81 lines
2.2 KiB
Markdown
81 lines
2.2 KiB
Markdown
# Workflows
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Workflows compose jobs with dependency relationships: sequential, fan-out, and fan-in patterns.
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```elixir
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alias Oban.Pro.Workflow
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Workflow.new()
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|> Workflow.add(:extract, ExtractWorker.new(%{source: "db"}))
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|> Workflow.add(:transform, TransformWorker.new(%{}), deps: :extract)
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|> Workflow.add(:notify, NotifyWorker.new(%{}), deps: :extract) # fan-out
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|> Workflow.add(:load, LoadWorker.new(%{}), deps: [:transform, :notify]) # fan-in
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|> Oban.insert_all()
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```
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## Patterns
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- **Sequential**: `deps: :previous_job`
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- **Fan-out**: Multiple jobs depend on the same parent
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- **Fan-in**: One job depends on multiple parents with `deps: [:a, :b, :c]`
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## Accessing upstream results
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Use `recorded: true` workers:
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```elixir
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def process(job) do
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{:ok, data} = Workflow.fetch_recorded(job, :extract)
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end
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```
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## Cascading Functions
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Function captures that automatically receive context and upstream results:
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```elixir
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Workflow.new()
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|> Workflow.put_context(%{source: source})
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|> Workflow.add_cascade(:extract, &extract/1)
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|> Workflow.add_cascade(:transform, &transform/1, deps: :extract)
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|> Workflow.add_cascade(:load, &load/1, deps: :transform)
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|> Oban.insert_all()
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def extract(%{source: source}), do: %{records: fetch_records(source)}
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def transform(%{extract: %{records: records}}), do: %{data: process(records)}
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def load(%{transform: %{data: data}}), do: insert_all(data)
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```
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Fan-out with `{enumerable, function/2}`:
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```elixir
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Workflow.add_cascade(:accounts, {account_ids, &sync_account/2})
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```
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## Sub-workflows
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Compose from reusable pieces:
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```elixir
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extract_flow =
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Workflow.new()
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|> Workflow.add(:fetch, FetchWorker.new(%{}))
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|> Workflow.add(:parse, ParseWorker.new(%{}), deps: :fetch)
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Workflow.new()
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|> Workflow.add(:setup, SetupWorker.new(%{}))
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|> Workflow.add_workflow(:extract, extract_flow, deps: :setup)
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|> Workflow.add(:cleanup, CleanupWorker.new(%{}), deps: :extract)
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|> Oban.insert_all()
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```
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## Unique workflows
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Ensure only one active workflow per name with `unique: true`. Duplicates while the first is still
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running come back flagged `conflict?: true` and aren't inserted:
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```elixir
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Workflow.new(unique: true, name: "nightly-etl")
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|> Workflow.add(:extract, ExtractWorker.new(%{}))
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|> Oban.insert_all()
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```
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