elsa v0.6.0 Elsa.Group.Worker
Defines the worker GenServer that is managed by the DynamicSupervisor. Workers are instantiated and assigned to a specific topic/partition and process messages according to the specified message handler module passed in from the manager before calling the manager's ack function to notify the cluster the messages have been successfully processed.
Link to this section Summary
Functions
Returns a specification to start this module under a supervisor.
Invoked to handle continue
instructions.
Invoked when the server is started. start_link/3
or start/3
will
block until it returns.
Start the worker process and init the state with the given config.
Trigger the worker to gracefully disengage itself from the supervision tree, unsubscribe from the topic and partition and initiate its own stop sequence.
Link to this section Functions
child_spec(init_arg)
Returns a specification to start this module under a supervisor.
See Supervisor
.
handle_continue(atom, state)
Invoked to handle continue
instructions.
It is useful for performing work after initialization or for splitting the work in a callback in multiple steps, updating the process state along the way.
Return values are the same as c:handle_cast/2
.
This callback is optional. If one is not implemented, the server will fail if a continue instruction is used.
This callback is only supported on Erlang/OTP 21+.
Callback implementation for GenServer.handle_continue/2
.
init(init_args)
Invoked when the server is started. start_link/3
or start/3
will
block until it returns.
init_arg
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 {:ok, state, {:continue, continue}}
is similar to
{:ok, state}
except that immediately after entering the loop
the c:handle_continue/2
callback will be invoked with the value
continue
as first argument.
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 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
.
kafka_message(args \\ []) (macro)
kafka_message(record, args) (macro)
kafka_message_set(args \\ []) (macro)
kafka_message_set(record, args) (macro)
start_link(init_args)
Start the worker process and init the state with the given config.
unsubscribe(pid)
Trigger the worker to gracefully disengage itself from the supervision tree, unsubscribe from the topic and partition and initiate its own stop sequence.