Sofa.Changes.Worker (sofa v0.5.1)

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One _changes request, run in its own process on behalf of a Sofa.Changes follower.

The worker is linked to the follower and reports back with messages tagged by the reference it was started with, so a follower can tell a stale connection from the current one:

  • {ref, :data, chunk} for each chunk of a continuous feed's body, sent only when the status is 200
  • {ref, :done, %Req.Response{}} once the response ends. For a non-continuous feed the body is the decoded JSON batch, for a failed request it is the decoded error object
  • {ref, :error, exception} when the request could not be made or the connection dropped, with a Req.TransportError

The worker then exits with reason :normal. Killing it closes the connection, which is how a follower stops or restarts a feed.

Summary

Types

message()

A message from the worker to its follower

Functions

request(sofa, query)

The Req request for query, without the streaming sink, exposed for inspection.

start_link(owner, ref, db, query)

Spawns a linked worker that requests /{db}/_changes with query on the database's Req client and reports to owner with ref.

Types

message()

@type message() ::
  {reference(), :data, binary()}
  | {reference(), :done, Req.Response.t()}
  | {reference(), :error, Exception.t()}

A message from the worker to its follower

Functions

request(sofa, query)

@spec request(Sofa.t(), Sofa.Changes.Query.t()) :: Req.Request.t()

The Req request for query, without the streaming sink, exposed for inspection.

start_link(owner, ref, db, query)

@spec start_link(owner :: pid(), reference(), Sofa.t(), Sofa.Changes.Query.t()) ::
  pid()

Spawns a linked worker that requests /{db}/_changes with query on the database's Req client and reports to owner with ref.