From d28f1e9cfe50db12b47d07bf22d4dd9387ef963b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ren=C3=A9=20Widera?= <r.widera@hzdr.de>
Date: Tue, 12 Dec 2023 08:14:23 +0100
Subject: [PATCH] fix modulo zero

Modulo zero is not allowed and results into an arithmetic error.
---
 redGrapes/memory/allocator.cpp | 2 +-
 redGrapes/redGrapes.cpp        | 5 +++++
 redGrapes/redGrapes.hpp        | 6 +++++-
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/redGrapes/memory/allocator.cpp b/redGrapes/memory/allocator.cpp
index 5a982283..7c256096 100644
--- a/redGrapes/memory/allocator.cpp
+++ b/redGrapes/memory/allocator.cpp
@@ -15,7 +15,7 @@ Allocator::Allocator()
 
 Allocator::Allocator( dispatch::thread::WorkerId worker_id )
   : worker_id(
-        worker_id % SingletonContext::get().n_workers
+        worker_id % SingletonContext::get().get_num_workers()
     )
 {}
 
diff --git a/redGrapes/redGrapes.cpp b/redGrapes/redGrapes.cpp
index 53a3aad3..7f542066 100644
--- a/redGrapes/redGrapes.cpp
+++ b/redGrapes/redGrapes.cpp
@@ -44,6 +44,11 @@ Context::~Context()
         
 }
 
+uint32_t Context::get_num_workers() const
+{
+    return n_workers == 0 ? 1 : n_workers;
+}
+
 std::shared_ptr<TaskSpace> Context::current_task_space() const
 {
     if( current_task )
diff --git a/redGrapes/redGrapes.hpp b/redGrapes/redGrapes.hpp
index 38c57eb9..18c57e08 100644
--- a/redGrapes/redGrapes.hpp
+++ b/redGrapes/redGrapes.hpp
@@ -61,6 +61,8 @@ struct Context
 
     void execute_task( Task & task );
 
+    uint32_t get_num_workers() const;
+
     /*! create a new task, as child of the currently running task (if there is one)
      *
      * @param f callable that takes "proprty-building" objects as args
@@ -83,7 +85,6 @@ struct Context
     static thread_local scheduler::WakerId current_waker_id;
     static thread_local std::shared_ptr< dispatch::thread::WorkerThread > current_worker;
 
-    unsigned n_workers;
     static thread_local unsigned current_arena;
     HwlocContext hwloc_ctx;
     std::shared_ptr< dispatch::thread::WorkerPool > worker_pool;
@@ -94,6 +95,9 @@ struct Context
 #if REDGRAPES_ENABLE_TRACE
     std::shared_ptr< perfetto::TracingSession > tracing_session;
 #endif
+
+  private:
+    unsigned n_workers;
 };