cdrs 2.2.0

Cassandra DB driver written in Rust
Documentation 
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use r2d2::{Builder, ManageConnection, Pool};
use std::cell::RefCell;
use std::error::Error;
use std::io;
use std::io::Write;

use crate::authenticators::Authenticator;
use crate::cluster::NodeTcpConfig;
use crate::compression::Compression;
use crate::error;
use crate::frame::parser::parse_frame;
use crate::frame::{Frame, IntoBytes, Opcode};
use crate::transport::{CDRSTransport, TransportTcp};

/// Shortcut for `r2d2::Pool` type of TCP-based CDRS connections.
pub type TcpConnectionPool<A> = Pool<TcpConnectionsManager<A>>;

/// `r2d2::Pool` of TCP-based CDRS connections.
///
/// Used internally for TCP Session for holding connections to a specific Cassandra node.
pub fn new_tcp_pool<'a, A: Authenticator + Send + Sync + 'static>(
  node_config: NodeTcpConfig<'a, A>,
) -> error::Result<TcpConnectionPool<A>> {
  let manager = TcpConnectionsManager::new(node_config.addr.to_string(), node_config.authenticator);

  Builder::new()
    .max_size(node_config.max_size)
    .min_idle(node_config.min_idle)
    .max_lifetime(node_config.max_lifetime)
    .idle_timeout(node_config.idle_timeout)
    .connection_timeout(node_config.connection_timeout)
    .build(manager)
    .map_err(|err| error::Error::from(err.description()))
}

/// `r2d2` connection manager.
pub struct TcpConnectionsManager<A> {
  addr: String,
  auth: A,
}

impl<A> TcpConnectionsManager<A> {
  pub fn new<S: ToString>(addr: S, auth: A) -> Self {
    TcpConnectionsManager {
      addr: addr.to_string(),
      auth,
    }
  }
}

impl<A: Authenticator + 'static + Send + Sync> ManageConnection for TcpConnectionsManager<A> {
  type Connection = RefCell<TransportTcp>;
  type Error = error::Error;

  fn connect(&self) -> Result<Self::Connection, Self::Error> {
    let transport = RefCell::new(TransportTcp::new(&self.addr)?);
    startup(&transport, &self.auth)?;

    Ok(transport)
  }

  fn is_valid(&self, conn: &mut Self::Connection) -> Result<(), Self::Error> {
    let options_frame = Frame::new_req_options().into_cbytes();
    conn.borrow_mut().write(options_frame.as_slice())?;

    parse_frame(conn, &Compression::None {}).map(|_| ())
  }

  fn has_broken(&self, conn: &mut Self::Connection) -> bool {
    !conn.borrow().is_alive()
  }
}

pub fn startup<'b, T: CDRSTransport + 'static, A: Authenticator + 'static + Sized>(
  transport: &RefCell<T>,
  session_authenticator: &'b A,
) -> error::Result<()> {
  let ref mut compression = Compression::None;
  let startup_frame = Frame::new_req_startup(compression.as_str()).into_cbytes();

  transport.borrow_mut().write(startup_frame.as_slice())?;

  let start_response = parse_frame(transport, compression)?;

  if start_response.opcode == Opcode::Ready {
    return Ok(());
  }

  if start_response.opcode == Opcode::Authenticate {
    let body = start_response.get_body()?;
    let authenticator = body.get_authenticator().expect(
      "Cassandra Server did communicate that it neededs
                authentication but the auth schema was missing in the body response",
    );

    // This creates a new scope; avoiding a clone
    // and we check whether
    // 1. any authenticators has been passed in by client and if not send error back
    // 2. authenticator is provided by the client and `auth_scheme` presented by
    //      the server and client are same if not send error back
    // 3. if it falls through it means the preliminary conditions are true

    let auth_check = session_authenticator
      .get_cassandra_name()
      .ok_or(error::Error::General(
        "No authenticator was provided".to_string(),
      ))
      .map(|auth| {
        if authenticator != auth {
          let io_err = io::Error::new(
            io::ErrorKind::NotFound,
            format!(
              "Unsupported type of authenticator. {:?} got,
                             but {} is supported.",
              authenticator, auth
            ),
          );
          return Err(error::Error::Io(io_err));
        }
        Ok(())
      });

    if let Err(err) = auth_check {
      return Err(err);
    }

    let auth_token_bytes = session_authenticator.get_auth_token().into_cbytes();
    transport.borrow_mut().write(
      Frame::new_req_auth_response(auth_token_bytes)
        .into_cbytes()
        .as_slice(),
    )?;
    parse_frame(transport, compression)?;

    return Ok(());
  }

  unreachable!();
}