expirationd - data expiration with custom quirks.

This package can turn Tarantool into a persistent memcache replacement, but is powerful enough so that your own expiration strategy can be defined.

You define two functions: one takes a tuple as an input and returns true in case it's expirted and false otherwise. The other takes the tuple and performs the expiry itself: either deletes it (memcache), or does something smarter, like put a smaller representation of the data being deleted into some other space.

Example

box.cfg{}
space = box.space.old
job_name = 'clean_all'
expirationd = require('expirationd')
function is_expired(args, tuple)
  return true
end
function delete_tuple(space_id, args, tuple)
  box.space[space_id]:delete{tuple[1]}
end
expirationd.start(job_name, space.id, is_expired, {
    process_expired_tuple = delete_tuple, args = nil,
    tuples_per_iteration = 50, full_scan_time = 3600
})

Expirationd API

expirationd.start (name, space_id, is_tuple_expired, options)

Run a named task

• name - task name
• space_id - space to look in for expired tuples
• is_tuple_expired - a function, must accept tuple and return true/false (is tuple expired or not), receives (args, tuple) as arguments opt
• options -- (table with named options, may be nil)
  • process_expired_tuple - applied to expired tuples, receives (space_id, args, tuple) as arguments. Can be nil: by default tuples are removed
  • args - passed to is_tuple_expired() and process_expired_tuple() as additional context
  • tuples_per_iteration - number of tuples will be checked by one iteration
  • full_scan_time - time required for full index scan (in seconds)
  • force - run, even on replica

expirationd.kill (name)

Kill an existing task with name 'name'

• name - task's name

expirationd.stats ([name])

if name is nil, then return map of name:stats, else return map with stats.

• name - task's name, may be nil

expirationd.task (name)

Get task with name name

expirationd.tasks ()

Get copy of task list

expirationd.update ()

Update expirationd version and restart all tasks

Task API

task:start()

Force start task (old guardian_fiber will be garbage collected, so do task:stop() before or task:restart() instead)

task:stop()

task:restart()

task:kill()

Stop task and delete it from list of tasks.

task:statistics()

Get statistics of task

Testing

Simply start tarantool test.lua