Ruby Ractor.send用法及代碼示例

send(msg, move: false) → self

向 Ractor 的傳入隊列發送消息以供 Ractor.receive 使用。

r = Ractor.new do
  value = Ractor.receive
  puts "Received #{value}"
end
r.send 'message'
# Prints: "Received: message"

該方法是非阻塞的(即使 ractor 還沒有準備好接收任何東西，也會立即返回)：

r = Ractor.new {sleep(5)}
r.send('test')
puts "Sent successfully"
# Prints: "Sent successfully" immediately

嘗試發送到已經完成執行的 ractor 將引發 Ractor::ClosedError 。

r = Ractor.new {}
r.take
p r
# "#<Ractor:#6 (irb):23 terminated>"
r.send('test')
# Ractor::ClosedError (The incoming-port is already closed)

如果 close_incoming 在 ractor 上被調用，該方法也會引發 Ractor::ClosedError 。

r =  Ractor.new do
  sleep(500)
  receive
end
r.close_incoming
r.send('test')
# Ractor::ClosedError (The incoming-port is already closed)
# The error would be raised immediately, not when ractor will try to receive

如果 obj 不可共享，默認情況下它將通過深度克隆複製到 ractor。如果傳遞了move: true，則對象是moved 進入ractor，並且發送者無法訪問。

r = Ractor.new {puts "Received: #{receive}"}
msg = 'message'
r.send(msg, move: true)
r.take
p msg

這打印：

Received: message
in `p': undefined method `inspect' for #<Ractor::MovedObject:0x000055c99b9b69b8>

所有對對象及其部分的引用在發送者中都將變為無效。

r = Ractor.new {puts "Received: #{receive}"}
s = 'message'
ary = [s]
copy = ary.dup
r.send(ary, move: true)

s.inspect
# Ractor::MovedError (can not send any methods to a moved object)
ary.class
# Ractor::MovedError (can not send any methods to a moved object)
copy.class
# => Array, it is different object
copy[0].inspect
# Ractor::MovedError (can not send any methods to a moved object)
# ...but its item was still a reference to `s`, which was moved

如果對象是可共享的，move: true 對其沒有影響：

r = Ractor.new {puts "Received: #{receive}"}
s = 'message'.freeze
r.send(s, move: true)
s.inspect #=> "message", still available