Re: [PATCH] lock_timeout and common SIGALRM framework

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Boszormenyi Zoltan <zb(at)cybertec(dot)at>
Cc: Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Marc Cousin <cousinmarc(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Hans-Juergen Schoenig <hs(at)cybertec(dot)at>, Ants Aasma <ants(at)cybertec(dot)at>
Subject: Re: [PATCH] lock_timeout and common SIGALRM framework
Date: 2012-06-26 11:50:21
Message-ID: CA+TgmoYTTFTnJBrfivECOFif2E8CpfX7k0izKrHC=OwmjPPa6g@mail.gmail.com
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On Tue, Jun 26, 2012 at 3:59 AM, Boszormenyi Zoltan <zb(at)cybertec(dot)at> wrote:
> Well, I can make the registration interface similar to how LWLocks
> are treated, but that doesn't avoid modification of the base_timeouts
> array in case a new internal use case arises. Say:
>
> #define USER_TIMEOUTS    4
>
> int    n_timeouts = TIMEOUT_MAX;
> static timeout_params base_timeouts[TIMEOUT_MAX + USER_TIMEOUTS];

Since timeouts - unlike lwlocks - do not need to touch shared memory,
there's no need for a hard-coded limit here. You can just allocate
the array using MemoryContextAlloc(TopMemoryContext, ...) and enlarge
it as necessary. To avoid needing to modify the base_timeouts array,
you can just have internal callers push their entries into the array
during process startup using the same function call that an external
module would use.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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