reactor — non-blocking reads and writes

Source

lib/reactor.low

Layer

L2 — host (wrappers over builtin ops)

Capabilities

all three ops take cap io

Reads and writes several channels without blocking. The state of a reactor lives in backing the caller provides; this module obtains no memory. A handle is a u64 and can be made up, so the capability (cap io) shows at every call. The module is three wrappers that pass the builtin ops reactor_new, r_read and r_write through.

use reactor .

proc echo_once input k cap io . input buf mut slice u8 . output usize . effects io . do
  let r option u64 reactor.new k. subslice buf. 0 32 . 1 . .
  guard is_some r. . else return 0 . .
  let n option usize reactor.read k. some_value r. . 0 subslice buf. 32 64 . . .
  guard is_some n. . else return 0 . .
  return some_value n. . .
end .

op	shape	notes
reactor_new	(cap io, backing mut slice u8, n u64) → option u64	Makes a reactor. backing is where its state lives; n is how many channels it handles at once
r_read	(cap io, r u64, d u64, dst mut slice u8) → option u64	Reads from channel d. 0 when nothing is there yet; none when the read failed
r_write	(cap io, r u64, d u64, b slice u8) → option u64	Writes to channel d. Returns the bytes written; none when the write failed

Table 50.1 — The ops of reactor

Not built: timers, ops to register and remove a channel, an op that waits on several channels at once.