From 59f70280dee90957a672810a3845af2dec8552e8 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Wed, 30 Nov 2022 11:49:56 +0200
Subject: Reserve targets, variables to avoid rehashing

---
 libbuild2/context.hxx | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

(limited to 'libbuild2/context.hxx')

diff --git a/libbuild2/context.hxx b/libbuild2/context.hxx
index b71a068..27c3cc0 100644
--- a/libbuild2/context.hxx
+++ b/libbuild2/context.hxx
@@ -652,6 +652,15 @@ namespace build2
     // Note: see also the trace_* data members that, if needed, must be set
     // separately, after construction.
     //
+    struct reserves
+    {
+      size_t targets;
+      size_t variables;
+
+      reserves (): targets (0), variables (0) {}
+      reserves (size_t t, size_t v): targets (t), variables (v) {}
+    };
+
     explicit
     context (scheduler&,
              global_mutexes&,
@@ -662,9 +671,17 @@ namespace build2
              bool no_diag_buffer = false,
              bool keep_going = true,
              const strings& cmd_vars = {},
+             reserves = {0, 160},
              optional<context*> module_context = nullptr,
              const loaded_modules_lock* inherited_mudules_lock = nullptr);
 
+    // Reserve elements in containers to avoid re-allocation/re-hashing. Zero
+    // values are ignored (that is, the corresponding container reserve()
+    // function is not called). Can only be called in the load phase.
+    //
+    void
+    reserve (reserves);
+
     // Enter project-wide (as opposed to global) variable overrides.
     //
     void
-- 
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