Support caching nil values (#16)

elixir-toniq · Feb 16, 2024 · 16dd1d9 · 16dd1d9
1 parent 7f18117
commit 16dd1d9
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Showing 5 changed files with 75 additions and 52 deletions.
diff --git a/.github/workflows/elixir.yml b/.github/workflows/elixir.yml
@@ -15,11 +15,11 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        elixir: [1.11]
-        otp: [23.3]
+        elixir: ['1.16']
+        otp: ['26.2']
     steps:
     - name: checkout
-      uses: actions/checkout@v2
+      uses: actions/checkout@v4
       with:
         fetch-depth: 0
     - name: setup
@@ -28,7 +28,7 @@ jobs:
         elixir-version: ${{ matrix.elixir }}
         otp-version: ${{ matrix.otp }}
     - name: Retrieve Cached Dependencies
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       id: mix-cache
       with:
         path: |
@@ -52,10 +52,10 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        elixir: [1.11]
-        otp: [23.3]
+        elixir: ['1.16']
+        otp: ['26.2']
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
       with:
         fetch-depth: 0
     - name: Setup elixir
@@ -64,7 +64,7 @@ jobs:
         elixir-version: ${{ matrix.elixir }}
         otp-version: ${{ matrix.otp }}
     - name: Retrieve Cached Dependencies
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       id: mix-cache
       with:
         path: |
@@ -83,18 +83,18 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        elixir: [1.11]
-        otp: [23.3]
+        elixir: ['1.16']
+        otp: ['26.2']
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
       with:
         fetch-depth: 0
     - uses: erlef/setup-beam@v1
       with:
         elixir-version: ${{ matrix.elixir }}
         otp-version: ${{ matrix.otp }}
     - name: Retrieve Cached Dependencies
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       id: mix-cache
       with:
         path: |

diff --git a/.tool-versions b/.tool-versions
@@ -1 +1,2 @@
-erlang 23.1
+erlang 26.2.1
+elixir 1.16.1-otp-26
diff --git a/lib/mentat.ex b/lib/mentat.ex
@@ -74,6 +74,10 @@ defmodule Mentat do
   returned, the value will be stored in the cache before its returned. See the
   "TTLs" section for a list of options.
 
+  Since `fetch` is logically the same as a `get` (and also a `put` if
+  `{:commit, term()}` is returned from the fallback function), it shares the
+  same Telemetry events (`[:mentat, :get]` and `[:mentat, :put]`).
+
   ## Example
 
   ```
@@ -90,14 +94,14 @@ defmodule Mentat do
   """
   @spec fetch(name(), key(), put_opts(), (key() -> {:commit, value()} | {:ignore, value()})) :: value()
   def fetch(cache, key, opts \\ [], fallback) do
-    with nil <- get(cache, key) do
-      case fallback.(key) do
-        {:commit, value} ->
-          put(cache, key, value, opts)
-          value
+    {status, value} = lookup(cache, key)
 
-        {:ignore, value} ->
-          value
+    if status == :hit do
+      value
+    else
+      case fallback.(key) do
+        {:commit, value} -> put(cache, key, value, opts)
+        {:ignore, value} -> value
       end
     end
   end
@@ -107,22 +111,8 @@ defmodule Mentat do
   """
   @spec get(name(), key()) :: value()
   def get(cache, key) do
-    config = get_config(cache)
-    now    = ms_time(config.clock)
-
-    case :ets.lookup(cache, key) do
-      [] ->
-        :telemetry.execute([:mentat, :get], %{status: :miss}, %{key: key, cache: cache})
-        nil
-
-      [{^key, _val, ts, ttl}] when is_integer(ttl) and ts + ttl <= now ->
-        :telemetry.execute([:mentat, :get], %{status: :miss}, %{key: key, cache: cache})
-        nil
-
-      [{^key, val, _ts, _expire_at}] ->
-        :telemetry.execute([:mentat, :get], %{status: :hit}, %{key: key, cache: cache})
-        val
-    end
+    {_status, value} = lookup(cache, key)
+    value
   end
 
 
@@ -278,6 +268,22 @@ defmodule Mentat do
     Supervisor.stop(name)
   end
 
+  defp lookup(cache, key) do
+    config = get_config(cache)
+    now    = ms_time(config.clock)
+
+    {status, value} =
+      case :ets.lookup(cache, key) do
+        [] -> {:miss, nil}
+        [{^key, _val, ts, ttl}] when is_integer(ttl) and ts + ttl <= now -> {:miss, nil}
+        [{^key, val, _ts, _expire_at}] -> {:hit, val}
+      end
+
+    :telemetry.execute([:mentat, :get], %{status: status}, %{key: key, cache: cache})
+
+    {status, value}
+  end
+
   defp put_config(cache, config) do
     :persistent_term.put({__MODULE__, cache}, config)
   end

diff --git a/mix.lock b/mix.lock
@@ -1,21 +1,21 @@
 %{
-  "bunt": {:hex, :bunt, "0.2.0", "951c6e801e8b1d2cbe58ebbd3e616a869061ddadcc4863d0a2182541acae9a38", [:mix], [], "hexpm", "7af5c7e09fe1d40f76c8e4f9dd2be7cebd83909f31fee7cd0e9eadc567da8353"},
-  "credo": {:hex, :credo, "1.5.5", "e8f422026f553bc3bebb81c8e8bf1932f498ca03339856c7fec63d3faac8424b", [:mix], [{:bunt, "~> 0.2.0", [hex: :bunt, repo: "hexpm", optional: false]}, {:file_system, "~> 0.2.8", [hex: :file_system, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "dd8623ab7091956a855dc9f3062486add9c52d310dfd62748779c4315d8247de"},
+  "bunt": {:hex, :bunt, "1.0.0", "081c2c665f086849e6d57900292b3a161727ab40431219529f13c4ddcf3e7a44", [:mix], [], "hexpm", "dc5f86aa08a5f6fa6b8096f0735c4e76d54ae5c9fa2c143e5a1fc7c1cd9bb6b5"},
+  "credo": {:hex, :credo, "1.7.4", "68ca5cf89071511c12fd9919eb84e388d231121988f6932756596195ccf7fd35", [:mix], [{:bunt, "~> 0.2.1 or ~> 1.0", [hex: :bunt, repo: "hexpm", optional: false]}, {:file_system, "~> 0.2 or ~> 1.0", [hex: :file_system, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "9cf776d062c78bbe0f0de1ecaee183f18f2c3ec591326107989b054b7dddefc2"},
   "decorator": {:hex, :decorator, "1.4.0", "a57ac32c823ea7e4e67f5af56412d12b33274661bb7640ec7fc882f8d23ac419", [:mix], [], "hexpm", "0a07cedd9083da875c7418dea95b78361197cf2bf3211d743f6f7ce39656597f"},
-  "dialyxir": {:hex, :dialyxir, "1.1.0", "c5aab0d6e71e5522e77beff7ba9e08f8e02bad90dfbeffae60eaf0cb47e29488", [:mix], [{:erlex, ">= 0.2.6", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "07ea8e49c45f15264ebe6d5b93799d4dd56a44036cf42d0ad9c960bc266c0b9a"},
-  "earmark_parser": {:hex, :earmark_parser, "1.4.13", "0c98163e7d04a15feb62000e1a891489feb29f3d10cb57d4f845c405852bbef8", [:mix], [], "hexpm", "d602c26af3a0af43d2f2645613f65841657ad6efc9f0e361c3b6c06b578214ba"},
+  "dialyxir": {:hex, :dialyxir, "1.4.3", "edd0124f358f0b9e95bfe53a9fcf806d615d8f838e2202a9f430d59566b6b53b", [:mix], [{:erlex, ">= 0.2.6", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "bf2cfb75cd5c5006bec30141b131663299c661a864ec7fbbc72dfa557487a986"},
+  "earmark_parser": {:hex, :earmark_parser, "1.4.39", "424642f8335b05bb9eb611aa1564c148a8ee35c9c8a8bba6e129d51a3e3c6769", [:mix], [], "hexpm", "06553a88d1f1846da9ef066b87b57c6f605552cfbe40d20bd8d59cc6bde41944"},
   "erlex": {:hex, :erlex, "0.2.6", "c7987d15e899c7a2f34f5420d2a2ea0d659682c06ac607572df55a43753aa12e", [:mix], [], "hexpm", "2ed2e25711feb44d52b17d2780eabf998452f6efda104877a3881c2f8c0c0c75"},
-  "ex_doc": {:hex, :ex_doc, "0.24.2", "e4c26603830c1a2286dae45f4412a4d1980e1e89dc779fcd0181ed1d5a05c8d9", [:mix], [{:earmark_parser, "~> 1.4.0", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1", [hex: :makeup_erlang, repo: "hexpm", optional: false]}], "hexpm", "e134e1d9e821b8d9e4244687fb2ace58d479b67b282de5158333b0d57c6fb7da"},
-  "file_system": {:hex, :file_system, "0.2.10", "fb082005a9cd1711c05b5248710f8826b02d7d1784e7c3451f9c1231d4fc162d", [:mix], [], "hexpm", "41195edbfb562a593726eda3b3e8b103a309b733ad25f3d642ba49696bf715dc"},
-  "jason": {:hex, :jason, "1.2.2", "ba43e3f2709fd1aa1dce90aaabfd039d000469c05c56f0b8e31978e03fa39052", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "18a228f5f0058ee183f29f9eae0805c6e59d61c3b006760668d8d18ff0d12179"},
-  "libgraph": {:hex, :libgraph, "0.13.3", "20732b7bafb933dcf7351c479e03076ebd14a85fd3202c67a1c197f4f7c2466b", [:mix], [], "hexpm", "78f2576eef615440b46f10060b1de1c86640441422832052686df53dc3c148c6"},
-  "makeup": {:hex, :makeup, "1.0.5", "d5a830bc42c9800ce07dd97fa94669dfb93d3bf5fcf6ea7a0c67b2e0e4a7f26c", [:mix], [{:nimble_parsec, "~> 0.5 or ~> 1.0", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "cfa158c02d3f5c0c665d0af11512fed3fba0144cf1aadee0f2ce17747fba2ca9"},
-  "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"},
-  "norm": {:hex, :norm, "0.12.0", "b27a629fea9aaf7757604e9d4ed06cd815c2c5fb335f38b33c1bf17db9b217b0", [:mix], [], "hexpm", "aecd53df72219966d9493e3426a32d83490c822ef618ef442721b1ae68cb6f0c"},
+  "ex_doc": {:hex, :ex_doc, "0.31.1", "8a2355ac42b1cc7b2379da9e40243f2670143721dd50748bf6c3b1184dae2089", [:mix], [{:earmark_parser, "~> 1.4.39", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_c, ">= 0.1.1", [hex: :makeup_c, repo: "hexpm", optional: true]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1", [hex: :makeup_erlang, repo: "hexpm", optional: false]}], "hexpm", "3178c3a407c557d8343479e1ff117a96fd31bafe52a039079593fb0524ef61b0"},
+  "file_system": {:hex, :file_system, "1.0.0", "b689cc7dcee665f774de94b5a832e578bd7963c8e637ef940cd44327db7de2cd", [:mix], [], "hexpm", "6752092d66aec5a10e662aefeed8ddb9531d79db0bc145bb8c40325ca1d8536d"},
+  "jason": {:hex, :jason, "1.4.1", "af1504e35f629ddcdd6addb3513c3853991f694921b1b9368b0bd32beb9f1b63", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "fbb01ecdfd565b56261302f7e1fcc27c4fb8f32d56eab74db621fc154604a7a1"},
+  "libgraph": {:hex, :libgraph, "0.16.0", "3936f3eca6ef826e08880230f806bfea13193e49bf153f93edcf0239d4fd1d07", [:mix], [], "hexpm", "41ca92240e8a4138c30a7e06466acc709b0cbb795c643e9e17174a178982d6bf"},
+  "makeup": {:hex, :makeup, "1.1.1", "fa0bc768698053b2b3869fa8a62616501ff9d11a562f3ce39580d60860c3a55e", [:mix], [{:nimble_parsec, "~> 1.2.2 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "5dc62fbdd0de44de194898b6710692490be74baa02d9d108bc29f007783b0b48"},
+  "makeup_elixir": {:hex, :makeup_elixir, "0.16.1", "cc9e3ca312f1cfeccc572b37a09980287e243648108384b97ff2b76e505c3555", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.2.3 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "e127a341ad1b209bd80f7bd1620a15693a9908ed780c3b763bccf7d200c767c6"},
+  "makeup_erlang": {:hex, :makeup_erlang, "0.1.4", "29563475afa9b8a2add1b7a9c8fb68d06ca7737648f28398e04461f008b69521", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "f4ed47ecda66de70dd817698a703f8816daa91272e7e45812469498614ae8b29"},
+  "nimble_parsec": {:hex, :nimble_parsec, "1.4.0", "51f9b613ea62cfa97b25ccc2c1b4216e81df970acd8e16e8d1bdc58fef21370d", [:mix], [], "hexpm", "9c565862810fb383e9838c1dd2d7d2c437b3d13b267414ba6af33e50d2d1cf28"},
+  "norm": {:hex, :norm, "0.13.0", "2c562113f3205e3f195ee288d3bd1ab903743e7e9f3282562c56c61c4d95dec4", [:mix], [{:stream_data, "~> 0.5", [hex: :stream_data, repo: "hexpm", optional: true]}], "hexpm", "447cc96dd2d0e19dcb37c84b5fc0d6842aad69386e846af048046f95561d46d7"},
   "oath": {:hex, :oath, "0.1.1", "9e96fc0bc94c8e2fe2deb84641f8b4533b7753575ac1829e1db4180f2b5656c4", [:mix], [{:decorator, "~> 1.3", [hex: :decorator, repo: "hexpm", optional: false]}], "hexpm", "d7e32cf0555905d422e5a90e8a7ce49c123710caa0fa2f7840bddbc1a0e93103"},
-  "propcheck": {:hex, :propcheck, "1.3.0", "0eda73220796262c8cb38d1bf4f7ca6eb428b414f495184132f317958bb9ad68", [:mix], [{:libgraph, "~> 0.13", [hex: :libgraph, repo: "hexpm", optional: false]}, {:proper, "~> 1.3", [hex: :proper, repo: "hexpm", optional: false]}], "hexpm", "3ef93a24dc5729bdf2c418045e1a4008a79446872fd5eb0f63dc58691ae47601"},
-  "proper": {:hex, :proper, "1.3.0", "c1acd51c51da17a2fe91d7a6fc6a0c25a6a9849d8dc77093533109d1218d8457", [:make, :mix, :rebar3], [], "hexpm", "4aa192fccddd03fdbe50fef620be9d4d2f92635b54f55fb83aec185994403cbc"},
-  "telemetry": {:hex, :telemetry, "0.4.3", "a06428a514bdbc63293cd9a6263aad00ddeb66f608163bdec7c8995784080818", [:rebar3], [], "hexpm", "eb72b8365ffda5bed68a620d1da88525e326cb82a75ee61354fc24b844768041"},
+  "propcheck": {:hex, :propcheck, "1.4.1", "c12908dbe6f572032928548089b34ff9d40672d5d70f1562e3a9e9058d226cc9", [:mix], [{:libgraph, "~> 0.13", [hex: :libgraph, repo: "hexpm", optional: false]}, {:proper, "~> 1.4", [hex: :proper, repo: "hexpm", optional: false]}], "hexpm", "e1b088f574785c3c7e864da16f39082d5599b3aaf89086d3f9be6adb54464b19"},
+  "proper": {:hex, :proper, "1.4.0", "89a44b8c39d28bb9b4be8e4d715d534905b325470f2e0ec5e004d12484a79434", [:rebar3], [], "hexpm", "18285842185bd33efbda97d134a5cb5a0884384db36119fee0e3cfa488568cbb"},
+  "telemetry": {:hex, :telemetry, "1.2.1", "68fdfe8d8f05a8428483a97d7aab2f268aaff24b49e0f599faa091f1d4e7f61c", [:rebar3], [], "hexpm", "dad9ce9d8effc621708f99eac538ef1cbe05d6a874dd741de2e689c47feafed5"},
 }
diff --git a/test/mentat_test.exs b/test/mentat_test.exs
@@ -36,6 +36,22 @@ defmodule MentatTest do
       Mentat.remove_expired(cache)
       assert Mentat.keys(cache, all: true) == []
     end
+
+    test "does not call the fallback function when a nil is cached", %{cache: cache} do
+      test_pid = self()
+      fallback = fn _key ->
+        send(test_pid, :called)
+        {:commit, 42}
+      end
+
+      assert nil == Mentat.put(cache, :key, nil)
+      assert nil == Mentat.fetch(cache, :key, fallback)
+      refute_received :called
+
+      assert nil == Mentat.fetch(cache, :another_key, fn _key -> {:commit, nil} end)
+      assert nil == Mentat.fetch(cache, :key, fallback)
+      refute_received :called
+    end
   end
 
   describe "delete/2" do