statifier_persistence

# StatifierPersistence cheatsheet

## Start
{: .col-2}

### Create an execution

```elixir
{:ok, execution, state} =
  Executions.create(store, "loan_01H8", machine,
    executor: executor,
    initialize: [invoke_types: invoke_types, send_types: send_types]
  )
```

The execution id is yours. Creating an id that exists answers `{:error, :execution_exists}`. See [How to persist an execution and resume it in another process](../guides/persist-and-resume.md).

### Create options

| Option | Default | Meaning |
| --- | --- | --- |
| `executor:` | required | Receives each effect, in order |
| `initialize:` | `[]` | Passed to the interpreter; `routes:`, `invoke_types:`, `send_types:` and `function_providers:` go here |
| `metadata:` | `%{}` | Host identities stored on the record |
| `serialization:` | the adapter's lock | `{module, config}` ordering strategy |

## Step
{: .col-2}

### Deliver one event

```elixir
{:ok, execution, state} =
  Executions.step(store, "loan_01H8", machine,
    Event.external("loan.due"), executor: executor)
```

### Answers

```elixir
{:ok, execution, state}
{:discarded, execution}
{:error, {:needs_migration, execution}}
{:error, {:identity_mismatch, stored, supplied}}
```

### Step options

| Option | Default | Meaning |
| --- | --- | --- |
| `executor:` | required | Receives each effect |
| `routes:` | `nil` | Live `<send>` targets for this step |
| `invoke_types:` | `nil` | Built-in set only |
| `send_types:` | `nil` | Unregistered `<send>` types are rejected |
| `function_providers:` | `nil` | Host functions for `cond` and `expr` |
| `serialization:` | the adapter's lock | `{module, config}` |

### End from the host

```elixir
Executions.fail(store, "loan_01H8", "copy lost")
Executions.cancel(store, "loan_01H8")
```

## Resume
{: .col-2}

### Another process, one id

```elixir
{:ok, record} = Storage.fetch_execution(store, "loan_01H8")
{:ok, %{chart_blob: blob}} = Storage.fetch_chart(store, record.content_hash)
{:ok, machine} = Chart.from_binary(blob)
```

Then `Executions.step/5` with that machine. See [How to persist an execution and resume it in another process](../guides/persist-and-resume.md).

### Store the chart first

```elixir
{:ok, machine} = Statifier.compile(source)
{:ok, chart_blob} = Chart.to_binary(machine)
:ok = Storage.save_chart(store, machine, chart_blob)
```

## Ecto adapter
{: .col-2}

### Persistence module

```elixir
defmodule MyApp.Persistence do
  use StatifierPersistence.Ecto, repo: MyApp.Repo
end
```

### Migration

```elixir
def up, do: StatifierPersistence.Ecto.Migrations.up(for: MyApp.Persistence)
def down, do: StatifierPersistence.Ecto.Migrations.down(for: MyApp.Persistence)
```

`from:` and `version:` bound the span, in both directions.

### Guarded store

```elixir
{:ok, store} =
  Storage.new(StatifierPersistence.Storage.Ecto,
    persistence: MyApp.Persistence)
```

### Store options

| Option | Default | Meaning |
| --- | --- | --- |
| `persistence:` | required | Module that called `use StatifierPersistence.Ecto` |
| `input_log_cap:` | `:infinity` | Per-execution cap on the input log |
| `sandbox:` | `false` | Check out an Ecto sandbox connection per test |

### `use` options

| Option | Default | Meaning |
| --- | --- | --- |
| `repo:` | required | Your `Ecto.Repo` |
| `key:` | `:uxid` | `:uuid`, `:bigserial` or `{module, opts}` |
| `table_prefix:` | `"statifier_"` | Prefix of the table names |
| `tables:` | `%{}` | Per-table name override |
| `prefix:` | `nil` | Postgres schema |
| `blob_type:` | `:binary` | Ecto type of the payload columns |
| `leading_columns:` | `[]` | Host columns placed after `id` |
| `timestamps_position:` | `:trailing` | Or `:leading` |
| `column_collations:` | `[]` | Collation per text column |

See [How to set up the Ecto adapter](../guides/ecto-adapter.md).

## Retire
{: .col-2}

### Retire a chart

```elixir
Executions.retire_chart(store, content_hash, [MyApp.TimerPins],
  retired_by: "ops@example.test")
```

### Answers

```elixir
{:ok, %{content_hash: _, retired_at: _, retired_by: _}}
{:error, {:pinned, counts}}
{:error, {:pin_source_failed, {module, reason}}}
{:error, :chart_retirement_unsupported}
```

### Options

| Option | Default | Meaning |
| --- | --- | --- |
| `retired_by:` | required | Opaque string recorded on the row |
| `now:` | `DateTime.utc_now/0` | Written as `retired_at` |

### Pin source

```elixir
@behaviour StatifierPersistence.PinSource

def pins(content_hash, %{execution_ids: ids}),
  do: %{pending_timers: MyApp.Timers.count_scheduled_for(ids)}
```

See [How to retire a chart and prune finished executions](../guides/retire-and-prune.md).

## Prune
{: .col-2}

### Prune finished executions

```elixir
{:ok, %{executions: _, position_blobs: _, inputs: _}} =
  StatifierPersistence.Retention.prune(store, cutoff)
```

`cutoff` is a `DateTime`; a duration raises `ArgumentError`.

### Options

| Option | Default | Meaning |
| --- | --- | --- |
| `batch_size:` | `500` | Executions per batch |
| `scope:` | whole store | Column equalities, such as `[tenant_id: "a"]` |
| `single_batch:` | `false` | One batch, answers `more?` |

See [What a finished execution leaves behind](../retention.md).