feat: terminates current running watcher upon config changes

relates to #106

.watch.yaml

@@ -53,6 +53,7 @@
     - "examples/*.yaml"
     - "examples/*.yml"
   ignore: 
+    - "examples/reload-config-example.yml"
     - "examples/workdir/ignored/**"
     - "**/*.log"
   run_on_init: true
@@ -72,4 +73,5 @@
     - "**/*.nix"
   ignore: 
     - "examples/workdir/**"
+    - "examples/reload-config-example.yml"
   run_on_init: true

examples/reload-config-example.yml

@@ -0,0 +1,32 @@
+# This example shows the auto reload feature
+#
+# This workflow efectivelly creates a dependency between tasks with conditionals
+# I don't want to give ideas, but one can create some pretty crazy workflows
+# maybe even turing complete.
+#
+#@#CHANGED#@
+#
+- name: task runs on init (1)
+  run: 
+    - echo 'run me first'
+    - sed  -i '1,7s/#THIS_WILL_CHANGE#@$/#CHANGED#@/' examples/reload-config-example.yml
+    - echo 1 > examples/workdir/trigger-first-task.txt
+  change: 
+    - '__noop__'
+    # LOL! To setup a LOOP uncomment this line
+    # - examples/workdir/trigger-start.txt
+  run_on_init: true
+
+- name: task that run at the end (3)
+  run: 
+    - echo 'then me in third'
+    - cat examples/reload-config-example.yml
+    - echo 1 > examples/workdir/trigger-start.txt
+  change: "examples/workdir/trigger-second-task.txt"
+
+- name: this task runs after on init (2) 
+  run: 
+    - echo 'then me in second'
+    - sed  -i '1,7s/#CHANGED#@$/#THIS_WILL_CHANGE#@/' examples/reload-config-example.yml
+    - echo 1 > examples/workdir/trigger-second-task.txt
+  change: "examples/workdir/trigger-first-task.txt"

examples/tasks-with-filepath-template.yml

@@ -3,7 +3,9 @@
     - "echo 'this file has changed: {{filepath}}'"
     - "cat '{{filepath}}' || echo 'nothing to run'"
   change: "examples/workdir/**/*"
-  ignore: "examples/workdir/ignored/**/*.txt"
+  ignore: 
+    - "examples/workdir/ignored/**/*.txt"
+    - "examples/workdir/another_ignored_file.foo"
   run_on_init: true
 
 - name: more advanced usage of {{filepath}}

examples/workdir/trigger-first-task.txt

@@ -0,0 +1 @@
+1

examples/workdir/trigger-second-task.txt

@@ -0,0 +1 @@
+1

examples/workdir/trigger-start.txt

@@ -0,0 +1 @@
+1

src/main.rs

@@ -14,6 +14,11 @@ mod workers;
 mod yaml;
 
 use cli::*;
+use nix::{
+    libc::signal,
+    sys::signal::{self, Signal},
+    unistd::Pid,
+};
 use watches::Watches;
 
 use serde_derive::Deserialize;
@@ -109,16 +114,20 @@ fn main() {
 
         _ => {
             let rules = if args.flag_config.is_empty() {
-                let default_filename = cli::watch::DEFAULT_FILENAME;
-                match rules::from_file(default_filename) {
-                    Ok(rules) => rules,
-                    Err(err) => {
-                        match rules::from_file(&default_filename.replace(".yaml", ".yml")) {
-                            Ok(rules) => rules,
-                            Err(_) => error("Failed to read default config file", err),
-                        }
-                    }
-                }
+                rules::from_default_file_config().unwrap_or_else(|err| {
+                    stdout::error(
+                        &vec![
+                            "Missing config file",
+                            "Expected file .watch.yaml or .watch.yml to be present",
+                            "in the current directory",
+                            "Debugging:",
+                            " - Did you forget to run 'fzz init'?",
+                        ]
+                        .join("\n"),
+                    );
+
+                    error("Failed to read default config file", err);
+                })
             } else {
                 match rules::from_file(&args.flag_config) {
                     Ok(rules) => rules,
@@ -157,17 +166,54 @@ fn main() {
                 execute_watch_command(Watches::new(rules), args);
             }
         }
-    }
+    };
 }
 
 pub fn execute_watch_command(watches: Watches, args: Args) {
+    let config_file_paths = if args.flag_config.is_empty() {
+        vec![
+            cli::watch::DEFAULT_FILENAME.replace("yaml", "yml"),
+            cli::watch::DEFAULT_FILENAME.to_string(),
+        ]
+    } else {
+        vec![format!("{}", &args.flag_config)]
+    };
+
+    // This here restarts the watcher if the config file changes
+    let watcher_pid = std::process::id();
+    let th = std::thread::spawn(move || {
+        watcher::events(
+            config_file_paths,
+            |file_changed| {
+                stdout::warn(
+                    &vec![
+                        "The config file has changed while an instance was running.",
+                        "Terminating the current watcher instance...",
+                        &format!("Config file: {}", file_changed),
+                    ]
+                    .join("\n"),
+                );
+
+                println!("Watcher PID: {}", watcher_pid);
+
+                match signal::kill(Pid::from_raw(watcher_pid as i32), Signal::SIGINT) {
+                    Ok(_) => stdout::info("Terminating watcher..."),
+                    Err(err) => panic!("Failed to terminate watcher forcefully.\nCause: {:?}", err),
+                }
+            },
+            false,
+        )
+    });
+
     let verbose = args.flag_V;
     let fail_fast = args.flag_fail_fast;
     if args.flag_non_block {
         execute(WatchNonBlockCommand::new(watches, verbose, fail_fast))
     } else {
         execute(WatchCommand::new(watches, verbose, fail_fast))
     }
+
+    let _ = th.join().expect("Failed to join config watcher thread");
 }
 
 fn execute<T: Command>(command: T) {

src/rules.rs

@@ -218,6 +218,17 @@ pub fn from_file(filename: &str) -> Result<Vec<Rules>, String> {
     }
 }
 
+pub fn from_default_file_config() -> Result<Vec<Rules>, String> {
+    let default_filename = cli::watch::DEFAULT_FILENAME;
+    match from_file(default_filename) {
+        Ok(rules) => Ok(rules),
+        Err(err) => match from_file(&default_filename.replace(".yaml", ".yml")) {
+            Ok(rules) => Ok(rules),
+            Err(_) => Err(format!("Failed to read default config file {}", err)),
+        },
+    }
+}
+
 fn pattern(pattern: &str) -> Pattern {
     Pattern::new(&format!("**{}", pattern))
         .expect(format!("Invalid glob pattern {}", pattern).as_str())

tests/watcher_reloads_config_file.rs

@@ -0,0 +1,39 @@
+use std::io::prelude::*;
+
+#[path = "./common/lib.rs"]
+mod setup;
+
+#[test]
+fn it_terminates_the_current_running_watcher_when_config_changes() {
+    setup::with_example(
+        setup::Options {
+            output_file: "it_terminates_the_current_running_watcher_when_config_changes.log",
+            example_file: "examples/reload-config-example.yml",
+        },
+        |fzz_cmd, mut output_log| {
+            let mut child = fzz_cmd
+                .arg("--non-block")
+                .arg("-V")
+                .spawn()
+                .expect("failed to spawn child");
+
+            defer!({
+                child.kill().expect("failed to kill child");
+            });
+
+            let mut output = String::new();
+            wait_until!(
+                {
+                    output_log
+                        .read_to_string(&mut output)
+                        .expect("failed to read from file");
+
+                    output.contains("The config file has changed")
+                        && output.contains("Terminating watcher...")
+                },
+                "No task in the example was configured with run_on_init {}",
+                output
+            );
+        },
+    );
+}

tests/watching_filtered_tasks_with_target_flag.rs

@@ -8,7 +8,7 @@ fn test_it_filter_tasks_with_target_flag() {
     setup::with_example(
         setup::Options {
             output_file: "test_it_filter_tasks_with_target_flag.log",
-            example_file: "examples/multiple-tasks.yml",
+            example_file: "examples/tasks-with-tags-to-filter.yml",
         },
         |fzz_cmd, mut output_log| {
             let mut child = fzz_cmd
@@ -77,7 +77,7 @@ fn test_it_list_the_available_tasks_when_nothing_matches() {
     setup::with_example(
         setup::Options {
             output_file: "test_it_list_the_available_tasks_when_nothing_matches.log",
-            example_file: "examples/multiple-tasks.yml",
+            example_file: "examples/tasks-with-tags-to-filter.yml",
         },
         |fzz_cmd, mut output_log| {
             let mut child = fzz_cmd
@@ -114,7 +114,9 @@ Available targets:
   run my lint @quick
 
 Finished there is no task to run.
-"
+",
+                "failed to find the expected output: {}",
+                output
             );
         },
     );