Reactor.
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Adds a child specification to a supervisor and starts that child.
See the documentation for Supervisor.start_child/2 for more information.
Result
The step returns a Reactor.Process.Step.StartChild.Result. The pid field
is the child process. The id field is the id from the child spec. The
started? field records whether this step started the child.
When fail_on_already_started? is false and the child is already started,
the step returns that child with started?: false.
When fail_on_already_present? is false and the child spec is present but
the child is stopped, the step restarts the child with restart_child/2 and
returns it with started?: true. If the supervisor module does not export
restart_child/2, the step fails with {:error, :already_present}.
Undo
Undo only acts on a child that this step started. Undo does not touch a
child with started?: false.
When terminate_on_undo? is true, undo terminates the child with
terminate_child/2, waits for it to exit, and then removes the child spec
with delete_child/2. This returns the supervisor to the state it had before
the step ran. If the supervisor module does not export delete_child/2, the
child spec stays in the supervisor.
Arguments
:supervisor- Required. The supervisor to query:child_spec- Required. The child spec
Options
:module(module/0) - The supervisor module. Must exportstart_child/2andterminate_child/2.restart_child/2anddelete_child/2are called when exported The default value isSupervisor.:fail_on_already_present?(boolean/0) - Whether the step should fail if the child spec is already present in the supervisor The default value istrue.:fail_on_already_started?(boolean/0) - Whether the step should fail if the start function returns an already started error The default value istrue.:terminate_on_undo?(boolean/0) - Whether to terminate the started process when the Reactor is undoing changes The default value istrue.:termination_timeout(timeout/0) - How long to wait for a process to terminate The default value is5000.