Added connection retry for cases where too many clients attempt to co…

…nnect at once

Improved error message for 'spraycc run'
Bumped version to 0.8

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "spraycc"
-version = "0.1.0"
+version = "0.8.0"
 authors = ["Jason McCampbell <jasonmccampbell@gmail.com>"]
 edition = "2018"
 
@@ -13,6 +13,7 @@ get_if_addrs = "0.5"
 gethostname = "0"
 home = "0.5"
 lazy_static = "1"
+rand = "^0.8"
 serde = { version = "1", features = ["derive"] }
 simple-process-stats = "^1"
 tempdir = "0.3"

src/client.rs

@@ -4,12 +4,13 @@
 /// results are available.
 ///
 extern crate lazy_static;
+extern crate rand;
 extern crate tokio;
 extern crate which;
 
 use lazy_static::lazy_static;
-use std::error::Error;
 use std::ffi::OsString;
+use std::{error::Error, time::Duration};
 use tokio::io::AsyncWriteExt;
 use tokio::net::TcpStream;
 use tokio::process;
@@ -76,7 +77,7 @@ pub async fn run(args: Vec<String>) -> Result<i32, Box<dyn Error + Send + Sync>>
     if run_local {
         status = run_local_task(task).await?;
     } else if let Some(callme) = config::read_server_contact_info() {
-        match TcpStream::connect(callme.addr).await {
+        match connect_w_retry(&callme).await {
             Ok(stream) => {
                 let mut conn = ipc::Connection::new(stream);
 
@@ -105,11 +106,7 @@ pub async fn run(args: Vec<String>) -> Result<i32, Box<dyn Error + Send + Sync>>
                     output_files.pop().unwrap().shutdown().await?
                 }
             }
-            Err(err) => {
-                println!(
-                    "Unable to connect to server at {}, please make sure it was started with 'spraycc server': {}",
-                    callme.addr, err
-                );
+            Err(_) => {
                 status = Some(-1);
             }
         }
@@ -122,6 +119,29 @@ pub async fn run(args: Vec<String>) -> Result<i32, Box<dyn Error + Send + Sync>>
     Ok(status.expect("No task status as set"))
 }
 
+async fn connect_w_retry(callme: &ipc::CallMe) -> Result<TcpStream, Box<dyn Error + Send + Send>> {
+    let mut count = 0;
+    loop {
+        match TcpStream::connect(callme.addr).await {
+            Ok(stream) => return Ok(stream),
+            Err(err) => {
+                if count < 5 {
+                    count += 1;
+                    println!("Retrying connection to {} ({}): {}", callme.addr, count, &err);
+                    let duration = Duration::from_millis(rand::random::<u64>() % 2048 + 512); // 2-2.5s backoff period
+                    tokio::time::sleep(duration).await;
+                } else {
+                    println!(
+                        "Unable to connect to server at {}, please make sure it was started with 'spraycc server': {}",
+                        callme.addr, &err
+                    );
+                    return Err(Box::new(err));
+                }
+            }
+        }
+    }
+}
+
 /// Handles messages coming from the client via the server. These will be stderr, stdout and generated files from
 /// the execution of the task, and then finally the task status.
 ///

src/main.rs

@@ -30,7 +30,7 @@ pub mod task;
 #[tokio::main]
 async fn main() {
     let matches = App::new("SprayCC")
-        .version("0.1.0")
+        .version("0.8.0")
         .about("SprayCC - distributed compiler wrapper")
         .setting(AppSettings::SubcommandRequiredElseHelp)
         .subcommand(
@@ -114,18 +114,22 @@ async fn main() {
             panic!("Error: access code must be a numeric value, got: {}", code);
         }
     } else if let Some(run) = matches.subcommand_matches("run") {
-        let args: Vec<String> = run.values_of("compiler_options").unwrap().map(String::from).collect();
-        match client::run(args).await {
-            Ok(ec) if ec > 0 => {
-                // Remote task failed so exit with the same exit code
-                std::process::exit(ec);
+        if let Some(compiler_opts) = run.values_of("compiler_options") {
+            let args: Vec<String> = compiler_opts.map(String::from).collect();
+            match client::run(args).await {
+                Ok(ec) if ec > 0 => {
+                    // Remote task failed so exit with the same exit code
+                    std::process::exit(ec);
+                }
+                Ok(ec) if ec < 0 => {
+                    // Remote task failed with signal
+                    std::process::exit(-1);
+                }
+                Ok(_) => Ok(()),
+                Err(e) => Err(e),
             }
-            Ok(ec) if ec < 0 => {
-                // Remote task failed with signal
-                std::process::exit(-1);
-            }
-            Ok(_) => Ok(()),
-            Err(e) => Err(e),
+        } else {
+            panic!("'spraycc run' must be followed by the command line to be run");
         }
     } else if let Some(fakecc) = matches.subcommand_matches("fakecc") {
         for output in fakecc.values_of("output_file").unwrap() {