added ZenServerInstance::SpawnServerAndWait (#334)

this change adds `ZenServerInstance::SpawnServerAndWait()` which as the name implies spawns a server and then waits for the instance to reach a usable state before returning to the caller.

It also changes the behaviour of `ZenServerInstance::AttachToRunningServer()` so it matches the Spawn behaviour wrt automatic termination on ZenServerInstance destruction. Previously it would always terminate the subprocess on exit.

2 files changed, 62 insertions, 6 deletions

diff --git a/src/zenutil/include/zenutil/zenserverprocess.h b/src/zenutil/include/zenutil/zenserverprocess.h
index a0a705f64..7b78261bc 100644
--- a/src/zenutil/include/zenutil/zenserverprocess.h
+++ b/src/zenutil/include/zenutil/zenserverprocess.h
@@ -58,6 +58,7 @@ struct ZenServerInstance
 	void			   WaitUntilReady();
 	[[nodiscard]] bool WaitUntilReady(int Timeout);
 	void			   EnableTermination() { m_Terminate = true; }
+	void			   DisableShutdownOnDestroy() { m_ShutdownOnDestroy = false; }
 	void			   Detach();
 	inline int		   GetPid() { return m_Process.Pid(); }
 	inline void		   SetOwnerPid(int Pid) { m_OwnerPid = Pid; }
@@ -68,7 +69,16 @@ struct ZenServerInstance
 		m_TestDir = TestDir;
 	}
 
-	void		SpawnServer(int BasePort = 0, std::string_view AdditionalServerArgs = std::string_view());
+	inline void SpawnServer(int BasePort = 0, std::string_view AdditionalServerArgs = std::string_view())
+	{
+		SpawnServer(BasePort, AdditionalServerArgs, /* WaitTimeoutMs */ 0);
+	}
+
+	inline void SpawnServerAndWait(int BasePort = 0, std::string_view AdditionalServerArgs = std::string_view(), int WaitTimeoutMs = 10000)
+	{
+		SpawnServer(BasePort, AdditionalServerArgs, WaitTimeoutMs);
+	}
+
 	void		AttachToRunningServer(int BasePort = 0);
 	std::string GetBaseUri() const;
 
@@ -77,12 +87,14 @@ private:
 	ProcessHandle		  m_Process;
 	NamedEvent			  m_ReadyEvent;
 	NamedEvent			  m_ShutdownEvent;
-	bool				  m_Terminate = false;
+	bool				  m_Terminate		  = false;
+	bool				  m_ShutdownOnDestroy = true;
 	std::filesystem::path m_TestDir;
 	int					  m_BasePort = 0;
 	std::optional<int>	  m_OwnerPid;
 
 	void CreateShutdownEvent(int BasePort);
+	void SpawnServer(int BasePort, std::string_view AdditionalServerArgs, int WaitTimeoutMs);
 };
 
 /** Shared Zen system state
diff --git a/src/zenutil/zenserverprocess.cpp b/src/zenutil/zenserverprocess.cpp
index ead919cb9..d1a91b93f 100644
--- a/src/zenutil/zenserverprocess.cpp
+++ b/src/zenutil/zenserverprocess.cpp
@@ -476,7 +476,7 @@ ZenServerInstance::SignalShutdown()
 void
 ZenServerInstance::Shutdown()
 {
-	if (m_Process.IsValid())
+	if (m_Process.IsValid() && m_ShutdownOnDestroy)
 	{
 		if (m_Terminate)
 		{
@@ -494,7 +494,7 @@ ZenServerInstance::Shutdown()
 }
 
 void
-ZenServerInstance::SpawnServer(int BasePort, std::string_view AdditionalServerArgs)
+ZenServerInstance::SpawnServer(int BasePort, std::string_view AdditionalServerArgs, int WaitTimeoutMs)
 {
 	ZEN_ASSERT(!m_Process.IsValid());  // Only spawn once
 
@@ -587,12 +587,55 @@ ZenServerInstance::SpawnServer(int BasePort, std::string_view AdditionalServerAr
 
 	ZEN_DEBUG("Server '{}' spawned OK", LogId);
 
-	if (IsTest)
+	m_Process.Initialize(ChildPid);
+
+	if (IsTest == false)
 	{
-		m_Process.Initialize(ChildPid);
+		DisableShutdownOnDestroy();
 	}
 
 	m_ReadyEvent = std::move(ChildEvent);
+
+	if (WaitTimeoutMs)
+	{
+		if (!WaitUntilReady(WaitTimeoutMs))
+		{
+			throw std::runtime_error(fmt::format("server start timeout after {}", NiceTimeSpanMs(WaitTimeoutMs)));
+		}
+
+		// Determine effective base port
+
+		ZenServerState State;
+		if (!State.InitializeReadOnly())
+		{
+			// TODO: return success/error code instead?
+			throw std::runtime_error("no zen state found");
+		}
+
+		const ZenServerState::ZenServerEntry* Entry = nullptr;
+
+		if (BasePort)
+		{
+			Entry = State.Lookup(BasePort);
+		}
+		else
+		{
+			State.Snapshot([&](const ZenServerState::ZenServerEntry& InEntry) {
+				if (InEntry.Pid == static_cast<uint32_t>(GetProcessId(ChildPid)))
+				{
+					Entry = &InEntry;
+				}
+			});
+		}
+
+		if (!Entry)
+		{
+			// TODO: return success/error code instead?
+			throw std::runtime_error("no server entry found");
+		}
+
+		m_BasePort = Entry->EffectiveListenPort;
+	}
 }
 
 void
@@ -634,6 +677,7 @@ ZenServerInstance::AttachToRunningServer(int BasePort)
 
 	m_Process.Initialize(Entry->Pid);
 	CreateShutdownEvent(Entry->EffectiveListenPort);
+	m_BasePort = Entry->EffectiveListenPort;
 }
 
 void