mqtt-users team mailing list archive

[Diogo Mamede <diogo.mamede@xxxxxxxxx>]

Hello,

I did go for option 3 as I'm not considering portability (yet). It compiled
with no problems now.
Thank you very much for your help.

On Sun, Nov 28, 2010 at 10:39, Roger Light <roger@xxxxxxxxxx> wrote:

> Hi Diogo,
>
> > /root/mosquitto-0.9/src/persist.c:472: undefined reference to `be64toh'
> > /root/mosquitto-0.9/src/persist.c:306: undefined reference to `htobe64'
>
> The be64toh() and htobe64() functions are in glibc from version 2.9.
> If you have an earlier version or nslu2 uses one of the other C
> libraries (which is quite likely), then those functions aren't
> available.
>
> The functions are used when writing out the persistent database, which
> stores subscriptions and retained messages for when the broker
> restarts. This is generally regarded as a good and useful thing.
>
> You've got three choices.
>
> 1. Uncomment the line "#define WITH_32BIT_DBID" in config.h and
> recompile. This means:
>
> Compile with 32-bit integer database IDs instead of 64-bit integers.
> May be useful in embedded systems or where be64toh()/htobe64() aren't
> available. There is the potential for bad things to happen after the
> IDs wrap around. This is especially likely if there are old retained
> messages. Note that at a sustained rate of 10,000 messages/s, the
> database ID would overflow every 5 days. It is also worth noting that
> a broker compiled with 64-bit DB IDs will not load a persistent
> database file saved from a 32-bit DB ID broker and vice versa.
>
> 2. Remove persistent database support completely by commenting out the
> line "#define WITH_PERSISTENCE" in config.h, then recompile. This will
> keep using 64-bit database IDs, but won't be writing them to disk at
> any time so won't need the missing functions.
>
> 3. Don't worry about the portability of the persistent database file.
> If the file isn't going to move to a different computer, it doesn't
> matter if the data is potentially stored with mixed endian.To do this,
> add the following to config.h and recompile.
>
> #define be64toh(x) (x)
> #define htobe64(x) (x)
>
> I'd probably go for option 3.
>
> It might be worth your while looking at some of the other options in
> config.h - unless you've been using mosquitto before you won't have
> any of the old sqlite dbs that need upgrading. You can comment out
> WITH_SQLITE_UPGRADE and remove "-lsqlite3" from config.mk to save on a
> bit of memory.
>
> Cheers,
>
> Roger
>
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-- 
Diogo Mamede