perf: avoid building module graph if dynamic specifier already in gra…

…ph (denoland#24035)

cli/module_loader.rs

@@ -171,7 +171,7 @@ impl ModuleLoadPreparer {
  )
  .await?;
 
- self.module_graph_builder.graph_roots_valid(graph, roots)?;
+ self.graph_roots_valid(graph, roots)?;
 
  // write the lockfile if there is one
  if let Some(lockfile) = &self.lockfile {
@@ -205,6 +205,14 @@ impl ModuleLoadPreparer {
 
  Ok(())
  }
+
+ pub fn graph_roots_valid(
+ &self,
+ graph: &ModuleGraph,
+ roots: &[ModuleSpecifier],
+ ) -> Result<(), AnyError> {
+ self.module_graph_builder.graph_roots_valid(graph, roots)
+ }
 }
 
 struct SharedCliModuleLoaderState {
@@ -806,8 +814,26 @@ impl<TGraphContainer: ModuleGraphContainer> ModuleLoader
  let inner = self.0.clone();
 
  async move {
- let graph_container = inner.graph_container.clone();
- let module_load_preparer = inner.shared.module_load_preparer.clone();
+ let graph_container = &inner.graph_container;
+ let module_load_preparer = &inner.shared.module_load_preparer;
+
+ if is_dynamic {
+ // When the specifier is already in the graph then it means it
+ // was previously loaded, so we can skip that and only check if
+ // this part of the graph is valid.
+ //
+ // This doesn't acquire a graph update permit because that will
+ // clone the graph which is a bit slow.
+ let graph = graph_container.graph();
+ if !graph.roots.is_empty() && graph.get(&specifier).is_some() {
+ log::debug!("Skipping prepare module load.");
+ // roots are already validated so we can skip those
+ if !graph.roots.contains(&specifier) {
+ module_load_preparer.graph_roots_valid(&graph, &[specifier])?;
+ }
+ return Ok(());
+ }
+ }
 
  let root_permissions = if is_dynamic {
  inner.dynamic_permissions.clone()

tests/specs/run/dynamic_already_prepared/__test__.jsonc

@@ -0,0 +1,8 @@
+{
+ "tests": {
+ "skips_prepare_module_load": {
+ "args": "run -A --log-level=debug main.ts",
+ "output": "main.out"
+ }
+ }
+}

tests/specs/run/dynamic_already_prepared/dynamic.ts

@@ -0,0 +1 @@
+console.log(1);

tests/specs/run/dynamic_already_prepared/dynamic2.ts

@@ -0,0 +1 @@
+await import("./dynamic3.ts");

tests/specs/run/dynamic_already_prepared/dynamic3.ts

@@ -0,0 +1 @@
+await import("./dynamic.ts");

tests/specs/run/dynamic_already_prepared/main.out

@@ -0,0 +1 @@
+[WILDCARD]Prepared module load.[WILDCARD]Skipping prepare module load.[WILDCARD]Skipping prepare module load.[WILDCARD]Skipping prepare module load.[WILDCARD]

tests/specs/run/dynamic_already_prepared/main.ts

@@ -0,0 +1,2 @@
+await import("./dynamic.ts");
+await import("./dynamic2.ts");