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Interleave downloads with installations when downloading a toolchain #4471

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9ff199a
fix(installation): extract installation of a component into a separat…
FranciscoTGouveia Aug 22, 2025
2ad06c8
feat(downloads): interleave the downloads with their installations
FranciscoTGouveia Aug 23, 2025
c1d1bbc
fix(installations): correct faulty output when interleaving a install…
FranciscoTGouveia Aug 30, 2025
2150965
feat(installations): add a new notification for the progress bar to s…
FranciscoTGouveia Sep 3, 2025
acfc43b
fix(downloads): correctly report progress for components that were al…
FranciscoTGouveia Sep 8, 2025
4ed8bb2
refactor(downloads): substitute RefCells with RwLocks for thread safety
FranciscoTGouveia Sep 18, 2025
750c216
refactor(downloads): remove some lifetime parameters to allow multi-t…
FranciscoTGouveia Sep 18, 2025
399b575
feat(downloads): use `spawn_blocking` to allow the downloads to conti…
FranciscoTGouveia Sep 16, 2025
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142 changes: 85 additions & 57 deletions src/dist/manifestation.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,10 +6,10 @@ mod tests;

use std::path::Path;

use anyhow::{Context, Result, anyhow, bail};
use anyhow::{Context, Error, Result, anyhow, bail};
use futures_util::stream::StreamExt;
use std::sync::Arc;
use tokio::sync::Semaphore;
use tokio::sync::{Semaphore, mpsc};
use tracing::info;
use url::Url;

Expand Down Expand Up @@ -154,8 +154,7 @@ impl Manifestation {
let altered = tmp_cx.dist_server != DEFAULT_DIST_SERVER;

// Download component packages and validate hashes
let mut things_to_install = Vec::new();
let mut things_downloaded = Vec::new();
let mut things_downloaded: Vec<String> = Vec::new();
let components = update.components_urls_and_hashes(new_manifest)?;
let components_len = components.len();

Expand All @@ -173,49 +172,7 @@ impl Manifestation {
.and_then(|s| s.parse().ok())
.unwrap_or(DEFAULT_MAX_RETRIES);

info!("downloading component(s)");
for bin in &components {
(download_cfg.notify_handler)(Notification::DownloadingComponent(
&bin.component.short_name(new_manifest),
&self.target_triple,
bin.component.target.as_ref(),
&bin.binary.url,
));
}

let semaphore = Arc::new(Semaphore::new(concurrent_downloads));
let component_stream = tokio_stream::iter(components.into_iter()).map(|bin| {
let sem = semaphore.clone();
async move {
let _permit = sem.acquire().await.unwrap();
let url = if altered {
utils::parse_url(
&bin.binary
.url
.replace(DEFAULT_DIST_SERVER, tmp_cx.dist_server.as_str()),
)?
} else {
utils::parse_url(&bin.binary.url)?
};

bin.download(&url, download_cfg, max_retries, new_manifest)
.await
.map(|downloaded| (bin, downloaded))
}
});
if components_len > 0 {
let results = component_stream
.buffered(components_len)
.collect::<Vec<_>>()
.await;
for result in results {
let (bin, downloaded_file) = result?;
things_downloaded.push(bin.binary.hash.clone());
things_to_install.push((bin, downloaded_file));
}
}

// Begin transaction
// Begin transaction before the downloads, as installations are interleaved with those
let mut tx = Transaction::new(
prefix.clone(),
tmp_cx,
Expand All @@ -227,6 +184,16 @@ impl Manifestation {
// to uninstall it first.
tx = self.maybe_handle_v2_upgrade(&config, tx, download_cfg.process)?;

info!("downloading component(s)");
for bin in &components {
(download_cfg.notify_handler)(Notification::DownloadingComponent(
&bin.component.short_name(new_manifest),
&self.target_triple,
bin.component.target.as_ref(),
&bin.binary.url,
));
}

// Uninstall components
for component in &update.components_to_uninstall {
let notification = if implicit_modify {
Expand All @@ -249,16 +216,77 @@ impl Manifestation {
)?;
}

// Install components
for (component_bin, installer_file) in things_to_install {
tx = self.install_component(
component_bin,
installer_file,
tmp_cx,
download_cfg,
new_manifest,
tx,
)?;
if components_len > 0 {
// Create a channel to communicate whenever a download is done and the component can be installed
// The `mpsc` channel was used as we need to send many messages from one producer (download's thread) to one consumer (install's thread)
// This is recommended in the official docs: https://docs.rs/tokio/latest/tokio/sync/index.html#mpsc-channel
Comment on lines +221 to +223
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I can't find it now, but I thought I wrote a comment on wondering why we're using a channel here, when we could instead compose the futures that download and install together.

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@rami3l rami3l Sep 28, 2025 •
edited
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Hmmm would you mind clarifying a little more what you meant by composing the futures?

The current constraints as we previously agreed was that the downloads are concurrent but the installations happening alongside them aren't concurrent within themselves, so I think a channel would be ideal for that case in favor of, say, a mutex.

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So you're saying, we only do one installation at a time? If that's the case, I would suggest something more like a FuturesUnordered containing all the downloads, and then pulling from that to run the installations.

let total_components = components.len();
let (download_tx, mut download_rx) =
mpsc::channel::<Result<(ComponentBinary<'_>, File)>>(total_components);

let semaphore = Arc::new(Semaphore::new(concurrent_downloads));
let component_stream = tokio_stream::iter(components.into_iter()).map(|bin| {
let sem = semaphore.clone();
let download_tx = download_tx.clone();
async move {
let _permit = sem.acquire().await.unwrap();
let url = if altered {
utils::parse_url(
&bin.binary
.url
.replace(DEFAULT_DIST_SERVER, tmp_cx.dist_server.as_str()),
)?
} else {
utils::parse_url(&bin.binary.url)?
};

let installer_file = bin
.download(&url, download_cfg, max_retries, new_manifest)
.await?;
let hash = bin.binary.hash.clone();
let _ = download_tx.send(Ok((bin, installer_file))).await;
Ok(hash)
}
});

let mut stream = component_stream.buffered(components_len);
let download_handle = async {
let mut hashes = Vec::new();
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Suggest writing this as a named function.

while let Some(result) = stream.next().await {
match result {
Ok(hash) => {
hashes.push(hash);
}
Err(e) => {
let _ = download_tx.send(Err(e)).await;
}
}
}
hashes
};
let install_handle = async {
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Suggest writing this as a named function.

let mut current_tx = tx;
let mut counter = 0;
while counter < total_components
&& let Some(message) = download_rx.recv().await
{
let (component_bin, installer_file) = message?;
current_tx = self.install_component(
component_bin,
installer_file,
tmp_cx,
download_cfg,
new_manifest,
current_tx,
)?;
counter += 1;
}
Ok::<_, Error>(current_tx)
};

let (download_results, install_result) = tokio::join!(download_handle, install_handle);
things_downloaded = download_results;
tx = install_result?;
}

// Install new distribution manifest
Expand Down
6 changes: 0 additions & 6 deletions tests/suite/cli_rustup.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,6 @@ async fn rustup_stable() {
.with_stderr(snapbox::str![[r#"
info: syncing channel updates for 'stable-[HOST_TRIPLE]'
info: latest update on 2015-01-02, rust version 1.1.0 (hash-stable-1.1.0)
info: downloading component[..]
...
info: cleaning up downloads & tmp directories

Expand Down Expand Up @@ -131,15 +130,12 @@ async fn rustup_all_channels() {
.with_stderr(snapbox::str![[r#"
info: syncing channel updates for 'stable-[HOST_TRIPLE]'
info: latest update on 2015-01-02, rust version 1.1.0 (hash-stable-1.1.0)
info: downloading component[..]
...
info: syncing channel updates for 'beta-[HOST_TRIPLE]'
info: latest update on 2015-01-02, rust version 1.2.0 (hash-beta-1.2.0)
info: downloading component[..]
...
info: syncing channel updates for 'nightly-[HOST_TRIPLE]'
info: latest update on 2015-01-02, rust version 1.3.0 (hash-nightly-2)
info: downloading component[..]
...
info: cleaning up downloads & tmp directories

Expand Down Expand Up @@ -208,12 +204,10 @@ async fn rustup_some_channels_up_to_date() {
.with_stderr(snapbox::str![[r#"
info: syncing channel updates for 'stable-[HOST_TRIPLE]'
info: latest update on 2015-01-02, rust version 1.1.0 (hash-stable-1.1.0)
info: downloading component[..]
...
info: syncing channel updates for 'beta-[HOST_TRIPLE]'
info: syncing channel updates for 'nightly-[HOST_TRIPLE]'
info: latest update on 2015-01-02, rust version 1.3.0 (hash-nightly-2)
info: downloading component[..]
...
info: cleaning up downloads & tmp directories

Expand Down