/**
* 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.hadoop.yarn.server.sharedcachemanager.store;
import java.util.Collection;
import java.util.HashSet;
import java.util.Set;
import org.apache.hadoop.classification.InterfaceAudience.Private;
import org.apache.hadoop.classification.InterfaceStability.Evolving;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.service.CompositeService;
import org.apache.hadoop.util.ReflectionUtils;
import org.apache.hadoop.yarn.conf.YarnConfiguration;
import org.apache.hadoop.yarn.exceptions.YarnException;
import org.apache.hadoop.yarn.exceptions.YarnRuntimeException;
import org.apache.hadoop.yarn.server.sharedcachemanager.AppChecker;
import com.google.common.annotations.VisibleForTesting;
/**
* An abstract class for the data store used by the shared cache manager
* service. All implementations of methods in this interface need to be thread
* safe and atomic.
*/
@Private
@Evolving
public abstract class SCMStore extends CompositeService {
protected AppChecker appChecker;
protected SCMStore(String name) {
super(name);
}
@VisibleForTesting
SCMStore(String name, AppChecker appChecker) {
super(name);
this.appChecker = appChecker;
}
@Override
protected void serviceInit(Configuration conf) throws Exception {
if (this.appChecker == null) {
this.appChecker = createAppCheckerService(conf);
}
addService(appChecker);
super.serviceInit(conf);
}
/**
* Add a resource to the shared cache and it's associated filename. The
* resource is identified by a unique key. If the key already exists no action
* is taken and the filename of the existing resource is returned. If the key
* does not exist, the resource is added, it's access time is set, and the
* filename of the resource is returned.
*
* @param key a unique identifier for a resource
* @param fileName the filename of the resource
* @return the filename of the resource as represented by the cache
*/
@Private
public abstract String addResource(String key, String fileName);
/**
* Remove a resource from the shared cache.
*
* @param key a unique identifier for a resource
* @return true if the resource was removed or did not exist, false if the
* resource existed, contained at least one
* <code>SharedCacheResourceReference</code> and was not removed.
*/
@Private
public abstract boolean removeResource(String key);
/**
* Add a <code>SharedCacheResourceReference</code> to a resource and update
* the resource access time.
*
* @param key a unique identifier for a resource
* @param ref the <code>SharedCacheResourceReference</code> to add
* @return String the filename of the resource if the
* <code>SharedCacheResourceReference</code> was added or already
* existed. null if the resource did not exist
*/
@Private
public abstract String addResourceReference(String key,
SharedCacheResourceReference ref);
/**
* Get the <code>SharedCacheResourceReference</code>(s) associated with the
* resource.
*
* @param key a unique identifier for a resource
* @return an unmodifiable collection of
* <code>SharedCacheResourceReferences</code>. If the resource does
* not exist, an empty set is returned.
*/
@Private
public abstract Collection<SharedCacheResourceReference> getResourceReferences(
String key);
/**
* Remove a <code>SharedCacheResourceReference</code> from a resource.
*
* @param key a unique identifier for a resource
* @param ref the <code>SharedCacheResourceReference</code> to remove
* @param updateAccessTime true if the call should update the access time for
* the resource
* @return true if the reference was removed, false otherwise
*/
@Private
public abstract boolean removeResourceReference(String key,
SharedCacheResourceReference ref, boolean updateAccessTime);
/**
* Remove a collection of <code>SharedCacheResourceReferences</code> from a
* resource.
*
* @param key a unique identifier for a resource
* @param refs the collection of <code>SharedCacheResourceReference</code>s to
* remove
* @param updateAccessTime true if the call should update the access time for
* the resource
*/
@Private
public abstract void removeResourceReferences(String key,
Collection<SharedCacheResourceReference> refs, boolean updateAccessTime);
/**
* Clean all resource references to a cache resource that contain application
* ids pointing to finished applications. If the resource key does not exist,
* do nothing.
*
* @param key a unique identifier for a resource
* @throws YarnException
*/
@Private
public void cleanResourceReferences(String key) throws YarnException {
Collection<SharedCacheResourceReference> refs = getResourceReferences(key);
if (!refs.isEmpty()) {
Set<SharedCacheResourceReference> refsToRemove =
new HashSet<SharedCacheResourceReference>();
for (SharedCacheResourceReference r : refs) {
if (!appChecker.isApplicationActive(r.getAppId())) {
// application in resource reference is dead, it is safe to remove the
// reference
refsToRemove.add(r);
}
}
if (refsToRemove.size() > 0) {
removeResourceReferences(key, refsToRemove, false);
}
}
}
/**
* Check if a specific resource is evictable according to the store's enabled
* cache eviction policies.
*
* @param key a unique identifier for a resource
* @param file the <code>FileStatus</code> object for the resource file in the
* file system.
* @return true if the resource is evicatble, false otherwise
*/
@Private
public abstract boolean isResourceEvictable(String key, FileStatus file);
/**
* Create an instance of the AppChecker service via reflection based on the
* {@link YarnConfiguration#SCM_APP_CHECKER_CLASS} parameter.
*
* @param conf
* @return an instance of the AppChecker class
*/
@Private
@SuppressWarnings("unchecked")
public static AppChecker createAppCheckerService(Configuration conf) {
Class<? extends AppChecker> defaultCheckerClass;
try {
defaultCheckerClass =
(Class<? extends AppChecker>) Class
.forName(YarnConfiguration.DEFAULT_SCM_APP_CHECKER_CLASS);
} catch (Exception e) {
throw new YarnRuntimeException("Invalid default scm app checker class"
+ YarnConfiguration.DEFAULT_SCM_APP_CHECKER_CLASS, e);
}
AppChecker checker =
ReflectionUtils.newInstance(conf.getClass(
YarnConfiguration.SCM_APP_CHECKER_CLASS, defaultCheckerClass,
AppChecker.class), conf);
return checker;
}
}