From 737877e62467b924eea0a43eab68258b0c13db78 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 13 Feb 2017 09:48:12 +0200
Subject: Add MT-safe variable_cache, use for variable overrides

---
 build2/scope | 12 ++++++++++++
 1 file changed, 12 insertions(+)

(limited to 'build2/scope')

diff --git a/build2/scope b/build2/scope
index 64aaf24..2b86200 100644
--- a/build2/scope
+++ b/build2/scope
@@ -177,6 +177,18 @@ namespace build2
     //
     variable_type_map target_vars;
 
+    // Variable override cache (project root and global scope only).
+    //
+    // The key is the variable plus the innermost (scope-wise) variable map to
+    // which this override applies. See find_override() for details.
+    //
+    // Note: since it can be modified on any lookup (including during the
+    // execute phase), the cache is protected by its own mutex shard.
+    //
+    mutable
+    variable_cache<pair<const variable*, const variable_map*>>
+    override_cache;
+
     // Meta/operations supported by this project (set on the root
     // scope only).
     //
-- 
cgit v1.1