From f5ee3331e336db8d8da543d2cb67b169dab57d07 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?K=C5=8Dan?= <koan.bot@atoomic.org>
Date: Sat, 28 Mar 2026 01:31:00 -0600
Subject: [PATCH] optimization: cache contents() in __open and
 _io_file_mock_open
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Cache the result of $mock_file->contents() before its first use in
both __open and _io_file_mock_open. For directories, contents() scans
all keys of %files_being_mocked and sorts — calling it twice per
open() was redundant work that grows linearly with mock count.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 lib/Test/MockFile.pm | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/lib/Test/MockFile.pm b/lib/Test/MockFile.pm
index deac888..9cdd2aa 100644
--- a/lib/Test/MockFile.pm
+++ b/lib/Test/MockFile.pm
@@ -2800,8 +2800,11 @@ sub _io_file_mock_open {
         return;
     }
 
+    # Cache contents() — it's non-trivial for directories (scans %files_being_mocked).
+    my $contents = $mock_file->contents();
+
     # If contents is undef and reading, file doesn't exist
-    if ( !defined $mock_file->contents() && grep { $mode eq $_ } qw/< +</ ) {
+    if ( !defined $contents && grep { $mode eq $_ } qw/< +</ ) {
         $! = ENOENT;
         return;
     }
@@ -2813,7 +2816,7 @@ sub _io_file_mock_open {
 
     # Permission check (GH #3)
     if ( defined $_mock_uid ) {
-        if ( defined $mock_file->contents() ) {
+        if ( defined $contents ) {
             # Existing file: check file permissions
             my $need = 0;
             $need |= 4 if $rw =~ /r/;
@@ -3136,8 +3139,11 @@ sub __open (*;$@) {
         return undef;
     }
 
+    # Cache contents() — it's non-trivial for directories (scans %files_being_mocked).
+    my $contents = $mock_file->contents();
+
     # If contents is undef, we act like the file isn't there.
-    if ( !defined $mock_file->contents() && grep { $mode eq $_ } qw/< +</ ) {
+    if ( !defined $contents && grep { $mode eq $_ } qw/< +</ ) {
         $! = ENOENT;
         _maybe_throw_autodie( 'open', @_ );
         return undef;
@@ -3150,7 +3156,7 @@ sub __open (*;$@) {
 
     # Permission check (GH #3) — IO::File path must match __open
     if ( defined $_mock_uid ) {
-        if ( defined $mock_file->contents() ) {
+        if ( defined $contents ) {
             my $need = 0;
             $need |= 4 if $rw =~ /r/;
             $need |= 2 if $rw =~ /w/;