[Patch] Possible memory optimization with presets cache

[Don-vip]

It seems we have two maps storing the same data twice, for about ~400Kb of memory each:

• TagChecker.presetsValueData:

    /** The spell check preset values */
    private static volatile MultiMap<String, String> presetsValueData;

• AutoCompletionManager.PRESET_TAG_CACHE:

    /**
     * the same as tagCache but for the preset keys and values can be accessed directly
     */
    protected static final MultiMap<String, String> PRESET_TAG_CACHE = new MultiMap<>();

This cache could be moved to TaggingPresets class and used everywhere in the application.

[anonymous]

Not sure if that improves much. TagChecker stores additional values in its version of the map, so one needs additional code. See attached patch.

[GerdP]

Oops, anonymous again. Patch was from me.

[GerdP]

v2 also moves PRESET_ROLE_CACHE from AutoCompletionManager to TaggingPresets. This allows to simplify the code in
AutoCompletionManager.
Probably I should use getters instead of public structures in TaggingPresets?

[Don-vip]

Thanks!

• one small typo: additinalPresetsValueData without "o"
• yes getters are welcome :)

[michael2402]

A note since you are optimizing for memory/performance:

• getPresetKeys does not need to create a copy - a simple unmodifiableSet would be enough.

Other than that, I think moving the cache to TaggingPresets is a matter of taste - but it seems to make the code cleaner.

I personally would change TaggingPresetItem, so that cachePresetItem can use the visitor pattern. It would make it easier for plugins and for us to add custom item types.

[GerdP]

Yes, I don't know why I didn't use unmodifiableSet here. I also think that TaggingPresets.getTaggingPresets() should use
unmodifiableCollection instead of creating a copy.
I've implemented these changes with v4.

Reg. visitor pattern: Sorry, I am not used to think in this pattern. Maybe you can create a 2nd patch which would help me to learn it.

[michael2402]

We can do this later.

If there are no objections, I would like to apply the patch the way it is now.

[Don-vip]

Milestone renamed

[Don-vip]

The patch does not apply anymore, could you please update it?

[bastiK]

In 12042/josm:

applied #13956 - memory optimization with presets cache (patch by GerdP)

[bastiK]

Patch was a bit outdated, hope it is okay like this.

[stoecker]

This change breaks "JOSM Integration" - I find the output always hard to read, but it seems kendzi3d is broken?

[bastiK]

Looks more like ​matsim plugin.

[bastiK]

In 12077/josm:

see #13956 - make cachePresets public