Domain¶

class lsst.ts.salobj.Domain¶

Bases: object

dds domain participant and quality of service information.

Notes

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

LSST_DDS_IP (optional) is used to set the host attribute. If provided, it must be a dotted numeric IP address, e.g. “192.168.0.1”.
OSPL_MASTER_PRIORITY (optional) is used to set the Master Priority. If present, it must be a value between 0 and 255.

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:

participant : dds.DomainParticipant: DDS domain participant.
host : int: Value for the private_host field of output samples. See environment variable LSST_DDS_IP for details.
origin : int: Process ID. Used to set the private_origin field of output samples.
idl_dir : pathlib.Path: Root directory of the ts_idl package.
qos_provider : dds.QosProvider: Quality of service provider.
topic_qos : dds.Qos: Quality of service for non-volatile DDS topics (those that want late-joiner data).
volatile_topic_qos : dds.Qos: Quality of service for volatile topics (those that do not want any late-joiner data). Note: we cannot just make readers volatile to avoid late-joiner data, as volatile readers receive late-joiner data from non-volatile writers. So we make readers, writers, and topics all volatile. According to ADLink it is a feature, not a bug.
reader_qos : dds.Qos: Quality of service for non-volatile DDS readers.
volatile_reader_qos : dds.Qos: Quality of service for volatile DDS readers.
writer_qos : dds.Qos: Quality of service for non-volatile DDS writers.
volatile_writer_qos : dds.Qos: Quality of service for volatile DDS writers.

Attributes Summary

salinfo_set

Methods Summary

`add_salinfo`(salinfo)	Add the specified salinfo to the internal registry.
`close`()	Close all registered `SalInfo` and the dds domain participant.
`close_dds`()	Close the dds DomainParticipant.
`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

close()¶

Close all registered SalInfo and the dds domain participant.

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

close_dds()¶: Close the dds DomainParticipant.

remove_salinfo(salinfo)¶

Remove the specified salinfo from the internal registry.

Parameters:	salinfo : `SalInfo` SAL component information
Returns:	removed : `boolean` True if removed, False if not found

Navigation

Domain¶