de.yaacc.yxc.YxcGroupService Class Reference

Links devices into a group ("link": one server plays, its clients play in sync) and takes them out again. More...

Collaboration diagram for de.yaacc.yxc.YxcGroupService:

Classes
interface	Action
interface	Call
interface	Check
interface	Operation

Public Member Functions
	YxcGroupService (YxcSleeper sleeper, Random random)
synchronized YxcGroupResult	link (YxcGroupMember server, List< YxcGroupMember > clients)
	Puts the clients into a group of the server.
synchronized YxcGroupResult	extend (YxcGroupMember server, List< YxcGroupMember > clients)
	Adds clients to the group the server already serves; fails if it serves none.
synchronized YxcGroupResult	reduce (YxcGroupMember server, List< YxcGroupMember > clients)
	Takes clients out of the group of the server.
synchronized YxcGroupResult	unlink (YxcGroupMember device, Collection< YxcGroupMember > knownMembers)
	Takes a device out of its group.
synchronized YxcGroupResult	rename (YxcGroupMember server, String name)
	Sets the name of the group the server serves; empty selects the default name.

Detailed Description

Links devices into a group ("link": one server plays, its clients play in sync) and takes them out again.

The call sequences and the expected-state checks follow the behavior of the open-source libraries (see docs/tech.md): clients first, then the server call that lists them, then the start; after each change the state is read again (a device needs a moment) for up to one second, and a step that did not reach its state is repeated once. The first slice has no event listener, so waiting means polling getDistributionInfo.

Expected failures (a device is unreachable, refuses a call, does not reach the state) are returned as YxcGroupResult, not thrown. An operation that fails part-way takes back what it did to the clients; it cannot restore a group that a client was taken out of. Operations of one service run one after another.

Constructor & Destructor Documentation

YxcGroupService()

de.yaacc.yxc.YxcGroupService.YxcGroupService	(	YxcSleeper	sleeper,
		Random	random )

Parameters

random

where new group ids come from (a SecureRandom in the app)

Member Function Documentation

link()

synchronized YxcGroupResult de.yaacc.yxc.YxcGroupService.link	(	YxcGroupMember	server,
		List< YxcGroupMember >	clients )

Puts the clients into a group of the server.

A server that already serves a group gets them added to it, otherwise a new group id is chosen. A client that is in another group leaves it first; a client that serves a group of its own ends that group first (the device refuses the client call while it serves).

Referenced by de.yaacc.yxc.YxcGroupOperations.applySelection().

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reduce()

synchronized YxcGroupResult de.yaacc.yxc.YxcGroupService.reduce	(	YxcGroupMember	server,
		List< YxcGroupMember >	clients )

Takes clients out of the group of the server.

Clients that are not in it are ignored; when nobody would be left the group is ended. A client that cannot be reached is still removed on the server side.

Referenced by de.yaacc.yxc.YxcGroupOperations.applySelection().

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unlink()

synchronized YxcGroupResult de.yaacc.yxc.YxcGroupService.unlink	(	YxcGroupMember	device,
		Collection< YxcGroupMember >	knownMembers )

Takes a device out of its group.

A server ends the group (the known members that are its clients leave first); a client leaves, and is removed from its server if that is among the known members. A device in no group is left alone and the result is success.

Parameters

knownMembers

other devices the caller knows; the clients of a group are only addressed when listed here

Referenced by de.yaacc.yxc.YxcGroupOperations.leave(), and de.yaacc.yxc.YxcGroupOperations.unlinkGroup().

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The documentation for this class was generated from the following file:

• /github/workspace/yaacc/src/main/java/de/yaacc/yxc/YxcGroupService.java