add spawn_blocking helper method to help with Results

src/utils/mod.rs

@@ -20,7 +20,7 @@ mod html;
 mod queue;
 pub(crate) mod queue_builder;
 mod rustc_version;
-use anyhow::Result;
+use anyhow::{Context as _, Result};
 use postgres::Client;
 use serde::de::DeserializeOwned;
 use serde::Serialize;
@@ -78,6 +78,40 @@ where
     )
 }
 
+/// a wrapper around tokio's `spawn_blocking` that
+/// enables us to write nicer code when the closure
+/// returns an `anyhow::Result`.
+///
+/// The join-error will also be converted into an `anyhow::Error`.
+///
+/// with standard `tokio::task::spawn_blocking`:
+/// ```ignore
+/// let data = spawn_blocking(move || -> anyhow::Result<_> {
+///     let data = get_the_data()?;
+///     Ok(data)
+/// })
+/// .await
+/// .context("failed to join thread")??;
+/// ```
+///
+/// with this helper function:
+/// ```ignore
+/// let data = spawn_blocking(move || {
+///     let data = get_the_data()?;
+///     Ok(data)
+/// })
+/// .await?
+/// ```
+pub(crate) async fn spawn_blocking<F, R>(f: F) -> Result<R>
+where
+    F: FnOnce() -> Result<R> + Send + 'static,
+    R: Send + 'static,
+{
+    tokio::task::spawn_blocking(f)
+        .await
+        .context("failed to join thread")?
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/web/releases.rs

@@ -5,7 +5,7 @@ use crate::{
     cdn::{self, CrateInvalidation},
     db::{Pool, PoolClient},
     impl_axum_webpage, impl_webpage,
-    utils::report_error,
+    utils::{report_error, spawn_blocking},
     web::{
         error::{Nope, WebResult},
         match_version,
@@ -14,7 +14,7 @@ use crate::{
     },
     BuildQueue, Config,
 };
-use anyhow::{anyhow, Context as _, Result};
+use anyhow::{anyhow, Result};
 use axum::{
     extract::{Extension, Path},
     response::IntoResponse,
@@ -31,7 +31,6 @@ use router::Router;
 use serde::{Deserialize, Serialize};
 use std::collections::{BTreeMap, HashMap};
 use std::str;
-use tokio::task::spawn_blocking;
 use tracing::{debug, warn};
 use url::form_urlencoded;
 
@@ -346,7 +345,7 @@ pub(crate) async fn releases_handler(
         }
     };
 
-    let releases = spawn_blocking(move || -> Result<_> {
+    let releases = spawn_blocking(move || {
         let mut conn = pool.get()?;
         get_releases(
             &mut conn,
@@ -356,8 +355,7 @@ pub(crate) async fn releases_handler(
             latest_only,
         )
     })
-    .await
-    .context("failed to join thread")??;
+    .await?;
 
     // Show next and previous page buttons
     let (show_next_page, show_previous_page) = (

src/web/sitemap.rs

@@ -2,21 +2,19 @@ use crate::{
     db::Pool,
     docbuilder::Limits,
     impl_axum_webpage, impl_webpage,
-    utils::{get_config, ConfigName},
+    utils::{get_config, spawn_blocking, ConfigName},
     web::{
         error::{AxumNope, WebResult},
         page::WebPage,
     },
 };
-use anyhow::Context;
 use axum::{
     extract::{Extension, Path},
     response::IntoResponse,
 };
 use chrono::{DateTime, TimeZone, Utc};
 use iron::{IronResult, Request as IronRequest, Response as IronResponse};
 use serde::Serialize;
-use tokio::task::spawn_blocking;
 
 /// sitemap index
 #[derive(Debug, Clone, PartialEq, Eq, Serialize)]
@@ -64,7 +62,7 @@ pub(crate) async fn sitemap_handler(
             return Err(AxumNope::ResourceNotFound);
         }
     }
-    let releases = spawn_blocking(move || -> anyhow::Result<_> {
+    let releases = spawn_blocking(move || {
         let mut conn = pool.get()?;
         let query = conn.query(
             "SELECT crates.name,
@@ -95,8 +93,7 @@ pub(crate) async fn sitemap_handler(
             })
             .collect())
     })
-    .await
-    .context("failed to join thread")??;
+    .await?;
 
     Ok(SitemapXml { releases })
 }
@@ -116,12 +113,11 @@ impl_axum_webpage!(AboutBuilds = "core/about/builds.html");
 pub(crate) async fn about_builds_handler(
     Extension(pool): Extension<Pool>,
 ) -> WebResult<impl IntoResponse> {
-    let rustc_version = spawn_blocking(move || -> anyhow::Result<_> {
+    let rustc_version = spawn_blocking(move || {
         let mut conn = pool.get()?;
         get_config::<String>(&mut conn, ConfigName::RustcVersion)
     })
-    .await
-    .context("failed to join thread")??;
+    .await?;
 
     Ok(AboutBuilds {
         rustc_version,