Concurrent::Promise.all? doesn't work

Question

I'm trying to make some calculations after I got all promises executed. But proc never calls:

cbr_promise = Concurrent::Promise.execute { CbrRatesService.call }
bitfinex_promise = Concurrent::Promise.execute { BitfinexService.call }

proc = Proc.new do
  puts 10
end
Concurrent::Promise.all?([cbr_promise, bitfinex_promise]).then { proc }

Made with concurrent-ruby gem.

Should I create a loop that will check this every 100 ms for example?

Update

I tried to add a loop and byebug the code (in sidekiq worker):

while @fl
  Concurrent::Promise.all?([cbr_promise, bitfinex_promise]).then { proc }
end

but the state of all promises is pending. It could be because of byebug, but anyway the proc never calls.

Answer 1

1. Concurrent::Promise.all? returns a Promise and you have to execute it
2. you have to pass proc as a block argument &proc
3. you have to wait for the Promises to finish (e.g. sleep)

This will work:

require 'concurrent'

cbr_promise       = Concurrent::Promise.new { p "cbr" }
bitfinex_promise  = Concurrent::Promise.new { p "bitfinex" }

proc = Proc.new do
  puts 10
end

e = Concurrent::Promise.all?(cbr_promise, bitfinex_promise).execute.then(&proc)

sleep 1

yields

"cbr"
"bitfinex"
10

Note how this will not execute proc because one of the Promises fails:

require 'concurrent'

cbr_promise       = Concurrent::Promise.new { p "cbr" }
bitfinex_promise  = Concurrent::Promise.new { p "bitfinex"; raise 'error' }

proc = Proc.new do
  puts 10
end

e = Concurrent::Promise.all?(cbr_promise, bitfinex_promise).execute.then(&proc)

sleep 1

yields

"cbr"
"bitfinex"