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Updating the async API client example
Added some code to show how you can run blocking Rust code inside a foreign task queue.
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/* This Source Code Form is subject to the terms of the Mozilla Public | ||
* License, v. 2.0. If a copy of the MPL was not distributed with this | ||
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | ||
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use crate::{run_task, ApiError, Result, TaskRunner}; | ||
use std::sync::Arc; | ||
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#[async_trait::async_trait] | ||
pub trait HttpClient: Send + Sync { | ||
async fn fetch(&self, url: String, credentials: String) -> Result<String>; | ||
} | ||
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impl From<serde_json::Error> for ApiError { | ||
fn from(e: serde_json::Error) -> Self { | ||
Self::Json { | ||
reason: e.to_string(), | ||
} | ||
} | ||
} | ||
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#[derive(Debug, serde::Deserialize)] | ||
pub struct Issue { | ||
pub url: String, | ||
pub title: String, | ||
pub state: IssueState, | ||
} | ||
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#[derive(Debug, serde::Deserialize)] | ||
pub enum IssueState { | ||
#[serde(rename = "open")] | ||
Open, | ||
#[serde(rename = "closed")] | ||
Closed, | ||
} | ||
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pub struct ApiClient { | ||
http_client: Arc<dyn HttpClient>, | ||
task_runner: Arc<dyn TaskRunner>, | ||
} | ||
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impl ApiClient { | ||
// Pretend this is a blocking call that needs to load the credentials from disk/network | ||
fn load_credentials_sync(&self) -> String { | ||
String::from("username:password") | ||
} | ||
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async fn load_credentials(self: Arc<Self>) -> String { | ||
let self_cloned = Arc::clone(&self); | ||
run_task(&self.task_runner, move || { | ||
self_cloned.load_credentials_sync() | ||
}) | ||
.await | ||
} | ||
} | ||
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impl ApiClient { | ||
pub fn new(http_client: Arc<dyn HttpClient>, task_runner: Arc<dyn TaskRunner>) -> Self { | ||
Self { | ||
http_client, | ||
task_runner, | ||
} | ||
} | ||
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pub async fn get_issue( | ||
self: Arc<Self>, | ||
owner: String, | ||
repository: String, | ||
issue_number: u32, | ||
) -> Result<Issue> { | ||
let credentials = self.clone().load_credentials().await; | ||
let url = | ||
format!("https://api.github.com/repos/{owner}/{repository}/issues/{issue_number}"); | ||
let body = self.http_client.fetch(url, credentials).await?; | ||
Ok(serde_json::from_str(&body)?) | ||
} | ||
} |
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,90 @@ | ||
/* This Source Code Form is subject to the terms of the Mozilla Public | ||
* License, v. 2.0. If a copy of the MPL was not distributed with this | ||
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | ||
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use std::sync::{Arc, Mutex}; | ||
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#[async_trait::async_trait] | ||
pub trait TaskRunner: Send + Sync { | ||
async fn run_task(&self, task: Arc<dyn RustTask>); | ||
} | ||
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pub trait RustTask: Send + Sync { | ||
fn execute(&self); | ||
} | ||
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pub async fn run_task<F, T>(runner: &Arc<dyn TaskRunner>, closure: F) -> T | ||
where | ||
F: FnOnce() -> T + Send + Sync + 'static, | ||
T: Send + 'static, | ||
{ | ||
let closure = Arc::new(TaskClosure::new(closure)); | ||
runner | ||
.run_task(Arc::clone(&closure) as Arc<dyn RustTask>) | ||
.await; | ||
closure.take_result() | ||
} | ||
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struct TaskClosure<F, T> | ||
where | ||
F: FnOnce() -> T + Send + Sync, | ||
T: Send, | ||
{ | ||
inner: Mutex<TaskClosureInner<F, T>>, | ||
} | ||
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enum TaskClosureInner<F, T> | ||
where | ||
F: FnOnce() -> T + Send + Sync, | ||
T: Send, | ||
{ | ||
Pending(F), | ||
Running, | ||
Complete(T), | ||
Finished, | ||
} | ||
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impl<F, T> TaskClosure<F, T> | ||
where | ||
F: FnOnce() -> T + Send + Sync, | ||
T: Send, | ||
{ | ||
fn new(closure: F) -> Self { | ||
Self { | ||
inner: Mutex::new(TaskClosureInner::Pending(closure)), | ||
} | ||
} | ||
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fn take_result(&self) -> T { | ||
let mut inner = self.inner.lock().unwrap(); | ||
match *inner { | ||
TaskClosureInner::Pending(_) => panic!("Task never ran"), | ||
TaskClosureInner::Running => panic!("Task still running"), | ||
TaskClosureInner::Finished => panic!("Task already finished"), | ||
TaskClosureInner::Complete(_) => (), | ||
}; | ||
match std::mem::replace(&mut *inner, TaskClosureInner::Finished) { | ||
TaskClosureInner::Complete(v) => v, | ||
_ => unreachable!(), | ||
} | ||
} | ||
} | ||
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impl<F, T> RustTask for TaskClosure<F, T> | ||
where | ||
F: FnOnce() -> T + Send + Sync, | ||
T: Send, | ||
{ | ||
fn execute(&self) { | ||
let mut inner = self.inner.lock().unwrap(); | ||
match std::mem::replace(&mut *inner, TaskClosureInner::Running) { | ||
TaskClosureInner::Pending(f) => { | ||
let result = f(); | ||
*inner = TaskClosureInner::Complete(result) | ||
} | ||
TaskClosureInner::Running => panic!("Task already started"), | ||
TaskClosureInner::Complete(_) => panic!("Task already executed"), | ||
TaskClosureInner::Finished => panic!("Task already finished"), | ||
} | ||
} | ||
} |
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