From d6f4bded25ee0b8f1216b806bf37c0d11e6b3e79 Mon Sep 17 00:00:00 2001
From: Joshua Spence <josh@joshuaspence.com>
Date: Thu, 23 Apr 2015 20:14:46 +1000
Subject: [PATCH] Memoize PHP compatibility info

Summary: Ref T7892. Avoid reading the PHP compatibility information for every file being linted.

Test Plan:
```name=Before
real    1m24.327s
user    1m19.571s
sys 0m5.239s
```

```lang=After
real    1m12.029s
user    1m5.756s
sys 0m5.502s
```

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Maniphest Tasks: T7892

Differential Revision: https://secure.phabricator.com/D12518
---
 src/lint/linter/ArcanistXHPASTLinter.php | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/lint/linter/ArcanistXHPASTLinter.php b/src/lint/linter/ArcanistXHPASTLinter.php
index 7b95511f..6a06039a 100644
--- a/src/lint/linter/ArcanistXHPASTLinter.php
+++ b/src/lint/linter/ArcanistXHPASTLinter.php
@@ -500,13 +500,17 @@ final class ArcanistXHPASTLinter extends ArcanistBaseXHPASTLinter {
   }
 
   private function lintPHPCompatibility(XHPASTNode $root) {
+    static $compat_info;
+
     if (!$this->version) {
       return;
     }
 
-    $target = phutil_get_library_root('phutil').
-      '/../resources/php_compat_info.json';
-    $compat_info = phutil_json_decode(Filesystem::readFile($target));
+    if ($compat_info === null) {
+      $target = phutil_get_library_root('phutil').
+        '/../resources/php_compat_info.json';
+      $compat_info = phutil_json_decode(Filesystem::readFile($target));
+    }
 
     // Create a whitelist for symbols which are being used conditionally.
     $whitelist = array(