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From: Chao Li <[email protected]>
To: Joel Jacobson <[email protected]>
Cc: Tom Lane <[email protected]>
Cc: Matheus Alcantara <[email protected]>
Cc: pgsql-hackers <[email protected]>
Subject: Re: Optimize LISTEN/NOTIFY
Date: Wed, 8 Oct 2025 12:36:35 +0800
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
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> On Oct 8, 2025, at 11:43, Chao Li <[email protected]> wrote:
> 
> 6
> ```
> +static inline void
> +ChannelHashPrepareKey(ChannelHashKey *key, Oid dboid, const char *channel)
> +{
> +	memset(key, 0, sizeof(ChannelHashKey));
> +	key->dboid = dboid;
> +	strlcpy(key->channel, channel, NAMEDATALEN);
> +}
> ```
> 
> Do we really need the memset()? If “channel” is of length NAMEDATALEN, then it still results in a non-0 terminated key->channel; if channel is shorter than NAMEDATALEN, strlcpy will auto add a tailing ‘\0’. I think previous code should have ensured length of channel should be less than NAMEDATALEN.


For comment 6, the result is the same that I don’t think memset() is needed. However, my previous explanation of strlcpy() was wrong, which should apply to strncpy(). For strlcpy(), it already makes a termination ‘\0’.

And one more nit comment:

9
```
+	int			allocated_listeners;	/* Allocated size of array */
```

For “size” here, I guess you meant “length”, though “size” also works, but usually “size” means bytes occupied by an array and “length” means number of elements of an array. So, “length” would be clearer here.

--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/

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