lool/lib/sched/scheduler.rs

299 lines
8.8 KiB
Rust

use std::sync::{
atomic::{AtomicBool, AtomicPtr, AtomicUsize, Ordering},
Arc, Mutex,
};
use {
super::SchedulingRule,
crate::utils::threads::threadpool::ThreadPool,
chrono::{DateTime, Local},
};
// TODO: add logging (always as debug)
type Action = Box<dyn FnMut() + Send + Sync + 'static>;
/// 🧉 » a scheduled task
///
/// this structs represents a task that has been scheduled in the scheduler.
///
/// this is returned by the `Scheduler::schedule` method, and can be used to check and control the
/// status of the task.
pub struct ScheduledTask {
#[allow(dead_code)]
index: Arc<AtomicUsize>,
name: String,
action: Action,
rules: Arc<Vec<SchedulingRule>>,
is_running: Arc<AtomicBool>,
is_stopped: Arc<AtomicBool>,
is_removed: Arc<AtomicBool>,
last_run: Arc<AtomicPtr<DateTime<Local>>>,
}
impl ScheduledTask {
fn run(&mut self) {
let action = self.action.as_mut();
action();
}
fn make_handler(&self) -> TaskHandler {
TaskHandler {
index: self.index.clone(),
name: self.name.clone(),
rules: self.rules.clone(),
is_running: self.is_running.clone(),
is_stopped: self.is_stopped.clone(),
is_removed: self.is_removed.clone(),
last_run: self.last_run.clone(),
}
}
}
/// 🧉 » a task scheduler.
///
/// this struct is responsible for scheduling tasks to be executed at specific times, depending on
/// the rules provided for each task.
///
/// Each task can have n rules, and the task will be executed when any of the rules is met.
pub struct Scheduler {
pool: ThreadPool,
tasks: Vec<Arc<Mutex<ScheduledTask>>>,
}
impl Default for Scheduler {
fn default() -> Self {
Self::new()
}
}
impl Scheduler {
/// 🧉 » create a new scheduler
///
/// default constructor, sets the internal thread pool to have 5 threads at most.
pub fn new() -> Self {
Self {
tasks: vec![],
pool: ThreadPool::create(5).unwrap(),
}
}
/// 🧉 » create a new scheduler
///
/// creates a new scheduler, just like `Scheduler::new`, but with a specific capacity for the
/// internal thread pool.
pub fn with_capacity(capacity: usize) -> Self {
Self {
tasks: vec![],
pool: ThreadPool::create(capacity).unwrap(),
}
}
/// 🧉 » schedule a task
///
/// schedules a task to be executed at times determined by the provided rules.
pub fn schedule<F>(&mut self, name: &str, action: F, rules: SchedulingRule) -> TaskHandler
where
F: FnMut() + Send + Sync + 'static,
{
self.schedule_many_rules(name, action, vec![rules])
}
/// 🧉 » schedule a task
///
/// schedules a task to be executed at times determined by the provided rules.
pub fn schedule_many_rules<F>(
&mut self,
name: &str,
action: F,
rules: Vec<SchedulingRule>,
) -> TaskHandler
where
F: FnMut() + Send + Sync + 'static,
{
let index = self.tasks.len();
let task = Arc::new(Mutex::new(ScheduledTask {
index: Arc::new(AtomicUsize::new(index)),
name: name.to_string(),
action: Box::new(action),
rules: Arc::new(rules),
is_running: Arc::new(AtomicBool::new(false)),
is_stopped: Arc::new(AtomicBool::new(false)),
is_removed: Arc::new(AtomicBool::new(false)),
last_run: Arc::new(AtomicPtr::new(std::ptr::null_mut())),
}));
self.tasks.push(task.clone());
run_in_pool(task.clone(), &self.pool);
let handler: TaskHandler = {
let task = task.lock().unwrap();
task.make_handler()
};
handler
}
}
/// 🧉 » task handler
///
/// returned by the `Scheduler::schedule` method,
/// this struct can be used to check and control
/// the status of the task.
#[derive(Clone)]
pub struct TaskHandler {
name: String,
index: Arc<AtomicUsize>,
rules: Arc<Vec<SchedulingRule>>,
is_running: Arc<AtomicBool>,
is_stopped: Arc<AtomicBool>,
is_removed: Arc<AtomicBool>,
last_run: Arc<AtomicPtr<DateTime<Local>>>,
}
impl TaskHandler {
/// 🧉 » last run date
///
/// returns a `DateTime<Local>` representing the last time the task was run or None if the task
/// has never been run before.
pub fn get_last_run(&self) -> Option<DateTime<Local>> {
let last_run = self.last_run.load(Ordering::Relaxed);
if last_run.is_null() {
None
} else {
Some(unsafe { *last_run })
}
}
/// 🧉 » next run date
///
/// returns a `DateTime<Local>` representing the next time the task is scheduled to run
pub fn get_next_run(&self) -> Option<DateTime<Local>> {
get_next_run_time(&self.rules, None)
}
/// 🧉 » is running?
///
/// returns a `bool` indicating if the task is currently running in this moment
pub fn is_running(&self) -> bool {
self.is_running.load(Ordering::Relaxed)
}
/// 🧉 » name
///
/// returns the name of the task
pub fn name(&self) -> &str {
&self.name
}
/// 🧉 » is active?
///
/// returns a `bool` indicating if the task is active
pub fn is_active(&self) -> bool {
!self.is_stopped.load(Ordering::Relaxed) && !self.is_removed.load(Ordering::Relaxed)
}
/// 🧉 » is stopped?
///
/// returns a `bool` indicating if the task has been stopped
///
/// a task being stopped means that it has been paused, but not removed from the scheduler.
/// So, although it's not running, it's still in the scheduler and can be resumed.
pub fn is_stopped(&self) -> bool {
self.is_stopped.load(Ordering::Relaxed)
}
/// 🧉 » is removed?
///
/// returns a `bool` indicating if the task has been removed
///
/// once a task is removed, it's no longer in the scheduler and can't be resumed.
pub fn is_removed(&self) -> bool {
self.is_removed.load(Ordering::Relaxed)
}
}
/// **main function to run the task in the thread pool**
///
/// it spawns a new job in the thread pool to run the task until the task is no longer scheduled to
/// run.
fn run_in_pool(task_mutex: Arc<Mutex<ScheduledTask>>, pool: &ThreadPool) {
pool.execute(move || {
let (mut maybe_next_run, name) = {
let task = task_mutex.lock().unwrap();
let rules = &task.rules;
(get_next_run_time(rules, None), task.name.clone())
};
while let Some(run_date) = maybe_next_run {
let now = Local::now();
if run_date > now {
// if the next run is in the future, go to bed until then
let sleep_until = run_date - now;
println!(
"task {} will run in {} seconds",
name,
sleep_until.num_seconds()
);
std::thread::sleep(sleep_until.to_std().unwrap());
} else {
// if the next run is in the past, run the task immediately, probably missed the
// run time for a few nanos
println!("task will run in 0 seconds");
}
let mut task = task_mutex.lock().unwrap();
let run_date_box = Box::new(run_date);
let run_date_raw = Box::into_raw(run_date_box);
task.last_run.store(run_date_raw, Ordering::Relaxed);
task.is_running.store(true, Ordering::SeqCst);
task.run();
task.is_running.store(false, Ordering::SeqCst);
let run_date_box = unsafe { Box::from_raw(task.last_run.load(Ordering::Relaxed)) };
maybe_next_run = get_next_run_time(&task.rules, Some(*run_date_box));
}
});
}
/// **get next run time**
///
/// this function takes a list of scheduling rules and a base time, and returns the next time the
/// task should run.
///
/// to determine the next run time, it iterates over the list of rules and calculates the next run
/// time for each of them, returning the earliest of them all.
fn get_next_run_time(
rules: &Vec<SchedulingRule>,
from: Option<DateTime<Local>>,
) -> Option<DateTime<Local>> {
let mut next_run_so_far: Option<DateTime<Local>> = None;
let base = if let Some(from) = from {
from
} else {
Local::now()
};
for rule in rules {
let rule_next_run = rule.next_from(base);
if let Some(next_run) = rule_next_run {
if let Some(d) = next_run_so_far {
if next_run < d {
next_run_so_far = Some(next_run);
}
} else {
next_run_so_far = Some(next_run);
}
}
}
next_run_so_far
}