This adds cron code which looks for question previews that have not been
touched for more than 24 hours, and deletes them.
We try to delete previews immediately. For example if the user clicks
start again, then we immediately delete their previous preview. However,
we can't do that if they just close the preview window. Hence we need
some cron code to clean up old preview that have got left lying around.
Normally, this code will not have much to do, so it will be very fast,
so we can afford to run it every cron.
This has been implemented in such a way that in future it will be easy
to add other cron code to the question bank.
Sadly, to make this work on MySQL, we require a horrible hack in the
already hacky delete_usage_records_for_mysql function.
MySQL only accepts 65536 (aprox) bytes in default TEXT
columns. So we define the max allowed as 32000 to allow
99.9% of utf-8 contents to fit. If some day MDL-19603 is
implemented and all current TEXTs are moved (MySQL) to
the BIG counterparts, this restriction can be out (MDL-19603).
1. So we will truncate the question summary to 65000 chars if necessary.
2. Also, fix one minor error in mutlianswer save_question_options.
question_bank::MAX_SUMMARY_LENGTH is not the most logical class to add
the constant to, but it needs to be accessible during upgrade, so I was
lazy and put it there.
While doing this, I found various bugs in the manages question types admin page, and so fixed them, and updated the code
there to use $OUTPUT and html_writer.
AMOS BEGIN
MOV [cannotdeletemissingqtype,admin],[cannotdeletemissingqtype,question]
MOV [cannotdeleteqtypeinuse,admin],[cannotdeleteqtypeinuse,question]
MOV [cannotdeleteqtypeneeded,admin],[cannotdeleteqtypeneeded,question]
MOV [deleteqtypeareyousure,admin],[deleteqtypeareyousure,question]
MOV [deleteqtypeareyousuremessage,admin],[deleteqtypeareyousuremessage,question]
MOV [deletingqtype,admin],[deletingqtype,question]
MOV [numquestions,admin],[numquestions,question]
MOV [numquestionsandhidden,admin],[numquestionsandhidden,question]
MOV [qtypedeletefiles,admin],[qtypedeletefiles,question]
MOV [uninstallqtype,admin],[uninstallqtype,question]
AMOS END
Tim Hunt