Interleave downloads with installations when downloading a toolchain

src/cli/download_tracker.rs

@@ -73,6 +73,14 @@ impl DownloadTracker {
                 self.retrying_download(url);
                 true
             }
+            Notification::Install(In::InstallingComponent(component, _, _)) => {
+                self.installing_component(component);
+                true
+            }
+            Notification::Install(In::ComponentInstalled(component, _, _)) => {
+                self.component_installed(component);
+                true
+            }
             _ => false,
         }
     }
@@ -125,10 +133,13 @@ impl DownloadTracker {
             return;
         };
         pb.set_style(
-            ProgressStyle::with_template("{msg:>12.bold}  downloaded {total_bytes} in {elapsed}")
-                .unwrap(),
+            ProgressStyle::with_template(if pb.position() != 0 {
+                "{msg:>12.bold}  downloaded {total_bytes} in {elapsed}"
+            } else {
+                "{msg:>12.bold}  component already downloaded"
+            })
+            .unwrap(),
         );
-        pb.finish();
     }
 
     /// Notifies self that the download has failed.
@@ -151,4 +162,50 @@ impl DownloadTracker {
         *retry_time = Some(Instant::now());
         pb.set_style(ProgressStyle::with_template("{msg:>12.bold}  retrying download").unwrap());
     }
+
+    /// Notifies self that the component is being installed.
+    pub(crate) fn installing_component(&mut self, component: &str) {
+        let key = self
+            .file_progress_bars
+            .keys()
+            .find(|comp| comp.contains(component))
+            .cloned();
+        if let Some(key) = key
+            && let Some((pb, _)) = self.file_progress_bars.get(&key)
+        {
+            pb.set_style(
+                ProgressStyle::with_template( if pb.position() != 0 {
+                    "{msg:>12.bold}  downloaded {total_bytes} in {elapsed} and installing {spinner:.green}"
+                } else {
+                    "{msg:>12.bold}  component already downloaded and installing {spinner:.green}"
+                }
+                )
+                .unwrap()
+                .tick_chars(r"|/-\ "),
+            );
+            pb.enable_steady_tick(Duration::from_millis(100));
+        }
+    }
+
+    /// Notifies self that the component has been installed.
+    pub(crate) fn component_installed(&mut self, component: &str) {
+        let key = self
+            .file_progress_bars
+            .keys()
+            .find(|comp| comp.contains(component))
+            .cloned();
+        if let Some(key) = key
+            && let Some((pb, _)) = self.file_progress_bars.get(&key)
+        {
+            pb.set_style(
+                ProgressStyle::with_template(if pb.position() != 0 {
+                    "{msg:>12.bold}  downloaded {total_bytes} and installed"
+                } else {
+                    "{msg:>12.bold}  component already downloaded and installed"
+                })
+                .unwrap(),
+            );
+            pb.finish();
+        }
+    }
 }