From 7c8d7a83c4c057c4f6e9026dbfcd494ecac44299 Mon Sep 17 00:00:00 2001
From: FritzFlorian <flo.fritz@t-online.de>
Date: Wed, 5 Feb 2020 18:14:44 +0100
Subject: [PATCH] WIP: Add minimal example to trigger tsan bugs.

---
 app/playground/CMakeLists.txt |  6 ++++--
 app/playground/barrier.cpp    | 13 +++++++++++++
 app/playground/barrier.h      | 27 +++++++++++++++++++++++++++
 app/playground/main.cpp       | 43 +++++++++++++++++++++++++++++++++++--------
 4 files changed, 79 insertions(+), 10 deletions(-)
 create mode 100644 app/playground/barrier.cpp
 create mode 100644 app/playground/barrier.h

diff --git a/app/playground/CMakeLists.txt b/app/playground/CMakeLists.txt
index 6673f70..018b19b 100644
--- a/app/playground/CMakeLists.txt
+++ b/app/playground/CMakeLists.txt
@@ -1,4 +1,6 @@
-add_executable(playground main.cpp)
+add_executable(playground
+        barrier.h barrier.cpp
+        main.cpp)
 
 # Example for adding the library to your app (as a cmake project dependency)
-target_link_libraries(playground context_switcher)
+target_link_libraries(playground context_switcher Threads::Threads)
diff --git a/app/playground/barrier.cpp b/app/playground/barrier.cpp
new file mode 100644
index 0000000..78b8ba2
--- /dev/null
+++ b/app/playground/barrier.cpp
@@ -0,0 +1,13 @@
+#include "barrier.h"
+
+barrier::barrier(const unsigned int count) : barrier_{} {
+  pthread_barrier_init(&barrier_, nullptr, count);
+}
+
+barrier::~barrier() {
+  pthread_barrier_destroy(&barrier_);
+}
+
+void barrier::wait() {
+  pthread_barrier_wait(&barrier_);
+}
diff --git a/app/playground/barrier.h b/app/playground/barrier.h
new file mode 100644
index 0000000..88b5c0e
--- /dev/null
+++ b/app/playground/barrier.h
@@ -0,0 +1,27 @@
+
+#ifndef PLS_BARRIER_H
+#define PLS_BARRIER_H
+
+#include <pthread.h>
+
+
+/**
+ * Provides standard barrier behaviour.
+ * `count` threads have to call `wait()` before any of the `wait()` calls returns,
+ * thus blocking all threads until everyone reached the barrier.
+ *
+ * PORTABILITY:
+ * Current implementation is based on pthreads.
+ */
+class barrier {
+  pthread_barrier_t barrier_;
+
+ public:
+  explicit barrier(unsigned int count);
+  ~barrier();
+
+  void wait();
+};
+
+
+#endif //PLS_BARRIER_H
diff --git a/app/playground/main.cpp b/app/playground/main.cpp
index 74bfe91..93bf83f 100644
--- a/app/playground/main.cpp
+++ b/app/playground/main.cpp
@@ -1,7 +1,11 @@
 #include <utility>
 #include <cstdio>
+#include <thread>
+
+#include "barrier.h"
 
 #include "context_switcher/context_switcher.h"
+
 using namespace context_switcher;
 using namespace std;
 
@@ -10,17 +14,40 @@ const size_t STACK_SIZE = 512 * 32;
 const size_t NUM_STACKS = 4;
 char custom_stacks[NUM_STACKS][STACK_SIZE];
 
-volatile int result;
-
 int main() {
+  context_switcher::continuation cont_t1, cont_main;
+  barrier bar{2};
+  int error = 0;
+
+  auto t1 = std::thread([&]() {
+    while (true) {
+      bar.wait();
+      auto cont = enter_context(custom_stacks[0], STACK_SIZE, [&](continuation &&cont) {
+        error++;
+        cont_t1 = std::move(cont);
+        bar.wait();
+        error++;
+        return std::move(cont_main);
+      });
+    }
+  });
+
+  int count = 0;
+
   while (true) {
-    context_switcher::continuation cont = enter_context(custom_stacks[0], STACK_SIZE, [](continuation &&main_cont) {
-//      main_cont = context_switcher::switch_context(std::move(main_cont));
-      return std::move(main_cont);
+    count++;
+    if (count % 100 == 0) {
+      printf("%d\n", count);
+    }
+    bar.wait();
+    auto cont = enter_context(custom_stacks[1], STACK_SIZE, [&](continuation &&cont) {
+      error++;
+      cont_main = std::move(cont);
+      bar.wait();
+      error++;
+      return std::move(cont_t1);
     });
-
-//    cont = context_switcher::switch_context(std::move(cont));
-  };
+  }
 
   return 0;
 }
--
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