Merge pull request #76 from aerosol/emit-telemetry-events-for-hit-and…

…-miss Emit telemetry events for hit and miss
sasa1977 · Apr 8, 2024 · 104362d · 104362d
2 parents 09b98ed + 3ccb5d1
commit 104362d
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Showing 6 changed files with 132 additions and 25 deletions.
diff --git a/lib/con_cache.ex b/lib/con_cache.ex
@@ -51,7 +51,8 @@ defmodule ConCache do
     :acquire_lock_timeout,
     :callback,
     :touch_on_read,
-    :lock_pids
+    :lock_pids,
+    :name
   ]
 
   @type t :: pid | atom | {:global, any} | {:via, atom, any}
@@ -223,7 +224,12 @@ defmodule ConCache do
   `touch_on_read` option is set while starting the cache.
   """
   @spec get(t, key) :: value
-  def get(cache_id, key), do: Operations.get(Owner.cache(cache_id), key)
+  def get(cache_id, key) do
+    case Operations.fetch(Owner.cache(cache_id), key) do
+      :error -> nil
+      {:ok, value} -> value
+    end
+  end
 
   @doc """
   Stores the item into the cache.

diff --git a/lib/con_cache/operations.ex b/lib/con_cache/operations.ex
@@ -20,19 +20,14 @@ defmodule ConCache.Operations do
   defp lock_pid(cache, key),
     do: elem(cache.lock_pids, :erlang.phash2(key, tuple_size(cache.lock_pids)))
 
-  def get(cache, key) do
-    case fetch(cache, key) do
-      {:ok, value} -> value
-      :error -> nil
-    end
-  end
-
-  defp fetch(%ConCache{ets: ets} = cache, key) do
+  def fetch(%ConCache{ets: ets} = cache, key, opts \\ []) do
     case :ets.lookup(ets, key) do
       [] ->
+        emit(telemetry_miss(), cache, opts)
         :error
 
       [{^key, value}] ->
+        emit(telemetry_hit(), cache, opts)
         read_touch(cache, key)
         {:ok, value}
 
@@ -42,6 +37,7 @@ defmodule ConCache.Operations do
           |> Enum.map(fn {^key, value} -> value end)
 
         read_touch(cache, key)
+        emit(telemetry_hit(), cache, opts)
         {:ok, values}
     end
   end
@@ -177,9 +173,13 @@ defmodule ConCache.Operations do
 
   def get_or_store(cache, key, fun) do
     if valid_ets_type?(cache) do
-      case get(cache, key) do
-        nil -> isolated_get_or_store(cache, key, fun)
-        value -> value
+      case fetch(cache, key, emit_telemetry?: false) do
+        :error ->
+          isolated_get_or_store(cache, key, fun)
+
+        {:ok, value} ->
+          emit(telemetry_hit(), cache)
+          value
       end
     else
       raise_ets_type(cache)
@@ -194,13 +194,14 @@ defmodule ConCache.Operations do
 
   def dirty_get_or_store(cache, key, fun) do
     if valid_ets_type?(cache) do
-      case get(cache, key) do
-        nil ->
+      case fetch(cache, key, emit_telemetry?: false) do
+        :error ->
           new_value = fun.()
           dirty_put(cache, key, new_value)
+          emit(telemetry_miss(), cache)
           value(new_value)
 
-        existing ->
+        {:ok, existing} ->
           existing
       end
     else
@@ -210,9 +211,11 @@ defmodule ConCache.Operations do
 
   def fetch_or_store(cache, key, fun) do
     if valid_ets_type?(cache) do
-      case fetch(cache, key) do
+      case fetch(cache, key, emit_telemetry?: false) do
         :error -> isolated_fetch_or_store(cache, key, fun)
-        {:ok, existing} -> {:ok, existing}
+        {:ok, existing} -> 
+          emit(telemetry_hit(), cache)
+          {:ok, existing}
       end
     else
       raise_ets_type(cache)
@@ -227,11 +230,12 @@ defmodule ConCache.Operations do
 
   def dirty_fetch_or_store(cache, key, fun) do
     if valid_ets_type?(cache) do
-      case fetch(cache, key) do
+      case fetch(cache, key, emit_telemetry?: false) do
         :error ->
           case fun.() do
             {:ok, new_value} ->
               dirty_put(cache, key, new_value)
+              emit(telemetry_miss(), cache)
               {:ok, value(new_value)}
 
             {:error, _reason} = error ->
@@ -273,13 +277,27 @@ defmodule ConCache.Operations do
   end
 
   defp with_existing(cache, key, fun) do
-    case get(cache, key) do
-      nil -> nil
-      existing -> fun.(existing)
+    case fetch(cache, key) do
+      :error -> nil
+      {:ok, existing} -> fun.(existing)
     end
   end
 
   def touch(cache, key) do
     set_ttl(cache, key, :renew)
   end
+
+  def telemetry_hit() do
+    [:con_cache, :stats, :hit]
+  end
+
+  def telemetry_miss() do
+    [:con_cache, :stats, :miss]
+  end
+
+  defp emit(event, cache, opts \\ []) do
+    if Keyword.get(opts, :emit_telemetry?, true) do
+      :telemetry.execute(event, %{}, %{cache: cache})
+    end
+  end
 end
diff --git a/lib/con_cache/owner.ex b/lib/con_cache/owner.ex
@@ -43,7 +43,8 @@ defmodule ConCache.Owner do
       acquire_lock_timeout: options[:acquire_lock_timeout] || 5000,
       callback: options[:callback],
       touch_on_read: options[:touch_on_read] || false,
-      lock_pids: List.to_tuple(ConCache.LockSupervisor.lock_pids(parent_process()))
+      lock_pids: List.to_tuple(ConCache.LockSupervisor.lock_pids(parent_process())),
+      name: options[:name]
     }
 
     {:ok, _} = Registry.register(ConCache, {parent_process(), __MODULE__}, cache)

diff --git a/mix.exs b/mix.exs
@@ -18,15 +18,16 @@ defmodule ConCache.Mixfile do
 
   def application do
     [
-      applications: [:logger],
+      applications: [:logger, :telemetry],
       mod: {ConCache.Application, []}
     ]
   end
 
   defp deps do
     [
       {:ex_doc, ">= 0.0.0", only: :dev, runtime: false},
-      {:dialyxir, "~> 1.0", only: :dev, runtime: false}
+      {:dialyxir, "~> 1.0", only: :dev, runtime: false},
+      {:telemetry, "~> 1.0"}
     ]
   end
 

diff --git a/mix.lock b/mix.lock
@@ -7,4 +7,5 @@
   "makeup_elixir": {:hex, :makeup_elixir, "0.15.1", "b5888c880d17d1cc3e598f05cdb5b5a91b7b17ac4eaf5f297cb697663a1094dd", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.1", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "db68c173234b07ab2a07f645a5acdc117b9f99d69ebf521821d89690ae6c6ec8"},
   "makeup_erlang": {:hex, :makeup_erlang, "0.1.1", "3fcb7f09eb9d98dc4d208f49cc955a34218fc41ff6b84df7c75b3e6e533cc65f", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "174d0809e98a4ef0b3309256cbf97101c6ec01c4ab0b23e926a9e17df2077cbb"},
   "nimble_parsec": {:hex, :nimble_parsec, "1.1.0", "3a6fca1550363552e54c216debb6a9e95bd8d32348938e13de5eda962c0d7f89", [:mix], [], "hexpm", "08eb32d66b706e913ff748f11694b17981c0b04a33ef470e33e11b3d3ac8f54b"},
+  "telemetry": {:hex, :telemetry, "1.2.1", "68fdfe8d8f05a8428483a97d7aab2f268aaff24b49e0f599faa091f1d4e7f61c", [:rebar3], [], "hexpm", "dad9ce9d8effc621708f99eac538ef1cbe05d6a874dd741de2e689c47feafed5"},
 }
diff --git a/test/con_cache_test.exs b/test/con_cache_test.exs
@@ -427,6 +427,7 @@ defmodule ConCacheTest do
       {:ok, _} = start_cache(name: name)
       ConCache.put(name, :a, 1)
       assert ConCache.get(name, :a) == 1
+      assert ConCache.Owner.cache(name).name == name
     end
   end
 
@@ -463,6 +464,85 @@ defmodule ConCacheTest do
     assert ConCache.get(cache, :key) == :value
   end
 
+  describe "telemetry" do
+    defmodule TestTelemetryHandler do
+      def handle_event(event, _measurments, metadata, _config) do
+        send(self(), {:telemetry_handled, event, metadata})
+      end
+    end
+
+    setup do
+      hit = ConCache.Operations.telemetry_hit()
+      miss = ConCache.Operations.telemetry_miss()
+
+      :telemetry.attach_many(
+        "test",
+        [
+          hit,
+          miss
+        ],
+        &TestTelemetryHandler.handle_event/4,
+        nil
+      )
+
+      {:ok, hit_event: hit, miss_event: miss}
+    end
+
+    test "get/2 emits telemetry events", %{hit_event: hit, miss_event: miss, test: test} do
+      {:ok, cache} = ConCache.start_link(ttl_check_interval: false, name: test)
+
+      ConCache.get(cache, :key)
+      assert_receive {:telemetry_handled, ^miss, %{cache: %{owner_pid: ^cache, name: ^test}}}
+
+      ConCache.put(cache, :key, :value)
+      ConCache.get(cache, :key)
+      assert_receive {:telemetry_handled, ^hit, %{cache: %{owner_pid: ^cache, name: ^test}}}
+      refute_receive _
+    end
+
+    test "get_or_store/3 emits telemetry events", %{hit_event: hit, miss_event: miss} do
+      {:ok, cache} = ConCache.start_link(ttl_check_interval: false)
+
+      ConCache.get_or_store(cache, :key, fn -> :value end)
+      assert_receive {:telemetry_handled, ^miss, %{cache: %{owner_pid: ^cache, name: nil}}}
+      refute_receive _
+
+      ConCache.get_or_store(cache, :key, fn -> :value end)
+      assert_receive {:telemetry_handled, ^hit, %{cache: %{owner_pid: ^cache, name: nil}}}
+      refute_receive _
+    end
+
+    test "get_or_store/3 emits telemetry hit after put/3 is made", %{hit_event: hit, test: test} do
+      assert {:ok, cache} = ConCache.start_link(ttl_check_interval: false, name: test)
+
+      ConCache.put(cache, :key, fn -> :value end)
+      ConCache.get_or_store(cache, :key, fn -> :value end)
+      assert_receive {:telemetry_handled, ^hit, %{cache: %{owner_pid: ^cache, name: ^test}}}
+      refute_receive _
+    end
+
+    test "fetch_or_store/3 emits telemetry events", %{hit_event: hit, miss_event: miss} do
+      {:ok, cache} = ConCache.start_link(ttl_check_interval: false)
+
+      ConCache.fetch_or_store(cache, :key, fn -> {:ok, :value} end)
+      assert_receive {:telemetry_handled, ^miss, %{cache: %{owner_pid: ^cache, name: nil}}}
+      refute_receive _
+
+      ConCache.fetch_or_store(cache, :key, fn -> {:ok, :value} end)
+      assert_receive {:telemetry_handled, ^hit, %{cache: %{owner_pid: ^cache, name: nil}}}
+      refute_receive _
+    end
+
+    test "fetch_or_store/3 emits telemetry hit after put/3 is made", %{hit_event: hit, test: test} do
+      assert {:ok, cache} = ConCache.start_link(ttl_check_interval: false, name: test)
+
+      ConCache.put(cache, :key, fn -> {:ok, :value} end)
+      ConCache.get_or_store(cache, :key, fn -> {:ok, :value} end)
+      assert_receive {:telemetry_handled, ^hit, %{cache: %{owner_pid: ^cache, name: ^test}}}
+      refute_receive _
+    end
+  end
+
   defp start_cache(opts \\ []) do
     ConCache.start_link(Keyword.merge([ttl_check_interval: false], opts))
   end