Examples + refinements

.github/copilot-instructions.md

@@ -94,3 +94,4 @@ Tests use ExUnit. See `test/httpd_integration_test.exs` for socket-level testing
 | `include/*.hrl` | Header files - HTTP codes, trace macros |
 | `priv/` | Static assets (served via `httpd_file_handler`) |
 | `test/support/` | Test-only modules |
+| `erlang_example` | Erlang example implementation |

.gitignore

@@ -22,4 +22,6 @@ atomvm_httpd-*.tar
 # Temporary files, for example, from tests.
 /tmp/
 
-.elixir_ls/
+.elixir_ls/
+
+.envrc

TODO.md

@@ -83,13 +83,28 @@ Tracking document for memory leak and VM stability issues identified during code
 
 ---
 
+## Code Quality Improvements
+
+### 9. ✅ Replace custom iolist_length with erlang:iolist_size
+**File:** `src/httpd.erl` line 582
+
+**Problem:** Used custom `iolist_length/1` function instead of the standard `erlang:iolist_size/1` BIF which is available in AtomVM. Custom implementation works correctly but adds unnecessary code maintenance burden.
+
+**Solution:** Replace with `erlang:iolist_size/1` and remove custom function.
+
+**Status:** Fixed - replaced custom implementation with standard BIF, all tests passing.
+
+---
+
 ## Progress Log
 
 | Date | Issue # | Status | Notes |
 |------|---------|--------|-------|
 | 2024-12-07 | - | - | Initial review and documentation |
 | 2024-12-07 | 5 | ✅ | Fixed map update operator in httpd.erl |
 | 2024-12-07 | 1 | ✅ | Fixed accept loop crash recovery in gen_tcp_server.erl |
+| 2026-01-11 | 9 | ✅ | Replaced custom iolist_length with erlang:iolist_size/1 |
+| 2026-01-11 | - | - | Added comprehensive iolist handler tests |
 
 ---
 

examples/elixir_http/.formatter.exs

@@ -0,0 +1,4 @@
+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]

examples/elixir_http/.gitignore

@@ -0,0 +1,26 @@
+# The directory Mix will write compiled artifacts to.
+/_build/
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover/
+
+# The directory Mix downloads your dependencies sources to.
+/deps/
+
+# Where third-party dependencies like ExDoc output generated docs.
+/doc/
+
+# Temporary files, for example, from tests.
+/tmp/
+
+# If the VM crashes, it generates a dump, let's ignore it too.
+erl_crash.dump
+
+# Also ignore archive artifacts (built via "mix archive.build").
+*.ez
+
+# Ignore package tarball (built via "mix hex.build").
+elixir_http-*.tar
+
+
+*.avm

examples/elixir_http/README.md

@@ -0,0 +1,21 @@
+# ElixirHttp
+
+**TODO: Add description**
+
+## Installation
+
+If [available in Hex](https://hex.pm/docs/publish), the package can be installed
+by adding `elixir_http` to your list of dependencies in `mix.exs`:
+
+```elixir
+def deps do
+  [
+    {:elixir_http, "~> 0.1.0"}
+  ]
+end
+```
+
+Documentation can be generated with [ExDoc](https://github.com/elixir-lang/ex_doc)
+and published on [HexDocs](https://hexdocs.pm). Once published, the docs can
+be found at <https://hexdocs.pm/elixir_http>.
+

examples/elixir_http/lib/elixir_http.ex

@@ -0,0 +1,82 @@
+defmodule ElixirHttp do
+  @moduledoc """
+  Elixir httpd example
+  """
+  @compile {:no_warn_undefined, :network}
+
+  def start do
+    :ok = start_network()
+
+    :ok = start_http()
+
+    Process.sleep(:infinity)
+  end
+
+  # resolved at compile time
+  @ssid System.get_env("SSID")
+  @psk System.get_env("PSK")
+
+  def start_network() do
+    Process.sleep(500)
+    config = [ssid: @ssid, psk: @psk]
+
+    case :network.wait_for_sta(config, 15_000) do
+      {:ok, _} ->
+        :ok
+
+      {:error, :disconnected} ->
+        # try again...
+        start_network()
+
+      {:error, {:already_started, _pid}} ->
+        Process.sleep(500)
+        :ok
+
+      {:error, err} ->
+        IO.puts("Error starting network #{inspect(err)}")
+
+        :error
+    end
+  end
+
+  defp start_http(port \\ 8080) do
+    config = [
+      # API endpoints at /api/*
+      {["api"],
+       %{
+         handler: :httpd_api_handler,
+         handler_config: %{
+           module: ElixirHttp.ApiHandler
+         }
+       }},
+      # WebSocket at /ws/*
+      {["ws"],
+       %{
+         handler: :httpd_ws_handler,
+         handler_config: %{
+           module: ElixirHttp.WsHandler
+         }
+       }},
+      # Static files from priv/ at root
+      {[],
+       %{
+         handler: :httpd_file_handler,
+         handler_config: %{
+           app: :elixir_http
+         }
+       }}
+    ]
+
+    IO.puts("Starting httpd on port #{port}...")
+
+    case :httpd.start(port, config) do
+      {:ok, _pid} ->
+        IO.puts("httpd started.")
+        :ok
+
+      error ->
+        IO.puts("An error occurred: #{inspect(error)}")
+        :error
+    end
+  end
+end

examples/elixir_http/lib/elixir_http/api_handler.ex

@@ -0,0 +1,56 @@
+defmodule ElixirHttp.ApiHandler do
+  @compile {:no_warn_undefined, :atomvm}
+
+  @moduledoc """
+  API handler for system info and memory endpoints.
+  Implements the httpd_api_handler behavior.
+  """
+
+  @behaviour :httpd_api_handler
+
+  @impl true
+  def handle_api_request(:get, ["system_info"], _http_request, _args) do
+    # = Map.get(http_request, :socket)
+    # {:ok, %{addr: host, port: port}} = :socket.peername(socket)
+    # IO.puts("GET system_info request from #{inspect(host)}:#{port}")
+
+    result = %{
+      platform: :atomvm.platform(),
+      system_architecture: :erlang.system_info(:system_architecture),
+      atomvm_version: :erlang.system_info(:atomvm_version),
+      word_size: :erlang.system_info(:wordsize),
+      esp32_chip_info: get_esp32_chip_info(),
+      esp_idf_version: :erlang.system_info(:esp_idf_version)
+    }
+
+    {:ok, result}
+  end
+
+  def handle_api_request(:get, ["memory"], _http_request, _args) do
+    # socket = Map.get(http_request, :socket)
+    # {:ok, %{addr: host, port: port}} = :socket.peername(socket)
+    # IO.puts("GET memory request from #{inspect(host)}:#{port}")
+
+    {:ok, get_memory_data()}
+  end
+
+  def handle_api_request(method, path, _http_request, _args) do
+    IO.puts("ERROR! Unsupported method #{inspect(method)} or path #{inspect(path)}")
+    {:error, :not_found}
+  end
+
+  def get_memory_data() do
+    %{
+      atom_count: :erlang.system_info(:atom_count),
+      process_count: :erlang.system_info(:process_count),
+      port_count: :erlang.system_info(:port_count),
+      esp32_free_heap_size: :erlang.system_info(:esp32_free_heap_size),
+      esp32_largest_free_block: :erlang.system_info(:esp32_largest_free_block),
+      esp32_minimum_free_size: :erlang.system_info(:esp32_minimum_free_size)
+    }
+  end
+
+  defp get_esp32_chip_info() do
+    :erlang.system_info(:esp32_chip_info)
+  end
+end

examples/elixir_http/lib/elixir_http/ws_handler.ex

@@ -0,0 +1,56 @@
+defmodule ElixirHttp.WsHandler do
+  @moduledoc """
+  WebSocket handler that sends memory updates to connected clients.
+  Implements the httpd_ws_handler behavior.
+  """
+
+  @behaviour :httpd_ws_handler
+
+  @impl true
+  def handle_ws_init(websocket, _path, _args) do
+    IO.puts("Initializing websocket pid=#{inspect(self())}")
+    last_memory = ElixirHttp.ApiHandler.get_memory_data()
+    spawn(fn -> update_loop(websocket, last_memory) end)
+    {:ok, nil}
+  end
+
+  @impl true
+  def handle_ws_message("ping", state) do
+    {:reply, "pong", state}
+  end
+
+  def handle_ws_message(message, state) do
+    # IO.puts("Received message from web socket. Message: #{inspect(message)}")
+    {:noreply, state}
+  end
+
+  defp update_loop(websocket, last_memory_data) do
+    Process.sleep(5000)
+    latest_memory_data = ElixirHttp.ApiHandler.get_memory_data()
+
+    new_memory_data = get_difference(last_memory_data, latest_memory_data)
+
+    case new_memory_data do
+      [] ->
+        :ok
+
+      _ ->
+        binary = :erlang.iolist_to_binary(:json_encoder.encode(Map.new(new_memory_data)))
+        # IO.puts("Sending websocket message to client #{inspect(binary)} ... ")
+        :httpd_ws_handler.send(websocket, binary)
+        IO.puts("sent.")
+    end
+
+    update_loop(websocket, latest_memory_data)
+  end
+
+  defp get_difference(map1, map2) do
+    Enum.reduce(map1, [], fn {key, value}, acc ->
+      case Map.get(map2, key) do
+        nil -> [{key, value} | acc]
+        ^value -> acc
+        new_value -> [{key, new_value} | acc]
+      end
+    end)
+  end
+end

examples/elixir_http/mix.exs

@@ -0,0 +1,37 @@
+defmodule ElixirHttp.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :elixir_http,
+      version: "0.1.0",
+      elixir: "~> 1.19",
+      start_permanent: Mix.env() == :prod,
+      deps: deps(),
+      atomvm: [
+        # Change to Lux.Test for minimal testing without networking
+        start: ElixirHttp,
+        flash_offset: 0x250000
+      ]
+    ]
+  end
+
+  # Run "mix help compile.app" to learn about applications.
+  def application do
+    [
+      extra_applications: [:logger]
+    ]
+  end
+
+  # Run "mix help deps" to learn about dependencies.
+  defp deps do
+    [
+      {:pythonx, "~> 0.4.7", runtime: false},
+      {:exatomvm, github: "atomvm/ExAtomVM", runtime: false},
+      {:atomvm_httpd, path: "../../"},
+      # Test-only dependencies
+      {:req, "~> 0.5", only: :test, runtime: false},
+      {:websockex, "~> 0.4.3", only: :test, runtime: false}
+    ]
+  end
+end

examples/elixir_http/mix.lock

@@ -0,0 +1,18 @@
+%{
+  "cc_precompiler": {:hex, :cc_precompiler, "0.1.11", "8c844d0b9fb98a3edea067f94f616b3f6b29b959b6b3bf25fee94ffe34364768", [:mix], [{:elixir_make, "~> 0.7", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "3427232caf0835f94680e5bcf082408a70b48ad68a5f5c0b02a3bea9f3a075b9"},
+  "elixir_make": {:hex, :elixir_make, "0.9.0", "6484b3cd8c0cee58f09f05ecaf1a140a8c97670671a6a0e7ab4dc326c3109726", [:mix], [], "hexpm", "db23d4fd8b757462ad02f8aa73431a426fe6671c80b200d9710caf3d1dd0ffdb"},
+  "exatomvm": {:git, "https://github.com/atomvm/ExAtomVM.git", "0f9351417673d347d442c3283cca1bfeb47458f6", []},
+  "finch": {:hex, :finch, "0.20.0", "5330aefb6b010f424dcbbc4615d914e9e3deae40095e73ab0c1bb0968933cadf", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:mint, "~> 1.6.2 or ~> 1.7", [hex: :mint, repo: "hexpm", optional: false]}, {:nimble_options, "~> 0.4 or ~> 1.0", [hex: :nimble_options, repo: "hexpm", optional: false]}, {:nimble_pool, "~> 1.1", [hex: :nimble_pool, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "2658131a74d051aabfcba936093c903b8e89da9a1b63e430bee62045fa9b2ee2"},
+  "fine": {:hex, :fine, "0.1.4", "b19a89c1476c7c57afb5f9314aed5960b5bc95d5277de4cb5ee8e1d1616ce379", [:mix], [], "hexpm", "be3324cc454a42d80951cf6023b9954e9ff27c6daa255483b3e8d608670303f5"},
+  "hpax": {:hex, :hpax, "1.0.3", "ed67ef51ad4df91e75cc6a1494f851850c0bd98ebc0be6e81b026e765ee535aa", [:mix], [], "hexpm", "8eab6e1cfa8d5918c2ce4ba43588e894af35dbd8e91e6e55c817bca5847df34a"},
+  "jason": {:hex, :jason, "1.4.4", "b9226785a9aa77b6857ca22832cffa5d5011a667207eb2a0ad56adb5db443b8a", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "c5eb0cab91f094599f94d55bc63409236a8ec69a21a67814529e8d5f6cc90b3b"},
+  "mime": {:hex, :mime, "2.0.7", "b8d739037be7cd402aee1ba0306edfdef982687ee7e9859bee6198c1e7e2f128", [:mix], [], "hexpm", "6171188e399ee16023ffc5b76ce445eb6d9672e2e241d2df6050f3c771e80ccd"},
+  "mint": {:hex, :mint, "1.7.1", "113fdb2b2f3b59e47c7955971854641c61f378549d73e829e1768de90fc1abf1", [:mix], [{:castore, "~> 0.1.0 or ~> 1.0", [hex: :castore, repo: "hexpm", optional: true]}, {:hpax, "~> 0.1.1 or ~> 0.2.0 or ~> 1.0", [hex: :hpax, repo: "hexpm", optional: false]}], "hexpm", "fceba0a4d0f24301ddee3024ae116df1c3f4bb7a563a731f45fdfeb9d39a231b"},
+  "nimble_options": {:hex, :nimble_options, "1.1.1", "e3a492d54d85fc3fd7c5baf411d9d2852922f66e69476317787a7b2bb000a61b", [:mix], [], "hexpm", "821b2470ca9442c4b6984882fe9bb0389371b8ddec4d45a9504f00a66f650b44"},
+  "nimble_pool": {:hex, :nimble_pool, "1.1.0", "bf9c29fbdcba3564a8b800d1eeb5a3c58f36e1e11d7b7fb2e084a643f645f06b", [:mix], [], "hexpm", "af2e4e6b34197db81f7aad230c1118eac993acc0dae6bc83bac0126d4ae0813a"},
+  "pythonx": {:hex, :pythonx, "0.4.7", "604a3a78377abdaa8739c561cb871c856b0e80d25fd057277839912017004af0", [:make, :mix], [{:cc_precompiler, "~> 0.1", [hex: :cc_precompiler, repo: "hexpm", optional: false]}, {:elixir_make, "~> 0.9", [hex: :elixir_make, repo: "hexpm", optional: false]}, {:fine, "~> 0.1.2", [hex: :fine, repo: "hexpm", optional: false]}], "hexpm", "20d8b456df995e6ccd6d88dcf118ba80464194515f71a5c89aacdb824d235c52"},
+  "req": {:hex, :req, "0.5.17", "0096ddd5b0ed6f576a03dde4b158a0c727215b15d2795e59e0916c6971066ede", [:mix], [{:brotli, "~> 0.3.1", [hex: :brotli, repo: "hexpm", optional: true]}, {:ezstd, "~> 1.0", [hex: :ezstd, repo: "hexpm", optional: true]}, {:finch, "~> 0.17", [hex: :finch, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}, {:mime, "~> 2.0.6 or ~> 2.1", [hex: :mime, repo: "hexpm", optional: false]}, {:nimble_csv, "~> 1.0", [hex: :nimble_csv, repo: "hexpm", optional: true]}, {:plug, "~> 1.0", [hex: :plug, repo: "hexpm", optional: true]}], "hexpm", "0b8bc6ffdfebbc07968e59d3ff96d52f2202d0536f10fef4dc11dc02a2a43e39"},
+  "telemetry": {:hex, :telemetry, "1.3.0", "fedebbae410d715cf8e7062c96a1ef32ec22e764197f70cda73d82778d61e7a2", [:rebar3], [], "hexpm", "7015fc8919dbe63764f4b4b87a95b7c0996bd539e0d499be6ec9d7f3875b79e6"},
+  "uf2tool": {:hex, :uf2tool, "1.1.0", "7091931234ca5a256b66ea691983867d51229798622d083f85c1ad779798a734", [:rebar3], [], "hexpm", "1a7e5ca7ef3d19c7a0b0acf3db804b3188e0980884acffa13fd57d733507b73d"},
+  "websockex": {:hex, :websockex, "0.4.3", "92b7905769c79c6480c02daacaca2ddd49de936d912976a4d3c923723b647bf0", [:mix], [], "hexpm", "95f2e7072b85a3a4cc385602d42115b73ce0b74a9121d0d6dbbf557645ac53e4"},
+}