Fix two related bugs: rescheduling periodic task + fetch manager restart of failed fetches

Apparently, posix_time::seconds() returns just seconds from [0, 59]
range and to get total number of seconds, total_seconds() call is
necessary

Change-Id: Idbc3cbd6a33e72d7f573f9cc905b73022ddf4847
diff --git a/scheduler/periodic-task.cc b/scheduler/periodic-task.cc
index 32bae6a..947107c 100644
--- a/scheduler/periodic-task.cc
+++ b/scheduler/periodic-task.cc
@@ -20,8 +20,11 @@
  */
 
 #include "periodic-task.h"
+#include "logging.h"
 #include <utility>
 
+INIT_LOGGER ("Scheduler.PeriodicTask");
+
 PeriodicTask::PeriodicTask(const Callback &callback, const Tag &tag, const SchedulerPtr &scheduler,
                            IntervalGeneratorPtr generator)
   : Task(callback, tag, scheduler)
@@ -34,9 +37,14 @@
 {
   if (!m_invoked)
   {
-    m_callback();
     m_invoked = true;
-    m_scheduler->rescheduleTask(m_tag);
+    m_callback();
+
+    if (m_invoked)
+      {
+        // m_invoked getting back if it is rescheduled inside the callback
+        m_scheduler->rescheduleTask(m_tag);
+      }
   }
 }
 
diff --git a/src/fetch-manager.cc b/src/fetch-manager.cc
index e9463b7..af72e08 100644
--- a/src/fetch-manager.cc
+++ b/src/fetch-manager.cc
@@ -181,7 +181,7 @@
       item->RestartPipeline ();
     }
 
-  m_scheduler->rescheduleTaskAt (m_scheduleFetchesTask, (nextSheduleCheck - currentTime).seconds ());
+  m_scheduler->rescheduleTaskAt (m_scheduleFetchesTask, (nextSheduleCheck - currentTime).total_seconds ());
 }
 
 void