From 2f7222da8a26d8be915b9467fc21649a18f54b77 Mon Sep 17 00:00:00 2001
From: David Sherret <dsherret@users.noreply.github.com>
Date: Sat, 4 Mar 2023 20:07:11 -0500
Subject: refactor: remove `Semaphore::new(1)` and use `TaskQueue` (#18014)

---
 cli/graph_util.rs | 24 +++++++++---------------
 1 file changed, 9 insertions(+), 15 deletions(-)

(limited to 'cli/graph_util.rs')

diff --git a/cli/graph_util.rs b/cli/graph_util.rs
index 31645824d..ecae9ea4e 100644
--- a/cli/graph_util.rs
+++ b/cli/graph_util.rs
@@ -19,6 +19,8 @@ use deno_core::error::custom_error;
 use deno_core::error::AnyError;
 use deno_core::parking_lot::RwLock;
 use deno_core::ModuleSpecifier;
+use deno_core::TaskQueue;
+use deno_core::TaskQueuePermit;
 use deno_graph::Module;
 use deno_graph::ModuleGraph;
 use deno_graph::ModuleGraphError;
@@ -29,8 +31,6 @@ use import_map::ImportMapError;
 use std::collections::HashMap;
 use std::collections::HashSet;
 use std::sync::Arc;
-use tokio::sync::Semaphore;
-use tokio::sync::SemaphorePermit;
 
 #[derive(Clone, Copy)]
 pub struct GraphValidOptions {
@@ -318,27 +318,21 @@ struct GraphData {
 }
 
 /// Holds the `ModuleGraph` and what parts of it are type checked.
-#[derive(Clone)]
+#[derive(Clone, Default)]
 pub struct ModuleGraphContainer {
-  update_semaphore: Arc<Semaphore>,
+  // Allow only one request to update the graph data at a time,
+  // but allow other requests to read from it at any time even
+  // while another request is updating the data.
+  update_queue: Arc<TaskQueue>,
   graph_data: Arc<RwLock<GraphData>>,
 }
 
-impl Default for ModuleGraphContainer {
-  fn default() -> Self {
-    Self {
-      update_semaphore: Arc::new(Semaphore::new(1)),
-      graph_data: Default::default(),
-    }
-  }
-}
-
 impl ModuleGraphContainer {
   /// Acquires a permit to modify the module graph without other code
   /// having the chance to modify it. In the meantime, other code may
   /// still read from the existing module graph.
   pub async fn acquire_update_permit(&self) -> ModuleGraphUpdatePermit {
-    let permit = self.update_semaphore.acquire().await.unwrap();
+    let permit = self.update_queue.acquire().await;
     ModuleGraphUpdatePermit {
       permit,
       graph_data: self.graph_data.clone(),
@@ -395,7 +389,7 @@ impl ModuleGraphContainer {
 /// everything looks fine, calling `.commit()` will store the
 /// new graph in the ModuleGraphContainer.
 pub struct ModuleGraphUpdatePermit<'a> {
-  permit: SemaphorePermit<'a>,
+  permit: TaskQueuePermit<'a>,
   graph_data: Arc<RwLock<GraphData>>,
   graph: ModuleGraph,
 }
-- 
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