Remove redundant async call in FRU collection threads (#588)

This commit removes the redundant std:async call in the detached thread
launched for parsing and publishing the VPD for an individual FRU.
Since we have a dedicated detached thread for each FRU, we can do VPD
parse and publish in a synchronous manner from the detached thread
itself, instead of launching a asynchronous task which adds unnecessary
performance cost. This commit also handles any exception thrown while
launching the detached thread for a FRU. Incase launching detached
thread for a FRU fails, we log a PEL and continue launching threads for
other FRUs.

This commit addresses issue #558.

Test:

```
1. Install bitbaked image on Everest (ever6bmc)
2. After initial boot, check:
	- BMC State Ready
	- vpd-manager's CollectionStatus property should be "Completed"
	busctl get-property com.ibm.VPD.Manager
	/com/ibm/VPD/Manager com.ibm.VPD.Manager
	CollectionStatus
	s "Completed"
	- vpd-manager status should be running with no restarts
	- vpd-manager should have only 1 thread running:
	  check "ls -la /proc/<vpd-manager PID>/task"
3. Reboot the BMC several times and repeat Step 2.
```

Change-Id: I603c64dc9b5057429a2288f0edfde6086755b851
Signed-off-by: Souvik Roy <[email protected]>

Author: Souvik Roy

vpd-manager/include/worker.hpp

@@ -80,6 +80,7 @@ class Worker
      * Note: Config JSON file path should be passed to worker class constructor
      * to make use of this API.
      *
+     * @throw std::runtime_error
      */
     void collectFrusFromJson();
 

vpd-manager/src/worker.cpp

@@ -1505,22 +1505,31 @@ void Worker::collectFrusFromJson()
             continue;
         }
 
-        std::thread{[vpdFilePath, this]() {
-            auto l_futureObject = std::async(&Worker::parseAndPublishVPD, this,
-                                             vpdFilePath);
-
-            std::tuple<bool, std::string> l_threadInfo = l_futureObject.get();
+        try
+        {
+            std::thread{[vpdFilePath, this]() {
+                const auto& l_parseResult = parseAndPublishVPD(vpdFilePath);
 
-            // thread returned.
-            m_mutex.lock();
-            m_activeCollectionThreadCount--;
-            m_mutex.unlock();
+                m_mutex.lock();
+                m_activeCollectionThreadCount--;
+                m_mutex.unlock();
 
-            if (!m_activeCollectionThreadCount)
-            {
-                m_isAllFruCollected = true;
-            }
-        }}.detach();
+                if (!m_activeCollectionThreadCount)
+                {
+                    m_isAllFruCollected = true;
+                }
+            }}.detach();
+        }
+        catch (const std::exception& l_ex)
+        {
+            // TODO: Should we re-try launching thread for this FRU?
+            EventLogger::createSyncPel(
+                types::ErrorType::InvalidVpdMessage, types::SeverityType::Alert,
+                __FILE__, __FUNCTION__, 0,
+                std::string("Failed to start collection thread for FRU :[" +
+                            vpdFilePath + "]. Error: " + l_ex.what()),
+                std::nullopt, std::nullopt, std::nullopt, std::nullopt);
+        }
     }
 }