Re: Incorrect comment for memset() on pgssHashKey?

From: Heikki Linnakangas <hlinnaka(at)iki(dot)fi>
To: Japin Li <japinli(at)hotmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Incorrect comment for memset() on pgssHashKey?
Date: 2023-06-27 07:18:11
Message-ID: c289366f-93a1-7fa6-37f9-aa3262478400@iki.fi
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On 27/06/2023 07:32, Japin Li wrote:
>
> Hi,
>
> Commit 6b4d23feef introduces a toplevel field in pgssHashKey, which leads
> padding. In pgss_store(), it comments that memset() is required when
> pgssHashKey is without padding only.
>
> @@ -1224,9 +1227,14 @@ pgss_store(const char *query, uint64 queryId,
> query = CleanQuerytext(query, &query_location, &query_len);
>
> /* Set up key for hashtable search */
> +
> + /* memset() is required when pgssHashKey is without padding only */
> + memset(&key, 0, sizeof(pgssHashKey));
> +
> key.userid = GetUserId();
> key.dbid = MyDatabaseId;
> key.queryid = queryId;
> + key.toplevel = (exec_nested_level == 0);
>
> /* Lookup the hash table entry with shared lock. */
> LWLockAcquire(pgss->lock, LW_SHARED);
>
> However, we need memset() only when pgssHashKey has padding, right?

Yep. I changed the comment to just "clear padding". Thanks!

--
Heikki Linnakangas
Neon (https://neon.tech)

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