Broadway v0.1.0 Broadway.TermStorage View Source

A simple term storage to avoid passing large amounts of data between processes.

If you have a large amount of data and you want to avoid passing it between processes, you can use the TermStorage. The TermStorage creates a unique reference for it, allowing you pass the reference around instead of the term.

If the same term is put multiple times, it is stored only once, avoiding generating garbage. However, the stored terms are never removed. A common use case for this feature is in Broadway.Producer, which may need to pass a lot of information to acknowledge messages. With this module, you can store those terms when the producer starts and only pass the reference between messages:

iex> ref = Broadway.TermStorage.put({:foo, :bar, :baz}) # On init
iex> Broadway.TermStorage.get!(ref) # On ack
{:foo, :bar, :baz}

Link to this section Summary

Functions

Returns a specification to start this module under a supervisor

Gets a previously stored term

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

Puts a term

Link to this section Functions

Returns a specification to start this module under a supervisor.

See Supervisor.

Gets a previously stored term.

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.

Puts a term.