openldap-technical November 2023

openldap-technical@openldap.org

22 participants
15 discussions

Thread Safety in LMDB with MDB_NOTLS and Readonly Cursors
by xiaoya2wei＠gmail.com 08 Nov '23

08 Nov '23

Greetings LMDB Community, I am delving into the thread-safety aspects of LMDB, specifically regarding the use of readonly cursors across multiple threads. With the MDB_NOTLS flag enabled, which disables thread-local storage, my understanding is that readonly transactions may be shared between threads, provided there is proper synchronization to prevent concurrent access. Building upon this, I seek clarity on the following: Can multiple threads safely access a single readonly cursor derived from such a synchronized readonly transaction when MDB_NOTLS is enabled? Upon reviewing the LMDB source code, I noticed that cursors are tied to transactions (see mdb.c#L1335). This suggests that if threads can synchronously share a transaction, they might also share a cursor associated with it for data retrieval. Meanwhile, while looking at the LMDB document (http://www.lmdb.tech/doc/group__mdb.html#gad7ea55da06b77513609efebd44b26920), it says “Cursors may not span transactions”, which is a little confusing for me. To be crystal transparent, does it mean that, even if MDB_NOTLS is set, a cursor opened by a readonly transaction still has to stay with one single thread for its entire lifetime, and cannot be used by another thread even at a different time? Thank you in advance for your assistance! Best, Xiaoya

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Issue with refint and rwm overlay
by Maksim Saroka 07 Nov '23

07 Nov '23

Hello, We have a strange situation with refint and rwm overlays on ldap replica. Looks like those overlays depend on each other and on position in the slapd.conf file regarding database section. However refint overlay is working in any position if rwm overlay is not specified. Here are the examples with positions in the file: Refint overlay work if: 1. rwm overlay section database section refint overlay section Refint overlay does not work if: 1. database section refint overlay section rwm overlay section 2. rwm overlay section refint overlay section database section Could you please explain to us the root cause of that as I can't find any explanation in the docs. -------- Maksim Saroka DevOps/System Administrator Exadel.com <https://exadel.com/> Follow Us on LinkedIn <https://www.linkedin.com/company/exadel/> -- CONFIDENTIALITY NOTICE: This email and files attached to it are confidential. If you are not the intended recipient you are hereby notified that using, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited. If you have received this email in error please notify the sender and delete this email.

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email aliases - extended version
by Chris Vogel 01 Nov '23

01 Nov '23

Hi, I moved from a mailserver using exim/mysql to one based on postfix/ldap and found a question I couldn't answer by searching: Is there a way to put "email aliases like I'm used to" into the directory? By "email aliases like I'm used to" I mean 1-m aliases with the following properties: - An email received for an alias address is send to multiple maildrops and/or email addresses Additinally I'd like to add information about ownership/permissions: - An alias has got one or more owner(s) who - are able to edit the list of receivers - are allowed to delete the alias - change permission on it like described below - An alias has properties that describe the permission local receivers have (for all of the local receivers or every single local): - its open to subscription by every uid (user on the system) or only the owners are allowed to add new receivers - delete oneself from the list of receivers - allowed to use the alias address as email sender for emails delivered by the account I know this sounds like mailinglist, but most of that has been possible in exim using files and file permissions or values in a mysql database. A listmanager would add some interface for managing this, but that is not what I'm looking for. I'm looking for an existing standard or quasi-official way on how to represent this in the directory before inventing the wheel a second time. Along my way I stumbled over this two messages on the list which seem to point in a similar direction: https://lists.openldap.org/hyperkitty/list/openldap-technical@openldap.org/… https://lists.openldap.org/hyperkitty/list/openldap-technical@openldap.org/… Thanks for any references or help Chris

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OpenLDAP 2.4 (released October 2007) - Question
by Steffano Festa 01 Nov '23

01 Nov '23

Hi team, Is the OpenLDAP 2.4 (released October 2007) still actively maintained? Or can we consider it as EOL? [cid:image001.png@01DA0CCC.4B603970]

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lastbind not working on consumer since version 2.6.3
by alexjl1＠thenode.info 01 Nov '23

01 Nov '23

Hi, I have a single provider / multiple consumers setup with olcLastBind enabled on all servers but excluding the pwdLastSuccess attribute from syncing, so that the provider and each consumer have their own values. After updating one of the consumers from 2.6.2 to 2.6.3, I noticed that pwdLastSuccess stopped refreshing on new binds. So, on a test machine I installed 2.6.3 and then 2.6.6 and verified that when the server is set to read only or as a simple consumer (no multiprovider), pwdLastSuccess is not modified. Is this a result of the fixes for ITS#9863 in 2.6.3? If this is not a bug, but intended behavior, is there a way to have lastbind work in a simple consumer (without making it writable)?

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openldap-technical November 2023