muontrap v0.4.1 MuonTrap.Daemon View Source
Wrap an OS process in a GenServer so that it can be supervised.
For example, in your children list add MuonTrap.Daemon like this:
children = [
{MuonTrap.Daemon, ["myserver", ["--options", "foo")], [cd: "/somedirectory"]]}
]
opts = [strategy: :one_for_one, name: MyApplication.Supervisor]
Supervisor.start_link(children, opts)
The same options as MuonTrap.cmd/3
are available with the following additions:
- {
log_output
, level} - Logs anything that the command sends to stdout
Link to this section Summary
Functions
Get the value of the specified cgroup variable
Modify a cgroup variable
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
Return the OS pid to the muontrap executable
Start/link a deamon GenServer for the specified command
Link to this section Functions
cgget(server, controller, variable_name)
View Source
cgget(GenServer.server(), binary(), binary()) :: binary()
cgget(GenServer.server(), binary(), binary()) :: binary()
Get the value of the specified cgroup variable.
cgset(server, controller, variable_name, value)
View Source
cgset(GenServer.server(), binary(), binary(), binary()) :: :ok | no_return()
cgset(GenServer.server(), binary(), binary(), binary()) :: :ok | no_return()
Modify a cgroup variable.
child_spec(init_arg) View Source
Returns a specification to start this module under a supervisor.
See Supervisor
.
init(list) View Source
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
.
os_pid(server)
View Source
os_pid(GenServer.server()) :: non_neg_integer()
os_pid(GenServer.server()) :: non_neg_integer()
Return the OS pid to the muontrap executable.
start_link(command, args, opts \\ [])
View Source
start_link(binary(), [binary()], keyword()) :: GenServer.on_start()
start_link(binary(), [binary()], keyword()) :: GenServer.on_start()
Start/link a deamon GenServer for the specified command.