delay-timer周期任务lib-技术圈

delay-timer是一个基于时间轮算法构建的lib，它可以很方便地管理定时任务，或者周期性地执行任意任务。

轻松打造一个延迟/周期任务的运行容器。可以想象成crontab，但可以处理同步/异步任务，但支持动态添加/取消/删除/更新，
单个任务支持配置任务的最大并行数量，运行时间等。

底层运行时基于的smol和tokio（可选的feature），你可以用其中一个来构建你的应用程序。

v0.4.0 新功能:
1.支持动态的修改运行中的任务。
2.支持了insert任务后获取句柄`TaskInstancesChain`，可以动态获取运行中的任务实例`TaskInstance`。
2.1. 运行中任务的任务实例可以动态取消。
2.2. 取消分为三种方式：同步阻塞取消、超时限制取消、异步取消。
2.3. 支持读取运行中任务的运行状态。
3.支持获取内部异步子任务进程的输出。

更新依赖:

替换 waitmap -> dashmap .
升级 cron_clock .

更新examples:

增加，async-std & tokio 使用案例。
增加，动态取消运行中任务实例案例。

丰富了文档。

小例子：
创建一个异步的调度任务，支持如下。
任务描述：每秒运行一次、只运行9次、最大并行运行数3、唯一id为:1.

``` rust

let body = create_async_fn_body!({
    // do something.
});

let task = TaskBuilder::default()
    .set_frequency_by_candy(CandyFrequency::CountDown(9, CandyCron::Secondly))
    .set_task_id(1)
    .set_maximun_parallel_runable_num(3)
    .spawn(body)?;


```

async-std 中的应用 :

``` rust

#[async_std::main]
async fn main() -> Result<()> {
    // Build an DelayTimer that uses the default configuration of the Smol runtime internally.
    let delay_timer = DelayTimerBuilder::default().build();

    // Develop a print job that runs in an asynchronous cycle.
    let task_instance_chain = delay_timer.insert_task(build_task_async_print())?;

    // Get the running instance of task 1.
    let task_instance = task_instance_chain.next_with_async_wait().await?;

    // Cancel running task instances.
    task_instance.cancel_with_async_wait().await?;

    // Remove task which id is 1.
    delay_timer.remove_task(1)?;

    // No new tasks are accepted; running tasks are not affected.
    delay_timer.stop_delay_timer()
}

```

tokio中的应用:

``` rust

#[tokio::main]
async fn main() -> Result<()> {
    // In addition to the mixed (smol & tokio) runtime
    // You can also share a tokio runtime with delayTimer, please see api `DelayTimerBuilder::tokio_runtime` for details.

    // Build an DelayTimer that uses the default configuration of the Smol runtime internally.
    let delay_timer = DelayTimerBuilder::default().build();

    // Develop a print job that runs in an asynchronous cycle.
    let task_instance_chain = delay_timer.insert_task(build_task_async_print())?;

    // Get the running instance of task 1.
    let task_instance = task_instance_chain.next_with_async_wait().await?;

    // Cancel running task instances.
    task_instance.cancel_with_async_wait().await?;

    // Remove task which id is 1.
    delay_timer.remove_task(1)?;

    // No new tasks are accepted; running tasks are not affected.
    delay_timer.stop_delay_timer()
}

```

非异步上下文的应用：

```

fn main() -> Result<()> {
    let delay_timer = DelayTimerBuilder::default().build();

    // Develop a print job that runs in an asynchronous cycle.
    let task_instance_chain = delay_timer.insert_task(build_task_async_print())?;

    // Develop an http request task that runs in an asynchronous cycle.
    delay_timer.add_task(build_task_async_request())?;

    // Get the running instance of task 1.
    let task_instance = task_instance_chain.next_with_wait()?;

    // Cancel running task instances.
    task_instance.cancel_with_wait()?;

    // Remove task which id is 1.
    delay_timer.remove_task(1)?;

    // No new tasks are accepted; running tasks are not affected.
    delay_timer.stop_delay_timer()?;

    Ok(())
}

```

## repo: [delay-timer](https://github.com/BinChengZhao/delay-timer)

## doc: [delay-timer-doc](https://docs.rs/delay_timer)

## crates: [delay-timer-crates](https://crates.io/crates/delay_timer)