Simplified Jython rule definition (similar to Rules DSL) using a universal decorator

[5iver (Scott Rushworth)]

@mjcumming

if(previousState == NULL) return;

I’m assuming you are at the start of a function…

def testFunction(event)
    if event.oldItemState == UnDefType.NULL:
        return
    # do stuff

I’ve added this to the README

[mjcumming (Michael Cumming)]

yes ,that is it.

[mjcumming (Michael Cumming)]

@5iver is it possible that group events are not being properly processed. For instance, I have an item that is a member of 3 groups. When it changes, I see the event in the group that I am monitoring. But then I also see events come in through the same rule, but with the other 2 groups the item is a member of …

item A is a member of Groups B,C,D

have a rule capturing any changes to members of Group B

log all events from the rule and print the item name.... and I see

A
C
D

when it should just be A

[5iver (Scott Rushworth)]

It looks like you have run into this bug…

Issue: [Automation] ItemStateChangeTrigger misfires

What I’ve done as a workaround, is to add this to the rule. It still misfires, but doesn’t execute the rest of the rule unless the triggering item is actually in the group. If this does not fit for you, share what the rule is triggering on.

@rule("Light: Area trigger")
@when("Member of gArea_Trigger changed")
def areaTrigger(event):
    if "gArea_Trigger" in ir.getItem(event.itemName).getGroupNames():
        # rest of rule

[lfs_alp5 (Alpoy)]

How is JSR223/Jython in regards to the “problems” with Thread::sleep and timers? are there any “static” limits on threads? Ie. Can I hypothetically run 10 different rules (in the same rules file or otherwise) with different sleep delays all at the same time?

Ref.:

(OH 1.x and OH 2.x Rules DSL only] Why have my Rules stopped running? Why Thread::sleep is a bad idea

EDIT: While the general advice in this article still applies (i.e. it’s always worth while to make short running rules), the problem described in this article only applies to OH 1.x and Rules DSL in OH 2.x. In OH 3 and beyond, this is no longer a problem so if your rules stop running in any version of OH released in the last two years (as of this edit in 1/2023) this is not your problem. By way of explanation, in OH 3 each rule gets it’s own thread. It is no longer possible for a rule to starve…

[5iver (Scott Rushworth)]

@lfs_alp5

Can I hypothetically run 10 different rules (in the same rules file or otherwise) with different sleep delays all at the same time?

I have not specifically looked through the code for a definitive answer, but from my experience, JSR223 rules do not have the same threadpool limitations found in the Rules DSL. Here is an example…

Sporadic delayed rule starting: Thread pool too small?

When changing the runtime.cfg based on this info… Cron based rules suddenly stop executing, I see an immediate change using the Karaf command in that post. I’ve used these settings for about a year, and my server has never had an issue with load… openhab> config:list "(service.pid=org.eclipse.smarthome.threadpool)" ---------------------------------------------------------------- Pid: org.eclipse.smarthome.threadpool BundleLocation: null Properties: discovery = 55 ruleEngine = …

I have not tried it, but there is potentially multi-processing support too!

[mjcumming (Michael Cumming)]

that will work as a work around…

[mjcumming (Michael Cumming)]

I am not a python expert, but it looks like the timer object is built on the thread tools of python - so I am guessing jython doen’t have the thread limitations of the dsl.

[5iver (Scott Rushworth)]

It goes deeper than that, but you should also be able to use the createTimer action. I haven’t tried it though, as I prefer to use Jython where available.

[mjcumming (Michael Cumming)]

Any thoughts on simplifying the code below?

item A belongs to groups F, G, H

Group F belongs to group Z

Using item A, I want to find the group item A is a member of (F,G,H) is also in group Z.

ie in this case group F

    triggeringItem = itemRegistry.getItem (event.itemName)
    gArea = itemRegistry.getItem ("gArea")
    areaItem = None
    for area in gArea.getMembers ():
        for name in triggeringItem.getGroupNames ():
            if name == area.name:
                areaItem =itemRegistry.getItem (name)
                break```

[rlkoshak (Rich Koshak)]

@lfs_alp5

How is JSR223/Jython in regards to the “problems” with Thread::sleep and timers? are there any “static” limits on threads? Ie. Can I hypothetically run 10 different rules (in the same rules file or otherwise) with different sleep delays all at the same time?

These should not be as much of a problem in jython. I don’t think JSR223 Rules use the thread pools, maybe the Quartz thread pool?

However, there is indeed a limit to the number of threads you can run in Python or any other programming language on a given system. I had a sensor module in sensorReporter that was working with BT. I was spinning off a separate thread to poll for nearby devices looking for known macs. I then put reelyActive on the same machine which also uses BT (it’s Node.js not python). So reelyActive got a permanent lock on the BT device and my sensorReporter scanning threads just got stuck and piled up. Eventually the program just died. I would expect something similar to happen in the JSR223.

But, I don’t think there is any hard and fast predefined limit. I think it will continue spawning threads until you run out of RAM to create new one.

[5iver (Scott Rushworth)]

The code you posted looks good and works, but here are some suggestions:

1. There are some spaces between the function names and (). This will work, but looks odd.
2. The break will only exit the current loop. You could add a check above the second for loop to see if areaItem is not None, and then break out of that loop too.
3. You can use ir as an alias to itemRegistry to save some typing.

    triggeringItem = ir.getItem(event.itemName)
    gArea = ir.getItem ("gArea")
    areaItem = None
    for area in gArea.getMembers():
        if areaItem is not None:
            break
        for name in triggeringItem.getGroupNames():
            if name == area.name:
                areaItem = ir.getItem (name)
                break

BUT, another approach is to use a list comprehension, which is a very powerful tool in Python. Makes your code a one-liner…

areaItem = list(group for group in ir.getItem("gArea").members if ir.getItem(event.itemName) in group.members)[0] 

What are you looking to achieve with the rule? There might be an easier way to get there. This weekend I plan to post about a rule strategy that uses nested groups containing triggering items and action items (Area_Trigger and Area_Action), and a single rule that takes care of all lighting automation (I use it to turn on speakers too), and then some others that make light level adjustments based on lux level. Looks like you may be doing something similar.

[mjcumming (Michael Cumming)]

@5iver

areaItem = list(group for group in ir.getItem(“gArea”).members if ir.getItem(event.itemName) in group.members)[0]

That worked perfectly… need to read more about python. Thank you

[mjcumming (Michael Cumming)]

Scott, have you done any work with creating items dynamically?

The rule above is part of an Occupancy concept I had been using in another HA software package. Now adopting it to OH.

[5iver (Scott Rushworth)]

When I saw your reply, I remembered there is a very slight performance gain using getGroupNames vs group.members…

areaItem = list(group for group in ir.getItem("gArea").members if group.name in ir.getItem(event.itemName).getGroupNames())[0]

[5iver (Scott Rushworth)]

@mjcumming

Scott, have you done any work with creating items dynamically?

Nope.

@mjcumming

The rule above is part of an Occupancy concept I had been using in another HA software package. Now adopting it to OH.

You may want to hold off until my post this weekend. Think of groups for each area within your house, holding items that would trigger whether the area is active or not. And groups holding the items that should respond to activity in the area. That is what my rule does. The special sauce is in the group functions… takes the logic out of the code and puts it into the groups, Get another light, motion sensor, door sensor, etc., add it to a group, and you’re done… no change in code needed.

[mjcumming (Michael Cumming)]

That’s very similar to what I am doing. I use tags for each area that describe the duration an area is to be occupied for and the actions to be taken when an area becomes vacant or occupied. Each item in an area also has tags that describe what happens when that item is triggered

[5iver (Scott Rushworth)]

@mjcumming

I use tags for each area that describe the duration an area is to be occupied for and the actions to be taken when an area becomes vacant or occupied. Each item in an area also has tags that describe what happens when that item is triggered

Nice! I use a dict (was a HashMap in Rules DSL) to store that info, but would like to use Item metadata. Just haven’t figured out how to access it yet.

[mjcumming (Michael Cumming)]

Never mind, typo was causing the the problem. getTags() works fine.

Scott, is it possible the item.getTags() is broken? I cannot get it to return the tags of an item that I know has tags…

==> /var/log/openhab2/openhab.log <==

2018-10-12 10:03:45.079 [INFO ] [eclipse.smarthome.model.script.Rules] - gOccupancyItem Changed  TF_Office_MotionSensor (Type=ContactItem, State=CLOSED, Label=Third Floor Motion, Category=motion, Tags=[OE:Motion_Standard], Groups=[gTF_Office, gSS_InteriorMotionSensor, gOccupancyItem])

[andirs (Andi)]

Hey Scott, thanks a lot for this library, it looks very promising.

Is it still compatible with the old rule decorators (e.g. item_triggered)?
I think i read about the compatibility some days ago but now i cannot find it anymore.
I do not find the definitions in your new triggers.py

I would test it, if it doesn’t brake my other rules, so that i can convert a few rules from time to time.

Best regards