Fix stale lockfile detection

[HebaruSan]

Background

CKAN creates a <KSP>/CKAN/registry.locked file when it loads an instance and deletes this file at exit. If CKAN terminates abnormally (e.g., pkill -KILL mono), then the registry.locked file can be left behind without a running CKAN. To make this condition detectable, the file contains the process ID of the CKAN process that created it.

Problem

If you have a stale lock file and you start CKAN, the staleness is not detected. The lock file dialog appears even though there is no process with the process ID contained in the lock file.

Cause

#2139 was supposed to address this, but it had a bug:

CKAN/Core/Registry/RegistryManager.cs

Line 171 in cd7c3a0

if (IsInstanceMaybeLocked(path))

That function takes the <KSP>/CKAN dir path as a parameter:

CKAN/Core/Registry/RegistryManager.cs

Lines 46 to 54 in cd7c3a0

	private static string InstanceRegistryLockPath(string path)
	{
	return Path.Combine(path, "registry.locked");
	}
	public static bool IsInstanceMaybeLocked(string path)
	{
	return File.Exists(InstanceRegistryLockPath(path));
	}

... but we're passing the path to the registry.json file, so the file path that we look for is <KSP>/CKAN/registry.json/registry.locked:

CKAN/Core/Registry/RegistryManager.cs

Line 62 in cd7c3a0

this.path = Path.Combine(path, "registry.json");

GameInstance.cs uses it correctly:

CKAN/Core/GameInstance.cs

Lines 84 to 91 in cd7c3a0

	/// <returns>
	/// true if the instance may be locked, false otherwise.
	/// Note that this is a tentative value; if it's true,
	/// we still need to try to acquire the lock to confirm it isn't stale.
	/// NOTE: Will throw NotKSPDirKraken if the instance isn't valid!
	/// Either be prepared to catch that exception, or check Valid first to avoid it.
	/// </returns>
	public bool IsMaybeLocked => RegistryManager.IsInstanceMaybeLocked(CkanDir());

Changes

• Now CheckStaleLock passes the path to the CKAN dir as intended, so the lock file deletion takes place

  1392 [1] DEBUG CKAN.RegistryManager (null) - Preparing to load registry at /home/user/.local/share/Steam/steamapps/common/Kerbal Space Program/CKAN
  1393 [1] DEBUG CKAN.RegistryManager (null) - Checking for stale lock file at /home/user/.local/share/Steam/steamapps/common/Kerbal Space Program/CKAN/registry.locked
  1393 [1] DEBUG CKAN.RegistryManager (null) - Lock file found at /home/user/.local/share/Steam/steamapps/common/Kerbal Space Program/CKAN/registry.locked
  1393 [1] DEBUG CKAN.RegistryManager (null) - Lock file contents: 122202
  1393 [1] DEBUG CKAN.RegistryManager (null) - Looking for process with ID: 122202
  1394 [1] DEBUG CKAN.RegistryManager (null) - Deleting stale lock file at /home/user/.local/share/Steam/steamapps/common/Kerbal Space Program/CKAN/registry.locked
  1394 [1] DEBUG CKAN.RegistryManager (null) - Trying to create lock file: /home/user/.local/share/Steam/steamapps/common/Kerbal Space Program/CKAN/registry.locked
  1394 [1] DEBUG CKAN.RegistryManager (null) - Lock file created: /home/user/.local/share/Steam/steamapps/common/Kerbal Space Program/CKAN/registry.locked
  1395 [1] DEBUG CKAN.RegistryManager (null) - Trying to load registry from /home/user/.local/share/Steam/steamapps/common/Kerbal Space Program/CKAN/registry.json
  

• RegistryManager.ksp is renamed gameInstance
• The parameters of InstanceRegistryLockPath and IsInstanceMaybeLocked are renamed from path to ckanDirPath to make it easier to know the correct thing to pass

Fixes #3686.

[techman83]

Yup, that makes sense. 🎉