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class method

Ractor.recv

recv

# File tmp/rubies/ruby-3.0.5/ractor.rb, line 415
def self.receive
  __builtin_cexpr! %q{
    ractor_receive(ec, rb_ec_ractor_ptr(ec))
  }
end

Alias of .receive

Receive an incoming message from the current Ractor’s incoming port’s queue, which was sent there by send.

Example

r = Ractor.new do
  v1 = Ractor.receive
  puts "Received: #{v1}"
end
r.send('message1')
r.take
# Here will be printed: "Received: message1"

Alternatively, private instance method receive may be used:

Example

r = Ractor.new do
  v1 = receive
  puts "Received: #{v1}"
end
r.send('message1')
r.take
# Here will be printed: "Received: message1"

The method blocks if the queue is empty.

Example

r = Ractor.new do
  puts "Before first receive"
  v1 = Ractor.receive
  puts "Received: #{v1}"
  v2 = Ractor.receive
  puts "Received: #{v2}"
end
wait
puts "Still not received"
r.send('message1')
wait
puts "Still received only one"
r.send('message2')
r.take

Output:

Before first receive
Still not received
Received: message1
Still received only one
Received: message2

If close_incoming was called on the ractor, the method raises Ractor::ClosedError if there are no more messages in incoming queue:

Example

Ractor.new do
  close_incoming
  receive
end
wait
# in `receive': The incoming port is already closed => #<Ractor:#2 test.rb:1 running> (Ractor::ClosedError)

See also .receive #recv .receive_if .select also in 4.1 · 4.0 · 3.4 · 3.3 · 3.2 · 3.1

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