Dockerfiles for Ch 04

Since Mac (and to a lesser extent Windows, though it has WSL) cannot work with epoll directly, Dockerfiles,
Docker compose yml, and simple run scripts have been created so that users who have docker can run and test the ch04 examples on their
system.

A docker file has been created for delayserver as well and docker
compose is used to run an epoll container and a delay server
container and coordinate the network between them.

Some slight modification has been made to the epoll code to allow
for an optional argument to be passed in which is the name of the
host. When running the examples without docker both are running on
"localhost". However when running docker containers epoll and
delayserver are in separate containers, so epoll needs to transmit
to the delayserver container (conveniently named "delayserver") instead of localhost.

Debian slim rust containers have been used as they are a convenient
and fairly small container for these kinds of rust projects.

README.md's have been updated to note that it is now possible to pass an optional argument for the hostname to connect to, which will default to "localhost" if no argument is passed.

Author: psalm842

ch04/a-epoll/Dockerfile

@@ -0,0 +1,9 @@
+FROM rust:1-slim-bookworm
+
+WORKDIR /usr/a-epoll
+
+COPY . .
+
+RUN cargo build
+
+CMD ["cargo", "run", "delayserver"]

ch04/a-epoll/README.md

@@ -5,6 +5,9 @@ additional comments that's not in the book.
 
 You can run the example by simply writing `cargo run`
 
+If running on a Mac system (which only supports kqueue but not epoll), docker
+can be used to run the example by running the epoll_docker.sh script
+
 ## Note
 
 There is one downside of having a local server on the same machine to mimic

ch04/a-epoll/docker-compose.yml

@@ -0,0 +1,17 @@
+services:
+  delayserver:
+    build: ../../delayserver/
+    ports:
+      - "8080:8080"
+    networks:
+      - delayserver_network
+
+  epoll:
+    build: .
+    depends_on:
+      - delayserver
+    networks:
+      - delayserver_network
+
+networks:
+  delayserver_network: {}

ch04/a-epoll/epoll_docker.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+
+docker compose up --build

ch04/a-epoll/src/main.rs

@@ -17,6 +17,7 @@ use std::{
     collections::HashSet,
     io::{self, Read, Result, Write},
     net::TcpStream,
+    env
 };
 
 use ffi::Event;
@@ -84,13 +85,21 @@ fn main() -> Result<()> {
     let n_events = 5;
 
     let mut streams = vec![];
-    let addr = "localhost:8080";
+
+    let args: Vec<String> = env::args().collect();
+    let base_url;
+    if args.len() > 1 {
+        base_url = args[1].clone();
+    } else {
+        base_url = String::from("localhost");
+    }
+    let addr = format!("{}:8080", &base_url);
 
     for i in 0..n_events {
         let delay = (n_events - i) * 1000;
         let url_path = format!("/{delay}/request-{i}");
         let request = get_req(&url_path);
-        let mut stream = std::net::TcpStream::connect(addr)?;
+        let mut stream = std::net::TcpStream::connect(&addr)?;
         stream.set_nonblocking(true)?;
 
         stream.write_all(request.as_bytes())?;

ch04/b-epoll-mio/Dockerfile

@@ -0,0 +1,9 @@
+FROM rust:1-slim-bookworm
+
+WORKDIR /usr/a-epoll
+
+COPY . .
+
+RUN cargo build
+
+CMD ["cargo", "run", "delayserver"]

ch04/b-epoll-mio/README.md

@@ -1,10 +1,13 @@
-# a-epoll-mio
+# b-epoll-mio
 
 This create contains the example code for chapter 4, but instead of using
 our own queue, we use one created by [mio](https://github.com/tokio-rs/mio). Since we modelled our own code after
 mio you only need to make a few very minor changes to get it working which I've
 commented and marked out as clearly as I can.
 
+If running on a Mac system (which only supports kqueue but not epoll), docker
+can be used to run the example by running the epoll_mio_docker.sh script
+
 You can run the example by simply writing `cargo run`
 
 ## Note

ch04/b-epoll-mio/docker-compose.yml

@@ -0,0 +1,17 @@
+services:
+  delayserver:
+    build: ../../delayserver/
+    ports:
+      - "8080:8080"
+    networks:
+      - delayserver_network
+
+  epoll-mio:
+    build: .
+    depends_on:
+      - delayserver
+    networks:
+      - delayserver_network
+
+networks:
+  delayserver_network: {}

ch04/b-epoll-mio/epoll_mio_docker.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+
+docker compose up --build

ch04/b-epoll-mio/src/main.rs

@@ -1,9 +1,9 @@
 //! # FIXES:
-//! 
+//!
 //! The number is identical to the number in the GitHub issue tracker
 //!
 //! ## FIX ISSUE #4:
-//! 
+//!
 //! See:https://github.com/PacktPublishing/Asynchronous-Programming-in-Rust/issues/4
 //! Some users reported false event notification causing the counter to increase
 //! due to the OS reporting a READ event after we already read the TcpStream to EOF.
@@ -13,24 +13,25 @@
 //! The fix for this is to account for false wakeups which is an easy fix but requires
 //! a few changes to the example. I've added an explicit comment: "FIX #4", the places
 //! I made a change so it's easy to spot the differences to the example code in the book.
-//! 
+//!
 //! ## TROUBLESHOOTING (KNOWN POTENTIAL ISSUE)
-//! 
+//!
 //! ### EXAMPLE DOESN'T WORK AS EXPECTED - PROBLEM WITH DNS LOOKUP
 //! If you first run this example on Linux under WSL and then immediately run it on
 //! Windows, I've observed issues with the DNS lookup for "localhost" being so slow
 //! that it defeats the purpose of the example. This issue could potentially also
 //! happen under other scenarios than the one mentioned here and the fix will be
 //! the same regardless.
-//! 
-//! I don't consider this a bug with our code but a surprising behavior of the 
-//! WSL/Windows network stack. Anyway, if you encounter this, the fix is simple: 
-//! 
-//! Change `let addr = "localhost:8080";` to `let addr = "127.0.0.1:8080";`.
+//!
+//! I don't consider this a bug with our code but a surprising behavior of the
+//! WSL/Windows network stack. Anyway, if you encounter this, the fix is simple:
+//!
+//! Change `base_url = String::from("localhost");` to `base_url = String::from("127.0.0.1");`.
 //!
 
 // FIX #4 (import `HashSet``)
 use std::collections::HashSet;
+use std::env;
 use std::io::{self, Read, Result, Write};
 
 use mio::event::Event;
@@ -91,13 +92,21 @@ fn main() -> Result<()> {
     let n_events = 5;
 
     let mut streams = vec![];
-    let addr = "localhost:8080";
+
+    let args: Vec<String> = env::args().collect();
+    let base_url;
+    if args.len() > 1 {
+        base_url = args[1].clone();
+    } else {
+        base_url = String::from("localhost");
+    }
+    let addr = format!("{}:8080", &base_url);
 
     for i in 0..n_events {
         let delay = (n_events - i) * 1000;
         let url_path = format!("/{delay}/request-{i}");
         let request = get_req(&url_path);
-        let std_stream = std::net::TcpStream::connect(addr)?;
+        let std_stream = std::net::TcpStream::connect(&addr)?;
         std_stream.set_nonblocking(true)?;
 
         // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
@@ -117,7 +126,7 @@ fn main() -> Result<()> {
 
         streams.push(stream);
     }
-    
+
     // FIX #4: store the handled IDs
     let mut handled_ids = HashSet::new();
 
@@ -139,7 +148,7 @@ fn main() -> Result<()> {
         // Events collection
         let events: Vec<Event> = events.into_iter().map(|e| e.clone()).collect();
         // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-        
+
         // ------------------------------------------------------⌄ FIX #4 (new signature)
         handled_events += handle_events(&events, &mut streams, &mut handled_ids)?;
     }