chore: refactor so that Task async/await is handled outside of the API

This gives us slightly better typing on the API methods and allows callers
to choose whether to launch async or not.

examples/basic.exs

@@ -1,24 +1,34 @@
 defmodule Momento.Examples.Basic do
-  @spec generate_key(integer) :: String.t
+  @spec generate_key(integer) :: String.t()
   def generate_key(i) do
     "key#{i}"
   end
 
-  @spec execute_set(Momento.CacheClient.t, String.t) :: String.t
-  def execute_set(cache_client, key) do
+  @spec issue_set(Momento.CacheClient.t(), String.t()) :: {String.t(), Task.t()}
+  def issue_set(cache_client, key) do
     IO.puts("Executing a 'set' for key: #{key}")
-    response = Task.await(Momento.CacheClient.set(cache_client, key, "foo", 42))
+    {key, Task.async(fn -> Momento.CacheClient.set(cache_client, key, "foo", 42) end)}
+  end
+
+  @spec await_set({String.t(), Task.t()}) :: String.t()
+  def await_set({key, set_task}) do
+    response = Task.await(set_task)
     case response do
       :success -> IO.puts("'set' successful for key #{key}")
       {:error, error} -> IO.puts("Got an error for key #{key}: #{inspect(error)}")
     end
     key
   end
 
-  @spec execute_get(Momento.CacheClient.t, String.t) :: String.t
-  def execute_get(cache_client, key) do
+  @spec issue_get(Momento.CacheClient.t(), String.t()) :: {String.t(), Task.t()}
+  def issue_get(cache_client, key) do
     IO.puts("Executing a 'get' for key: #{key}")
-    response = Task.await(Momento.CacheClient.get(cache_client, key))
+    {key, Task.async(fn -> Momento.CacheClient.get(cache_client, key) end)}
+  end
+
+  @spec await_get({String.t(), Task.t()}) :: String.t()
+  def await_get({key, get_task}) do
+    response = Task.await(get_task)
     case response do
       :hit -> IO.puts("'get' resulted in a 'hit' for key #{key}: #{inspect(response)}")
       :miss -> IO.puts("'get' resulted in a 'miss' for key #{key}.")
@@ -34,8 +44,17 @@ config = %Momento.Configuration{}
 cache_client = %Momento.CacheClient{config: config}
 
 
-1..20
+set_tasks = 1..20
 |> Stream.map(&Momento.Examples.Basic.generate_key(&1))
-|> Stream.map(&Momento.Examples.Basic.execute_set(cache_client, &1))
-|> Stream.map(&Momento.Examples.Basic.execute_get(cache_client, &1))
+|> Stream.map(&Momento.Examples.Basic.issue_set(cache_client, &1))
+|> Enum.to_list
+
+get_tasks = set_tasks
+|> Stream.map(&Momento.Examples.Basic.await_set(&1))
+|> Stream.map(&Momento.Examples.Basic.issue_get(cache_client, &1))
+|> Enum.to_list
+
+# force the completion of the tasks
+get_tasks
+|> Stream.map(&Momento.Examples.Basic.await_get(&1))
 |> Enum.to_list

src/lib/momento/cache_client.ex

@@ -15,15 +15,16 @@ defmodule Momento.CacheClient do
       TODO
 
   """
-  @spec set(String.t(), binary, binary, float) :: Task.t()
+  @spec set(String.t(), binary, binary, float) :: Momento.Responses.Set.t()
   def set(cache_name, key, value, ttl_seconds) do
-    Task.async(fn ->
-      rand = :rand.uniform(2)
-      case rand do
-        1 -> :success
-        2 -> {:error, %{}}
-      end
-    end)
+    time_to_sleep = :rand.uniform(100)
+    :timer.sleep(time_to_sleep)
+    IO.puts("Completed 'set' for key #{key}")
+    rand = :rand.uniform(2)
+    case rand do
+      1 -> :success
+      2 -> {:error, %{}}
+    end
   end
 
 
@@ -35,15 +36,16 @@ defmodule Momento.CacheClient do
       TODO
 
   """
-  @spec get(String.t(), binary) :: Task.t()
+  @spec get(String.t(), binary) :: Momento.Responses.Get.t()
   def get(cache_name, key) do
-    Task.async(fn ->
-      rand = :rand.uniform(3)
-      case rand do
-        1 -> :hit
-        2 -> :miss
-        3 -> {:error, %{}}
-      end
-    end)
+    time_to_sleep = :rand.uniform(100)
+    :timer.sleep(time_to_sleep)
+    IO.puts("Completed 'get' for key #{key}")
+    rand = :rand.uniform(3)
+    case rand do
+      1 -> :hit
+      2 -> :miss
+      3 -> {:error, %{}}
+    end
   end
 end