Where branches are kept while no process holds them.
A branch process persists its state here when it unloads (after idle_timeout), when the supervisor shuts down,
and when a branch is created, merged or discarded. Writes between two of those moments live only in the process.
The process loads from here on demand, so the host never needs to know whether a branch is in memory.
Every callback receives the storage config as its last argument: whatever options were given to Ramal.Supervisor
(the Postgres backend reads :repo from it). Implementations return {:error, %Ramal.Error{reason: :storage}} for
failures of the backend itself.
| backend | where | lifetime |
|---|---|---|
Ramal.Storage.ETS | an ETS table owned by Ramal.Supervisor | until the supervisor stops |
Ramal.Storage.Postgres | the ramal_branches table | durable |
Example
iex> Ramal.Storage.ETS in [Ramal.Storage.ETS, Ramal.Storage.Postgres]
trueSummary
Callbacks
How many branches of a domain have one of the statuses, without loading them.
Removes the branch. Removing a missing id is not an error.
The branch with that id, or {:error, %Ramal.Error{reason: :not_found}}.
The branches of a domain, optionally filtered by status:, oldest first.
Stores the branch, replacing any earlier copy with the same id.
Types
@type config() :: keyword()
Callbacks
@callback count(domain :: module(), statuses :: [Ramal.Branch.status()], config()) :: {:ok, non_neg_integer()} | {:error, Ramal.Error.t()}
How many branches of a domain have one of the statuses, without loading them.
Optional. Ramal.Supervisor's :max_active_branches limit calls it before every branch is created; a backend that
does not define it is counted with list/3, which reads every stored branch of the domain.
@callback delete(id :: String.t(), config()) :: :ok | {:error, Ramal.Error.t()}
Removes the branch. Removing a missing id is not an error.
@callback fetch(id :: String.t(), config()) :: {:ok, Ramal.Branch.t()} | {:error, Ramal.Error.t()}
The branch with that id, or {:error, %Ramal.Error{reason: :not_found}}.
@callback list(domain :: module(), filters :: keyword(), config()) :: {:ok, [Ramal.Branch.t()]} | {:error, Ramal.Error.t()}
The branches of a domain, optionally filtered by status:, oldest first.
@callback put(Ramal.Branch.t(), config()) :: :ok | {:error, Ramal.Error.t()}
Stores the branch, replacing any earlier copy with the same id.