[Bug] CKAN already running dialog appears even if PID in registry.locked is stale

[ghost]

Problem

If you need to close CKAN with SIGKILL, the <GameDir>/CKAN/registry.locked file keeps the PID of your SIGKILL'ed PID of previous CKAN session, which results in a CKAN already running error on the next start.

Suggestions

Add a check if that PID in registry.locked exists and belongs to a CKAN process. If true show the already running error dialog, otherwise open CKAN without error dialog.

Describe alternatives you've considered

Additional context
Linux

[HebaruSan]

Yup, this line is bugged:

CKAN/Core/Registry/RegistryManager.cs

Line 171 in cd7c3a0

if (IsInstanceMaybeLocked(path))

That function takes the <KSP>/CKAN dir path as a parameter, but we're passing the path to the registry.json file.

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));
	}

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());

[HebaruSan]

Confirmed that fixing that problem fixes the overall issue:

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

[ghost]

Tested it on latest build, couldn't reproduce that behaviour. Thanks 👍

[HebaruSan]

Let's leave this issue open until the fix is merged. If we did a release from the master branch right now, the bug would still be present.