

	Set<Map<String, Object>> propertyMaps = new HashSet<Map<String, Object>>();

	for (Predicate predicate : predicates) {
	propertyMaps.add(PredicateHelper.getProperties(predicate));
	}
	return propertyMaps;
	}

	/**
	* Get a set of properties from the given property map and predicate. The
	* returned set of property/value mappings is required to generate update
	* requests to the back end which does not deal with Predicates. Note that
	* the single property map & predicate can result in multiple backend requests.
	*
	* @param requestPropertyMap the request update properties; may not be null
	* @param givenPredicate the predicate
	*
	* @return the set of properties used to build request objects
	*/
	protected Set<Map<String, Object>> getPropertyMaps(Map<String, Object> requestPropertyMap, Predicate givenPredicate)
	throws UnsupportedPropertyException, SystemException, NoSuchResourceException, NoSuchParentResourceException {

	Set<Map<String, Object>> propertyMaps = new HashSet<Map<String, Object>>();

	// If the predicate specifies a unique resource then we can simply return a single
	// property map for the update. Otherwise we need to do a get with the given predicate
	// to get the set of property maps for the resources that need to be updated.
	if (specifiesUniqueResource(givenPredicate)) {
	Map<String, Object> propertyMap = new HashMap<String, Object>(PredicateHelper.getProperties(givenPredicate));
	propertyMap.putAll(requestPropertyMap);
	propertyMaps.add(propertyMap);
	} else {
	for (Resource resource : getResources(givenPredicate)) {
	Map<String, Object> propertyMap = new HashMap<String, Object>(PropertyHelper.getProperties(resource));
	propertyMap.putAll(requestPropertyMap);
	propertyMaps.add(propertyMap);
	}
	}
	return propertyMaps;
	}

	/**
	* Get a request status
	*
	* @return the request status
	*/
	protected RequestStatus getRequestStatus(RequestStatusResponse response, Set<Resource> associatedResources) {
	return getRequestStatus(response, associatedResources, null);
	}

	protected RequestStatus getRequestStatus(RequestStatusResponse response, Set<Resource> associatedResources, RequestStatusMetaData requestStatusMetaData) {
	if (response != null){
	Resource requestResource = new ResourceImpl(Resource.Type.Request);
	if (response.getMessage() != null){
	requestResource.setProperty(PropertyHelper.getPropertyId("Requests", "message"), response.getMessage());
	}
	requestResource.setProperty(PropertyHelper.getPropertyId("Requests", "id"), response.getRequestId());
	requestResource.setProperty(PropertyHelper.getPropertyId("Requests", "status"), "Accepted");
	return new RequestStatusImpl(requestResource, associatedResources, requestStatusMetaData);
	}
	return new RequestStatusImpl(null, associatedResources, requestStatusMetaData);
	}

	/**
	* Get a request status
	*
	* @return the request status
	*/
	protected RequestStatus getRequestStatus(RequestStatusResponse response) {
	return getRequestStatus(response, null) ;
	}

	/**
	* Extracting given query_parameter value from the predicate
	* @param queryParameterId query parameter id
	* @param predicate predicate
	* @return the query parameter
	*/
	protected static Object getQueryParameterValue(String queryParameterId, Predicate predicate) {

	Object result = null;

	if (predicate instanceof EqualsPredicate) {
	EqualsPredicate equalsPredicate = (EqualsPredicate) predicate;
	if (queryParameterId.equals(equalsPredicate.getPropertyId())) {
	return equalsPredicate.getValue();
	}
	} else if (predicate instanceof ArrayPredicate) {
	ArrayPredicate arrayPredicate = (ArrayPredicate) predicate;
	for (Predicate predicateItem : arrayPredicate.getPredicates()) {
	result = getQueryParameterValue(queryParameterId, predicateItem);
	if (result != null) {
	return result;
	}
	}

	}
	return result;
	}

	/**
	* Invoke a command against the Ambari backend to create resources and map
	* any {@link AmbariException} to the types appropriate for the
	* {@link ResourceProvider} interface.
	*
	* @param command the command to invoke
	* @param <T> the type of the response
	*
	* @return the response
	*
	* @throws SystemException thrown if a system exception occurred
	* @throws ResourceAlreadyExistsException thrown if a resource already exists
	* @throws NoSuchParentResourceException thrown if a parent of a resource doesn't exist
	*/
	protected <T> T createResources(Command<T> command)
	throws SystemException, ResourceAlreadyExistsException, NoSuchParentResourceException {
	try {
	return invokeWithRetry(command);
	} catch (ParentObjectNotFoundException e) {
	throw new NoSuchParentResourceException(e.getMessage(), e);
	} catch (DuplicateResourceException e) {
	throw new ResourceAlreadyExistsException(e.getMessage());
	} catch (AmbariException e) {
	if (LOG.isErrorEnabled()) {
	LOG.error("Caught AmbariException when creating a resource", e);
	}
	throw new SystemException("An internal system exception occurred: " + e.getMessage(), e);
	}
	}

	/**
	* Invoke a command against the Ambari backend to get resources and map
	* any {@link AmbariException} to the types appropriate for the
	* {@link ResourceProvider} interface.
	*
	* @param command the command to invoke
	* @param <T> the type of the response
	*
	* @return the response
	*
	* @throws SystemException thrown if a system exception occurred
	* @throws NoSuchParentResourceException thrown if a parent of a resource doesn't exist
	*/
	protected <T> T getResources (Command<T> command)
	throws SystemException, NoSuchResourceException, NoSuchParentResourceException {
	try {
	return command.invoke();
	} catch (ParentObjectNotFoundException e) {
	throw new NoSuchParentResourceException(e.getMessage(), e);
	} catch (ObjectNotFoundException e) {
	throw new NoSuchResourceException("The requested resource doesn't exist: " + e.getMessage(), e);
	} catch (AmbariException e) {
	if (LOG.isErrorEnabled()) {
	LOG.error("Caught AmbariException when getting a resource", e);
	}
	throw new SystemException("An internal system exception occurred: " + e.getMessage(), e);
	}
	}

	/**
	* Invoke a command against the Ambari backend to modify resources and map
	* any {@link AmbariException} to the types appropriate for the
	* {@link ResourceProvider} interface.
	*
	* @param command the command to invoke
	* @param <T> the type of the response
	*
	* @return the response
	*
	* @throws SystemException thrown if a system exception occurred
	* @throws NoSuchParentResourceException thrown if a parent of a resource doesn't exist
	*/
	protected <T> T modifyResources (Command<T> command)
	throws SystemException, NoSuchResourceException, NoSuchParentResourceException {
	try {
	return invokeWithRetry(command);
	} catch (ParentObjectNotFoundException e) {
	throw new NoSuchParentResourceException(e.getMessage(), e);
	} catch (ObjectNotFoundException e) {
	throw new NoSuchResourceException("The specified resource doesn't exist: " + e.getMessage(), e);
	} catch (AmbariException e) {
	if (LOG.isErrorEnabled()) {
	LOG.error("Caught AmbariException when modifying a resource", e);
	}
	throw new SystemException("An internal system exception occurred: " + e.getMessage(), e);
	}
	}

	/**
	* Helper method to get a configuration request, if one exists.
	* @param parentCategory the parent category name. Checks for a property
	* whose category is the parent and marked as a desired config.
	* @param properties the properties on the request.
	*/
	public static List<ConfigurationRequest> getConfigurationRequests(String parentCategory, Map<String, Object> properties) {

	List<ConfigurationRequest> configs = new LinkedList<ConfigurationRequest>();

	String desiredConfigKey = parentCategory + "/desired_config";
	// Multiple configs to be updated
	if (properties.containsKey(desiredConfigKey)
	&& properties.get(desiredConfigKey) instanceof Set) {

	Set<Map<String, Object>> configProperties =
	(Set<Map<String, Object>>) properties.get(desiredConfigKey);
	for (Map<String, Object> value: configProperties) {
	ConfigurationRequest newConfig = new ConfigurationRequest();

	for (Entry<String, Object> e : value.entrySet()) {
	String propName =
	PropertyHelper.getPropertyName(desiredConfigKey + '/' + e.getKey());
	String absCatategory =
	PropertyHelper.getPropertyCategory(desiredConfigKey + '/' + e.getKey());
	parseProperties(newConfig, absCatategory, propName, e.getValue() == null ? null : e.getValue().toString());
	}
	configs.add(newConfig);
	}
	return configs;
	}

	ConfigurationRequest config = null;
	// as a convenience, allow consumers to specify name/value overrides in this
	// call instead of forcing a cluster call to do that work
	for (Entry<String, Object> entry : properties.entrySet()) {
	String absCategory = PropertyHelper.getPropertyCategory(entry.getKey());
	String propName = PropertyHelper.getPropertyName(entry.getKey());

	if (absCategory != null && absCategory.startsWith(desiredConfigKey)) {
	config = (null == config) ? new ConfigurationRequest() : config;
	if(entry.getValue() != null) {
	parseProperties(config, absCategory, propName, entry.getValue().toString());
	}
	}
	}
	if (config != null) {
	configs.add(config);
	}
	return configs;
	}

	public static void parseProperties(ConfigurationRequest config, String absCategory, String propName, String propValue) {
	if (propName.equals("type"))
	config.setType(propValue);
	else if (propName.equals("tag"))
	config.setVersionTag(propValue);
	else if (propName.equals("selected")) {
	config.setSelected(Boolean.parseBoolean(propValue));
	}
	else if (propName.equals("service_config_version_note")) {
	config.setServiceConfigVersionNote(propValue);
	}
	else if (absCategory.endsWith("/properties")) {
	config.getProperties().put(propName, propValue);
	}
	else if (propertiesAttributesPattern.matcher(absCategory).matches()) {
	String attributeName = absCategory.substring(absCategory.lastIndexOf('/') + 1);
	Map<String, Map<String, String>> configAttributesMap = config.getPropertiesAttributes();
	if (null == configAttributesMap) {
	configAttributesMap = new HashMap<String, Map<String,String>>();
	config.setPropertiesAttributes(configAttributesMap);
	}
	Map<String, String> attributesMap = configAttributesMap.get(attributeName);
	if (null == attributesMap) {
	attributesMap = new HashMap<String, String>();
	configAttributesMap.put(attributeName, attributesMap);
	}
	attributesMap.put(propName, propValue);
	}
	}

	// get the resources (id fields only) for the given predicate.
	private Set<Resource> getResources(Predicate givenPredicate)
	throws SystemException, UnsupportedPropertyException, NoSuchResourceException, NoSuchParentResourceException {

	// TODO : Check for case where we should pass the request out to the cluster controller.
	return getResources(PropertyHelper.getReadRequest(getPKPropertyIds()), givenPredicate);
	}

	// determine whether or not the given predicate specifies a unique resource for this provider.
	private boolean specifiesUniqueResource(Predicate predicate) {
	SimplifyingPredicateVisitor visitor = new SimplifyingPredicateVisitor(this);
	PredicateHelper.visit(predicate, visitor);
	List<Predicate> predicates = visitor.getSimplifiedPredicates();

	return predicates.size() == 1 && PredicateHelper.getPropertyIds(predicate).containsAll(getPKPropertyIds());
	}

	//invoke command with retry support in case of database fail
	private <T> T invokeWithRetry(Command<T> command) throws AmbariException, AuthorizationException {
	RetryHelper.clearAffectedClusters();
	int retryAttempts = RetryHelper.getOperationsRetryAttempts();
	do {

	try {
	return command.invoke();
	} catch (Exception e) {
	if (RetryHelper.isDatabaseException(e)) {

	RetryHelper.invalidateAffectedClusters();

	if (retryAttempts > 0) {
	LOG.error("Ignoring database exception to perform operation retry, attempts remaining: " + retryAttempts, e);
	retryAttempts--;
	} else {
	RetryHelper.clearAffectedClusters();
	throw e;
	}
	} else {
	RetryHelper.clearAffectedClusters();
	throw e;
	}
	}

	} while (true);
	}


	// ----- Inner interface ---------------------------------------------------

	/**
	* Command to invoke against the Ambari backend.
	*
	* @param <T> the response type
	*/
	protected interface Command<T> {
	/**
	* Invoke this command.
	*
	* @return the response
	*
	* @throws AmbariException thrown if a problem occurred during invocation
	*/
	public T invoke() throws AmbariException, AuthorizationException;
	}
	}