debugging heartbeat and buggy worker

Chapter09/Cargo.toml

@@ -71,3 +71,11 @@ path = "performance_reference.rs"
 [[bin]]
 name = "debugging_result"
 path = "debugging_result.rs"
+
+[[bin]]
+name = "debugging_heartbeat"
+path = "debugging_heartbeat.rs"
+
+[[bin]]
+name = "debugging_buggy_worker"
+path = "debugging_buggy_worker.rs"

Chapter09/debugging_buggy_worker.rs

@@ -0,0 +1,10 @@
+use std::{thread,time,process};
+
+fn main() {
+   let life_expectancy = process::id() % 8;
+   let t = time::Duration::from_millis(1000);
+   for _ in 0..life_expectancy {
+      thread::sleep(t);
+   }
+   println!("process {} dies unexpectedly.", process::id());
+}

Chapter09/debugging_heartbeat.rs

@@ -0,0 +1,32 @@
+use std::process::Command;
+use std::env::current_exe;
+use std::{thread,time};
+
+fn main() {
+   let path = current_exe()
+             .expect("could not find current executable");
+   let path = path.with_file_name("debugging_buggy_worker");
+
+   let mut children = Vec::new();
+   for _ in 0..3 {
+      children.push(
+         Command::new(path.as_os_str())
+                 .spawn()
+                 .expect("failed to spawn child")
+      );
+   }
+
+   let t = time::Duration::from_millis(1000);
+   loop {
+      thread::sleep(t);
+      for ci in 0..children.len() {
+         let is_dead = children[ci].try_wait().expect("failed to try_wait");
+         if let Some(_exit_code) = is_dead {
+            children[ci] = Command::new(path.as_os_str())
+                                   .spawn()
+                                   .expect("failed to spawn child");
+            println!("starting a new process from parent.");
+         }
+      }
+   }
+}