harden attach sponsor process (#14)

- Improvement: Delay exiting due to no sponsor processes by one second to handle race conditions
- Improvement: Safer IsProcessRunning check
- Improvement: make sure we can RequestApplicationExit safely from any thread

1 files changed, 7 insertions, 10 deletions

diff --git a/src/zenutil/zenserverprocess.cpp b/src/zenutil/zenserverprocess.cpp
index 3667ad2c6..7725d0af6 100644
--- a/src/zenutil/zenserverprocess.cpp
+++ b/src/zenutil/zenserverprocess.cpp
@@ -308,7 +308,7 @@ ZenServerState::Sweep()
 
 		if (Entry.DesiredListenPort)
 		{
-			if (IsProcessRunning(Entry.Pid) == false)
+			if (Entry.Pid != 0 && IsProcessRunning(Entry.Pid) == false)
 			{
 				ZEN_DEBUG("Sweep - pid {} not running, reclaiming entry (port {})", Entry.Pid.load(), Entry.DesiredListenPort.load());
 
@@ -363,18 +363,15 @@ ZenServerState::ZenServerEntry::AddSponsorProcess(uint32_t PidToAdd)
 {
 	for (std::atomic<uint32_t>& PidEntry : SponsorPids)
 	{
-		if (PidEntry.load(std::memory_order_relaxed) == 0)
+		if (PidEntry.load(std::memory_order_relaxed) == PidToAdd)
 		{
-			uint32_t Expected = 0;
-			if (PidEntry.compare_exchange_strong(Expected, PidToAdd))
-			{
-				// Success!
-				return true;
-			}
+			// Success, the because pid is already in the list
+			return true;
 		}
-		else if (PidEntry.load(std::memory_order_relaxed) == PidToAdd)
+		uint32_t Expected = 0;
+		if (PidEntry.compare_exchange_strong(Expected, PidToAdd))
 		{
-			// Success, the because pid is already in the list
+			// Success!
 			return true;
 		}
 	}