Cache metamethods, finalize references

[RoosterDragon]

This improves performance in two ways:

• We cache the reflection needed when making calls involving a LuaCustomClrObject. If a caller reuses the same object in multiple calls, they now only invoke the reflection overhead on the first call. A call involving any LuaTransparentClrObject benefits even more as we can cache this once for the whole app-domain.
• We add a missing GC.SuppressFinalize call to LuaReference. Callers that take care to dispose these properly can now avoid finalizing these objects.

Fixes OpenRA/OpenRA#9142

[penev92]

FWIW changes seem reasonable to me.

[chrisforbes]

What's the plan for getting these changes upstream?

[RoosterDragon]

I'm happy to submit this PR upstream too. Figured I'd do one review committee at a time though :)

Having thought about it a bit, I'm wondering if an alternate caching strategy may be better. For example we could cache all this reflection inside the LuaRuntime (as a dictionary lookup on the type). That would remove all the ongoing reflection overhead in OpenRA for scripting. On the other hand, such a cache represents a memory sink if you throw enough types at it. Not a problem for an application that's willing to accept it, but a bit lame in library code.

[RoosterDragon]

Fixes OpenRA/OpenRA#9142, by speeding up the Lua calls for Damaged and Killed.

[chrisforbes]

👍
On Nov 27, 2015 10:29 AM, "RoosterDragon" notifications@github.com wrote:

Fixes OpenRA/OpenRA#9142 OpenRA/OpenRA#9142,
by speeding up the Lua calls for Damaged and Killed.

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[Mailaender]

Test builds available at:

• https://build.opensuse.org/package/show/games:openra/eluant
• https://build.opensuse.org/package/show/games:openra/development

[Mailaender]

Can't spot regressions in-game. ✅