Mailing List Archive: 49091 messages
  • Home
  • Script library
  • AltME Archive
  • Mailing list
  • Articles Index
  • Site search

[REBOL] Re: Multiuser database

From: Paavo::Nevalainen::saunalahti::fi at: 21-Mar-2006 14:44

I have been quite happy with semaphores. A typical cgi app needs an expiration mechanism, since it is very hard to guarantee any sensible logic for user behaviour. Here is a unit test for a semaphore-handler I use. It has to use some until -- loop -- try - disarm construct to make it working sensibly. File based dbs have never crashed... (I found a semaphore example from some public source, don't remember where it was). test: has [ max-period-locked semaphore-handler ][ max-period-locked: 0:0:30 semaphore-handler: make-semaphore-handler %locks/ max-period-locked print semaphore-handler/lock 0 ; --> true print semaphore-handler/lock/meek 0 ; ---> false print semaphore-handler/release 0 ; --> true ] Above, a non-meek lock attempt simply waits until it succeeds. The locks are used to change the state of objects, for example obj/state == 'free --> obj/state: 'edited . So others can check the obj and see if it is available. Summary: rather non-programmer guy can survive well with file dbs.