BCUtils.PubSubManager (bc_utils v0.14.0)

Manages Phoenix.PubSub startup to avoid conflicts when multiple applications in the same VM try to start the same PubSub instance.

This module provides utilities to:

  • Check if a PubSub instance is already running
  • Conditionally start PubSub only if needed
  • Provide graceful fallbacks for shared PubSub instances
  • Health check existing PubSub instances

Usage

In your supervision tree:

children = [
  BCUtils.PubSubManager.maybe_child_spec(:my_pubsub),
  # other children...
]
|> Enum.filter(& &1)  # Remove nil entries

Dependencies

This module requires phoenix_pubsub to be available at runtime. Add it to your mix.exs:

{:phoenix_pubsub, "~> 2.1"}

Summary

Functions

maybe_child_spec(pubsub_name)

Returns a child spec for Phoenix.PubSub if not already started, otherwise nil.

Functions

maybe_child_spec(pubsub_name)

@spec maybe_child_spec(atom()) :: {module(), keyword()} | nil

Returns a child spec for Phoenix.PubSub if not already started, otherwise nil.

This is the recommended way to use this module in supervision trees.

Examples

# Will start PubSub if not running
BCUtils.PubSubManager.maybe_child_spec(:my_pubsub)

# Will return nil if already running
BCUtils.PubSubManager.maybe_child_spec(:my_pubsub)

# Usage in supervision tree
children = [
  BCUtils.PubSubManager.maybe_child_spec(:ex_esdb_pubsub),
  # other children...
]
|> Enum.filter(& &1)  # Remove nil entries

Parameters

  • pubsub_name - The atom name for the PubSub instance, or nil
  • opts - Additional options to pass to Phoenix.PubSub (default: [])

Returns

  • {Phoenix.PubSub, keyword()} - Child spec if PubSub needs to be started
  • nil - If PubSub is already running or pubsub_name is nil