# genmarkov
HTTP server connecting to a Markov chain

# Build requirements
Unix & Rust nightly are currently requirements to build, for now.

# Configuration
When ran with no arguments, `markov` will attempt to load the config file at `markov.toml`. If it does not exist, it will use the default configuration. (On debug builds, it will also create the default `markov.toml`.)

An example default configuration file is provided at [./markov.toml](markov.toml).

When ran with an argument specifying the config file however, it will attempt to load that. If it fails to load the file, the default will be used.

## Config file entries
| Name                    | Description                                             | Default          | Optional |
|-------------------------|---------------------------------------------------------|------------------|----------|
| `bindpoint`             | Address or Unix domain socket for the server to bind to | `127.0.0.1:8001` | No       |
| `file`                  | File to save and load the chain from                    | `chain.dat`      | No       |
| `max_content_length`    | Max request body length to allow                        | `4194304` (4MB)  | No       |
| `max_gen_size`          | Max number of strings for a request to generate at once | `256`            | No       |
| `save_interval_secs`    | Number of seconds to ensure waiting before saving chain | `2`              | Yes      |
| `trust_x_forwarded_for` | Trust the `X-Forwarded-For` HTTP header                 | `false`          | No       |
| `filter`                | Remove characters from incoming and/or outgoing text    | None             | Yes      |

### AF_UNIX note
When binding to a Unix domain socket, prefix the path with `unix:/` (e.g. `unix://var/markov.socket`)
The server will not attempt to remove already existing sockets at the path, so ensure there isn't one before launching.

## Logging

Set the `RUST_LOG` environment variable to one of the following to switch runtime logging levels.
* `trace` - Most verbose
* `debug` - Verbose
* `info` - Show input and output to/from the chain and requests
* `warn` - Only show warnings (default)
* `error` - Only show errors

## Signals
On Unix systems at runtime, some signals are trapped:

| Signal    | Description                                                            |
|-----------|------------------------------------------------------------------------|
| `SIGUSR1` | Immediately save the chain                                             |
| `SIGUSR2` | Immediately load the chain                                             |
| `SIGQUIT` | Ensure the chain is properly saved and then immediately call `abort()` |
| `SIGINT`  | Perform a full graceful shutdown                                       |

# Usage
The server exposes several paths for access of the chain

## Feeding
### `PUT /put`
Request body is fed to the chain

#### NOTE
Strings fed to the chain must be valid UTF-8 and a size below the value specified in the config file.

## Generating
### `GET /get`
Generate a string from the chain

### `GET /get/<number>`
Generate `<number>` strings from the chain

### `GET /get/sentance`
Generate a single sentance from the chain

### `GET /get/sentance/<number>`
Generate `<number>` sentances from the chain

#### NOTE
Number of strings/sentances must be lower than the value specified in the config file.

# License
GPL'd with <3