tree 1854e929e4325f8281670e1bc9b47e887f15a190
parent 716366aecc075ea4bd5d050f33b6fb9791256f0e
author Shawn McCarney <shawnmm@us.ibm.com> 1722885454 -0500
committer Shawn McCarney <shawnmm@us.ibm.com> 1723144583 -0500

Add support for re-finding interfaces/system types

The DBusInterfacesFinder class simplifies the task of finding interface
instances on D-Bus.  Similarly, the CompatibleSystemTypesFinder class
simplifies the task of finding the list of compatible system types for
the current system.

Both classes initially find the D-Bus objects that already exist at the
time the classes are constructed.  They use InterfacesAdded listeners to
find new D-Bus objects that are created later.

This behavior handles most use cases.  However, sometimes a caller may
not be receiving D-Bus signals, but they still need to find new D-Bus
objects that have been created.  For example, the caller may be looping
within a timeout period waiting for a D-Bus object to be created.

To handle this use case, add `refind()` methods to both classes that
will re-find all matching D-Bus objects that now exist, including those
created since the classes were constructed.

Tested:
* DBusInterfacesFinder
  * Verify finds all interface instances that exist at time class is
    constructed
    * None found
    * Instances found
  * Verify finds new interface instances via InterfacesAdded listener
  * Verify refind() finds all interface instances, including those that
    were created after the class was constructed.
    * None found
    * Instances found
* CompatibleSystemTypesFinder
  * Verify finds all compatible system type lists that exist at time
    class is constructed
    * None found
    * Lists found
  * Verify finds new compatible system type lists via InterfacesAdded
    listener
  * Verify refind() finds all compatible system type lists, including
    those that were created after the class was constructed.
    * None found
    * Lists found

Change-Id: I975b37524f687e6d2f3d4ff48abb5e4486a84bfe
Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>