gen_registry v1.0.1 GenRegistry View Source
GenRegistry provides a Registry
like interface for managing processes.
Link to this section Summary
Functions
Callback called by Supervisor.init/2
Return the number of running processes in this registry
Invoked when the server is started. start_link/3
or start/3
will
block until it returns
Lookup a running a process
Attempts to lookup a running process by id
Loop over all the processes and return result
Start a registry instance
Safely stops a process managed by the GenRegistry
Link to this section Types
GenRegistry State.
- worker_module: Module to spawn
- worker_type:
:supervisor
if the worker_module is a supervisor,:worker
otherwise - workers: ETS table id holding the worker tracking records.
Link to this section Functions
child_spec(opts :: Keyword.t()) :: Supervisor.child_spec()
Callback called by Supervisor.init/2
It is required that you provide a :worker_module
argument or the call will fail.
Return the number of running processes in this registry.
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 {: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
.
lookup(table :: :ets.tid(), id :: GenRegistry.Types.id()) :: {:ok, pid()} | {:error, :not_found}
Lookup a running a process.
This is a fast path to the ETS table.
lookup_or_start( registry :: GenServer.server(), id :: GenRegistry.Types.id(), args :: [any()], timeout :: integer() ) :: {:ok, pid()} | {:error, any()}
Attempts to lookup a running process by id.
If the id is not associated with a running process then it is spawned, the optional third
argument will be passed to start_link
of the worker_module
to spawn a new process.
Loop over all the processes and return result.
The function will be called with two arguments, a two-tuple of {id, pid}
and then accumulator,
the function should return the accumulator.
There is no ordering guarantee when reducing.
Start a registry instance.
GenRegistry should be run under a supervision tree, it is not recommended to call this directly.
stop(registry :: GenServer.server(), id :: GenRegistry.Types.id()) :: :ok | {:error, :not_found}
Safely stops a process managed by the GenRegistry
In addition to stopping the process, the id is also removed from the GenRegistry
If the id provided is not registered this will return {:error, :not_found}