Task Status refactorings

CHANGELOG.md

@@ -6,6 +6,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ## \[4.0.0\] - unreleased
 
+This release aims to improve Pueue and to rectify some old design decisions.
+
+### Multi-threaded architecture
+
 Up until recently, Pueue had the subprocesses' (tasks') state live in a dedicated thread.
 Client commands that directly affected subprocesses, such as `pueue start --immediate`, were forwarded to that special thread via an `mpsc` channel to be further processed.
 
@@ -15,13 +19,29 @@ Commands like `pueue add --immediate install_something && pueue send 0 'y\n'` wo
 
 The new state design fixes this issue, which allows Pueue to do subprocess state manipulation directly inside of the client message handlers, effectively removing any delays.
 
+TLDR: Commands that start/stop/kill/pause tasks only return when the task is actually started/stopped/killed/paused.
+
+### Runtime invariants
+
+Previously, various state related runtime invariants were enforced by convention. For example, a task that is queued should not have a `start` or `enqueued_at` time set.
+However, this approach is highly error-prone as it's really hard to always think of everything that needs to be set or cleaned up on every possible state transition.
+
+Luckily, this is an issue that can be fixed in a (rather) elegant way in Rust, using struct enums. That way, those invariants are enforced via the type system during the compile time.
+The code is a bit more verbose (~25%), but it prevents a whole category of bugs and while doing this refactoring I actually found at least 2 cases where I forgot to clear a variable.
+
+TLDR: The new task state handling is a bit more verbose, but a lot cleaner and type safe.
+
 ### Fixed
 
 - Fixed delay after sending process related commands from client. [#548](https://github.com/Nukesor/pueue/pull/548)
 
 ### Change
 
-- **Breaking**: Streamlined `pueue log` parameters to behave the same way was `start`, `pause` or `kill`. [#509](https://github.com/Nukesor/pueue/issues/509)
+- **Breaking**: Refactor internal task state. Some task variables have been moved into the `TaskStatus` enum, which now enforces various invariants during compile time via the type system.
+  Due to this, several subtle time related inconsistencies (task start/stop/enqueue times) have been fixed. [#556](https://github.com/Nukesor/pueue/pull/556) \
+  **Important: This completely breaks backwards compatibility, including previous state.**
+  **Important: The Pueue daemon needs to be restarted and the state will be wiped clean.**
+- **Breaking**: Streamlined `pueue log` parameters to behave the same way as `start`, `pause` or `kill`. [#509](https://github.com/Nukesor/pueue/issues/509)
 - **Breaking**: Remove the `--children` commandline flags, that have been deprecated and no longer serve any function since `v3.0.0`.
 
 ### Add

pueue/Cargo.toml

@@ -43,6 +43,7 @@ tokio = { workspace = true }
 [dev-dependencies]
 anyhow = { workspace = true }
 assert_cmd = "2"
+assert_matches = "1"
 better-panic = { workspace = true }
 # Make it easy to view log output for select tests.
 # Set log level for tests with RUST_LOG=<level>, use with failed tests or

pueue/src/client/commands/restart.rs

@@ -1,5 +1,6 @@
 use anyhow::{bail, Result};
 
+use chrono::Local;
 use pueue_lib::network::message::*;
 use pueue_lib::network::protocol::*;
 use pueue_lib::settings::Settings;
@@ -32,7 +33,9 @@
     let new_status = if stashed {
         TaskStatus::Stashed { enqueue_at: None }
     } else {
-        TaskStatus::Queued
+        TaskStatus::Queued {
+            enqueued_at: Local::now(),
+        }
     };
 
     let state = get_state(stream).await?;
@@ -50,13 +53,19 @@
             state.filter_tasks(done_filter, None)
         };
 
-        // now pick the failed tasks
+        // Now pick the failed tasks
         let failed = filtered_tasks
             .matching_ids
             .into_iter()
             .filter(|task_id| {
                 let task = state.tasks.get(task_id).unwrap();
-                !matches!(task.status, TaskStatus::Done(TaskResult::Success))
+                !matches!(
+                    task.status,
+                    TaskStatus::Done {
+                        result: TaskResult::Success,
+                        ..
+                    }
+                )
             })
             .collect();
 

pueue/src/client/commands/wait.rs

@@ -140,15 +140,27 @@
 fn reached_target_status(task: &Task, target_status: &WaitTargetStatus) -> bool {
     match target_status {
         WaitTargetStatus::Queued => {
-            task.status == TaskStatus::Queued
-                || task.status == TaskStatus::Running
-                || matches!(task.status, TaskStatus::Done(_))
+            matches!(
+                task.status,
+                TaskStatus::Queued { .. } | TaskStatus::Running { .. } | TaskStatus::Done { .. }
+            )
         }
         WaitTargetStatus::Running => {
-            task.status == TaskStatus::Running || matches!(task.status, TaskStatus::Done(_))
+            matches!(
+                task.status,
+                TaskStatus::Running { .. } | TaskStatus::Done { .. }
+            )
+        }
+        WaitTargetStatus::Done => matches!(task.status, TaskStatus::Done { .. }),
+        WaitTargetStatus::Success => {
+            matches!(
+                task.status,
+                TaskStatus::Done {
+                    result: TaskResult::Success,
+                    ..
+                }
+            )
         }
-        WaitTargetStatus::Done => matches!(task.status, TaskStatus::Done(_)),
-        WaitTargetStatus::Success => matches!(task.status, TaskStatus::Done(TaskResult::Success)),
     }
 }
 
@@ -201,7 +213,7 @@
     // Check if the task has finished.
     // In case it has, show the task's result in human-readable form.
     // Color some parts of the output depending on the task's outcome.
-    if let TaskStatus::Done(result) = &task.status {
+    if let TaskStatus::Done { result, .. } = &task.status {
         let text = match result {
             TaskResult::Success => {
                 let status = style.style_text("0", Some(Color::Green), None);
@@ -246,8 +258,15 @@
 
 fn get_color_for_status(task_status: &TaskStatus) -> Color {
     match task_status {
-        TaskStatus::Running | TaskStatus::Done(_) => Color::Green,
-        TaskStatus::Paused | TaskStatus::Locked => Color::White,
+        TaskStatus::Paused { .. } | TaskStatus::Locked { .. } => Color::White,
+        TaskStatus::Running { .. } => Color::Green,
+        TaskStatus::Done { result, .. } => {
+            if matches!(result, TaskResult::Success) {
+                Color::Green
+            } else {
+                Color::Red
+            }
+        }
         _ => Color::White,
     }
 }

pueue/src/client/display/helper.rs

@@ -45,9 +45,10 @@ pub fn sort_tasks_by_group(tasks: Vec<Task>) -> BTreeMap<String, Vec<Task>> {
 /// If the task doesn't have a start and/or end yet, an empty string will be returned
 /// for the respective field.
 pub fn formatted_start_end(task: &Task, settings: &Settings) -> (String, String) {
-    // Get the start time.
+    let (start, end) = task.start_and_end();
+
     // If the task didn't start yet, just return two empty strings.
-    let start = match task.start {
+    let start = match start {
         Some(start) => start,
         None => return ("".into(), "".into()),
     };
@@ -65,8 +66,8 @@ pub fn formatted_start_end(task: &Task, settings: &Settings) -> (String, String)
             .to_string()
     };
 
-    // Get finish time, if already set. Otherwise only return the formatted start.
-    let end = match task.end {
+    // If the task didn't finish yet, only return the formatted start.
+    let end = match end {
         Some(end) => end,
         None => return (formatted_start, "".into()),
     };

pueue/src/client/display/log/mod.rs

@@ -97,7 +97,7 @@
         if let Some((_, task_log)) = task_iter.peek() {
             if matches!(
                 &task_log.task.status,
-                TaskStatus::Done(_) | TaskStatus::Running | TaskStatus::Paused,
+                TaskStatus::Done { .. } | TaskStatus::Running { .. } | TaskStatus::Paused { .. }
             ) {
                 println!();
             }
@@ -122,7 +122,7 @@
     // We only show logs of finished or running tasks.
     if !matches!(
         task.status,
-        TaskStatus::Done(_) | TaskStatus::Running | TaskStatus::Paused
+        TaskStatus::Done { .. } | TaskStatus::Running { .. } | TaskStatus::Paused { .. }
     ) {
         return;
     }
@@ -148,9 +148,9 @@
     );
 
     let (exit_status, color) = match &task.status {
-        TaskStatus::Paused => ("paused".into(), Color::White),
-        TaskStatus::Running => ("running".into(), Color::Yellow),
-        TaskStatus::Done(result) => match result {
+        TaskStatus::Paused { .. } => ("paused".into(), Color::White),
+        TaskStatus::Running { .. } => ("running".into(), Color::Yellow),
+        TaskStatus::Done { result, .. } => match result {
             TaskResult::Success => ("completed successfully".into(), Color::Green),
             TaskResult::Failed(exit_code) => {
                 (format!("failed with exit code {exit_code}"), Color::Red)
@@ -197,14 +197,16 @@
         ]);
     }
 
+    let (start, end) = task.start_and_end();
+
     // Start and end time
-    if let Some(start) = task.start {
+    if let Some(start) = start {
         table.add_row(vec![
             style.styled_cell("Start:", None, Some(ComfyAttribute::Bold)),
             Cell::new(start.to_rfc2822()),
         ]);
     }
-    if let Some(end) = task.end {
+    if let Some(end) = end {
         table.add_row(vec![
             style.styled_cell("End:", None, Some(ComfyAttribute::Bold)),
             Cell::new(end.to_rfc2822()),

pueue/src/client/display/table_builder.rs

@@ -208,9 +208,11 @@
                 // Determine the human readable task status representation and the respective color.
                 let status_string = task.status.to_string();
                 let (status_text, color) = match &task.status {
-                    TaskStatus::Running => (status_string, Color::Green),
-                    TaskStatus::Paused | TaskStatus::Locked => (status_string, Color::White),
-                    TaskStatus::Done(result) => match result {
+                    TaskStatus::Running { .. } => (status_string, Color::Green),
+                    TaskStatus::Paused { .. } | TaskStatus::Locked { .. } => {
+                        (status_string, Color::White)
+                    }
+                    TaskStatus::Done { result, .. } => match result {
                         TaskResult::Success => (TaskResult::Success.to_string(), Color::Green),
                         TaskResult::DependencyFailed => {
                             ("Dependency failed".to_string(), Color::Red)

pueue/src/client/query/filters.rs

@@ -115,13 +115,15 @@ pub fn datetime(section: Pair<'_, Rule>, query_result: &mut QueryResult) -> Resu
                 enqueue_at
             }
             Rule::column_start => {
-                let Some(start) = task.start else {
+                let (start, _) = task.start_and_end();
+                let Some(start) = start else {
                     return false;
                 };
                 start
             }
             Rule::column_end => {
-                let Some(end) = task.end else {
+                let (_, end) = task.start_and_end();
+                let Some(end) = end else {
                     return false;
                 };
                 end
@@ -311,16 +313,22 @@ pub fn status(section: Pair<'_, Rule>, query_result: &mut QueryResult) -> Result
     // Build the filter function for the task's status.
     let filter_function = Box::new(move |task: &Task| -> bool {
         let matches = match operand {
-            Rule::status_queued => matches!(task.status, TaskStatus::Queued),
+            Rule::status_queued => matches!(task.status, TaskStatus::Queued { .. }),
             Rule::status_stashed => matches!(task.status, TaskStatus::Stashed { .. }),
-            Rule::status_running => matches!(task.status, TaskStatus::Running),
-            Rule::status_paused => matches!(task.status, TaskStatus::Paused),
+            Rule::status_running => matches!(task.status, TaskStatus::Running { .. }),
+            Rule::status_paused => matches!(task.status, TaskStatus::Paused { .. }),
             Rule::status_success => {
-                matches!(&task.status, TaskStatus::Done(TaskResult::Success))
+                matches!(
+                    &task.status,
+                    TaskStatus::Done {
+                        result: TaskResult::Success,
+                        ..
+                    }
+                )
             }
             Rule::status_failed => {
                 let mut matches = false;
-                if let TaskStatus::Done(result) = &task.status {
+                if let TaskStatus::Done { result, .. } = &task.status {
                     if !matches!(result, TaskResult::Success) {
                         matches = true;
                     }

pueue/src/client/query/mod.rs

@@ -77,11 +77,11 @@
                 fn rank_status(task: &Task) -> u8 {
                     match &task.status {
                         TaskStatus::Stashed { .. } => 0,
-                        TaskStatus::Locked => 1,
-                        TaskStatus::Queued => 2,
-                        TaskStatus::Paused => 3,
-                        TaskStatus::Running => 4,
-                        TaskStatus::Done(result) => match result {
+                        TaskStatus::Locked { .. } => 1,
+                        TaskStatus::Queued { .. } => 2,
+                        TaskStatus::Paused { .. } => 3,
+                        TaskStatus::Running { .. } => 4,
+                        TaskStatus::Done { result, .. } => match result {
                             TaskResult::Success => 6,
                             _ => 5,
                         },
@@ -93,8 +93,16 @@
             Rule::column_label => task1.label.cmp(&task2.label),
             Rule::column_command => task1.command.cmp(&task2.command),
             Rule::column_path => task1.path.cmp(&task2.path),
-            Rule::column_start => task1.start.cmp(&task2.start),
-            Rule::column_end => task1.end.cmp(&task2.end),
+            Rule::column_start => {
+                let (start1, _) = task1.start_and_end();
+                let (start2, _) = task2.start_and_end();
+                start1.cmp(&start2)
+            }
+            Rule::column_end => {
+                let (_, end1) = task1.start_and_end();
+                let (_, end2) = task2.start_and_end();
+                end1.cmp(&end2)
+            }
             _ => std::cmp::Ordering::Less,
         });
 

pueue/src/daemon/callbacks.rs

@@ -64,7 +64,7 @@
     parameters.insert("group", task.group.clone());
 
     // Result takes the TaskResult Enum strings, unless it didn't finish yet.
-    if let TaskStatus::Done(result) = &task.status {
+    if let TaskStatus::Done { result, .. } = &task.status {
         parameters.insert("result", result.to_string());
     } else {
         parameters.insert("result", "None".into());
@@ -75,8 +75,9 @@
         time.map(|time| time.timestamp().to_string())
             .unwrap_or_default()
     };
-    parameters.insert("start", print_time(task.start));
-    parameters.insert("end", print_time(task.end));
+    let (start, end) = task.start_and_end();
+    parameters.insert("start", print_time(start));
+    parameters.insert("end", print_time(end));
 
     // Read the last lines of the process' output and make it available.
     if let Ok(output) = read_last_log_file_lines(
@@ -95,7 +96,7 @@
     parameters.insert("output_path", out_path.display().to_string());
 
     // Get the exit code
-    if let TaskStatus::Done(result) = &task.status {
+    if let TaskStatus::Done { result, .. } = &task.status {
         match result {
             TaskResult::Success => parameters.insert("exit_code", "0".into()),
             TaskResult::Failed(code) => parameters.insert("exit_code", code.to_string()),

pueue/src/daemon/network/message_handler/add.rs

@@ -35,20 +35,19 @@ pub fn add_task(settings: &Settings, state: &SharedState, message: AddMessage) -
         message.path,
         message.envs,
         message.group,
-        TaskStatus::Locked,
+        TaskStatus::Queued {
+            enqueued_at: Local::now(),
+        },
         message.dependencies,
         message.priority.unwrap_or(0),
         message.label,
     );
 
-    // Set the starting status.
+    // Handle if the command is to be stashed and/or automatically enqueued later.
     if message.stashed || message.enqueue_at.is_some() {
         task.status = TaskStatus::Stashed {
             enqueue_at: message.enqueue_at,
         };
-    } else {
-        task.status = TaskStatus::Queued;
-        task.enqueued_at = Some(Local::now());
     }
 
     // Check if there're any aliases that should be applied.