exq v0.13.0 Exq.Scheduler.Server

The Scheduler is responsible for monitoring the schedule and retry queues. These queues use a Redis sorted set (term?) to schedule and pick off due jobs. Once a job is at or past it's execution date, the Scheduler moves the job into the live execution queue.

Runs on a timed loop according to scheduler_poll_timeout.

Initialization:

:name - Name of target registered process
:namespace - Redis namespace to store all data under. Defaults to "exq".
:queues - Array of currently active queues (TODO: Remove, I suspect it's not needed).
:redis - pid of Redis process.
:scheduler_poll_timeout - How often to poll Redis for scheduled / retry jobs.

Link to this section Summary

Functions

child_spec(arg)

Returns a specification to start this module under a supervisor

dequeue(state)

Dequeue any active jobs in the scheduled and retry queues, and enqueue them to live queue

init(opts)

Invoked when the server is started. start_link/3 or start/3 will block until it returns

server_name(name)

start_link(opts \\ [])

start_timeout(pid)

Link to this section Functions

child_spec(arg)

Returns a specification to start this module under a supervisor.

See Supervisor.

dequeue(state)

Dequeue any active jobs in the scheduled and retry queues, and enqueue them to live queue.

init(opts)

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 calling Supervisor.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.