Deno: Convert all Flatbuffer ops to JSON

[ry]

To all contributors who are listening -

We want to convert all of the flatbuffer ops to JSON. Here is a commit showing how to do it. And another.

There's many ops to convert, and if you are interested, this is would be a helpful contribution.

I'm currently working on js/os.ts - please let me know if you want to work on some of the ops, I'll try to coordinate people so there's no double work happening. Base work off https://github.com/denoland/deno/pull/2799

Here is a list of ops we need to convert:

• compiler.rs // @bartlomieju https://github.com/denoland/deno/pull/2804
• errors.rs // @bartlomieju https://github.com/denoland/deno/pull/2804
• fetch.rs // @bartlomieju
• files.rs // @bartlomieju
• fs.rs
• metrics.rs // @romainPrignon https://github.com/denoland/deno/pull/2805
• net.rs // @bartlomieju #2809
• os.rs // @ry https://github.com/denoland/deno/pull/2802
• performance.rs // @bartlomieju
• permissions.rs // @bartlomieju
• process.rs // @bartlomieju
• random.rs // @bartlomieju #2809
• repl.rs // @bartlomieju #2809
• resources.rs // @bartlomieju #2809
• timers.rs // @bartlomieju
• workers.rs // @bartlomieju

The only ops we are not converting are read, write, readSync, and writeSync.

[bartlomieju]

I'll take these for a good start:

* compiler.rs
* errors.rs
* fetch.rs
* files.rs

[romainPrignon]

I can work on metrics.rs

[bartlomieju]

I should convert following files tomorrow:

* net.ts
* performance.rs
* permissions.rs
* process.rs
* random.rs
* repl.rs
* resources.rs
* timers.rs
* utils.rs
* workers.rs

[s-panferov]

Hello @ry, may I ask why do you want to convert everything to JSON? Did you find it faster than flatbuffers?

[ry]

@s-panferov actually the opposite - we found flatbuffers too slow and we don’t yet know the speed of this JSON serialization.
We have some ops which are very hot: Deno.read and Deno.write. These we converted to a custom serialization and got some perf increases.

The other ops are not measured in our benchmarks - so we don’t particularly care how fast they are. More important is the ease of implementing and maintaining them. The flatbuffer API is unfortunately very verbose. It also complicated our build at a time when we’re trying to move from gn/ninja to cargo based. So the JSON serialization will help simplify things and not effect the benchmarks.

[bartlomieju]

@ry I believe io.rs shouldn't be ported - it already uses minimal dispatch

[bartlomieju]

I think I'm gonna go ahead and port remaining ops from fs.rs

[ry]

This is complete now thanks to a massive effort from @bartlomieju !

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