Problem: writing custom servers is difficult

Basically, it requires duplicating a lot of code that is currently
in pumpkindb_server (with respect to mio and putting all the necessary
engine elements together)

Writing such servers is very useful when one needs to add new
built-in functionality to PumpkinDB yet retain its standard communication
protocol.

Solution: extract pumpkindb_mio_server crate that focuses primarily
on the mio part) and let pumpkindb_server handle the rest.

Note that this is still requiring one to at least look at pumpkindb_server
to implement their own custom server, but this is far better than before.

Also, the separation is not very clean, but this will start the ball
rolling.

Cargo.toml

@@ -3,6 +3,7 @@ members = [
   "./pumpkinscript",
   "./pumpkindb_engine",
   "./pumpkindb_client",
+  "./pumpkindb_mio_server",
   "./pumpkindb_server",
   "./pumpkindb_term",
   "./tests/doctests"

Dockerfile

@@ -46,6 +46,7 @@ COPY Makefile /pumpkindb/
 COPY Cargo.* /pumpkindb/
 COPY pumpkindb_engine /pumpkindb/pumpkindb_engine
 COPY pumpkindb_server /pumpkindb/pumpkindb_server
+COPY pumpkindb_mio_server /pumpkindb/pumpkindb_mio_server
 COPY pumpkindb_term /pumpkindb/pumpkindb_term
 COPY pumpkinscript /pumpkindb/pumpkinscript
 COPY tests /pumpkindb/tests

pumpkindb_mio_server/Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "pumpkindb_mio_server"
+version = "0.2.0"
+license = "MPL-2.0"
+repository = "https://github.com/PumpkinDB/PumpkinDB"
+homepage = "http://pumpkindb.org"
+keywords = [ "pumpkindb", "database" ]
+categories = [ "database" ]
+
+authors = ["Yurii Rashkovskii <yrashk@gmail.com>"]
+
+[dependencies]
+mio = "0.6.4"
+byteorder = "1.0.0"
+memmap = "0.5.2"
+slab = "0.3.0"
+num-bigint = "0.1.35"
+num-traits = "0.1.36"
+rand = "0.3.15"
+log = "0.3.6"
+log4rs = { version = "0.6.1", features = ["toml_format"] }
+lmdb-zero = "0.4.0"
+uuid = { version = "0.4", features = ["v4"] }
+
+pumpkindb_engine = { version = "0.2", path = "../pumpkindb_engine" }

pumpkindb_mio_server/src/lib.rs

@@ -0,0 +1,49 @@
+// Copyright (c) 2017, All Contributors (see CONTRIBUTORS file)
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+#![feature(slice_patterns, advanced_slice_patterns)]
+
+extern crate mio;
+extern crate memmap;
+extern crate byteorder;
+extern crate rand;
+#[macro_use]
+extern crate log;
+extern crate log4rs;
+extern crate slab;
+extern crate num_bigint;
+extern crate num_traits;
+extern crate lmdb_zero as lmdb;
+extern crate uuid;
+
+extern crate pumpkindb_engine;
+
+mod connection;
+mod server;
+
+use mio::Poll;
+use mio::tcp::TcpListener;
+
+use mio::channel as mio_chan;
+
+use pumpkindb_engine::script;
+
+pub fn run(port: i64,
+           senders: Vec<script::Sender<script::RequestMessage>>,
+           relay_sender: mio_chan::Sender<server::RelayedPublishedMessage>,
+           relay_receiver: mio_chan::Receiver<server::RelayedPublishedMessage>) {
+    let addr = format!("0.0.0.0:{}", port).parse().unwrap();
+
+    info!("Listening on {}", addr);
+
+    let sock = TcpListener::bind(&addr).expect("Failed to bind address");
+
+    let mut poll = Poll::new().expect("Failed to initialize polling");
+
+    let mut server = server::Server::new(sock, relay_sender, relay_receiver, senders);
+    server.run(&mut poll).expect("Failed to run server");
+
+}
+

pumpkindb_server/Cargo.toml

@@ -15,20 +15,14 @@ name = "pumpkindb"
 
 [dependencies]
 clap = "2.22.1"
-mio = "0.6.4"
-byteorder = "1.0.0"
-memmap = "0.5.2"
-slab = "0.3.0"
-num-bigint = "0.1.35"
-num-traits = "0.1.36"
-rand = "0.3.15"
+config = "0.3.1"
+lazy_static = "0.2.2"
 num_cpus = "1.3.0"
+memmap = "0.5.2"
 log = "0.3.6"
 log4rs = { version = "0.6.1", features = ["toml_format"] }
-config = "0.3.1"
-lazy_static = "0.2.2"
 lmdb-zero = "0.4.0"
-uuid = { version = "0.4", features = ["v4"] }
+mio = "0.6.4"
 
-pumpkinscript = { version = "0.2", path = "../pumpkinscript" }
 pumpkindb_engine = { version = "0.2", path = "../pumpkindb_engine" }
+pumpkindb_mio_server = { version = "0.2", path = "../pumpkindb_mio_server" }

pumpkindb_server/src/main.rs

@@ -3,47 +3,39 @@
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
-#![feature(slice_patterns, advanced_slice_patterns)]
 
-extern crate mio;
-extern crate memmap;
-extern crate byteorder;
-extern crate rand;
-extern crate num_cpus;
 #[macro_use]
-extern crate log;
-extern crate log4rs;
-extern crate slab;
-extern crate num_bigint;
-extern crate num_traits;
-extern crate lmdb_zero as lmdb;
+extern crate clap;
 #[macro_use]
 extern crate lazy_static;
 extern crate config;
+extern crate pumpkindb_engine;
+extern crate num_cpus;
+extern crate memmap;
 #[macro_use]
-extern crate clap;
-extern crate uuid;
+extern crate log;
+extern crate log4rs;
+extern crate lmdb_zero as lmdb;
+extern crate mio;
 
-extern crate pumpkinscript;
-extern crate pumpkindb_engine;
+extern crate pumpkindb_mio_server as server;
+
+use pumpkindb_engine::{script, storage, timestamp};
+use pumpkindb_engine::script::dispatcher;
+use pumpkindb_engine::messaging;
+
+use clap::{App, Arg};
+use memmap::{Mmap, Protection};
 
-mod connection;
-mod server;
+use std::thread;
 
 use std::fs;
 use std::fs::OpenOptions;
 use std::path::PathBuf;
-use std::thread;
 use std::sync::Arc;
 
-use memmap::{Mmap, Protection};
-use mio::*;
-use mio::tcp::*;
-use clap::{App, Arg};
+use mio::channel as mio_chan;
 
-use pumpkindb_engine::{script, storage, timestamp};
-use pumpkindb_engine::script::dispatcher;
-use pumpkindb_engine::messaging;
 
 lazy_static! {
  static ref ENVIRONMENT: lmdb::Environment = {
@@ -62,27 +54,6 @@ lazy_static! {
  };
 }
 
-use mio::channel as mio_chan;
-
-
-
-pub fn run(port: i64,
-           senders: Vec<script::Sender<script::RequestMessage>>,
-           relay_sender: mio_chan::Sender<server::RelayedPublishedMessage>,
-           relay_receiver: mio_chan::Receiver<server::RelayedPublishedMessage>) {
-    let addr = format!("0.0.0.0:{}", port).parse().unwrap();
-
-    info!("Listening on {}", addr);
-
-    let sock = TcpListener::bind(&addr).expect("Failed to bind address");
-
-    let mut poll = Poll::new().expect("Failed to initialize polling");
-
-    let mut server = server::Server::new(sock, relay_sender, relay_receiver, senders);
-    server.run(&mut poll).expect("Failed to run server");
-
-}
-
 /// Accepts storage path, filename and length and prepares the file. It is important that the length
 /// is the total length of the memory mapped file, otherwise the application _will segfault_ when
 /// trying to read those sections later. There is no way to handle that.
@@ -103,7 +74,7 @@ fn prepare_mmap(storage_path: &str, filename: &str, length: u64) -> Mmap {
     Mmap::open_path(scratchpad_path, Protection::ReadWrite).expect("Could not open scratchpad")
 }
 
-fn main() {
+pub fn main() {
     let args = App::new("PumpkinDB Server")
         .version(crate_version!())
         .about("Event Sourcing Database Engine http://pumpkindb.org")
@@ -192,7 +163,6 @@ fn main() {
         senders.push(sender)
     }
 
-    run(config::get_int("server.port").unwrap(),
+    server::run(config::get_int("server.port").unwrap(),
                 senders, relay_sender, relay_receiver);
-
-}
+}