# `Sftpd.Backends.Memory`
[🔗](https://github.com/elixir-ssh/sftpd/blob/v0.1.1/lib/sftpd/backends/memory.ex#L1)

In-memory storage backend for testing and development.

This backend stores all files in memory using an Agent. It's useful for:
- Testing without external dependencies (no S3-compatible service needed)
- Development and experimentation
- As a reference implementation for custom backends

## Usage

    {:ok, ref} = Sftpd.start_server(
      port: 2222,
      backend: Sftpd.Backends.Memory,
      backend_opts: [],
      auth: {:passwords, [{"user", "pass"}]},
      system_dir: "path/to/ssh_keys"
    )

## State Structure

The backend maintains a map of paths to file data:

    %{
      "path/to/file.txt" => %{content: "...", mtime: ~N[...]},
      "path/to/dir/.keep" => %{content: "", mtime: ~N[...]}
    }

Directories are represented by `.keep` marker files (like S3).

## Examples

    iex> {:ok, state} = Sftpd.Backends.Memory.init(
    ...>   files: %{"hello.txt" => %{content: "hi", mtime: ~N[2024-01-01 00:00:00]}}
    ...> )
    iex> Sftpd.Backends.Memory.list_dir(~c"/", state)
    {:ok, [~c".", ~c"..", ~c"hello.txt"]}

    iex> {:ok, state} = Sftpd.Backends.Memory.init([])
    iex> :ok = Sftpd.Backends.Memory.write_file(~c"/notes.txt", "hello", state)
    iex> Sftpd.Backends.Memory.read_file(~c"/notes.txt", state)
    {:ok, "hello"}

See the `Backends` and `Custom Backends` extras in HexDocs for how this
backend fits into the wider package model.

# `file_data`

```elixir
@type file_data() :: %{content: binary(), mtime: NaiveDateTime.t()}
```

File data stored in memory

# `state`

```elixir
@type state() :: %{agent: pid()}
```

Memory backend state containing the Agent process

---

*Consult [api-reference.md](api-reference.md) for complete listing*