Update name of file that indicates installation version

[jamill]

Update name of file that the GVFS installer creates when an on disk version 16 capable GVFS is first installed.

After discussions on how GVFS determines whether the GitStatusCache should be enabled to ensure that the machine has been rebooted since a GitStatusCache aware GVFS was installed, we decided on two changes:

1. The name of the file created by the GVFS installer should be changed to OnDiskVersion16CapableInstallation.dat

2. Move the logic for determining whether the GitStatusCache should enabled for a GVFS installation from the GVFS.Service to individual mount processes. This means we could get rid of the EnableGitStatusCacheToken.dat file that exists in the GVFS.Service common application directory.

This PR addresses issue 1.

I want to get agreement on the changes for the file written out by the installer. I can follow up with the changes for the second issue, either for the M139 release, or as a future change.

I am doing another round of testing on these changes, and can do a final verification after we agree on the name.

[sanoursa]

I think we should get rid of this file. Comparing the capability file and reboot time should be enough, shouldn't it?

[sanoursa]

I see that you discussed this in the PR comments and left it as a TODO. I do think we should drop it, since it's another point of failure and not a necessary one, it would seem.

[jrbriggs]

@sanoursa I think we should take this PR in isolation for M139 so we can get it out the door.

That would leave us in a state where we could take the second point up in master moving forward, if we felt we needed to revisit it.

[sanoursa]

That works for me. The file that is dropped by the installer is one that we will have to maintain forever. The status cache token file is not, so I agree we could clean it up later.

[jamill]

Thanks! This approach seems reasonable.

[jamill]

Scenarios I tested:

• mounting a repository with out an EnableGitStatusCacheToken.dat file leaves git status cache disabled

• mount a repository with an EnableGitStatusCacheToken.dat file enables git status cache

• OnDiskVersion16CapableInstallation.dat is written by the installer

• EnableGitStatusCacheToken.dat is not written if OnDiskVersion16CapableInstallation.dat is not present

[8/21/2018 1:40:30 PM] Error {"ErrorMessage":"Unable to determine GVFS installation time: C:\\Program Files\\GVFS\\OnDiskVersion16CapableInstallation.dat does not exist."}

• EnableGitStatusCacheToken.dat is not written if the creation time for OnDiskVersion16CapableInstallation.dat is before last reboot

[8/21/2018 1:52:32 PM] Information {"Message":"CheckEnableGitStatusCache: Not writing EnableGitStatusCacheToken file - machine has not been rebooted since OnDiskVersion16Capable installation. GVFS installation time: 8/21/2018 1:48:55 PM, last reboot time: 8/21/2018 10:45:16 AM"}

• EnableGitStatusCacheToken.dat is written if the creation time for OnDiskVersion16CapableInstallation.dat is after last reboot

[8/21/2018 1:56:29 PM] Information {"Message":"CheckEnableGitStatusCache: Writing out EnableGitStatusCacheToken file. GVFS installation time: 8/21/2018 1:48:55 PM, last Reboot time: 8/21/2018 1:56:06 PM."}