The current version of GET-CON is broken. The code reads:
(defmethod get-con ((instance persistent))
(let ((con (fast-lookup-con-spec (db-spec instance))))
(cond ((not con)
(aif (slow-lookup-con-spec (db-spec instance))
(progn
(setf (db-spec instance)
(car (find it *dbconnection-spec* :key #'cdr)))
(get-con instance))
(restart-case
(signal-controller-lost-error instance)
(reopen-controller ()
:report "Re-open the store controller"
(open-controller
(get-controller (db-spec instance)))))))
;; If it's valid and open
((and con (connection-is-indeed-open con))
con)
;; If the controller object exists but is closed, reopen
(t (open-controller con)))))
(defun open-store (spec &rest args)
"Conveniently open a store controller. Set *store-controller* to the new
controller
unless it is already set (opening a second controller means you must
keep track of
controllers yourself. *store-controller* is a convenience variable for
single-store
applications or single-store per thread apps. Multi-store apps should
either confine
their *store-controller* to a given dynamic context or wrap each
store-specific op in
a transaction using with or ensure transaction. Returns the opened
store controller."
(assert (consp spec))
;; Ensure that parameters are set
(initialize-user-parameters)
(let ((controller (get-controller spec)))
(apply #'open-controller controller args)
(if *store-controller*
(progn
;; (warn "Store controller already set so was not updated") ;; this was
annoying me
controller)
(setq *store-controller* controller))))
Unfortunately OPEN-CONTROLLER has some arguments which can be
very important to set properly; e.g. in
(defmethod open-controller ((sc bdb-store-controller) &key (recover t)
(recover-fatal nil) (thread t) (register nil)
(deadlock-detect t)
(cache-size elephant::*berkeley-db-cachesize*)
(max-locks elephant::*berkeley-db-max-locks*)
(max-objects
elephant::*berkeley-db-max-objects*)
(max-transactions
elephant::*berkeley-db-max-transactions*)
(mvcc elephant::*default-mvcc*)
error-log)
It is imperative that :REGISTER T be passed if one is to properly access
a DB environment from two separate processes (otherwise, each process
gets a DB_RUNRECOVERY error if the other one uses the store.
However you can see from the code that if the controller gets reopened
by GET-CON, it does not apply all of the arguments which are passed to
OPEN-STORE.
I'm currently changing the default value of :REGISTER in OPEN-CONTROLLER
to T in my code, but that's hardly a fix; the bug exists for all other
arguments.
The correct fix involved capturing the ARGS which are required to
properly reopen a store controller. I'm not sure where those should
be captured (Perhaps as a slot on the store-controller?) I'm happy to
attempt a fix if someone would confirm that the approach I propose is
likely not to break something else.
--Alain
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