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//! # JobScheduler //! //! A simple cron-like job scheduling library for Rust. //! //! ## Usage //! //! Be sure to add the job_scheduler crate to your `Cargo.toml`: //! //! ```toml //! [dependencies] //! job_scheduler = "*" //! ``` //! //! Creating a schedule for a job is done using the `FromStr` impl for the //! `Schedule` type of the [cron](https://github.com/zslayton/cron) library. //! //! The scheduling format is as follows: //! //! ```text //! sec min hour day of month month day of week year //! * * * * * * * //! ``` //! //! Note that the year may be omitted. //! //! Comma separated values such as `5,8,10` represent more than one time //! value. So for example, a schedule of `0 2,14,26 * * * *` would execute //! on the 2nd, 14th, and 26th minute of every hour. //! //! Ranges can be specified with a dash. A schedule of `0 0 * 5-10 * *` //! would execute once per hour but only on day 5 through 10 of the month. //! //! Day of the week can be specified as an abbreviation or the full name. //! A schedule of `0 0 6 * * Sun,Sat` would execute at 6am on Sunday and //! Saturday. //! //! A simple usage example: //! //! ```rust,ignore //! extern crate job_scheduler; //! use job_scheduler::{JobScheduler, Job}; //! use std::time::Duration; //! //! fn main() { //! let mut sched = JobScheduler::new(); //! //! sched.add(Job::new("1/10 * * * * *".parse().unwrap(), || { //! println!("I get executed every 10 seconds!"); //! })); //! //! loop { //! sched.tick(); //! //! std::thread::sleep(Duration::from_millis(500)); //! } //! } //! ``` extern crate chrono; extern crate cron; extern crate uuid; use chrono::DateTime; use chrono::Utc; pub use cron::Schedule; use uuid::Uuid; /// A schedulable `Job`. pub struct Job<'a> { schedule: Schedule, run: Box<(FnMut() -> ()) + 'a>, last_tick: Option<DateTime<Utc>>, limit_missed_runs: usize, job_id: Uuid, } impl<'a> Job<'a> { /// Create a new job. /// /// ```rust,ignore /// // Run at second 0 of the 15th minute of the 6th, 8th, and 10th hour /// // of any day in March and June that is a Friday of the year 2017. /// let s: Schedule = "0 15 6,8,10 * Mar,Jun Fri 2017".into().unwrap(); /// Job::new(s, || println!("I have a complex schedule...") ); /// ``` pub fn new<T>(schedule: Schedule, run: T) -> Job<'a> where T: 'a, T: FnMut() -> () { Job { schedule, run: Box::new(run), last_tick: None, limit_missed_runs: 1, job_id: Uuid::new_v4(), } } fn tick(&mut self) { let now = Utc::now(); if self.last_tick.is_none() { self.last_tick = Some(now); return; } if self.limit_missed_runs > 0 { for event in self.schedule.after(&self.last_tick.unwrap()).take(self.limit_missed_runs) { if event > now { break; } (self.run)(); } } else { for event in self.schedule.after(&self.last_tick.unwrap()) { if event > now { break; } (self.run)(); } } self.last_tick = Some(now); } /// Set the limit for missed jobs in the case of delayed runs. Setting to 0 means unlimited. /// /// ```rust,ignore /// let mut job = Job::new("0/1 * * * * *".parse().unwrap(), || { /// println!("I get executed every 1 seconds!"); /// }); /// job.limit_missed_runs(99); /// ``` pub fn limit_missed_runs(&mut self, limit: usize) { self.limit_missed_runs = limit; } } #[derive(Default)] /// The JobScheduler contains and executes the scheduled jobs. pub struct JobScheduler<'a> { jobs: Vec<Job<'a>>, } impl<'a> JobScheduler<'a> { /// Create a new `JobScheduler`. pub fn new() -> JobScheduler<'a> { JobScheduler { jobs: Vec::new() } } /// Add a job to the `JobScheduler` /// /// ```rust,ignore /// let mut sched = JobScheduler::new(); /// sched.add(Job::new("1/10 * * * * *".parse().unwrap(), || { /// println!("I get executed every 10 seconds!"); /// })); /// ``` pub fn add(&mut self, job: Job<'a>) -> Uuid { let job_id = job.job_id; self.jobs.push(job); job_id } /// Remove a job from the `JobScheduler` /// /// ```rust,ignore /// let mut sched = JobScheduler::new(); /// let job_id = sched.add(Job::new("1/10 * * * * *".parse().unwrap(), || { /// println!("I get executed every 10 seconds!"); /// })); /// sched.remove(job_id); /// ``` pub fn remove(&mut self, job_id: Uuid) -> bool { let mut found_index = None; for (i, job) in self.jobs.iter().enumerate() { if job.job_id == job_id { found_index = Some(i); break; } } if found_index.is_some() { self.jobs.remove(found_index.unwrap()); } found_index.is_some() } /// The `tick` method increments time for the JobScheduler and executes /// any pending jobs. It is recommended to sleep for at least 500 /// milliseconds between invocations of this method. /// /// ```rust,ignore /// loop { /// sched.tick(); /// std::thread::sleep(Duration::from_millis(500)); /// } /// ``` pub fn tick(&mut self) { for mut job in &mut self.jobs { job.tick(); } } }