From 0b9b482df96d1bd971151fb28614b3faafdaf451 Mon Sep 17 00:00:00 2001
From: Stefan Boberg <stefan@boberg.org>
Date: Mon, 9 Aug 2021 14:13:30 +0200
Subject: Added ZenServerState implementation, used to track and enumerate live
 Zen server instances

---
 zenutil/include/zenserverprocess.h | 42 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

(limited to 'zenutil/include')

diff --git a/zenutil/include/zenserverprocess.h b/zenutil/include/zenserverprocess.h
index 239841a04..60ed273cb 100644
--- a/zenutil/include/zenserverprocess.h
+++ b/zenutil/include/zenserverprocess.h
@@ -6,6 +6,7 @@
 
 #include <spdlog/spdlog.h>
 
+#include <atomic>
 #include <filesystem>
 
 class ZenServerEnvironment
@@ -58,3 +59,44 @@ private:
 	std::filesystem::path m_TestDir;
 	bool				  m_MeshEnabled = false;
 };
+
+/** Shared system state
+ *
+ * Used as a scratchpad to identify running instances etc
+ *
+ * The state lives in a memory-mapped file backed by the swapfile
+ *
+ */
+
+class ZenServerState
+{
+public:
+	ZenServerState();
+	~ZenServerState();
+
+	struct ZenServerEntry
+	{
+		std::atomic<uint32_t> Pid;
+		std::atomic<uint16_t> ListenPort;
+		uint16_t			  Flags;
+		uint8_t				  SessionId[12];
+		uint8_t				  Padding[12];
+
+		void Reset();
+	};
+
+	static_assert(sizeof(ZenServerEntry) == 32);
+
+	void			   Initialize();
+	[[nodiscard]] bool InitializeReadOnly();
+	ZenServerEntry*	   Lookup(int ListenPort);
+	ZenServerEntry*	   Register(int ListenPort);
+	void			   Sweep();
+	void			   Snapshot(std::function<void(const ZenServerEntry&)>&& Callback);
+
+private:
+	void*			m_hMapFile = nullptr;
+	ZenServerEntry* m_Data;
+	int				m_MaxEntryCount = 4096 / sizeof(ZenServerEntry);
+	ZenServerEntry* m_OurEntry		= nullptr;
+};
-- 
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