fix(npm): ensure npm package downloaded once per run when using `--reload` (#16842)

1 files changed, 28 insertions, 6 deletions

diff --git a/cli/npm/cache.rs b/cli/npm/cache.rs
index b2c842309..5e2f06ef7 100644
--- a/cli/npm/cache.rs
+++ b/cli/npm/cache.rs
@@ -1,14 +1,17 @@
 // Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
 
+use std::collections::HashSet;
 use std::fs;
 use std::path::Path;
 use std::path::PathBuf;
+use std::sync::Arc;
 
 use deno_ast::ModuleSpecifier;
 use deno_core::anyhow::bail;
 use deno_core::anyhow::Context;
 use deno_core::error::custom_error;
 use deno_core::error::AnyError;
+use deno_core::parking_lot::Mutex;
 use deno_core::url::Url;
 
 use crate::cache::DenoDir;
@@ -317,6 +320,8 @@ pub struct NpmCache {
   cache_setting: CacheSetting,
   http_client: HttpClient,
   progress_bar: ProgressBar,
+  /// ensures a package is only downloaded once per run
+  previously_reloaded_packages: Arc<Mutex<HashSet<String>>>,
 }
 
 impl NpmCache {
@@ -331,6 +336,7 @@ impl NpmCache {
       cache_setting,
       http_client,
       progress_bar,
+      previously_reloaded_packages: Default::default(),
     }
   }
 
@@ -338,6 +344,26 @@ impl NpmCache {
     self.readonly.clone()
   }
 
+  pub fn cache_setting(&self) -> &CacheSetting {
+    &self.cache_setting
+  }
+
+  /// Checks if the cache should be used for the provided name and version.
+  /// NOTE: Subsequent calls for the same package will always return `true`
+  /// to ensure a package is only downloaded once per run of the CLI. This
+  /// prevents downloads from re-occurring when someone has `--reload` and
+  /// and imports a dynamic import that imports the same package again for example.
+  fn should_use_global_cache_for_package(
+    &self,
+    package: (&str, &NpmVersion),
+  ) -> bool {
+    self.cache_setting.should_use_for_npm_package(package.0)
+      || !self
+        .previously_reloaded_packages
+        .lock()
+        .insert(format!("{}@{}", package.0, package.1))
+  }
+
   pub async fn ensure_package(
     &self,
     package: (&str, &NpmVersion),
@@ -352,10 +378,6 @@ impl NpmCache {
       })
   }
 
-  pub fn should_use_cache_for_npm_package(&self, package_name: &str) -> bool {
-    self.cache_setting.should_use_for_npm_package(package_name)
-  }
-
   async fn ensure_package_inner(
     &self,
     package: (&str, &NpmVersion),
@@ -367,11 +389,11 @@ impl NpmCache {
       package.1,
       registry_url,
     );
-    if package_folder.exists()
+    if self.should_use_global_cache_for_package(package)
+      && package_folder.exists()
       // if this file exists, then the package didn't successfully extract
       // the first time, or another process is currently extracting the zip file
       && !package_folder.join(NPM_PACKAGE_SYNC_LOCK_FILENAME).exists()
-      && self.should_use_cache_for_npm_package(package.0)
     {
       return Ok(());
     } else if self.cache_setting == CacheSetting::Only {