From 2f188290e203780752597b0263581590af3a69b2 Mon Sep 17 00:00:00 2001
From: Ryan Liptak <squeek502@hotmail.com>
Date: Wed, 7 Jun 2023 22:37:53 -0700
Subject: [PATCH] Use `iterateAssumeFirstIteration` in `Walker.next` to avoid
 unnecessary lseek calls
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Since we are opening each directory for iteration, we know that we don't need to reset the cursor's directory before iterating. Using `iterateAssumeFirstIteration` skips the cursor resetting which eliminates an `lseek` syscall for every directory opened on non-Windows platforms.

This doesn't seem to actually matter much for performance (1.01 ± 0.02 times faster when walking /home/ on my system) but avoiding unnecessary syscalls is always nice anyway.
---
 lib/std/fs.zig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/std/fs.zig b/lib/std/fs.zig
index 037f0c81f6..d3c8fb322e 100644
--- a/lib/std/fs.zig
+++ b/lib/std/fs.zig
@@ -972,7 +972,7 @@ pub const IterableDir = struct {
                         {
                             errdefer new_dir.close();
                             try self.stack.append(StackItem{
-                                .iter = new_dir.iterate(),
+                                .iter = new_dir.iterateAssumeFirstIteration(),
                                 .dirname_len = self.name_buffer.items.len,
                             });
                             top = &self.stack.items[self.stack.items.len - 1];