lkn-core v0.4.3 Lkn.Core.Instance View Source
A Process to arbitrate the Systems of a given Map.
There are two things to remember about Instances:
- There can be several Instances of a single Map
- They are dynamically created by the
Lkn.Core.Pool
of a Map when required
In other words, it is not the developer job to spawn an Instance. You can see
an instance as the entry point of a game scene. It acts as a proxy between
Lkn.Core.Puppeteer
s and Lkn.Core.System
s.
An Instance will stay alive as long as it hosts at least one
Lkn.Core.Puppeteer
. Once it has became empty, it warns its Lkn.Core.Pool
so that the Pool can kill it.
Link to this section Summary
Functions
Returns a specification to start this module under a supervisor
Invoked when the server is started. start_link/3
or start/3
will
block until it returns
Insert a new Puppet into an Instance
Remove a Puppet from an Instance
Notify an Instance that a given Puppeteer is leaving
Link to this section Types
A key to identify and reach an Instance.
Link to this section Functions
Returns a specification to start this module under a supervisor.
See Supervisor
.
Invoked when the server is started. start_link/3
or start/3
will
block until it returns.
args
is the argument term (second argument) passed to start_link/3
.
Returning {:ok, state}
will cause start_link/3
to return
{:ok, pid}
and the process to enter its loop.
Returning {:ok, state, timeout}
is similar to {:ok, state}
except handle_info(:timeout, state)
will be called after timeout
milliseconds if no messages are received within the timeout.
Returning {:ok, state, :hibernate}
is similar to
{:ok, state}
except the process is hibernated before entering the loop. See
c:handle_call/3
for more information on hibernation.
Returning :ignore
will cause start_link/3
to return :ignore
and the
process will exit normally without entering the loop or calling c:terminate/2
.
If used when part of a supervision tree the parent supervisor will not fail
to start nor immediately try to restart the GenServer
. The remainder of the
supervision tree will be (re)started and so the GenServer
should not be
required by other processes. It can be started later with
Supervisor.restart_child/2
as the child specification is saved in the parent
supervisor. The main use cases for this are:
- The
GenServer
is disabled by configuration but might be enabled later. - An error occurred and it will be handled by a different mechanism than the
Supervisor
. Likely this approach involves callingSupervisor.restart_child/2
after a delay to attempt a restart.
Returning {:stop, reason}
will cause start_link/3
to return
{:error, reason}
and the process to exit with reason reason
without
entering the loop or calling c:terminate/2
.
Callback implementation for GenServer.init/1
.
register_puppet(k(), Lkn.Core.Puppet.k(), %{optional(Lkn.Core.System.m()) => Keyworld.t()}) :: boolean()
Insert a new Puppet into an Instance.
This function can be used by a Lkn.Core.Puppeteer
to insert a new Puppet
into an Instance. There is no notion of Puppet owner, from an Instance point
of view. Therefore, any Puppeteer can send a command “on behalf of a given
Puppet. This Puppeteer will have the obligation to unregister it.
Under the hood, this function dispatches the register event to each system the Puppet has a Component for.
unregister_puppet(k(), Lkn.Core.Puppet.k()) :: boolean()
Remove a Puppet from an Instance.
This function can be used by a Lkn.Core.Puppeteer
to an Instance. An
Instance will never do it by itself, so it needs to be done by the Puppeteer
owner, e.g. before it registers istelf. Note that, if the Puppeteer forgets to
unregister one of its Puppets, this Puppets will stay in this Instance as long
as at least one Puppeteer stays registered (and it will probably do nothing at
all).
unregister_puppeteer(k(), Lkn.Core.Puppeteer.k()) :: :ok
Notify an Instance that a given Puppeteer is leaving.
This function needs to be used by a Puppeteer, after it has removed all of
its Puppets. Right now, a Puppeteer cannot choose its Instance to join, and
the Lkn.Core.Pool.register_puppeteer
is the function to use to join the
Instance of a given Map.