MFA — module, function, arguments
F — function
procs.exs
defmodule Procs do
def greeter(count) do
receive do
{:boom, reason} ->
exit(reason)
{:add, n} ->
greeter(count+n)
{:reset} ->
greeter(0)
msg ->
IO.puts "#{count}: #{inspect msg}"
greeter(count)
end
end
end
# run in iex
c "proc.exs"
spawn Procs, :greeter, ["mlx"]
spawn(fn -> IO.puts "Hi Process" end)
# create 100 process
Enum.each(1..1000, fn _ -> spawn(fn -> Process.sleep(5000) end) end)
:observer.start()
Sending and Receiving Messages
pid = spawn Procs, :greeter, []
send pid, "wonder man"
Linking Our Fate to Our Children’s Fate
- spawn 开启独立process
- spawn_link 开启的是child process, 只要一个非正常挂掉，另一个也随之被kill
exit(:bad) 表示非正常挂掉。exit(:normal) 表示正常退出。
# 增加100个process 10秒后结束
inner_process = fn -> Process.sleep(10_000) end
outer_process = fn -> spawn(inner_process); exit(:bad) end
Enum.each(1..100, fn _ -> spawn(outer_process) end)
################
#process 数量不变：原因就是spawn_link
inner_process = fn -> Process.sleep(10_000) end
outer_process = fn -> spawn_link(inner_process); exit(:bad) end
Enum.each(1..100, fn _ -> spawn(outer_process) end)
Agents—Simple State Holders
#初始化
{:ok, pid} = Agent.start_link(fn -> 0 end)
#读取process的值
Agent.get(pid, fn count -> count end)
#更新process的值
Agent.update(pid, fn count -> count+1 end)
#读取并更新process的值 (返回值为读取到的值，然后再做的更新)
Agent.get_and_update(pid, fn count -> {count, count+1} end)
Example:
defmodule HitCount do
def start() do
Agent.start_link(fn -> 0 end)
end
def record_hit(agent) do
Agent.update(agent, &(&1 + 1))
end
def get_count(agent) do
Agent.get(agent, &(&1))
end
end
{:ok, agent} = HitCount.start()
IO.puts HitCount.record_hit(agent)
IO.puts HitCount.get_count(agent)
IO.puts HitCount.record_hit(agent)
IO.puts HitCount.get_count(agent)
