core: Add test for snapshotting from Rust (#2197)

1 files changed, 26 insertions, 13 deletions

diff --git a/core/shared_queue.js b/core/shared_queue.js
index aa3ff0aee..3a447cedb 100644
--- a/core/shared_queue.js
+++ b/core/shared_queue.js
@@ -16,6 +16,8 @@ SharedQueue Binary Layout
 +---------------------------------------------------------------+
  */
 
+/* eslint-disable @typescript-eslint/no-use-before-define */
+
 (window => {
   const GLOBAL_NAMESPACE = "Deno";
   const CORE_NAMESPACE = "core";
@@ -32,6 +34,25 @@ SharedQueue Binary Layout
 
   let sharedBytes;
   let shared32;
+  let initialized = false;
+
+  function maybeInit() {
+    if (!initialized) {
+      init();
+      initialized = true;
+    }
+  }
+
+  function init() {
+    let shared = Deno.core.shared;
+    assert(shared.byteLength > 0);
+    assert(sharedBytes == null);
+    assert(shared32 == null);
+    sharedBytes = new Uint8Array(shared);
+    shared32 = new Int32Array(shared);
+    // Callers should not call Deno.core.recv, use setAsyncHandler.
+    Deno.core.recv(handleAsyncMsgFromRust);
+  }
 
   function assert(cond) {
     if (!cond) {
@@ -40,12 +61,14 @@ SharedQueue Binary Layout
   }
 
   function reset() {
+    maybeInit();
     shared32[INDEX_NUM_RECORDS] = 0;
     shared32[INDEX_NUM_SHIFTED_OFF] = 0;
     shared32[INDEX_HEAD] = HEAD_INIT;
   }
 
   function head() {
+    maybeInit();
     return shared32[INDEX_HEAD];
   }
 
@@ -121,6 +144,7 @@ SharedQueue Binary Layout
 
   let asyncHandler;
   function setAsyncHandler(cb) {
+    maybeInit();
     assert(asyncHandler == null);
     asyncHandler = cb;
   }
@@ -135,17 +159,8 @@ SharedQueue Binary Layout
     }
   }
 
-  function init(shared) {
-    assert(shared.byteLength > 0);
-    assert(sharedBytes == null);
-    assert(shared32 == null);
-    sharedBytes = new Uint8Array(shared);
-    shared32 = new Int32Array(shared);
-    // Callers should not call Deno.core.recv, use setAsyncHandler.
-    window.Deno.core.recv(handleAsyncMsgFromRust);
-  }
-
   function dispatch(control, zeroCopy = null) {
+    maybeInit();
     // First try to push control to shared.
     const success = push(control);
     // If successful, don't use first argument of core.send.
@@ -170,6 +185,4 @@ SharedQueue Binary Layout
   assert(window[GLOBAL_NAMESPACE] != null);
   assert(window[GLOBAL_NAMESPACE][CORE_NAMESPACE] != null);
   Object.assign(core, denoCore);
-
-  init(Deno.core.shared);
-})(globalThis);
+})(this);