monitor if a state-maker file still exists, and if not error out and exit (#283)

* monitor if a state-maker file still exists, and if not error out and exit

2 files changed, 26 insertions, 0 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3b16398ca..1eca8ede9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,5 @@
 ##
+- Feature: zenserver now writes a state_marker file in the root of the data directory. Deleting this file will cause zenserver to exit. This is used to detect if user is deleting the data folder while zenserver is running
 - Feature: Disk writes are now blocked early and return an insufficient storage error if free disk space falls below the `--low-diskspace-threshold` value
 - Feature: zenserver: Add command line option `--sentry-allow-personal-info` to allow personally identifiable information in sentry reports, disabled by default
 - Feature: Age-based GC of oplogs in project store
diff --git a/src/zenserver/zenserver.cpp b/src/zenserver/zenserver.cpp
index c6ec4b82b..2469c5c85 100644
--- a/src/zenserver/zenserver.cpp
+++ b/src/zenserver/zenserver.cpp
@@ -512,6 +512,24 @@ public:
 		EnsureIoRunner();
 	}
 
+	void EnqueueStateMarkerTimer()
+	{
+		m_StateMakerTimer.expires_after(std::chrono::seconds(5));
+		m_StateMakerTimer.async_wait([this](const asio::error_code&) { CheckStateMarker(); });
+		EnsureIoRunner();
+	}
+
+	void CheckStateMarker()
+	{
+		std::filesystem::path StateMarkerPath = m_DataRoot / "state_marker";
+		if (!std::filesystem::exists(StateMarkerPath))
+		{
+			ZEN_ERROR("state marker at {} has been deleted, exiting", StateMarkerPath);
+			RequestExit(0);
+		}
+		EnqueueStateMarkerTimer();
+	}
+
 	void CheckOwnerPid()
 	{
 		// Pick up any new "owner" processes
@@ -595,6 +613,7 @@ private:
 	std::thread						m_IoRunner;
 	asio::io_context				m_IoContext;
 	asio::steady_timer				m_PidCheckTimer{m_IoContext};
+	asio::steady_timer				m_StateMakerTimer{m_IoContext};
 	zen::ProcessMonitor				m_ProcessMonitor;
 	zen::NamedMutex					m_ServerMutex;
 
@@ -758,6 +777,12 @@ ZenServer::InitializeState(const ZenServerOptions& ServerOptions)
 
 		WriteFile(ManifestPath, m_RootManifest.GetBuffer().AsIoBuffer());
 	}
+	{
+		std::filesystem::path		  StateMarkerPath	 = m_DataRoot / "state_marker";
+		static const std::string_view StateMarkerContent = "deleting this file will cause " ZEN_APP_NAME " to exit"sv;
+		WriteFile(StateMarkerPath, IoBuffer(IoBuffer::Wrap, StateMarkerContent.data(), StateMarkerContent.size()));
+		EnqueueStateMarkerTimer();
+	}
 }
 
 void