Java tutorial
/** * 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.apache.aurora.scheduler.http; import java.util.Map; import java.util.Objects; import javax.inject.Inject; import javax.ws.rs.GET; import javax.ws.rs.Path; import javax.ws.rs.Produces; import javax.ws.rs.core.MediaType; import javax.ws.rs.core.Response; import com.google.common.collect.ImmutableMap; import com.google.common.collect.ImmutableMultimap; import com.google.common.collect.ImmutableSet; import com.google.common.collect.Iterables; import com.google.common.collect.Multimap; import com.google.common.collect.Multimaps; import org.apache.aurora.gen.MaintenanceMode; import org.apache.aurora.scheduler.base.Query; import org.apache.aurora.scheduler.base.Tasks; import org.apache.aurora.scheduler.storage.Storage; import org.apache.aurora.scheduler.storage.Storage.StoreProvider; import org.apache.aurora.scheduler.storage.entities.IHostAttributes; import org.apache.aurora.scheduler.storage.entities.IScheduledTask; import static org.apache.aurora.gen.MaintenanceMode.DRAINED; import static org.apache.aurora.gen.MaintenanceMode.DRAINING; import static org.apache.aurora.gen.MaintenanceMode.SCHEDULED; /** * Servlet that exposes the maintenance state of hosts. */ @Path("/maintenance") public class Maintenance { private final Storage storage; @Inject Maintenance(Storage storage) { this.storage = Objects.requireNonNull(storage); } @GET @Produces(MediaType.APPLICATION_JSON) public Response getHosts() { return storage.read(storeProvider -> { Multimap<MaintenanceMode, String> hostsByMode = Multimaps.transformValues(Multimaps .index(storeProvider.getAttributeStore().getHostAttributes(), IHostAttributes::getMode), IHostAttributes::getHost); Map<MaintenanceMode, Object> hosts = ImmutableMap.of(DRAINED, ImmutableSet.copyOf(hostsByMode.get(DRAINED)), SCHEDULED, ImmutableSet.copyOf(hostsByMode.get(SCHEDULED)), DRAINING, getTasksByHosts(storeProvider, hostsByMode.get(DRAINING)).asMap()); return Response.ok(hosts).build(); }); } private Multimap<String, String> getTasksByHosts(StoreProvider provider, Iterable<String> hosts) { if (Iterables.isEmpty(hosts)) { return ImmutableMultimap.of(); } ImmutableSet.Builder<IScheduledTask> drainingTasks = ImmutableSet.builder(); drainingTasks.addAll( provider.getTaskStore().fetchTasks(Query.slaveScoped(hosts).byStatus(Tasks.SLAVE_ASSIGNED_STATES))); return Multimaps.transformValues(Multimaps.index(drainingTasks.build(), Tasks::scheduledToSlaveHost), Tasks::id); } }