Image upload-thinkphp I want to be a hook. How do i automatically delete a temporary image when the session ends?

thinkphp Upload a picture of the product with the Ajax pass, to prevent the mid-way to cancel the product upload, and then the picture with a zero table saved, I want to do a hook at the end of the session automatically delete the temporary image to do?
Where to put the hooks,
Where the code should be placed,
The thinkphp version is 3.2.2

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thinkphp Upload a picture of the product with the Ajax pass, to prevent the mid-way to cancel the product upload, and then the picture with a zero table saved, I want to do a hook at the end of the session automatically delete the temporary image to do?
Where to put the hooks,
Where the code should be placed,
The thinkphp version is 3.2.2

Can you change the idea ~
Temporary table records the time of every image generation ~
And then the next day with the crontab clear the previous picture ~

