我目前正在Rocket上构建一个API引擎，和现代应用程序一样，我想包括一个自动调度程序，以便在Rocket API运行时运行异步任务(也称为crons).
我决定使用火箭整流罩来启用所说的日程表建立在东京-日程表上的"升空"事件.
事实是，我设置了所有需要的部分(登录到数据库、 struct 和特征)，但在编译关于我的整流罩的生命周期时，我得到了一个奇怪的错误.
下面是我的代码演练:
->；这是我的"命令"模块，包含与应用程序一起构建和移动命令(也称为crons)的所有 struct 部分.
/// Synthetize a command execution result.
pub enum CommandResult {
SUCCESS,
ERROR(String),
SKIPPED(String),
}
/// Trait to define structs as runnable async crons with tokio_scheduler
#[async_trait]
pub trait Command: Send + Sync {
/// returns the current command name
fn get_command_name(&self) -> String;
/// returns the current command argument payload
fn get_command_args(&self) -> Option<HashMap<String, String>>;
/// returns the "cron_middleware"
fn get_cron_middleware(&self) -> CronLogMiddleware<CronLogRepository>;
/// real body for the command execution, must be overriden in impls.
async fn do_run(&self) -> Result<CommandResult>;
/// starts the command process by validating command lock, and registering an open cron log into database.
async fn begin(&self) -> Result<CronLog> {
// ...
}
/// ends the command process by releasing command lock, and registering the result of the command to an opened cron log into database.
async fn end(&self, cron_log: &CronLog, result: CommandResult) -> Result<()> {
// ...
}
/// hidden runner of commands, uses begin, end and do_run, and will be used by runner.
async fn run(&self) -> Result<()> {
// ...
}
/// generates a unique key for this command name + args, for locks purposes
fn generate_unicity_key(&self) -> String {
// ...
}
/// converts command args as a string payload
#[allow(clippy::or_fun_call)]
fn get_command_args_as_string(&self) -> String {
// ...
}
}
/// struct to move a command + its cron schedule into scheduler.
pub struct CommandHandle<T: Command + ?Sized + Send + Sync> {
pub command: Box<T>,
pub schedule: String,
}
然后，出于测试目的，我创建了一个测试命令 struct ，如下所示:
/// a testing purpose command
pub struct TestCommand {
pub name: String,
pub args: Option<HashMap<String, String>>,
pub cron_log_middleware: CronLogMiddleware<CronLogRepository>,
}
#[async_trait]
impl Command for TestCommand {
// accessors (get_... functions)
async fn do_run(&self) -> Result<CommandResult> {
debug!("executed !");
Ok(CommandResult::SUCCESS)
}
}
火箭建造者看起来是这样的:
let mut sched = CronScheduler::default();
sched.add_cron(CommandHandle {
command: Box::new(TestCommand {
name: "app:test".to_string(),
args: None,
cron_log_middleware: cron_log_middleware.clone(),
}),
schedule: "*/1 * * * *".to_string(),
});
// then I add sched to rocket with .manage()
整流罩看起来是这样的:
/// a rocket fairing enabling async tasks (eg crons) while rocket is launching
#[derive(Default)]
pub struct CronScheduler {
crons: Vec<CommandHandle<dyn Command>>,
}
impl CronScheduler {
/// adds a cron (eg CommandHandle with a given command) to run with the scheduler.
pub fn add_cron(&mut self, cron: CommandHandle<dyn Command>) {
self.crons.push(cron);
}
}
#[rocket::async_trait]
impl Fairing for CronScheduler {
//...
v -- error is here
async fn on_liftoff(&self, _rocket: &Rocket<Orbit>) {
let sched = SchedulerBuilder::build().await;
for handle in self.crons.iter() {
let job = Job::new_cron_job_async(handle.schedule.as_str(), |_uid, _lock| {
Box::pin(async move {
handle.command.run().await;
})
})
.unwrap();
sched.add(job).await.unwrap();
}
sched.start().await.unwrap();
}
}
AAA和我得到了这个错误:
error[E0759]: `self` has lifetime `'life0` but it needs to satisfy a `'static` lifetime requirement
--> src/core/fairings/cron_scheduler.rs:34:26
|
34 | async fn on_liftoff(&self, rocket: &Rocket<Orbit>) {
| ^^^^ this data with lifetime `'life0`...
...
39 | / Box::pin(async move {
40 | | handle.command.run().await;
41 | | })
| |__________________- ...is used and required to live as long as `'static` here
|
note: `'static` lifetime requirement introduced by the return type
--> src/core/fairings/cron_scheduler.rs:34:5
|
34 | async fn on_liftoff(&self, rocket: &Rocket<Orbit>) {
| ^^^^^ requirement introduced by this return type
...
39 | / Box::pin(async move {
40 | | handle.command.run().await;
41 | | })
| |__________________- because of this returned expression
我的货架也缩短了:
[dependencies]
rocket = {version = "0.5.0-rc.2", features = ["json"]}
// ...
tokio-cron-scheduler = {version = "0.8.1", features = ["signal"]}
// ...
我try 了不同的解决方案，并指出这就是导致问题的命令，就好像我将"Box::Pin(...)"的内容替换为类似println！的内容一样，没有任何问题.
我不知道这是异步性和火箭异步性之间的冲突，还是其他，但我搞不清楚.
编辑1:缩短了大量代码，因为罚单太长了.
编辑2:由于经过验证的答案，找到了解决方案；如果可以帮助任何人，这里是最终的代码补丁.
FTR，我不得不自己实现Clone(不使用宏)，并使用固定答案的代码作为参考.
// command
pub struct CommandHandle<T: Command + ?Sized + Send + Sync> {
pub command: Arc<T>,
pub schedule: String,
}
impl<T> Clone for CommandHandle<T>
where
T: Command + ?Sized + Send + Sync,
{
fn clone(&self) -> Self {
Self {
command: self.command.clone(),
schedule: self.schedule.clone(),
}
}
}
// fairing
async fn on_liftoff(&self, _rocket: &Rocket<Orbit>) {
let sched = SchedulerBuilder::build().await;
for handle in self.crons.iter() {
let schedule = handle.schedule.clone();
let handle = handle.clone();
let job = Job::new_cron_job_async(schedule.as_str(), move |_uid, _lock| {
let handle = handle.clone();
Box::pin(async move {
handle.command.run().await.unwrap();
})
})
.unwrap();
sched.add(job).await.unwrap();
}
sched.start().await.unwrap();
}