Re: Add comments for a postgres program in bootstrap mode

Hi Shiraishi-san,

On Thu, Sep 26, 2019 at 3:06 PM Youki Shiraishi <shiraishi(at)computer(dot)org> wrote:
>
> Hi,
>
> I have just started to read the PostgreSQL code and found a lack of comments for a postgres backend program in bootstrap mode.
> When I saw the --boot option implemented in src/backend/main/main.c at first time, I did not understand why the --boot option is not documented and what it is used for.
> The only way to know these things is to type `grep -r '\--boot' .` on a project root.
> It is easy to see that the --boot option is used in initdb for some historical reasons, but it is painful for a beginner like me.
> I believe the attached patch which adds a few comments might help a beginner.

Thanks for the patch. It might be a good idea to demystify this
secret --boot option.

+ /* Bootstrap mode for initdb */
if (argc > 1 && strcmp(argv[1], "--boot") == 0)
AuxiliaryProcessMain(argc, argv); /* does not return */
else if (argc > 1 && strcmp(argv[1], "--describe-config") == 0)

How about expanding that comment just a little bit, say:

/*
* Bootstrapping is handled by AuxiliaryProcessMain() for historic
* reasons.
*/

@@ -190,7 +190,8 @@ static IndexList *ILHead = NULL;
* AuxiliaryProcessMain
*
* The main entry point for auxiliary processes, such as the bgwriter,
- * walwriter, walreceiver, bootstrapper and the shared memory checker code.
+ * walwriter, walreceiver, postgres program in bootstrap mode and the
+ * shared memory checker code.

This change may not be necessary, because, bootstrapper is a good
short name for 'postgres program in bootstrap mode'. Also, this name
is similar in style to the names of other auxiliary processes.

Thanks,
Amit