From: Jeff Hostetler <git@jeffhostetler.com>
Date: Fri, 30 Apr 2021 15:18:51 GMT
Subject: Re: [PATCH 09/23] fsmonitor--daemon: implement daemon command options
Message-ID: <a7e8ef01-b707-5b4a-2652-cc3e08bb85f2@jeffhostetler.com>
In-Reply-To: <3aa3c802-0ad1-0a65-d646-0cd574cb8036@gmail.com>



On 4/26/21 12:12 PM, Derrick Stolee wrote:
> On 4/26/2021 11:47 AM, Derrick Stolee wrote:
>> On 4/1/21 11:40 AM, Jeff Hostetler via GitGitGadget wrote:
>>> From: Jeff Hostetler <jeffhost@microsoft.com>
>> ...
>>> +	/* Prepare to (recursively) watch the <worktree-root> directory. */
>>> +	strbuf_init(&state.path_worktree_watch, 0);
>>> +	strbuf_addstr(&state.path_worktree_watch, absolute_path(get_git_work_tree()));
>>> +	state.nr_paths_watching = 1;
>>
>> Yes, let's watch the working directory.
>>
>>> +	/*
>>> +	 * If ".git" is not a directory, then <gitdir> is not inside the
>>> +	 * cone of <worktree-root>, so set up a second watch for it.
>>> +	 */
>>> +	strbuf_init(&state.path_gitdir_watch, 0);
>>> +	strbuf_addbuf(&state.path_gitdir_watch, &state.path_worktree_watch);
>>> +	strbuf_addstr(&state.path_gitdir_watch, "/.git");
>>> +	if (!is_directory(state.path_gitdir_watch.buf)) {
>>> +		strbuf_reset(&state.path_gitdir_watch);
>>> +		strbuf_addstr(&state.path_gitdir_watch, absolute_path(get_git_dir()));
>>> +		state.nr_paths_watching = 2;
>>> +	}
>>
>> But why watch the .git directory, especially for a worktree (or
>> submodule I guess)? What benefit do we get from events within the
>> .git directory? I'm expecting any event within the .git directory
>> should be silently ignored.
> 
> I see in a following patch that we place a cookie file within the
> .git directory. I'm reminded that this is done for a reason: other
> filesystem watchers can get into a loop if we place the cookie
> file outside of the .git directory. The classic example is VS Code
> running 'git status' in a loop because Watchman writes a cookie
> into the root of the working directory.

Yes.  I'll add a comment explaining the need for the second watch.