wormhole v1.4.3 Wormhole

Link to this section Summary

Functions

Invokes callback in separate process and waits for message from callback process containing callback return value if finished successfully or error reason if callback process failed for any reason

Invokes callback in separate process and waits for message from callback process containing callback return value if finished successfully or error reason if callback process failed for any reason

Called when an application is started

Link to this section Functions

Link to this function capture(callback, options \\ [])

Invokes callback in separate process and waits for message from callback process containing callback return value if finished successfully or error reason if callback process failed for any reason.

If callback execution is not finished within specified timeout, kills callback process and returns error. Default timeout is 5000 milliseconds. User can specify timeout_ms in options keyword list.

By default there is no retry, but user can specify retry_count and backoff_ms in options. Default backoff_ms is 1000 milliseconds.

By default exceptions in callback-process are handled so that supervisor does not generate CRUSH REPORT (when released - Exrm/Distillery). This behavior can be overridden by setting crush_report to true. Note:

  • Crush report is not generated in Elixir by default.
  • Letting exceptions propagate might be useful for some other applications too (e.g sentry client).

Examples:

iex> capture(fn-> :a end)
{:ok, :a}

iex> capture(fn-> raise "Something happened" end)
{:error, {:shutdown, %RuntimeError{message: "Something happened"}}}

iex> capture(fn-> throw "Something happened" end)
{:error, {:shutdown, {:throw, "Something happened"}}}

iex> capture(fn-> exit :foo end)
{:error, {:shutdown, {:exit, :foo}}}

iex> capture(fn-> Process.exit(self, :foo) end)
{:error, :foo}

iex> capture(fn-> :timer.sleep 20 end, timeout_ms: 50)
{:ok, :ok}

iex> capture(fn-> :timer.sleep :infinity end, timeout_ms: 50)
{:error, {:timeout, 50}}

iex> capture(fn-> exit :foo end, [retry_count: 3, backoff_ms: 100])
{:error, {:shutdown, {:exit, :foo}}}
Link to this function capture(module, function, args, options \\ [])

Invokes callback in separate process and waits for message from callback process containing callback return value if finished successfully or error reason if callback process failed for any reason.

If callback execution is not finished within specified timeout, kills callback process and returns error. Default timeout is 5000 milliseconds. User can specify timeout_ms in options keyword list.

By default there is no retry, but user can specify retry_count and backoff_ms in options. Default backoff_ms is 1000 milliseconds.

By default exceptions in callback-process are handled so that supervisor does not generate CRUSH REPORT (when released - Exrm/Distillery). This behavior can be overridden by setting crush_report to true. Note:

  • Crush report is not generated in Elixir by default.
  • Letting exceptions propagate might be useful for some other applications too (e.g sentry client).

Examples:

iex> capture(Enum, :count, [[]])
{:ok, 0}

iex> capture(Enum, :count, [:foo]) |> elem(0)
:error

iex> capture(:timer, :sleep, [20], timeout_ms: 50)
{:ok, :ok}

iex> capture(:timer, :sleep, [:infinity], timeout_ms: 50)
{:error, {:timeout, 50}}

iex> capture(Kernel, :exit, [:foos], [retry_count: 3, backoff_ms: 100]) {:error, {:shutdown, {:exit, :foos}}}

Link to this function start(type, args)

Called when an application is started.

This function is called when an the application is started using Application.start/2 (and functions on top of that, such as Application.ensure_started/2). This function should start the top-level process of the application (which should be the top supervisor of the application’s supervision tree if the application follows the OTP design principles around supervision).

start_type defines how the application is started:

  • :normal - used if the startup is a normal startup or if the application is distributed and is started on the current node because of a failover from another mode and the application specification key :start_phases is :undefined.
  • {:takeover, node} - used if the application is distributed and is started on the current node because of a failover on the node node.
  • {:failover, node} - used if the application is distributed and is started on the current node because of a failover on node node, and the application specification key :start_phases is not :undefined.

start_args are the arguments passed to the application in the :mod specification key (e.g., mod: {MyApp, [:my_args]}).

This function should either return {:ok, pid} or {:ok, pid, state} if startup is successful. pid should be the PID of the top supervisor. state can be an arbitrary term, and if omitted will default to []; if the application is later stopped, state is passed to the stop/1 callback (see the documentation for the c:stop/1 callback for more information).

use Application provides no default implementation for the start/2 callback.

Callback implementation for Application.start/2.