CLOUDSTACK-5610: Host doesn't go to Down/Alert state even though it is powered off. VM

deployment fails because of that as cloudstack tries to deploy it on a host which is
ctually down. An investigator wasn't present for hyper-v; so cloudstack wasn't able to
determine the status of the host. Wrote an investigator for hyper-v which checks with
other hosts in the cluster for the status of the host being investigated.

plugins/hypervisors/hyperv/resources/META-INF/cloudstack/hyperv-compute/spring-hyperv-compute-context.xml

@@ -20,5 +20,7 @@
     <bean id="HypervGuru" class="com.cloud.hypervisor.hyperv.guru.HypervGuru">
         <property name="name" value="HypervGuru" />
     </bean>
-
+    <bean id="HypervInvestigator" class="com.cloud.ha.HypervInvestigator">
+        <property name="name" value="HypervInvestigator" />
+    </bean>
 </beans>

plugins/hypervisors/hyperv/src/com/cloud/ha/HypervInvestigator.java

@@ -0,0 +1,77 @@
+/*
+ * 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 com.cloud.ha;
+
+import com.cloud.agent.AgentManager;
+import com.cloud.agent.api.Answer;
+import com.cloud.agent.api.CheckOnHostCommand;
+import com.cloud.host.Host;
+import com.cloud.host.HostVO;
+import com.cloud.host.Status;
+import com.cloud.host.dao.HostDao;
+import com.cloud.hypervisor.Hypervisor;
+import com.cloud.resource.ResourceManager;
+import com.cloud.utils.component.AdapterBase;
+import org.apache.log4j.Logger;
+
+import javax.ejb.Local;
+import javax.inject.Inject;
+import java.util.List;
+
+@Local(value=Investigator.class)
+public class HypervInvestigator extends AdapterBase implements Investigator {
+    private final static Logger s_logger = Logger.getLogger(HypervInvestigator.class);
+    @Inject HostDao _hostDao;
+    @Inject AgentManager _agentMgr;
+    @Inject ResourceManager _resourceMgr;
+
+    @Override
+    public Boolean isVmAlive(com.cloud.vm.VirtualMachine vm, Host host) {
+        Status status = isAgentAlive(host);
+        if (status == null) {
+            return null;
+        }
+        return status == Status.Up ? true : null;
+    }
+
+    @Override
+    public Status isAgentAlive(Host agent) {
+        if (agent.getHypervisorType() != Hypervisor.HypervisorType.Hyperv) {
+            return null;
+        }
+        CheckOnHostCommand cmd = new CheckOnHostCommand(agent);
+        List<HostVO> neighbors = _resourceMgr.listHostsInClusterByStatus(agent.getClusterId(), Status.Up);
+        for (HostVO neighbor : neighbors) {
+            if (neighbor.getId() == agent.getId() || neighbor.getHypervisorType() != Hypervisor.HypervisorType.Hyperv) {
+                continue;
+            }
+
+            try {
+                Answer answer = _agentMgr.easySend(neighbor.getId(), cmd);
+                if (answer != null) {
+                    return answer.getResult() ? Status.Down : Status.Up;
+                }
+            } catch (Exception e) {
+                s_logger.debug("Failed to send command to host: " + neighbor.getId());
+            }
+        }
+
+        return null;
+    }
+}