View Source Dune.Opts (dune v0.3.4)

Defines and validates the options for Dune.

The available options are explained below:


Parsing restriction options

  • atom_pool_size: Defines the maximum total number of atoms that can be created. Must be an integer >= 0. Defaults to 5000. See the section below for more information.
  • max_length: Defines the maximum length of code strings that can be parsed. Defaults to 5000.


Execution restriction options

  • allowlist: Defines which module and functions are considered safe or restricted. Should be a module implementing the Dune.Allowlist behaviour. Defaults to Dune.Allowlist.Default.
  • max_heap_size: Limits the memory usage of the evaluation process using the max_heap_size flag. Should be an integer > 0. Defaults to 30_000.
  • max_reductions: Limits the number of CPU cycles of the evaluation process. The erlang pre-emptive scheduler is using reductions to measure work being done by processes, which is useful to prevent users to run CPU intensive code such as infinite loops. Should be an integer > 0. Defaults to 30_000.
  • timeout: Limits the time the evaluation process is authorized to run (in milliseconds). Should be an integer > 0. Defaults to 50.

The evaluation process will still need to parse and execute the sanitized AST, so using too low limits here would leave only a small margin to actually run user code.


Other options

  • pretty: Use pretty printing when inspecting the result. Should be a boolean. Defaults to false.


Extra note about atom_pool_size

Atoms are reused from one evaluation to the other so the total is not expected to grow. Atoms will not be leaked.

Also, the atom pool is actually split into several pools: regular atoms, module names, unused variable names, ... So defining a value of 100 does not mean that 100 atoms will be available, but rather 25 of each type.

Atoms being very lightweight, there is no need to use a low value, as long as there is an upper bound preventing atom leaks.

Link to this section Summary


Validates untrusted options from a keyword or a map and returns a Dune.Opts struct.

Link to this section Types

@type t() :: %Dune.Opts{
  allowlist: module(),
  atom_pool_size: non_neg_integer(),
  max_heap_size: pos_integer(),
  max_length: pos_integer(),
  max_reductions: pos_integer(),
  pretty: boolean(),
  timeout: pos_integer()

Link to this section Functions

@spec validate!(Keyword.t() | map()) :: t()

Validates untrusted options from a keyword or a map and returns a Dune.Opts struct.



iex> Dune.Opts.validate!([])
  allowlist: Dune.Allowlist.Default,
  atom_pool_size: 5000,
  max_heap_size: 50000,
  max_length: 5000,
  max_reductions: 30000,
  pretty: false,
  timeout: 50

iex> Dune.Opts.validate!(atom_pool_size: 10)
%Dune.Opts{atom_pool_size: 10, allowlist: Dune.Allowlist.Default}

iex> Dune.Opts.validate!(atom_pool_size: -10)
** (ArgumentError) atom_pool_size should be an integer >= 0

iex> Dune.Opts.validate!(max_length: 0)
** (ArgumentError) atom_pool_size should be an integer > 0

iex> Dune.Opts.validate!(allowlist: DoesNotExists)
** (ArgumentError) could not load module DoesNotExists due to reason :nofile

iex> Dune.Opts.validate!(allowlist: List)
** (ArgumentError) List does not implement the Dune.Allowlist behaviour

iex> Dune.Opts.validate!(max_reductions: 10_000, max_heap_size: 10_000, timeout: 20)
%Dune.Opts{max_heap_size: 10_000, max_reductions: 10_000, timeout: 20}

iex> Dune.Opts.validate!(max_heap_size: 0)
** (ArgumentError) max_heap_size should be an integer > 0

iex> Dune.Opts.validate!(max_reductions: 0)
** (ArgumentError) max_reductions should be an integer > 0

iex> Dune.Opts.validate!(timeout: "55")
** (ArgumentError) timeout should be an integer > 0

iex> Dune.Opts.validate!(pretty: :maybe)
** (ArgumentError) pretty should be a boolean