From eac95c866ab16983b0d1a5c00c64e895b3a6df3c Mon Sep 17 00:00:00 2001
From: iarspider <iarspider@gmail.com>
Date: Mon, 1 Feb 2021 20:18:04 +0100
Subject: [PATCH] FastJet: add optional patch to make random generator
 thread-local (#21395)

---
 .../builtin/packages/fastjet/atlas.patch      | 22 +++++++++++++++++++
 .../repos/builtin/packages/fastjet/package.py |  3 +++
 2 files changed, 25 insertions(+)
 create mode 100644 var/spack/repos/builtin/packages/fastjet/atlas.patch

diff --git a/var/spack/repos/builtin/packages/fastjet/atlas.patch b/var/spack/repos/builtin/packages/fastjet/atlas.patch
new file mode 100644
index 0000000000..66b9cc1d1f
--- /dev/null
+++ b/var/spack/repos/builtin/packages/fastjet/atlas.patch
@@ -0,0 +1,22 @@
+--- include/fastjet/GhostedAreaSpec.hh.orig	2020-06-03 13:15:12.952183980 +0200
++++ include/fastjet/GhostedAreaSpec.hh	2020-06-03 13:16:00.676275264 +0200
+@@ -232,7 +232,7 @@
+ 
+ 
+   std::vector<int> _random_checkpoint;
+-  static BasicRandom<double> _random_generator;
++  thread_local static BasicRandom<double> _random_generator;
+   //mutable BasicRandom<double> _random_generator;
+ 
+   static LimitedWarning _warn_fj2_placement_deprecated;
+--- src/GhostedAreaSpec.cc.orig	2020-06-04 11:37:41.196758510 +0200
++++ src/GhostedAreaSpec.cc	2020-06-04 11:38:07.499240761 +0200
+@@ -37,7 +37,7 @@
+ 
+ FASTJET_BEGIN_NAMESPACE      // defined in fastjet/internal/base.hh
+ 
+-BasicRandom<double> GhostedAreaSpec::_random_generator;
++thread_local BasicRandom<double> GhostedAreaSpec::_random_generator;
+ LimitedWarning GhostedAreaSpec::_warn_fj2_placement_deprecated;
+ 
+ /// explicit constructor
diff --git a/var/spack/repos/builtin/packages/fastjet/package.py b/var/spack/repos/builtin/packages/fastjet/package.py
index b6aec4d8e8..ea2bb05c3e 100644
--- a/var/spack/repos/builtin/packages/fastjet/package.py
+++ b/var/spack/repos/builtin/packages/fastjet/package.py
@@ -52,6 +52,9 @@ class Fastjet(AutotoolsPackage):
 
     variant('shared', default=True, description='Builds a shared version of the library')
     variant('auto-ptr', default=False, description='Use auto_ptr')
+    variant('atlas', default=False, description='Patch to make random generator thread_local')
+
+    patch('atlas.patch', when='+atlas')
 
     def configure_args(self):
         extra_args = ["--enable-allplugins"]