Add exercises 1 and 2 from chapter 14

Author: Bernard Pietraga

chapter_14/working_with_multiple_processes_1.exs

@@ -0,0 +1,20 @@
+# Exercises 1 from chapter 14.
+# Results from Macbook Pro Retina 15" 2012 running elixir 1.4
+
+# elixir -r chain.ex  -e "Chain.run(10)"
+{3383, "Result is 10"}
+
+# elixir -r chain.ex  -e "Chain.run(100)"
+{3595, "Result is 100"}
+
+# elixir -r chain.ex  -e "Chain.run(1_000)"
+{11614, "Result is 1000"}
+
+# elixir -r chain.ex  -e "Chain.run(10_000)"
+{89265, "Result is 10000"}
+
+# elixir -r chain.ex -e "Chain.run(400_00)"
+{337519, "Result is 40000"}
+
+# elixir --erl "+P 1000000" -r chain.ex -e "Chain.run(1_000_000)"
+{7283403, "Result is 1000000"}

chapter_14/working_with_multiple_processes_2.exs

@@ -0,0 +1,83 @@
+defmodule TwoProcessesSpawner do
+  def receive_token(process) do
+    receive do
+      token ->
+        send(process, token)
+    end
+  end
+
+  def generate_process(token) do
+    spawn(TwoProcessesSpawner, :receive_token, [self()])
+    |> send(token)
+
+    receive do
+      response ->
+        IO.inspect(response)
+    end
+  end
+
+  def run do
+    generate_process(:fred)
+    generate_process(:betty)
+  end
+end
+
+ExUnit.start
+
+defmodule TwoProcessesSpawnerTest do
+  use ExUnit.Case
+  import ExUnit.CaptureIO
+
+  test "run used 5 times returns :fred" do
+    io_string = """
+    :fred
+    :betty
+    :fred
+    :betty
+    :fred
+    :betty
+    :fred
+    :betty
+    :fred
+    :betty
+    """
+
+    result = capture_io fn ->
+      Enum.each(1..5, fn(_n) -> TwoProcessesSpawner.run end)
+    end
+
+    assert result == io_string
+  end
+
+
+  test "run used 10 times returns :fred" do
+    io_string = """
+    :fred
+    :betty
+    :fred
+    :betty
+    :fred
+    :betty
+    :fred
+    :betty
+    :fred
+    :betty
+    :fred
+    :betty
+    :fred
+    :betty
+    :fred
+    :betty
+    :fred
+    :betty
+    :fred
+    :betty
+    """
+
+    result = capture_io fn ->
+      Enum.each(1..10, fn(_n) -> TwoProcessesSpawner.run end)
+    end
+
+    assert result == io_string
+  end
+end