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From: Daniel Gustafsson <[email protected]>
To: Masahiko Sawada <[email protected]>
Cc: Melanie Plageman <[email protected]>
Cc: Kyotaro Horiguchi <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Cc: Andres Freund <[email protected]>
Cc: [email protected]
Subject: Re: Should vacuum process config file reload more often
Date: Thu, 30 Mar 2023 21:26:47 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAD21AoCGdxYAJHmE_nXw_MFw1+Qtn3vcThRu5FiadukgQnpWeQ@mail.gmail.com>
References: <CAAKRu_ZnG2nYcvzb4a-CGwg33_4RX83qitGGVmjhHZZtqeSrRA@mail.gmail.com>
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	<CAD21AoCGdxYAJHmE_nXw_MFw1+Qtn3vcThRu5FiadukgQnpWeQ@mail.gmail.com>

> On 30 Mar 2023, at 04:57, Masahiko Sawada <[email protected]> wrote:

> As another idea, why don't we use macros for that? For example,
> suppose VacuumCostStatus is like:
> 
> typedef enum VacuumCostStatus
> {
>    VACUUM_COST_INACTIVE_LOCKED = 0,
>    VACUUM_COST_INACTIVE,
>    VACUUM_COST_ACTIVE,
> } VacuumCostStatus;
> VacuumCostStatus VacuumCost;
> 
> non-vacuum code can use the following macros:
> 
> #define VacuumCostActive() (VacuumCost == VACUUM_COST_ACTIVE)
> #define VacuumCostInactive() (VacuumCost <= VACUUM_COST_INACTIVE) //
> or we can use !VacuumCostActive() instead.

I'm in favor of something along these lines.  A variable with a name that
implies a boolean value (active/inactive) but actually contains a tri-value is
easily misunderstood.  A VacuumCostState tri-value variable (or a better name)
with a set of convenient macros for extracting the boolean active/inactive that
most of the code needs to be concerned with would more for more readable code I
think.

--
Daniel Gustafsson

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