server/worker_task: split task list file into two

one for only the active tasks and one for up to 1000 finished tasks

factor out the parsing of a task file (we will later need this again)
and use iterator combinators for easier code

we now sort the tasks ascending (this will become important in a later patch)
but reverse (for now) it to keep compatibility

this code also omits the converting into an intermittent hash
since it cannot really happen that we have duplicate tasks in this list
(since the call is locked by an flock, and it is the only place where we
write into the lists)

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

src/server/worker_task.rs

@@ -31,6 +31,9 @@ pub const PROXMOX_BACKUP_LOG_DIR: &str = PROXMOX_BACKUP_LOG_DIR_M!();
 pub const PROXMOX_BACKUP_TASK_DIR: &str = PROXMOX_BACKUP_TASK_DIR_M!();
 pub const PROXMOX_BACKUP_TASK_LOCK_FN: &str = concat!(PROXMOX_BACKUP_TASK_DIR_M!(), "/.active.lock");
 pub const PROXMOX_BACKUP_ACTIVE_TASK_FN: &str = concat!(PROXMOX_BACKUP_TASK_DIR_M!(), "/active");
+pub const PROXMOX_BACKUP_INDEX_TASK_FN: &str = concat!(PROXMOX_BACKUP_TASK_DIR_M!(), "/index");
+
+const MAX_INDEX_TASKS: usize = 1000;
 
 lazy_static! {
     static ref WORKER_TASK_LIST: Mutex<HashMap<usize, Arc<WorkerTask>>> = Mutex::new(HashMap::new());
@@ -343,76 +346,47 @@ fn update_active_workers(new_upid: Option<&UPID>) -> Result<Vec<TaskListInfo>, E
 
     let lock = lock_task_list_files(true)?;
 
-    let reader = match File::open(PROXMOX_BACKUP_ACTIVE_TASK_FN) {
+    let mut finish_list: Vec<TaskListInfo> = read_task_file_from_path(PROXMOX_BACKUP_INDEX_TASK_FN)?;
-        Ok(f) => Some(BufReader::new(f)),
+    let mut active_list: Vec<TaskListInfo> = read_task_file_from_path(PROXMOX_BACKUP_ACTIVE_TASK_FN)?
-        Err(err) => {
+        .into_iter()
-            if err.kind() ==  std::io::ErrorKind::NotFound {
+        .filter_map(|info| {
-                 None
+            if info.state.is_some() {
-            } else {
+                // this can happen when the active file still includes finished tasks
-                bail!("unable to open active worker {:?} - {}", PROXMOX_BACKUP_ACTIVE_TASK_FN, err);
+                finish_list.push(info);
+                return None;
             }
-        }
-    };
 
-    let mut active_list = vec![];
+            if !worker_is_active_local(&info.upid) {
-    let mut finish_list = vec![];
+                println!("Detected stopped UPID {}", &info.upid_str);
-
-    if let Some(lines) = reader.map(|r| r.lines()) {
-
-        for line in lines {
-            let line = line?;
-            match parse_worker_status_line(&line) {
-                Err(err) => bail!("unable to parse active worker status '{}' - {}", line, err),
-                Ok((upid_str, upid, state)) => match state {
-                    None if worker_is_active_local(&upid) => {
-                        active_list.push(TaskListInfo { upid, upid_str, state: None });
-                    },
-                    None => {
-                        println!("Detected stopped UPID {}", upid_str);
                 let now = proxmox::tools::time::epoch_i64();
-                        let status = upid_read_status(&upid)
+                let status = upid_read_status(&info.upid)
                     .unwrap_or_else(|_| TaskState::Unknown { endtime: now });
                 finish_list.push(TaskListInfo {
-                            upid, upid_str, state: Some(status)
+                    upid: info.upid,
+                    upid_str: info.upid_str,
+                    state: Some(status)
                 });
-                    },
+                return None;
-                    Some(status) => {
-                        finish_list.push(TaskListInfo {
-                            upid, upid_str, state: Some(status)
-                        })
-                    }
-                }
-            }
-        }
             }
 
+            Some(info)
+        }).collect();
+
     if let Some(upid) = new_upid {
         active_list.push(TaskListInfo { upid: upid.clone(), upid_str: upid.to_string(), state: None });
     }
 
-    // assemble list without duplicates
+    let active_raw = render_task_list(&active_list);
-    // we include all active tasks,
-    // and fill up to 1000 entries with finished tasks
 
-    let max = 1000;
+    replace_file(
+        PROXMOX_BACKUP_ACTIVE_TASK_FN,
+        active_raw.as_bytes(),
+        CreateOptions::new()
+            .owner(backup_user.uid)
+            .group(backup_user.gid),
+    )?;
 
-    let mut task_hash = HashMap::new();
+    finish_list.sort_unstable_by(|a, b| {
-
-    for info in active_list {
-        task_hash.insert(info.upid_str.clone(), info);
-    }
-
-    for info in finish_list {
-        if task_hash.len() > max { break; }
-        if !task_hash.contains_key(&info.upid_str) {
-            task_hash.insert(info.upid_str.clone(), info);
-        }
-    }
-
-    let mut task_list: Vec<TaskListInfo> = vec![];
-    for (_, info) in task_hash { task_list.push(info); }
-
-    task_list.sort_unstable_by(|b, a| { // lastest on top
         match (&a.state, &b.state) {
             (Some(s1), Some(s2)) => s1.cmp(&s2),
             (Some(_), None) => std::cmp::Ordering::Less,
@@ -421,11 +395,13 @@ fn update_active_workers(new_upid: Option<&UPID>) -> Result<Vec<TaskListInfo>, E
         }
     });
 
-    let raw = render_task_list(&task_list[..]);
+    let start = (finish_list.len()-MAX_INDEX_TASKS).max(0);
+    let end = (start+MAX_INDEX_TASKS).min(finish_list.len());
+    let index_raw = render_task_list(&finish_list[start..end]);
 
     replace_file(
-        PROXMOX_BACKUP_ACTIVE_TASK_FN,
+        PROXMOX_BACKUP_INDEX_TASK_FN,
-        raw.as_bytes(),
+        index_raw.as_bytes(),
         CreateOptions::new()
             .owner(backup_user.uid)
             .group(backup_user.gid),
@@ -433,7 +409,9 @@ fn update_active_workers(new_upid: Option<&UPID>) -> Result<Vec<TaskListInfo>, E
 
     drop(lock);
 
-    Ok(task_list)
+    finish_list.append(&mut active_list);
+    finish_list.reverse();
+    Ok(finish_list)
 }
 
 /// Returns a sorted list of known tasks
@@ -463,6 +441,44 @@ fn render_task_list(list: &[TaskListInfo]) -> String {
     raw
 }
 
+// note this is not locked, caller has to make sure it is
+// this will skip (and log) lines that are not valid status lines
+fn read_task_file<R: Read>(reader: R) -> Result<Vec<TaskListInfo>, Error>
+{
+    let reader = BufReader::new(reader);
+    let mut list = Vec::new();
+    for line in reader.lines() {
+        let line = line?;
+        match parse_worker_status_line(&line) {
+            Ok((upid_str, upid, state)) => list.push(TaskListInfo {
+                upid_str,
+                upid,
+                state
+            }),
+            Err(err) => {
+                eprintln!("unable to parse worker status '{}' - {}", line, err);
+                continue;
+            }
+        };
+    }
+
+    Ok(list)
+}
+
+// note this is not locked, caller has to make sure it is
+fn read_task_file_from_path<P>(path: P) -> Result<Vec<TaskListInfo>, Error>
+where
+    P: AsRef<std::path::Path> + std::fmt::Debug,
+{
+    let file = match File::open(&path) {
+        Ok(f) => f,
+        Err(err) if err.kind() == std::io::ErrorKind::NotFound => return Ok(Vec::new()),
+        Err(err) => bail!("unable to open task list {:?} - {}", path, err),
+    };
+
+    read_task_file(file)
+}
+
 /// Launch long running worker tasks.
 ///
 /// A worker task can either be a whole thread, or a simply tokio