After CPP encapsulates the timer, how to use the alarm function to trigger correctly?

I would like to ask you, when I seal the timer and use the alarm function to send the signal at a fixed time, how can I correctly use the signal function to set the signal handling function?
then the signal handling function is an in-class function tick , and other members are used in tick , so it is not suitable to set it to a static function, so what should I do

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May.22,2022
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1beaeb7-311ba.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1beaeb7-311ba.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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