Rrd4j persistence - rrd

I am using rrd4j to do what rrd4j does, and it works great. However, if I shut down my app and start it back up again, the data from the previous session will be gone.
I am using a normal file backend, like so:
RrdDef rrdDef = new RrdDef( "/path/to/my/file", 3000 );
Is there a setting or something I need to trigger to make rrd4j load the data from the previous session?

Seems you should use RrdDb("/path/to/my/file") instead. From Javadocs:
RrdDb(java.lang.String path): Constructor used to open already
existing RRD in R/W mode, with a
default storage (backend) type (file
on the disk).
And also:
RrdDb(RrdDef rrdDef):
Constructor used to create new RRD object from the definition.

Related

How can I configure a specific serialization method to use only for Celery ping?

I have a celery app which has to be pinged by another app. This other app uses json to serialize celery task parameters, but my app has a custom serialization protocol. When the other app tries to ping my app (app.control.ping), it throws the following error:
"Celery ping failed: Refusing to deserialize untrusted content of type application/x-stjson (application/x-stjson)"
My whole codebase relies on this custom encoding, so I was wondering if there is a way to configure a json serialization but only for this ping, and to continue using the custom encoding for the other tasks.
These are the relevant celery settings:
accept_content = [CUSTOM_CELERY_SERIALIZATION, "json"]
result_accept_content = [CUSTOM_CELERY_SERIALIZATION, "json"]
result_serializer = CUSTOM_CELERY_SERIALIZATION
task_serializer = CUSTOM_CELERY_SERIALIZATION
event_serializer = CUSTOM_CELERY_SERIALIZATION
Changing any of the last 3 to [CUSTOM_CELERY_SERIALIZATION, "json"] causes the app to crash, so that's not an option.
Specs: celery=5.1.2
python: 3.8
OS: Linux docker container
Any help would be much appreciated.
Changing any of the last 3 to [CUSTOM_CELERY_SERIALIZATION, "json"] causes the app to crash, so that's not an option.
Because result_serializer, task_serializer, and event_serializer doesn't accept list but just a single str value, unlike e.g. accept_content
The list for e.g. accept_content is possible because if there are 2 items, we can check if the type of an incoming request is one of the 2 items. It isn't possible for e.g. result_serializer because if there were 2 items, then what should be chosen for the result of task-A? (thus the need for a single value)
This means that if you set result_serializer = 'json', this will have a global effect where all the results of all tasks (the returned value of the tasks which can be retrieved by calling e.g. response.get()) would be serialized/deserialized using the json-serializer. Thus, it might work for the ping but it might not for the tasks that can't be directly serialized/deserialized to/from JSON which really needs the custom stjson-serializer.
Currently with Celery==5.1.2, it seems that task-specific setting of result_serializer isn't possible, thus we can't set a single task to be encoded in 'json' and not 'stjson' without setting it globally for all, I assume the same case applies to ping.
Open request to add result_serializer option for tasks
A short discussion in another question
Not the best solution but a workaround is that instead of fixing it in your app's side, you may opt to just add support to serialize/deserialize the contents of type 'application/x-stjson' in the other app.
other_app/celery.py
import ast
from celery import Celery
from kombu.serialization import register
# This is just a possible implementation. Replace with the actual serializer/deserializer for stjson in your app.
def stjson_encoder(obj):
return str(obj)
def stjson_decoder(obj):
obj = ast.literal_eval(obj)
return obj
register(
'stjson',
stjson_encoder,
stjson_decoder,
content_type='application/x-stjson',
content_encoding='utf-8',
)
app = Celery('other_app')
app.conf.update(
accept_content=['json', 'stjson'],
)
You app remains to accept and respond stjson format, but now the other app is configured to be able to parse such format.

"Could not get Timeline data" when using Timeline Visualization with Comma IDE

After implementing the answer to this question on how to set up a script for time visualization in this project (which uses a small extension to the published Log::Timeline that allows me to set the logging file from the program itself), I still get the same error
12:18 Timeline connection error: Could not get timeline data: java.net.ConnectException: Conexión rehusada
(which means refused connection). I've also checked the created files, and they are empty, they don't receive anything. I'm using this to log:
class Events does Log::Timeline::Event['ConcurrentEA', 'App', 'Log'] { }
(as per the README.md file). It's probably the case that there's no such thing as a default implementation, as shown in the tests, but, in that case, what would be the correct way of making it print to the file and also connect to the timeline visualizer?
If you want to use the timeline visualization, leave the defaults for logging, commenting out any modification of the standard logging output. In my case:
#BEGIN {
# PROCESS::<$LOG-TIMELINE-OUTPUT>
# = Log::Timeline::Output::JSONLines.new(
# path => log-file
# )
#}
Not really sure if this would have happened if an output file is defined using an environment variable, but in any case, better to be on the safe side. You can use the output file when you eventually drop the script into production.

Change AR session config after fragment created

I want to re-configure AR session after session has been running. I want to change Augmented Images database.
I don't seem to find a way to set the reset the session configuration.
getSessionConfiguration(Session session)
This function only seems to be called once at the beginning.
Is there a way to re-configure? Should I not be using the fragment?
I make changes to my config on the fly. You can accomplish this by extending ARFragment and having access to the config or simply be accessing the ARFragment from your xml within your activity. Here is an example.
arSceneView.session?.apply {
val changedConfig = config
changedConfig.planeFindingMode = Config.PlaneFindingMode.HORIZONTAL_AND_VERTICAL
configure(changedConfig)
}
That's it, just call configure(myNewConfig) and it will update it for you.
Of course in this example, I get the current config, modify it and put it back, but you could replace it if preferred.

How to read values dynamically from a file for a property in updateAttribute?

I added some custom properties in the 'updateAttribute' processor using the '+' button. For example: I declared a property 'DBConnectionURL' and gave the value as 'jdbc:mysql://localhost:3306/test'. Then, in the 'DBCPConnectionPool' service controller, I simple used the value'${DBConnectionURL}' for 'Database Connection URL' property. But, I manually gave the value for 'DBConnectionURL' property.I want a way where I can feed the value dynamically from a file, so that i just need to change the value in the file and the value for 'DBConnectionURL' changes dynamically based on the value present in the file. Is there a way to do it?
Rishab,
You have to use nifi variable registry.
In conf/nifi.properties, you could configure the below configuration in it for dynamically update a value in your data flow.
nifi.variable.registry.properties=./dynamic.properties
You can give your variables in that file dynamic.properties it should present in conf directory.
For an example, If dynamic.properties files contains below values
DBCPURL= jdbc://<host>:<port>
you can use that in your data flow by using ${DBCPURL}
Note: You should restart nifi services if you change any configuration in conf/nifi.properties.Otherwise your changes not worked in dataflow.
Feel free to accept it be answer if it worked for you.

DBD::Oracle, Cursors and Environment under mod_perl

Need some help, because I can't find any solution for my problems with DBD::Oracle.
So at first, this is the current situation:
We are running Apache2 with mod_perl 2.0.4 at our company
Apache web server was set up with a startup script which is setting some environment variables (LD_LIBRARY_PATH, ORACLE_HOME, NLS_LANG)
In httpd.conf there are also environment variables for LD_LIBRARY_PATH and ORACLE_HOME (via SetEnv)
We are generally using the perl module DBI with driver DBD::Oracle to connect to our main database
Before we create a new instance of DBI we are setting some perl env variables, too (%ENV). We are setting ORACLE_HOME and NLS_LANG.
So far, this works fine. But now we are extending our system and need to connect to a remote database. Again, we are using DBI and DBD::Oracle. But for now there are some new conditions:
New connection must run in parallel to the existing one
TNSNAMES.ORA for the new connection is placed at a different location (not at $ORACLE_HOME.'/network/admin')
New database contents are provided by stored procedures, which we are fetching with DBD::Oracle and cursors (like explained here: https://metacpan.org/pod/DBD::Oracle#Binding-Cursors)
The stored procedures are returning object types and collection types, containing attributes of oracle type DATE
To get these dates in a readable format, we set a new env variable $ENV{NLS_DATE_FORMAT}
To ensure the date format we additionally alter the session by alter session set nls_date_format ...
Okay, this works fine, too. But only if we make a new connection on the console. New TNS location is found by the script, connection could be established and fetching data from the procedures by cursor is also working. Alle DATE types are formatted as specified.
Now, if we try to make this connection at apache environment, it fails. At first the datasource name could not resolved by DBI/DBD::Oracle. I think this is because of our new TNSNAMES.ORA file or rather the location is not found by DBI/DBD::Oracle in Apache context (published by $ENV{TNS_ADMIN}). But I don't know why???
The second problem is (if I create a dirty workaround for our first one) that the date format, published by $ENV{NLS_DATE_FORMAT} is only working on first level of our cursor select.
BEGIN OPEN :cursor FOR SELECT * FROM TABLE(stored_procedure) END;
The example above returns collection types of object which are containing date attributes. In Apache context the format published by NLS_DATE_FORMAT is not recognized. If I use a simple form of the example like this
BEGIN OPEN :cursor FOR SELECT SYSDATE FROM TABLE(stored_procedure) END;
the result (a single date field) is formatted well. So I think subordinated structures were not formatted because $ENV{NLS_DATE_FORMAT} works only in console context and not in Apache context, too.
So there must be a problem with the perl environment variables (%ENV) running under Apache and mod_perl. Maybe a problem of mod_perl?
I am at my wit's end. Maybe anyone in the whole wide world has a solution ... and excuse my english :-) If you need some further explanations, I will try to define it more precisely.
If your problem is that changes to %ENV made while processing a request don't seem to be honoured, this is because mod_perl assumes you might be running multiple threads and doesn't actually change the process environment when you change %ENV, so external libraries (like the oracle client) or child processes don't see the change.
You can work around it by first using the prefork MPM, so there aren't any threading issues, and then making changes to the environment using Env::C instead of the %ENV hash.