Class: Holder::Tenant

Inherits:
Object
  • Object
show all
Defined in:
lib/holder/tenant.rb

Overview

Builds and launches a child process, returning a Handle that owns its teardown.

in:, out:, and err: each accept an IO (or nil) to redirect that stream to; any other keyword (+chdir+, umask, ...) is forwarded to the spawn. The child always runs in its own process group so the whole group can be torn down together -- this is not overridable.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*args, in: nil, out: nil, err: nil, **kwargs) ⇒ Tenant

Returns a new instance of Tenant.



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# File 'lib/holder/tenant.rb', line 16

def initialize(*args, in: nil, out: nil, err: nil, **kwargs)
  @args = args
  @io_defs = { in:, out:, err: }
  @pgroup = true
  @kwargs = kwargs
end

Instance Attribute Details

#handle ⇒ Object

Returns the value of attribute handle.



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# File 'lib/holder/tenant.rb', line 12

def handle
  @handle
end

#kwargs ⇒ Object (readonly)

Returns the value of attribute kwargs.



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# File 'lib/holder/tenant.rb', line 12

def kwargs
  @kwargs
end

#pgroup ⇒ Object (readonly)

Returns the value of attribute pgroup.



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# File 'lib/holder/tenant.rb', line 12

def pgroup
  @pgroup
end

Instance Method Details

#run ⇒ Object

rubocop:disable Metrics/AbcSize, Metrics/MethodLength



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# File 'lib/holder/tenant.rb', line 23

def run # rubocop:disable Metrics/AbcSize, Metrics/MethodLength
  # Validate the three streams up front. The one-line pattern match checks each
  # is an IO or nil (in: is a keyword, so it can't be named as a local); we then
  # read the values out by key. A bad stream raises ArgumentError here rather
  # than slipping through and detonating later inside a pump.
  unless @io_defs in { in: StreamType | nil, out: StreamType | nil, err: StreamType | nil }
    raise ArgumentError, "in:, out:, and err: must each be an IO object or nil"
  end

  u_sin, u_sout, u_serr = @io_defs.values_at(:in, :out, :err)

  # Open3 ALWAYS pipes stdin and stdout, so in:/out: are always pumped; err is
  # the only stream that can go direct, and only via popen2. So the entire
  # 8-case dispatch is just this, and the only thing handed to spawn directly
  # is a redirected err:. Any extra kwargs (chdir, umask, unsetenv_others,
  # close_others, ...) are forwarded to spawn; they go in first so our
  # pgroup: true and err redirect win on collision and the group-teardown
  # invariant is never overridden.
  meth = u_serr ? :popen2 : :popen3
  spawn_redirects = u_serr ? { err: u_serr } : {}

  # Each form uses its matching Open3 form: block -> Open3's block form (its
  # close+reap is a backstop under our kill); no-block -> Open3's non-block
  # form (the handle owns teardown).
  if block_given?
    Open3.public_send(meth, *args, **kwargs, pgroup:, **spawn_redirects) do |*streams|
      self.handle = build_handle(streams, meth, u_sin, u_sout, u_serr)
      begin
        yield handle
      ensure
        handle.terminate
      end
    end
  else
    streams = Open3.public_send(meth, *args, **kwargs, pgroup:, **spawn_redirects)
    self.handle = build_handle(streams, meth, u_sin, u_sout, u_serr)
  end
end