diff --git a/.formatter.exs b/.formatter.exs
new file mode 100644
index 0000000..d2cda26
--- /dev/null
+++ b/.formatter.exs
@@ -0,0 +1,4 @@
+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..82ed752
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,48 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+jobs:
+  test:
+    runs-on: ubuntu-20.04
+    env:
+      MIX_ENV: test
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - pair:
+              elixir: 1.15.0
+              otp: 26.0.1
+            lint: lint
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: erlef/setup-beam@v1
+        with:
+          otp-version: ${{matrix.pair.otp}}
+          elixir-version: ${{matrix.pair.elixir}}
+
+      - name: Install Dependencies
+        run: mix deps.get --only test
+
+      - run: mix format --check-formatted
+        if: ${{ matrix.lint }}
+
+      - run: mix deps.get && mix deps.unlock --check-unused
+        if: ${{ matrix.lint }}
+
+      - run: mix deps.compile
+
+      - run: mix compile --warnings-as-errors
+        if: ${{ matrix.lint }}
+        
+      - run: mix credo
+
+      - run: mix test
+
+      - run: mix dialyzer --unmatched_returns
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..b263cd1
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,10 @@
+/_build
+/cover
+/deps
+/doc
+/.fetch
+erl_crash.dump
+*.ez
+*.beam
+/config/*.secret.exs
+.elixir_ls/
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..942e911
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,7 @@
+# Changelog for Jop
+
+
+
+## v0.1.0 (2023-12-02)
+
+  * First release.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..ae51114
--- /dev/null
+++ b/README.md
@@ -0,0 +1,117 @@
+# JOP: an in-memory key value logger
+[![Test](https://github.com/bougueil/jop_ex/actions/workflows/ci.yml/badge.svg)](https://github.com/bougueil/jop_ex/actions/workflows/ci.yml)
+
+Logs in memory, spatially and temporally, key value events.<br>
+These events, generated by multiple processes, are then flushed to disk for analysis (e.g. to detect locks).
+
+
+## Installation
+
+
+```elixir
+def deps do
+  [
+    {:jop_ex, git: "https://github.com/bougueil/jop_ex"}
+  ]
+end
+```
+
+## Usage
+```
+  iex> "myjop"
+  ...> |> Jop.init()
+  ...> |> Jop.log("key_1", :any_term_112)
+  ...> |> Jop.log("key_2", :any_term_133)
+  ...> |> Jop.flush()
+log stored in jop_myjop.2020_05_12_21.42.49_dates.gz
+log stored in jop_myjop.2020_05_12_21.42.49_keys.gz
+#Jop<myjop:uninitialized>
+```
+
+## Performance
+Excerpt from a run of the unit test :
+```
+througput 1267456 logs/s.
+```
+
+## Basic example
+```
+# prepare for logging and return a handle
+myjop = Jop.init("myjop")
+
+# log with handle event "key_1", :any_term_112
+Jop.log myjop, "key_1", :any_term_112
+Process.sleep 12
+
+# clear logs
+Jop.clear myjop
+
+Jop.log myjop, "key_2", :any_term_113
+Process.sleep 12
+
+Jop.log myjop, "key_1", :any_term_112
+Process.sleep 12
+
+Jop.log myjop, "key_2", :any_term_113
+# flush to disk and erase the log
+Jop.flush myjop
+
+log stored in jop_myjop.2020_05_12_21.42.49_dates.gz
+log stored in jop_myjop.2020_05_12_21.42.49_keys.gz
+#Jop<myjop:uninitialized>
+```
+will generate both a temporal (by date) and a spatial (by key) log files:
+
+### Temporal log file
+```
+# list all operations by date
+zcat jop_myjop.2020_05_12_21.42.49_dates.gz
+
+00:00:00_000.482 "key_2": :any_term_113
+00:00:00_014.674 "key_1": :any_term_112
+00:00:00_028.568 "key_2": :any_term_113
+
+```
+
+### Spatial (by key) log file
+```
+# list all operations by key :
+zcat jop_myjop.2020_05_12_21.42.49_keys.gz
+
+"key_1": 00:00:00_014.674 :any_term_112
+"key_2": 00:00:00_000.482 :any_term_113
+"key_2": 00:00:00_028.568 :any_term_113
+```
+## Real life: multiple processes logging
+Processes log in myjop as follow:
+```
+# Handle can be saved in process state
+myjop = Jop.ref("myjop")
+
+# Log if logging is activated
+Jop.log myjop, "key_1", :any_term_112
+```
+Console activate / deactivate the logging:
+```
+# Activate the logging
+# Starts the logging
+myjop = Jop.init("myjop")
+
+# Do some queries while the logging is on
+inspect myjop # see how many records
+Enum.count mylog
+Enum.member? mylog, "mykey"
+ ...
+
+# Flush the logs on disk, keep on logging
+Jop.flush myjop, :nostop
+
+# Clear the logs, keep on logging
+Jop.clear myjop  # clear all entries and continue logging
+
+# Flush the logs on disk and deactivate the logging
+Jop.flush myjop
+
+# Start logging again
+Jop.init("myjop")
+```
\ No newline at end of file
diff --git a/config/config.exs b/config/config.exs
new file mode 100644
index 0000000..dd82180
--- /dev/null
+++ b/config/config.exs
@@ -0,0 +1,7 @@
+import Config
+
+# https://spapas.github.io/2020/05/15/elixir-osmon-alerts/
+# config :os_mon,
+#   memsup_system_only: true,
+#   start_disk_sup: false,
+#   start_cpu_sup: false
diff --git a/lib/common.ex b/lib/common.ex
new file mode 100644
index 0000000..1bc1203
--- /dev/null
+++ b/lib/common.ex
@@ -0,0 +1,39 @@
+# See LICENSE for licensing information.
+
+defmodule JLValid do
+  @moduledoc false
+
+  defmacro ets?(tab, clauses) do
+    valid_if(tab, clauses)
+  end
+
+  defp valid_if(tab, do: do_clause) do
+    valid_if(tab, do: do_clause, else: nil)
+  end
+
+  defp valid_if(tab, do: do_clause, else: else_clause) do
+    quote do
+      case :undefined != :ets.info(unquote(tab), :size) do
+        x when :"Elixir.Kernel".in(x, [false, nil]) -> unquote(else_clause)
+        _ -> unquote(do_clause)
+      end
+    end
+  end
+end
+
+defmodule JLCommon do
+  @moduledoc false
+
+  @date_format ".~p_~2.2.0w_~2.2.0w_~2.2.0w.~2.2.0w.~2.2.0w"
+
+  def date_str do
+    hms =
+      List.flatten(
+        for e <- Tuple.to_list(:calendar.universal_time_to_local_time(:calendar.universal_time())) do
+          Tuple.to_list(e)
+        end
+      )
+
+    :io_lib.format(@date_format, hms)
+  end
+end
diff --git a/lib/jop_log.ex b/lib/jop_log.ex
new file mode 100644
index 0000000..5be89e6
--- /dev/null
+++ b/lib/jop_log.ex
@@ -0,0 +1,180 @@
+# See LICENSE for licensing information.
+
+defmodule Jop do
+  require JLValid
+  @tag_start "jop_start"
+
+  @moduledoc """
+  Documentation for Jop an in memory log
+
+  ## Example
+
+  iex> "mylog"
+  ...> |> Jop.init()
+  ...> |> Jop.log("device_1", data: 112)
+  ...> |> Jop.log("device_2", data: 113)
+  ...> |> Jop.flush()
+
+  """
+
+  defstruct [:ets]
+  @type t :: %__MODULE__{ets: atom()}
+
+  @doc """
+    Initialize Jop with a log name.
+  returns a handle %Joplog{}
+  """
+  @spec init(log_name :: binary()) :: Jop.t()
+  def init(log_name) when is_binary(log_name) do
+    tab = String.to_atom(log_name)
+
+    JLValid.ets? tab do
+      Jop.ref(log_name)
+      |> reset()
+    end
+
+    _ = :ets.new(tab, [:bag, :named_table, :public])
+
+    joplog = Jop.ref(log_name)
+
+    IO.puts("Jop now logging on memory joplog #{joplog.ets}.")
+    log(joplog, @tag_start, "#{JLCommon.date_str()}")
+  end
+
+  @doc """
+  returns a handle from a log name
+  does not require JOP doesn't require init/1
+  """
+  @spec ref(log_name :: String.t()) :: Jop.t()
+  def ref(log_name) when is_binary(log_name) do
+    tab = String.to_atom(log_name)
+
+    %Jop{ets: tab}
+  end
+
+  @doc """
+  log with the handle jop a key and its value
+  returns the handle.
+  """
+  @spec log(Jop.t(), any, any) :: Jop.t()
+  def log(%Jop{ets: tab} = jop, key, value) do
+    JLValid.ets?(tab, do: :ets.insert(tab, {key, value, now_μs()}))
+    jop
+  end
+
+  @doc """
+  write a joplog on disk from a handle.
+  2 logs are generated : dates.gz and keys.gz
+  unless option :notstop is used, logging is stopped.
+  """
+  @spec flush(Jop.t(), opt :: atom) :: Jop.t()
+  def flush(%Jop{ets: tab} = joplog, opt \\ nil) do
+    JLValid.ets? tab do
+      {logs, t0} =
+        case lookup_tag_start(tab) do
+          nil ->
+            {[], 0}
+
+          t0 ->
+            {:ets.tab2list(tab), t0}
+        end
+
+      if opt == :nostop do
+        IO.puts(
+          "Jop continue logging.\nflushing memory joplog #{tab} (#{Enum.count(joplog)} records) on files ..."
+        )
+
+        clear(joplog)
+      else
+        IO.puts(
+          "Jop logging stopped.\nflushing memory joplog #{tab} (#{Enum.count(joplog)} records) on files ..."
+        )
+
+        reset(joplog)
+      end
+
+      JL.Writer.flush(tab, t0, logs)
+    end
+
+    joplog
+  end
+
+  defp reset(%Jop{ets: tab}),
+    do: JLValid.ets?(tab, do: :ets.delete(tab))
+
+  defp lookup_tag_start(tab) do
+    case :ets.lookup(tab, @tag_start) do
+      [{_, _, t0}] ->
+        t0
+
+      [] ->
+        nil
+    end
+  end
+
+  @doc """
+  erase all entries from the jop handle
+  """
+  @spec clear(Jop.t()) :: Jop.t()
+  def clear(%Jop{ets: tab} = jop) do
+    JLValid.ets? tab do
+      t0 = lookup_tag_start(tab)
+      :ets.delete_all_objects(tab)
+
+      if t0 do
+        :ets.insert(tab, {@tag_start, t0, now_μs()})
+      end
+    end
+
+    jop
+  end
+
+  defp now_μs, do: System.monotonic_time(:microsecond)
+
+  @doc """
+  returns if the handle  is initialized with an ets table
+  """
+  def is_initialized(%Jop{ets: tab}),
+    do: JLValid.ets?(tab, do: true, else: false)
+
+  defimpl Enumerable do
+    @doc """
+    returns the size of the Jop log
+    """
+    def count(%Jop{ets: tab}) do
+      {:ok, max(0, :ets.info(tab, :size) - 1)}
+    end
+
+    @doc """
+    returns if `key`is member of Jop
+    """
+    @spec member?(Jop.t(), any) :: {:ok, boolean}
+    def member?(%Jop{ets: tab}, key) do
+      {:ok, :ets.member(tab, key)}
+    end
+
+    def reduce(%Jop{ets: tab}, acc, fun) do
+      :ets.tab2list(tab)
+      |> List.keysort(2)
+      |> Enum.drop(1)
+      |> Enum.map(fn {k, v, _t} -> {k, v} end)
+      |> Enumerable.List.reduce(acc, fun)
+    end
+
+    def slice(_id) do
+      {:error, __MODULE__}
+    end
+  end
+
+  defimpl Inspect do
+    import Inspect.Algebra
+
+    def inspect(%Jop{ets: tab} = jop, opts) do
+      JLValid.ets? tab do
+        concat(["#Jop<#{tab}:size(", to_doc(Enum.count(jop), opts), ")>"])
+      else
+        concat(["#Jop<#{tab}:uninitialized>"])
+      end
+    end
+  end
+end
diff --git a/lib/writer.ex b/lib/writer.ex
new file mode 100644
index 0000000..cbd8d29
--- /dev/null
+++ b/lib/writer.ex
@@ -0,0 +1,49 @@
+# See LICENSE for licensing information.
+
+defmodule JL.Writer do
+  @moduledoc false
+
+  @usecond_format "~2.2.0w:~2.2.0w:~2.2.0w_~3.3.0w.~3.3.0w"
+
+  defp fname(tab, ext), do: ["jop_#{tab}", JLCommon.date_str(), "_", ext]
+
+  defp fmt_duration_us(duration_us) do
+    sec = div(duration_us, 1_000_000)
+    rem_us = rem(duration_us, 1_000_000)
+    ms = div(rem_us, 1000)
+    us = rem(rem_us, 1000)
+    {_, {h, m, s}} = :calendar.gregorian_seconds_to_datetime(sec)
+    :io_lib.format(@usecond_format, [h, m, s, ms, us])
+  end
+
+  def flush(tab, t0, logs) do
+    names = for f <- ~w(dates keys), do: fname(tab, "#{f}.gz")
+    [fa, fb] = for name <- names, do: File.open!(name, [:write, :compressed, encoding: :unicode])
+
+    # factorize
+    # flush log to the 'temporal' log file
+    awaits = [
+      {Task.async(fn ->
+         for {k, op, t} <- List.keysort(logs, 2) do
+           IO.puts(fa, "#{fmt_duration_us(t - t0)} #{inspect(k)}: #{inspect(op)}")
+         end
+       end), fa},
+      # flush log to 'spatial' log file
+      {Task.async(fn ->
+         for {k, op, t} <- List.keysort(logs, 0) do
+           IO.puts(fb, "#{inspect(k)}: #{fmt_duration_us(t - t0)} #{inspect(op)}")
+         end
+       end), fb}
+    ]
+
+    for {task, fd} <- awaits,
+        do:
+          (
+            Task.await(task, :infinity)
+            _ = File.close(fd)
+          )
+
+    IO.puts("log stored in :")
+    for name <- names, do: IO.puts("- #{name}")
+  end
+end
diff --git a/mix.exs b/mix.exs
new file mode 100644
index 0000000..d05a9e6
--- /dev/null
+++ b/mix.exs
@@ -0,0 +1,46 @@
+defmodule Jop.Mixfile do
+  use Mix.Project
+
+  @version "0.1.0"
+  def project do
+    [
+      app: :jop,
+      version: @version,
+      elixir: ">= 1.14.1",
+      package: package(),
+      start_permanent: Mix.env() == :prod,
+      deps: deps(),
+      docs: [
+        main: "Superls",
+        source_ref: "v#{@version}",
+        source_url: "https://github.com/bougueil/superls"
+      ]
+    ]
+  end
+
+  def application do
+    [
+      extra_applications: [
+        :logger
+        # , :os_mon
+      ]
+    ]
+  end
+
+  # Run "mix help deps" to learn about dependencies.
+  defp deps do
+    [
+      {:ex_doc, "~> 0.30", only: [:docs, :test], runtime: false},
+      {:dialyxir, "~> 1.2", only: [:dev, :test], runtime: false},
+      {:credo, "~> 1.6", only: [:dev, :test], runtime: false}
+    ]
+  end
+
+  defp package do
+    %{
+      licenses: ["Apache-2.0"],
+      maintainers: ["Renaud Mariana"],
+      links: %{"GitHub" => "https://github.com/bougueil/jop"}
+    }
+  end
+end
diff --git a/mix.lock b/mix.lock
new file mode 100644
index 0000000..14fa243
--- /dev/null
+++ b/mix.lock
@@ -0,0 +1,14 @@
+%{
+  "bunt": {:hex, :bunt, "0.2.1", "e2d4792f7bc0ced7583ab54922808919518d0e57ee162901a16a1b6664ef3b14", [:mix], [], "hexpm", "a330bfb4245239787b15005e66ae6845c9cd524a288f0d141c148b02603777a5"},
+  "credo": {:hex, :credo, "1.7.1", "6e26bbcc9e22eefbff7e43188e69924e78818e2fe6282487d0703652bc20fd62", [:mix], [{:bunt, "~> 0.2.1", [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", "e9871c6095a4c0381c89b6aa98bc6260a8ba6addccf7f6a53da8849c748a58a2"},
+  "dialyxir": {:hex, :dialyxir, "1.4.2", "764a6e8e7a354f0ba95d58418178d486065ead1f69ad89782817c296d0d746a5", [:mix], [{:erlex, ">= 0.2.6", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "516603d8067b2fd585319e4b13d3674ad4f314a5902ba8130cd97dc902ce6bbd"},
+  "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, "0.30.9", "d691453495c47434c0f2052b08dd91cc32bc4e1a218f86884563448ee2502dd2", [:mix], [{:earmark_parser, "~> 1.4.31", [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", "d7aaaf21e95dc5cddabf89063327e96867d00013963eadf2c6ad135506a8bc10"},
+  "file_system": {:hex, :file_system, "0.2.10", "fb082005a9cd1711c05b5248710f8826b02d7d1784e7c3451f9c1231d4fc162d", [:mix], [], "hexpm", "41195edbfb562a593726eda3b3e8b103a309b733ad25f3d642ba49696bf715dc"},
+  "jason": {:hex, :jason, "1.4.1", "af1504e35f629ddcdd6addb3513c3853991f694921b1b9368b0bd32beb9f1b63", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "fbb01ecdfd565b56261302f7e1fcc27c4fb8f32d56eab74db621fc154604a7a1"},
+  "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, "0.1.2", "ad87296a092a46e03b7e9b0be7631ddcf64c790fa68a9ef5323b6cbb36affc72", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "f3f5a1ca93ce6e092d92b6d9c049bcda58a3b617a8d888f8e7231c85630e8108"},
+  "nimble_parsec": {:hex, :nimble_parsec, "1.4.0", "51f9b613ea62cfa97b25ccc2c1b4216e81df970acd8e16e8d1bdc58fef21370d", [:mix], [], "hexpm", "9c565862810fb383e9838c1dd2d7d2c437b3d13b267414ba6af33e50d2d1cf28"},
+}
diff --git a/test/jop_test.exs b/test/jop_test.exs
new file mode 100644
index 0000000..c687ecc
--- /dev/null
+++ b/test/jop_test.exs
@@ -0,0 +1,104 @@
+defmodule JopTest do
+  use ExUnit.Case
+  @jop_log "test_jop_log"
+
+  #  doctest Jop
+
+  setup do
+    on_exit(fn -> clean_jop_files(@jop_log) end)
+  end
+
+  test "ref from uninitialized" do
+    jop = Jop.ref(@jop_log)
+    refute Jop.is_initialized(jop)
+  end
+
+  test "ref from initialized" do
+    joplog = Jop.init(@jop_log)
+    assert try do: Jop.ref(@jop_log), catch: (any -> false), else: (_ -> true)
+    assert is_struct(joplog, Jop)
+  end
+
+  test "double init" do
+    joplog = Jop.init(@jop_log)
+    ^joplog = Jop.init(@jop_log)
+    assert is_struct(joplog, Jop)
+    assert Enum.empty?(joplog)
+    assert joplog == Jop.flush(joplog)
+    assert all_logs_are_present?(@jop_log)
+  end
+
+  test "clear" do
+    joplog = Jop.init(@jop_log)
+    Jop.log(joplog, "key_1", :any_term_112)
+    Jop.clear(joplog)
+    assert Enum.empty?(joplog)
+    assert joplog == Jop.flush(joplog)
+    assert all_logs_are_present?(@jop_log)
+  end
+
+  test "flush" do
+    joplog = Jop.init(@jop_log)
+    Jop.log(joplog, "key_1", :any_term_112)
+    Jop.flush(joplog)
+    refute Jop.is_initialized(joplog)
+    assert all_logs_are_present?(@jop_log)
+  end
+
+  test "flush nostop" do
+    joplog = Jop.init(@jop_log)
+    Jop.log(joplog, "key_1", :any_term_112)
+    Jop.flush(joplog, :nostop)
+    assert joplog == Jop.log(joplog, "mykey2", {:vv, 113})
+    assert Enum.count(joplog) == 1
+    assert joplog == Jop.flush(joplog)
+    assert all_logs_are_present?(@jop_log)
+  end
+
+  test "log_and_dump" do
+    joplog = Jop.init(@jop_log)
+    assert is_struct(joplog, Jop)
+
+    assert joplog == Jop.log(joplog, "mykey1", {:vv, 112})
+    :timer.sleep(12)
+    assert joplog == Jop.init(@jop_log)
+
+    assert joplog == Jop.log(joplog, "mykey2", {:vv, 113})
+
+    :timer.sleep(12)
+    assert joplog = Jop.log(joplog, "mykey1", {:vv, 112})
+
+    :timer.sleep(12)
+    assert joplog == Jop.log(joplog, "mykey2", {:vv, 113})
+
+    assert Enum.count(joplog) == 3
+    assert joplog == Jop.flush(joplog)
+    assert all_logs_are_present?(@jop_log)
+  end
+
+  test "is_initialized" do
+    job_ref = Jop.ref(@jop_log)
+    joplog = Jop.init(@jop_log)
+    assert Jop.is_initialized(joplog)
+    assert joplog == Jop.flush(joplog)
+    assert all_logs_are_present?(@jop_log)
+  end
+
+  test "enumerable" do
+    joplog = Jop.init(@jop_log)
+    assert is_struct(joplog, Jop)
+    assert joplog == Jop.log(joplog, "mykey", "myvalue")
+    assert joplog == Jop.log(joplog, "mykey", "myvalue777")
+    assert Enum.count(joplog) == 2
+    assert Enum.member?(joplog, "mykey")
+    assert 10 == Enum.reduce(joplog, 0, fn {_k, val}, acc -> max(byte_size(val), acc) end)
+  end
+
+  defp all_logs_are_present?(id),
+    do: 2 == length(Path.wildcard("jop_#{id}*.gz"))
+
+  def clean_jop_files(id) do
+    for file <- Path.wildcard("jop_#{id}*.gz"),
+        do: File.rm!(file)
+  end
+end
diff --git a/test/perf_test.exs b/test/perf_test.exs
new file mode 100644
index 0000000..faa48ec
--- /dev/null
+++ b/test/perf_test.exs
@@ -0,0 +1,21 @@
+defmodule PerfTest do
+  use ExUnit.Case
+  @jop_log "test_jop_log"
+
+  test "measure logging" do
+    joplog = Jop.init(@jop_log)
+
+    n = 1_000_000
+
+    {tlog, _} =
+      fn ->
+        for i <- 1..n,
+            do: Jop.log(joplog, <<i::size(40)>>, {<<"data.", <<i::size(40)>>::binary>>})
+      end
+      |> :timer.tc()
+
+    througput = div(n * 1_000_000, tlog)
+    IO.puts("througput #{througput} logs/s.")
+    assert Enum.count(joplog) == n
+  end
+end
diff --git a/test/test_helper.exs b/test/test_helper.exs
new file mode 100644
index 0000000..869559e
--- /dev/null
+++ b/test/test_helper.exs
@@ -0,0 +1 @@
+ExUnit.start()