MapDb persistence

[JSurf]

A simple persistence provider that only saves the last value. Intention is to use this for "reloadOnStartup" items because all other presistence options have their drawbacks if values are only needed for reload

They:
a) grow in time
b) require complex installs (mysql, influxdb, ...)
c) rrd4j can't store all item types

See:
https://groups.google.com/forum/#!category-topic/openhab/umfFKg5uAM4

[buildhive]

openhab » openhab #2475 SUCCESS
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[paulianttila]

Great work Jens!

Few additions which would make me happy (at least). Many of us is running OH in flash based systems, so to minimize unnecessary writes to flash based systems.

1. Commit db to file only if item value is changed. Maybe this should be configurable.
2. Introduce commit interval, which define how often db is saved to the file. So updated items are normally just stored to memory map and after commit interval is exceeded, map is saved to file (if any items are updated).

-Pali

[JSurf]

1. should be easy, will implement this

i have to think a bit more about 2) Calling commit in an extra thread sounds a little arkward.

You could workaround this requirement with the persistence configuration and define a time based strategy, so i'm not sure if code in the persistence module is required.

// persistence strategies have a name and a definition and are referred to in the "Items" section
Strategies {
    everyFiveMinutes : "*/5 * * * * ?"

    // if no strategy is specified for an item entry below, the default list will be used
    default = everyChange
}

/* 
 * Each line in this section defines for which item(s) which strategy(ies) should be applied.
 * You can list single items, use "*" for all items or "groupitem*" for all members of a group
 * item (excl. the group item itself).
 */
Items {
    * : strategy = everyFiveMinutes, restoreOnStartup   
}

[paulianttila]

2. Timer should be enough, I think? When item (any one) is updated, start timer if it's not already running. And when persistence service is shutdown, store to file if map is "dirty".

[teichsta]

1. please keep in mind that you'd have to a) retain the old state as member variable or b) query the old State from the Service before committing the old c) implement a mixture of both … i would not consider that too easy
2. using a timer seems to me an appropriate approach. See Db4oPersistenceService where i've implemented such a time already.

@JSurf please keep us posted when you'd consider this PR "mergeable".

Thanks, Thomas E.-E.

[JSurf]

Thanks for the feedback, will keep you updated about the progress

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openhab » openhab #2525 SUCCESS
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[JSurf]

Current version seems to work fine on fast systems, but hung openhab on my raspberry while starting up. Maybe i have hit another "startup timing"-bug on slow hardware

[JSurf]

Wanted to dive deeper in this, and tried again on my raspberry pi. This time it worked flawlessly. Don't know what happened last time. so i would be happy if you could review/comment my latest changes @teichsta @paulianttila

[AcidReptile]

Works fine as far as I can judge. Thanks, useful binding.

[teichsta]

please change version to 1.7.0.qualifier

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openhab » openhab #2605 SUCCESS
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[JSurf]

Added Wiki Page:
https://github.com/openhab/openhab/wiki/mapdb-Persistence

[AcidReptile]

Do not forget that user need to create folder %openhabdir%/etc/mapdb manually. Otherwise service is not working.

[theoweiss]

Meanwhile there was a decision to rename openhab.userdata to smarthome.userdata for openHAB2 compatibility reasons. Therefore you should adapt the plugin accordingly.

[teichsta]

… and please squash all commits into one. Thanks, Thomas E.-E.

[JSurf]

Will have a look soon

[JSurf]

Changed openhab.userdata to smarthome.userdata, added code to automatically create mapdb folder when not available and squashed to one commit

[buildhive]

openhab » openhab #2700 SUCCESS
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openhab » openhab #2701 SUCCESS
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