From ad21210edd5aabdeebe70809672b4224cc6f41c9 Mon Sep 17 00:00:00 2001
From: Ryan Dahl <ry@tinyclouds.org>
Date: Sun, 1 Mar 2020 17:17:59 -0500
Subject: perf: use subarray instead of slice in dispatch minimal (#4180)

---
 core/shared_queue.js | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

(limited to 'core/shared_queue.js')

diff --git a/core/shared_queue.js b/core/shared_queue.js
index 093cc223f..742a90995 100644
--- a/core/shared_queue.js
+++ b/core/shared_queue.js
@@ -115,7 +115,8 @@ SharedQueue Binary Layout
       if (index == 0) {
         return HEAD_INIT;
       } else {
-        return shared32[INDEX_OFFSETS + 2 * (index - 1)];
+        const prevEnd = shared32[INDEX_OFFSETS + 2 * (index - 1)];
+        return (prevEnd + 3) & ~3;
       }
     } else {
       return null;
@@ -125,16 +126,18 @@ SharedQueue Binary Layout
   function push(opId, buf) {
     const off = head();
     const end = off + buf.byteLength;
+    const alignedEnd = (end + 3) & ~3;
     const index = numRecords();
-    if (end > shared32.byteLength || index >= MAX_RECORDS) {
+    if (alignedEnd > shared32.byteLength || index >= MAX_RECORDS) {
       // console.log("shared_queue.js push fail");
       return false;
     }
     setMeta(index, end, opId);
+    assert(alignedEnd % 4 === 0);
     assert(end - off == buf.byteLength);
     sharedBytes.set(buf, off);
     shared32[INDEX_NUM_RECORDS] += 1;
-    shared32[INDEX_HEAD] = end;
+    shared32[INDEX_HEAD] = alignedEnd;
     return true;
   }
 
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