Domain

class lsst.ts.salobj.Domain

Bases: object

Information common to all SalInfo instances.

The name comes from DDS; the class originally contained a DDS domain participant and associated quality of service information.

origin

Process ID. Used to set the private_origin field of output samples.

Type:

int

default_identity

Default value used for the identity field of SalInfo. Initalized to user_host but Controller‘s constructor sets it to SalInfo.user_index so that all Remotes constructed with the controller’s domain will have the controller’s identity. For testing purposes, it is allowed to change this field before constructing a Remote.

Type:

str

user_host

username@host. This will match identity unless the latter is set to a CSC name.

Type:

str

Notes

Reads the following Environment Variables; follow the link for details:

Cleanup

It is important to close a Domain when you are done with it, especially in unit tests, because otherwise unreleased resources may cause problems. To make this easier Domain is a context manager.

Domain contains a registry of SalInfo instances, so that it can close them when the domain is closed. The registry uses weak references to avoid circular dependencies (since SalInfo stores the domain). SalInfo instances automatically register themselves with the provided domain.

To conserve resources you should have only one Domain per process. Thus:

• Controller creates its own Domain as attribute domain and closes it when the controller is closed. To create a Remote for a controller, use the domain from the controller, e.g.:

  controller = Controller(name="Test", index=47)
  try:
      remote = Remote(domain=controller.domain, name="Test", index=47)
      ...
  finally:
      await controller.close()
  
  # or if you only want the objects for the duration of a function,
  # e.g in a unit test:
  async with Controller(name="Test", index=47) as controller:
      remote = Remote(domain=controller.domain, name="Test", index=47)
      ...
  

• If you are creating Remotes without a Controller then you must create the Domain yourself and close it when you are finished, e.g.:

  domain = salobj.Domain()
  try:
      remote = salobj.Remote(domain=domain, name="Test", index=47)
      ...
  finally:
      await domain.close()
  
  # or if you only want the objects for the duration of a function,
  # e.g in a unit test:
  async with salobj.Domain() as domain:
      test_remote = salobj.Remote(domain=domain, name="Test", index=5)
  

Attributes Summary

salinfo_set

Methods Summary

add_salinfo(salinfo)	Add the specified salinfo to the internal registry.
basic_close()	A synchronous and less thorough version of close.
close()	Close all registered SalInfo.
remove_salinfo(salinfo)	Remove the specified salinfo from the internal registry.

Attributes Documentation

salinfo_set

Methods Documentation

add_salinfo(salinfo)

Add the specified salinfo to the internal registry.

Parameters:

salinfo (SalInfo) – SAL component information

Raises:

RuntimeError – If the salinfo is already present

Return type:

None

basic_close()

A synchronous and less thorough version of close.

Intended for exit handlers and constructor error handlers.

Return type:

None

async close()

Close all registered SalInfo.

May be called multiple times. The first call closes the Domain; subsequent calls wait until the Domain is closed.

Return type:

None

remove_salinfo(salinfo)

Remove the specified salinfo from the internal registry.

Parameters:

salinfo (SalInfo) – SAL component information

Returns:

removed – True if removed, False if not found

Return type:

boolean