Stefano Cossu wrote:
On 6/29/20 8:12 AM, Howard Chu wrote:
> Stefano Cossu wrote:
>> I'd like to be able to know if a LMDB transaction is active, valid, dirty,
> Why? There is no valid reason for these details to be exposed to LMDB callers.
I am working on a library where functions use a (possibly write) transaction that is
passed around several (possibly reentrant) functions. Some operations may
start with a write transaction and reuse it for writing at multiple points, some others
may start with a read transaction and may need to temporarily open a
separate write transaction depending on some conditions.
I don't want to commit a write transaction until I am sure that all inter-dependent
operations are completed successfully.
I thought about nested transactions, but I still need to know whether the starting txn is
a write one and it is valid.
If this is not the right pattern to use with LMDB I'd like to know how otherwise I
can keep arbitrarily deep call stacks atomic.
This sounds pretty messy indeed. The caller that creates a transaction is expected to know
what operations it is going
to perform on it, and thus when it is done using it.
> All LMDB users need to
> know is whether they have created a valid txn, and whether they want to abort it or
How do I know if a transaction is valid?
Always zero out the txn pointer immediately after calling abort or commit. Then if the txn
is non-NULL, it is valid.
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/