(sorry for a potentially lame question, but I'm really not fluent in this area)


(In reply to Christian Heimes from comment #0)
> 
> Design proposal:
> 

Does this take different replicas in account?

I.e. does https://directory.fedoraproject.org/docs/389ds/design/dna-plugin.html :: "Usage with Multi-Master Replication" apply here?

How "The entire range of the high bit" is going to be split between replicas?

The DNA plugin (distributed numeric assignment) handles cluster-wide assignments and allocation automatically. IPA will set up the new DNA plugin configuration similar to the existing "cn=Posix IDs,cn=Distributed Numeric Assignment Plugin,cn=plugins,cn=config" configuration. dnaNextValue is set to the beginning of the range, dnaMaxValue to the end of the range. 389-DS automatically takes care of the splitting internally.

DNA allocates a number pickup from a given range and is able to request/grant new range.
The known interval of allocation (default 1, else dnaIntervalAttr) is used to compute remaining available numbers and threshold to request/(grant ?) ranges. The interval will change on each allocation, so the remaining available numbers is always wrong and threshold will not be correctly enforced.

DNA allocates a number in anticipating the next allocated value ('nextval'), with a known interval this is easy. But with dereferenced attribute it is not possible to precompute the 'nextval'. For example, current being '10', entry E1.dnaIntervalAttr_val: 65536 and E2.dnaIntervalAttr: 5. It is expected that E1 gets 65546 and E2 gets 65551 but the current mechanism may apply E1=10, E2=65546. It could be easy to change but mean that 'nextval' may become useless.

The prototype https://github.com/tiran/389-ds-base/tree/dna_interval_attr/ldap/servers/plugins/dna, implement a fixed interval assuming that all dereferenced attributes have the same value. This solution is easy to implement and actually does not need a new attribute dnaMaxInterval as I think it could be done with dnaInterval configuration (so without change in the plugin).

In conclusion:
Regarding the implementation, derefencing the attribute would require to add target entry parameter to several functions (dna_get_next_value, dna_notice_allocation, dna_parse_config_entry...
Requesting of ranges (remaining and threshold) may be based on the last dnaIntervallAttr_val but changes the behavior and require tests.
Needs an evaluation if 'nextval' is still usable or becomes useless with referenced interval

Thierry,

I see two problems with dnaInterval:

* It is disabled by default and not compiled in. Mark mentioned some problems with the feature. I don't recall the details.
* It may not do what I need.

If I understand the examples at https://directory.fedoraproject.org/docs/389ds/design/dna-plugin.html#interval-method correctly, then dnaInterval does not give correct results.


    Master 1
        dnaNextVal = 1
        dnaMaxVal = 300
        dnaInterval = 3
    Master 2
        dnaNextVal = 2
        dnaMaxVal = 300
        dnaInterval = 3
    Master 3
        dnaNextVal = 3
        dnaMaxVal = 300
        dnaInterval = 3

Master 1 gets 1,4,7,10,etc.
Master 2 gets 2,5,8,11,etc.
Master 3 gets 3,6,9,12,etc.

For subordinate ids the DNA plugin must not use any values in the gaps. When a master assigned value N, then it must consider value "N" to "N + INTERVAL - 1" as used. In the example above Master 2 and 3 must not use values 2,5,8 and 3,6,9.

Change merged upstream, but still need to add CI tests.  Leaving in ASSIGNED for now...

https://github.com/389ds/389-ds-base/issues/4773

]# PYTHONPATH=src/lib389/ py.test -sv dirsrvtests/tests/suites/plugins/dna_interval_test.py 
re-exec with libfaketime dependencies



===================================== test session starts =====================================
platform linux -- Python 3.6.8, pytest-6.2.4, py-1.10.0, pluggy-0.13.1 -- /usr/bin/python3.6
cachedir: .pytest_cache
metadata: {'Python': '3.6.8', 'Platform': 'Linux-4.18.0-310.el8.x86_64-x86_64-with-redhat-8.5-Ootpa', 'Packages': {'pytest': '6.2.4', 'py': '1.10.0', 'pluggy': '0.13.1'}, 'Plugins': {'metadata': '1.11.0', 'html': '3.1.1', 'libfaketime': '0.1.2', 'flaky': '3.7.0'}}
389-ds-base: 1.4.3.23-2.module+el8.5.0+11209+cb479c8d
nss: 3.53.1-17.el8_3
nspr: 4.25.0-2.el8_2
openldap: 2.4.46-16.el8
cyrus-sasl: 2.1.27-5.el8
FIPS: disabled
rootdir: /mnt/tests/rhds/tests/upstream/ds/dirsrvtests, configfile: pytest.ini
plugins: metadata-1.11.0, html-3.1.1, libfaketime-0.1.2, flaky-3.7.0
collected 1 item                                                                              

dirsrvtests/tests/suites/plugins/dna_interval_test.py::test_dna_interval INFO:lib389.topologies:Instance with parameters {'ldap-port': 38901, 'ldap-secureport': 63601, 'server-id': 'standalone1', 'suffix': 'dc=example,dc=com'} was created.
INFO:dirsrvtests.tests.suites.plugins.dna_interval_test:Add dna plugin config entry...
INFO:dirsrvtests.tests.suites.plugins.dna_interval_test:Enable the DNA plugin and restart...
INFO:dirsrvtests.tests.suites.plugins.dna_interval_test:Test DNA is working...
INFO:dirsrvtests.tests.suites.plugins.dna_interval_test:Adding user1
INFO:dirsrvtests.tests.suites.plugins.dna_interval_test:Test DNA interval assignment is working...
PASSEDInstance slapd-standalone1 removed.


========================================================== 1 passed in 12.39s ===========================================================


marking as verified/tested

As per comment 12, marking as VERIFIED