From 8c6fb0e3120e80e0682b5666b13e70d640e58daf Mon Sep 17 00:00:00 2001
From: Nitin Kumar Maharana <nitinkumar.maharana@accelerite.com>
Date: Mon, 11 Dec 2017 21:50:37 +0530
Subject: [PATCH] CLOUDSTACK-10157: Wrong notification while migration (#2337)

Root Cause:
Earlier, it was failing with ArrayIndexOutOfBoundsException, when the list is empty and accessing the first element.
The error was only observed in Log, but was not showing in UI as it was not throwing any exception.
Hence the API call was in turn successful.

Solution:
Added the empty check before sending device details.
Which says either the required GPU device is not available or out of capacity.
---
 .../cloud/resource/ResourceManagerImpl.java   | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/server/src/com/cloud/resource/ResourceManagerImpl.java b/server/src/com/cloud/resource/ResourceManagerImpl.java
index 9feb9b7f683..33c36de2f8e 100755
--- a/server/src/com/cloud/resource/ResourceManagerImpl.java
+++ b/server/src/com/cloud/resource/ResourceManagerImpl.java
@@ -29,6 +29,10 @@ import java.util.Map;
 import javax.inject.Inject;
 import javax.naming.ConfigurationException;
 
+import org.apache.commons.lang.ObjectUtils;
+import org.apache.log4j.Logger;
+import org.springframework.stereotype.Component;
+
 import org.apache.cloudstack.api.ApiConstants;
 import org.apache.cloudstack.api.command.admin.cluster.AddClusterCmd;
 import org.apache.cloudstack.api.command.admin.cluster.DeleteClusterCmd;
@@ -44,9 +48,7 @@ import org.apache.cloudstack.framework.config.dao.ConfigurationDao;
 import org.apache.cloudstack.storage.datastore.db.PrimaryDataStoreDao;
 import org.apache.cloudstack.storage.datastore.db.StoragePoolVO;
 import org.apache.cloudstack.utils.identity.ManagementServerNode;
-import org.apache.commons.lang.ObjectUtils;
-import org.apache.log4j.Logger;
-import org.springframework.stereotype.Component;
+import org.apache.commons.collections.CollectionUtils;
 
 import com.cloud.agent.AgentManager;
 import com.cloud.agent.api.Answer;
@@ -2755,8 +2757,15 @@ public class ResourceManagerImpl extends ManagerBase implements ResourceManager,
 
     @Override
     public GPUDeviceTO getGPUDevice(final long hostId, final String groupName, final String vgpuType) {
-        final HostGpuGroupsVO gpuDevice = listAvailableGPUDevice(hostId, groupName, vgpuType).get(0);
-        return new GPUDeviceTO(gpuDevice.getGroupName(), vgpuType, null);
+        final List<HostGpuGroupsVO> gpuDeviceList = listAvailableGPUDevice(hostId, groupName, vgpuType);
+
+        if (CollectionUtils.isEmpty(gpuDeviceList)) {
+            final String errorMsg = "Host " + hostId + " does not have required GPU device or out of capacity. GPU group: " + groupName + ", vGPU Type: " + vgpuType;
+            s_logger.error(errorMsg);
+            throw new CloudRuntimeException(errorMsg);
+        }
+
+        return new GPUDeviceTO(gpuDeviceList.get(0).getGroupName(), vgpuType, null);
     }
 
     @Override