Base branch for protocol v2

[masad-frost]

All the changes are documented in Protocol.md but here's a summary:

• Handle invalid client requests by sending a close with an error back
  • This was the main motivation for the change. While we could sort-of implement this error response without the other changes, things are setup in such a way where it is very hard to implement correctly without deeper changes in how we handle closing.
• Add more robust closing mechanics
  • Half-close states
  • Close signals from read end of the pipes
  • Abort full-closure (for errors and cancellation)
• Switch from Pushable and AsyncIterator APIs to a ReadStream and WriteStream
• All procedures have init and some have input

While the changes are not strictly backwards compatible, hence the major protocol bump, the system can still operate across versions to some extent.

See PRs linked below for more information on the above

TODOs

• Define protocol and update doc [protocol v2] RFC PROTOCOL V2 #111

• Design stream abstractions [protocol v2] RFC: custom streams #118

  • Redsigned in RFC: take 2 on streams #249

• Implement stream abstractions

  • ReadStream ReadStream implementation #130
  • WriteStream WriteStream implementation #132

• All streams have init, some have input.

  • Protocol change documented in [protocolv2] always expect init, input sometimes (docs only) #153
  • Implementation change [protocolv2] Init always exists #159

• Use stream abstractions & implement protocol closing semantics

  • Protocol: Implement close requests from readers [protocolv2] Implement close requests #165
  • Protocol: Implement half-close
    • Client [protocolv2] Half-close client #162
    • Server [protocolv2] Half-close server #163
  • Simple s/Pushable/Stream replacement
    • Client Client uses ReadStream and WriteStream #136
    • Server Server uses ReadStream and WriteStream #136  #137
  • Make Input iterator on the server use Result so we can signal stream closes, client disconnects, and aborts [protocolv2] Make ReadStream always emit Result values #172

• Add Abort mechanism

  • Docs update [protocolv2] Add abort support, move protocol errors to abort status (docs only) #175
  • Implement abort
    • Client [protocolv2] Implement client abort #193
    • Server [protocolv2] Implement server abort #200
  • Add INVALID_REQUEST to schema Add INVALID_REQUEST to RiverUncaughtSchema #107
  • Handle/send back INVALID_REQUEST errors with an abort bit [protocolv2] Handle invalid requests and internal server errors #203
  • Handle/send back INTERNAL_RIVER_ERROR with an abort bit [protocolv2] Handle invalid requests and internal server errors #203
  • Send abort bit with UNCAUGHT_ERROR [protocolv2] Treat uncaught handler errors as abort #201
  • Abort tombstones [protocolv2] Ignore follow up messages to a stream after server aborts it #204

• Try to find uncovered areas to test

  • undefined value for init, input, & output.

• Update docs

• Changelog

[jackyzha0]

talked more IRL, going to think a bit more about the stream interface and ergonomics broadly

i think directionally very correct but could use a lot of simplification

[jackyzha0]

probably needs an update too

[jackyzha0]

same with await client.example.add.rpc below

[masad-frost]

docs

[masad-frost]

good review, i'll be sending some PRs and we can sync up afterwards

[jackyzha0]

its time.

[masad-frost]

a couple of things left that we'll fix against main