Auto merge of #26678 - gterzian:shutdown_net_runtime, r=Manishearth

Net: shutdown async runtime on exit

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Shutting down the async runtime as part of exiting the core resource thread.

---
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- [ ] `./mach test-tidy` does not report any errors
- [ ] These changes fix #___ (GitHub issue number if applicable)

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because ___

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components/net/http_loader.rs

@@ -59,7 +59,7 @@ use tokio::prelude::{future, Future, Stream};
 use tokio::runtime::Runtime;
 
 lazy_static! {
-    pub static ref HANDLE: Mutex<Runtime> = Mutex::new(Runtime::new().unwrap());
+    pub static ref HANDLE: Mutex<Option<Runtime>> = Mutex::new(Some(Runtime::new().unwrap()));
 }
 
 /// The various states an entry of the HttpCache can be in.
@@ -95,7 +95,10 @@ impl HttpState {
             history_states: RwLock::new(HashMap::new()),
             http_cache: RwLock::new(HttpCache::new()),
             http_cache_state: Mutex::new(HashMap::new()),
-            client: create_http_client(tls_config, HANDLE.lock().unwrap().executor()),
+            client: create_http_client(
+                tls_config,
+                HANDLE.lock().unwrap().as_ref().unwrap().executor(),
+            ),
         }
     }
 }
@@ -1613,7 +1616,7 @@ fn http_network_fetch(
     let timing_ptr3 = context.timing.clone();
     let url1 = request.url();
     let url2 = url1.clone();
-    HANDLE.lock().unwrap().spawn(
+    HANDLE.lock().unwrap().as_mut().unwrap().spawn(
         res.into_body()
             .map_err(|_| ())
             .fold(res_body, move |res_body, chunk| {

components/net/resource_thread.rs

@@ -152,7 +152,7 @@ fn create_http_states(
         http_cache_state: Mutex::new(HashMap::new()),
         client: create_http_client(
             create_tls_config(&certs, ALPN_H2_H1),
-            HANDLE.lock().unwrap().executor(),
+            HANDLE.lock().unwrap().as_ref().unwrap().executor(),
         ),
     };
 
@@ -165,7 +165,7 @@ fn create_http_states(
         http_cache_state: Mutex::new(HashMap::new()),
         client: create_http_client(
             create_tls_config(&certs, ALPN_H2_H1),
-            HANDLE.lock().unwrap().executor(),
+            HANDLE.lock().unwrap().as_ref().unwrap().executor(),
         ),
     };
 
@@ -591,6 +591,9 @@ impl CoreResourceManager {
         // or a short timeout has been reached.
         self.thread_pool.exit();
 
+        // Shut-down the async runtime used by fetch workers.
+        drop(HANDLE.lock().unwrap().take());
+
         debug!("Exited CoreResourceManager");
     }