elsa v0.10.0 Elsa.Wrapper
Provides a supervisable wrapper for the Elsa supervision tree to manage brod producers and consumers. Provides convenience functions for starting producer and consumer processes directly without the default supervisors brod interposes between them and the application.
By taking over supervision of the processes directly interacting with Kafka by way of a brod client, these processes can be registered independently from the client process so in the event of the client dropping its connection, the record of what processes should be producing or consuming from what topics and partitions can be immediately reconstructed instead of being dropped.
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.
Link to this section Functions
child_spec(init_arg)
Returns a specification to start this module under a supervisor.
See Supervisor
.
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
.