MishkaCmsCore.Isolated (Mishka CMS Core v0.0.1)

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Runs one function in a separate operating-system process: a peer BEAM started for the call (:peer, in OTP's stdlib) and stopped after it.

For work done by native code that could take the server down with it: a NIF that crashes on a malformed file ends the whole BEAM, and no supervisor can catch that. Run through run/4, the crash ends the peer, and the caller gets {:error, reason} back. Every site keeps serving.

{:ok, png} = Isolated.run(MyApp.Thumbnail, :draw, [path])
{:error, _reason} = Isolated.run(:erlang, :halt, [139])

What the peer has

The caller's code path (:code.get_path/0), so every module of the release or the project is there to call; no application is started, and no configuration is loaded. function starts what it needs.

It is the same Erlang the caller runs: the erl of its own ERTS, booted with the start_clean boot file beside the caller's own — in a release releases/<version>/start_clean, with its RELEASE_LIB — so it starts the same in development and in a release, with nothing on PATH.

Options

  • :timeout — milliseconds to wait for the answer, default 30_000; past it the peer is killed and the answer is {:error, :timeout}
  • :env — [{name, value}] of charlists for the peer's environment; false as the value removes a variable the caller has
  • :nice — 0..19, the peer's scheduling priority below the caller's, given to it by the system's nice (/usr/bin/nice or /bin/nice); default 0. Where neither is there, the peer runs at the caller's priority

Answers

{:ok, result} with what function returned, else {:error, reason}: it raised, it exited, the peer died, or it took too long. The caller is never linked to the peer, so nothing it does can end the caller.

Summary

Types

option()

Functions

run(module, function, args, opts \\ [])

Types

option()

@type option() ::
  {:timeout, timeout()}
  | {:env, [{charlist(), charlist() | false}]}
  | {:nice, 0..19}

Functions

run(module, function, args, opts \\ [])

@spec run(module(), atom(), list(), [option()]) :: {:ok, term()} | {:error, term()}