[vs] Fail switch create when warm boot requested and no warm boot sta…

…te (sonic-net#739)

* [vs] Fail switch create when warm boot requested and no warm boot state

Print extra information about loading warm boot state file, like file
size and number of switches loaded from that file.

* [syncd] Add explicit warning log when syncd start type is overridden

syncd/Syncd.cpp

@@ -202,6 +202,9 @@ void Syncd::performStartupLogic()
 
     if (m_isWarmStart && (m_commandLineOptions->m_startType != SAI_START_TYPE_FASTFAST_BOOT))
     {
+        SWSS_LOG_WARN("override command line startType=%s via SAI_START_TYPE_WARM_BOOT",
+                CommandLineOptions::startTypeToString(m_commandLineOptions->m_startType).c_str());
+
         m_commandLineOptions->m_startType = SAI_START_TYPE_WARM_BOOT;
     }
 

vslib/src/VirtualSwitchSaiInterface.cpp

@@ -649,8 +649,10 @@ sai_status_t VirtualSwitchSaiInterface::create(
 
             if (warmBootState == nullptr)
             {
-                SWSS_LOG_WARN("warm boot was requested on switch %s, but warm boot state is NULL, will perform COLD boot",
+                SWSS_LOG_ERROR("warm boot was requested on switch %s, but warm boot state is NULL",
                         sai_serialize_object_id(switchId).c_str());
+
+                return SAI_STATUS_FAILURE;
             }
         }
 
@@ -1362,6 +1364,11 @@ bool VirtualSwitchSaiInterface::readWarmBootFile(
         return false;
     }
 
+    {
+        std::ifstream in(warmBootFile, std::ifstream::ate | std::ifstream::binary);
+        SWSS_LOG_NOTICE("%s file size: %zu", warmBootFile, (size_t)in.tellg());
+    }
+
     std::ifstream ifs;
 
     ifs.open(warmBootFile);
@@ -1467,7 +1474,7 @@ bool VirtualSwitchSaiInterface::readWarmBootFile(
 
     ifs.close();
 
-    SWSS_LOG_NOTICE("warm boot file %s stats:", warmBootFile);
+    SWSS_LOG_NOTICE("warm boot file %s stats, loaded switches: %zu", warmBootFile, m_warmBootState.size());
 
     for (auto& kvp: m_warmBootState)
     {