/
mnesia.ex
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/
mnesia.ex
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defmodule Ash.DataLayer.Mnesia do
@behaviour Ash.DataLayer
@mnesia %Spark.Dsl.Section{
name: :mnesia,
describe: """
A section for configuring the mnesia data layer
""",
examples: [
"""
mnesia do
table :custom_table
end
"""
],
schema: [
table: [
type: :atom,
doc: "The table name to use, defaults to the name of the resource"
]
]
}
@moduledoc """
An Mnesia backed Ash Datalayer.
In your application initialization, you will need to call `Mnesia.create_schema([node()])`.
Additionally, you will want to create your mnesia tables there.
This data layer is *unoptimized*, fetching all records from a table and filtering them
in memory. For that reason, it is not recommended to use it with large amounts of data. It can be
great for prototyping or light usage, though.
"""
use Spark.Dsl.Extension,
sections: [@mnesia],
verifiers: [Ash.DataLayer.Verifiers.RequirePreCheckWith]
alias Ash.Actions.Sort
alias :mnesia, as: Mnesia
@doc """
Creates the table for each mnesia resource in an api
"""
def start(api, resources \\ []) do
Mnesia.create_schema([node()])
Mnesia.start()
Code.ensure_compiled(api)
api
|> Ash.Api.Info.resources()
|> Enum.concat(resources)
|> Enum.filter(&(__MODULE__ in Spark.extensions(&1)))
|> Enum.flat_map(fn resource ->
resource
|> Ash.DataLayer.Mnesia.Info.table()
|> List.wrap()
end)
|> Enum.each(&Mnesia.create_table(&1, attributes: [:_pkey, :val]))
end
defmodule Query do
@moduledoc false
defstruct [
:api,
:resource,
:filter,
:limit,
:sort,
relationships: %{},
offset: 0,
aggregates: [],
calculations: []
]
end
@deprecated "use Ash.DataLayer.Mnesia.Info.table/1 instead"
defdelegate table(resource), to: Ash.DataLayer.Mnesia.Info
@doc false
@impl true
def can?(_, :async_engine), do: true
def can?(_, :multitenancy), do: true
def can?(_, :composite_primary_key), do: true
def can?(_, :upsert), do: true
def can?(_, :create), do: true
def can?(_, :read), do: true
def can?(_, :update), do: true
def can?(_, :destroy), do: true
def can?(_, :sort), do: true
def can?(_, :filter), do: true
def can?(_, {:filter_relationship, _}), do: true
def can?(_, {:query_aggregate, :count}), do: true
def can?(_, :expression_calculation), do: true
def can?(_, :expression_calculation_sort), do: true
def can?(_, :limit), do: true
def can?(_, :offset), do: true
def can?(_, :boolean_filter), do: true
def can?(_, :transact), do: true
def can?(_, :aggregate_filter), do: true
def can?(_, :aggregate_sort), do: true
def can?(_, :expr_error), do: true
def can?(_, {:aggregate_relationship, _}), do: true
def can?(_, {:aggregate, :count}), do: true
def can?(_, {:aggregate, :first}), do: true
def can?(_, {:aggregate, :sum}), do: true
def can?(_, {:aggregate, :list}), do: true
def can?(_, {:aggregate, :max}), do: true
def can?(_, {:aggregate, :min}), do: true
def can?(_, {:aggregate, :avg}), do: true
def can?(_, {:aggregate, :exists}), do: true
def can?(_, {:join, resource}) do
# This is to ensure that these can't join, which is necessary for testing
# if someone needs to use these both and *actually* needs real joins for private
# ets resources then we can talk about making this only happen in ash tests
not (Ash.DataLayer.data_layer(resource) == Ash.DataLayer.Ets &&
Ash.DataLayer.Ets.Info.private?(resource))
end
def can?(_, {:filter_expr, _}), do: true
def can?(_, :nested_expressions), do: true
def can?(_, {:sort, _}), do: true
def can?(_, _), do: false
@doc false
@impl true
def resource_to_query(resource, api) do
%Query{
resource: resource,
api: api
}
end
@doc false
@impl true
def in_transaction?(_), do: Mnesia.is_transaction()
@doc false
@impl true
def limit(query, offset, _), do: {:ok, %{query | limit: offset}}
@doc false
@impl true
def offset(query, offset, _), do: {:ok, %{query | offset: offset}}
@doc false
@impl true
def filter(query, filter, _resource) do
if query.filter do
{:ok, %{query | filter: Ash.Filter.add_to_filter!(query.filter, filter)}}
else
{:ok, %{query | filter: filter}}
end
end
@doc false
@impl true
def sort(query, sort, _resource) do
{:ok, %{query | sort: sort}}
end
@doc false
@impl true
def add_aggregate(query, aggregate, _),
do: {:ok, %{query | aggregates: [aggregate | query.aggregates]}}
@doc false
@impl true
def add_calculations(query, calculations, _),
do: {:ok, %{query | calculations: query.calculations ++ calculations}}
@doc false
@impl true
def run_aggregate_query(%{api: api} = query, aggregates, resource) do
case run_query(query, resource) do
{:ok, results} ->
Enum.reduce_while(aggregates, {:ok, %{}}, fn
%{
kind: kind,
name: name,
query: query,
field: field,
resource: resource,
uniq?: uniq?,
default_value: default_value
},
{:ok, acc} ->
results
|> filter_matches(Map.get(query || %{}, :filter), api)
|> case do
{:ok, matches} ->
field = field || Enum.at(Ash.Resource.Info.primary_key(resource), 0)
value =
Ash.DataLayer.Ets.aggregate_value(matches, kind, field, uniq?, default_value)
{:cont, {:ok, Map.put(acc, name, value)}}
{:error, error} ->
{:halt, {:error, error}}
end
end)
{:error, error} ->
{:error, error}
end
|> case do
{:error, error} ->
{:error, Ash.Error.to_ash_error(error)}
{:aborted, error} ->
{:error, error}
end
end
@doc false
@impl true
def run_query(
%Query{
api: api,
resource: resource,
filter: filter,
offset: offset,
calculations: calculations,
limit: limit,
sort: sort,
aggregates: aggregates
},
_resource
) do
with {:atomic, records} <-
Mnesia.transaction(fn ->
Mnesia.select(table(resource), [{:_, [], [:"$_"]}])
end),
{:ok, records} <-
records |> Enum.map(&elem(&1, 2)) |> Ash.DataLayer.Ets.cast_records(resource),
{:ok, filtered} <- filter_matches(records, filter, api),
offset_records <-
filtered |> Sort.runtime_sort(sort, api: api) |> Enum.drop(offset || 0),
limited_records <- do_limit(offset_records, limit),
{:ok, records} <-
Ash.DataLayer.Ets.do_add_aggregates(
limited_records,
api,
resource,
aggregates
),
{:ok, records} <-
Ash.DataLayer.Ets.do_add_calculations(
records,
resource,
calculations,
api
) do
{:ok, records}
else
{:error, error} ->
{:error, error}
{:aborted, reason} ->
{:error, reason}
end
end
defp do_limit(records, nil), do: records
defp do_limit(records, limit), do: Enum.take(records, limit)
defp filter_matches(records, nil, _api), do: {:ok, records}
defp filter_matches(records, filter, api) do
Ash.Filter.Runtime.filter_matches(api, records, filter)
end
@doc false
@impl true
def create(resource, changeset) do
{:ok, record} = Ash.Changeset.apply_attributes(changeset)
pkey =
resource
|> Ash.Resource.Info.primary_key()
|> Enum.map(fn attr ->
Map.get(record, attr)
end)
resource
|> Ash.Resource.Info.attributes()
|> Map.new(&{&1.name, Map.get(record, &1.name)})
|> Ash.DataLayer.Ets.dump_to_native(Ash.Resource.Info.attributes(resource))
|> case do
{:ok, values} ->
case Mnesia.transaction(fn ->
Mnesia.write({table(resource), pkey, values})
end) do
{:atomic, _} ->
{:ok, %{record | __meta__: %Ecto.Schema.Metadata{state: :loaded, schema: resource}}}
{:aborted, error} ->
{:error, error}
end
{:error, error} ->
{:error, error}
end
end
@doc false
@impl true
def destroy(resource, %{data: record}) do
pkey =
resource
|> Ash.Resource.Info.primary_key()
|> Enum.map(&Map.get(record, &1))
result =
Mnesia.transaction(fn ->
Mnesia.delete({table(resource), pkey})
end)
case result do
{:atomic, _} -> :ok
{:aborted, error} -> {:error, error}
end
end
@doc false
@impl true
def update(resource, changeset) do
pkey = pkey_list(resource, changeset.data)
result =
Mnesia.transaction(fn ->
with {:ok, record} <- Ash.Changeset.apply_attributes(%{changeset | action_type: :update}),
{:ok, record} <- do_update(table(resource), {pkey, record}, resource),
{:ok, record} <- Ash.DataLayer.Ets.cast_record(record, resource) do
new_pkey = pkey_list(resource, record)
if new_pkey != pkey do
case destroy(resource, changeset) do
:ok ->
{:ok,
%{record | __meta__: %Ecto.Schema.Metadata{state: :loaded, schema: resource}}}
{:error, error} ->
{:error, error}
end
else
{:ok, %{record | __meta__: %Ecto.Schema.Metadata{state: :loaded, schema: resource}}}
end
else
{:error, error} ->
{:error, error}
end
end)
case result do
{:atomic, {:error, error}} ->
{:error, error}
{:atomic, {:ok, result}} ->
{:ok, result}
{:aborted, {reason, stacktrace}} when is_exception(reason) ->
{:error, Ash.Error.to_ash_error(reason, stacktrace)}
{:aborted, reason} ->
{:error, reason}
end
end
defp pkey_list(resource, data) do
resource
|> Ash.Resource.Info.primary_key()
|> Enum.map(&Map.get(data, &1))
end
defp do_update(table, {pkey, record}, resource) do
attributes = Ash.Resource.Info.attributes(resource)
case Ash.DataLayer.Ets.dump_to_native(record, attributes) do
{:ok, casted} ->
case Mnesia.read({table(resource), pkey}) do
[] ->
{:error, "Record not found matching: #{inspect(pkey)}"}
[{_, _, record}] ->
Mnesia.write({table, pkey, Map.merge(record, casted)})
[{_, _, record}] = Mnesia.read({table, pkey})
{:ok, record}
end
{:error, error} ->
{:error, error}
end
end
@doc false
@impl true
def upsert(resource, changeset, keys) do
keys = keys || Ash.Resource.Info.primary_key(resource)
if Enum.any?(keys, &is_nil(Ash.Changeset.get_attribute(changeset, &1))) do
create(resource, changeset)
else
key_filters =
Enum.map(keys, fn key ->
{key, Ash.Changeset.get_attribute(changeset, key)}
end)
query = Ash.Query.do_filter(resource, and: [key_filters])
resource
|> resource_to_query(changeset.api)
|> Map.put(:filter, query.filter)
|> Map.put(:tenant, changeset.tenant)
|> run_query(resource)
|> case do
{:ok, []} ->
create(resource, changeset)
{:ok, [result]} ->
to_set = Ash.Changeset.set_on_upsert(changeset, keys)
changeset =
changeset
|> Map.put(:attributes, %{})
|> Map.put(:data, result)
|> Ash.Changeset.force_change_attributes(to_set)
update(resource, changeset)
{:ok, _} ->
{:error, "Multiple records matching keys"}
end
end
end
@doc false
@impl true
def transaction(_, func, _timeout, _reason) do
case Mnesia.transaction(func, 1) do
{:atomic, result} ->
{:ok, result}
{:aborted, {reason, stacktrace}} when is_exception(reason) ->
{:error, Ash.Error.to_ash_error(reason, stacktrace)}
{:aborted, %Ash.Changeset{} = changeset} ->
{:error, changeset}
{:aborted, %Ash.Query{} = query} ->
{:error, query}
{:aborted, reason} ->
if Ash.Error.ash_error?(reason) do
{:error, reason}
else
{:error, Ash.Error.to_ash_error(Exception.format_exit(reason))}
end
end
end
@doc false
@impl true
@spec rollback(term, term) :: no_return
def rollback(_, value) do
Mnesia.abort(value)
end
end