Replace string literals with symbols or frozen strings

[janester]

Context

Ruby strings take up new spots of memory every time they are used. Generally it's not a problem but the memory adds up at scale. Symbols and frozen strings will always occupy the same spot in memory, which reduces the memory load and increases performance.

This Change

• Convert some of the strings to symbols. I did this in places that it made sense for them to be symbols anyway (e.g. the strings that were getting to_sym-ed)
• Freeze the strings that will not be changing and are used multiple times per call
• Convert the array of arrays to hashes and use named arguments for the key and value when iterating over the hashes.

@jnunemaker @aroben @vmg can you take a look at this and let me know what you think/if I'm missing something? 🙏 💖

[jnunemaker]

Looks good to me. Thanks for tackling this. Curious to see feedback from anyone at DataDog.

[jnunemaker]

fyi @pengwynn who is probably curious about this work

[vmg]

It's a good start @janester! I'm afraid that saving these allocations won't do much with the amount of gsub and string duplication there's currently in the code. I think the next step would be to switch over to bang methods and incremental string composition, like @aroben did for our fork of statsd. :)

[degemer]

Thank you for the improvement @janester !
LGTM, will be part of the next release (~ in the next 2 weeks).

[janester]

Thanks for the review @vmg! 💖

I think the next step would be to switch over to bang methods and incremental string composition, like @aroben did for our fork of statsd. :)

👍 I'll make a new PR with those changes 😊

LGTM, will be part of the next release (~ in the next 2 weeks).

Thanks @degemer! 👍 🎉