Hi All,
just thinking on how to implement a distributed locking system in web2py
using a DB: one row per each lock, lock_name is unique, if the row doesn't
exist, then it is locked, if the row exist already, then it cannot be lock
as it is already locked !
I'd like to create a module like this (that can be called from anywhere in
web2py)
def lock(lock name):
begin transaction
does the row exist ?
no => insert new row
commit transaction
return result
def unlock(lock_name):
begin transaction
delete row where name = lock_name
commit transaction
BUT.... not sure if this is possible (of course it is !) in web2py...
consider this controller
def hello1():
do a lot of things
db.commit()
do more things in the DB
### here is my doubt: #######################
if lock("some resource"): ### I'm calling a method that opens and close
a transaction inside a transaction !!!
do something
unlock("some resource")
else
do something else
#### another example ####################3
if lock("resource A"):
if lock("resource B"):
do a lot of things woth both resources
unlock("resource B")
unlock("resource A")
else
so other things
unlock("resource A")
do more things
db.commit()
do more staff
any better idea ?
thansk
