tests: Fix data race in fibers test

Previous to this commit, the tests were using operator[] from
unordered_map to query elements but this silently inserts empty elements
when they don't exist. If all threads were executed without concurrency,
this wouldn't be an issue, but the same unordered_map could be written
from two threads at the same time. This is a data race and makes some
previously inserted elements invisible for a short period of time,
causing them to insert and return an empty element. This default
constructed element (a zero) was used to index an array of fibers that
asserted when one of them was nullptr, shutting the test session off.

To address this issue, lock on thread id reads and writes. This could be
a shared mutex to allow concurrent reads, but the definition of
std::this_thread::get_id is fuzzy when using non-standard techniques
like fibers. I opted to use a standard mutex.

While we are at it, fix the included headers.

src/tests/common/fibers.cpp

@@ -6,18 +6,40 @@
 #include <cstdlib>
 #include <functional>
 #include <memory>
+#include <mutex>
+#include <stdexcept>
 #include <thread>
 #include <unordered_map>
 #include <vector>
 
 #include <catch2/catch.hpp>
-#include <math.h>
+
 #include "common/common_types.h"
 #include "common/fiber.h"
-#include "common/spin_lock.h"
 
 namespace Common {
 
+class ThreadIds {
+public:
+    void Register(u32 id) {
+        const auto thread_id = std::this_thread::get_id();
+        std::scoped_lock lock{mutex};
+        if (ids.contains(thread_id)) {
+            throw std::logic_error{"Registering the same thread twice"};
+        }
+        ids.emplace(thread_id, id);
+    }
+
+    [[nodiscard]] u32 Get() const {
+        std::scoped_lock lock{mutex};
+        return ids.at(std::this_thread::get_id());
+    }
+
+private:
+    mutable std::mutex mutex;
+    std::unordered_map<std::thread::id, u32> ids;
+};
+
 class TestControl1 {
 public:
     TestControl1() = default;
@@ -26,7 +48,7 @@ public:
 
     void ExecuteThread(u32 id);
 
-    std::unordered_map<std::thread::id, u32> ids;
+    ThreadIds thread_ids;
     std::vector<std::shared_ptr<Common::Fiber>> thread_fibers;
     std::vector<std::shared_ptr<Common::Fiber>> work_fibers;
     std::vector<u32> items;
@@ -39,8 +61,7 @@ static void WorkControl1(void* control) {
 }
 
 void TestControl1::DoWork() {
-    std::thread::id this_id = std::this_thread::get_id();
+    const u32 id = thread_ids.Get();
-    u32 id = ids[this_id];
     u32 value = items[id];
     for (u32 i = 0; i < id; i++) {
         value++;
@@ -50,8 +71,7 @@ void TestControl1::DoWork() {
 }
 
 void TestControl1::ExecuteThread(u32 id) {
-    std::thread::id this_id = std::this_thread::get_id();
+    thread_ids.Register(id);
-    ids[this_id] = id;
     auto thread_fiber = Fiber::ThreadToFiber();
     thread_fibers[id] = thread_fiber;
     work_fibers[id] = std::make_shared<Fiber>(std::function<void(void*)>{WorkControl1}, this);
@@ -98,8 +118,7 @@ public:
             value1 += i;
         }
         Fiber::YieldTo(fiber1, fiber3);
-        std::thread::id this_id = std::this_thread::get_id();
+        const u32 id = thread_ids.Get();
-        u32 id = ids[this_id];
         assert1 = id == 1;
         value2 += 5000;
         Fiber::YieldTo(fiber1, thread_fibers[id]);
@@ -115,8 +134,7 @@ public:
     }
 
     void DoWork3() {
-        std::thread::id this_id = std::this_thread::get_id();
+        const u32 id = thread_ids.Get();
-        u32 id = ids[this_id];
         assert2 = id == 0;
         value1 += 1000;
         Fiber::YieldTo(fiber3, thread_fibers[id]);
@@ -125,14 +143,12 @@ public:
     void ExecuteThread(u32 id);
 
     void CallFiber1() {
-        std::thread::id this_id = std::this_thread::get_id();
+        const u32 id = thread_ids.Get();
-        u32 id = ids[this_id];
         Fiber::YieldTo(thread_fibers[id], fiber1);
     }
 
     void CallFiber2() {
-        std::thread::id this_id = std::this_thread::get_id();
+        const u32 id = thread_ids.Get();
-        u32 id = ids[this_id];
         Fiber::YieldTo(thread_fibers[id], fiber2);
     }
 
@@ -145,7 +161,7 @@ public:
     u32 value2{};
     std::atomic<bool> trap{true};
     std::atomic<bool> trap2{true};
-    std::unordered_map<std::thread::id, u32> ids;
+    ThreadIds thread_ids;
     std::vector<std::shared_ptr<Common::Fiber>> thread_fibers;
     std::shared_ptr<Common::Fiber> fiber1;
     std::shared_ptr<Common::Fiber> fiber2;
@@ -168,15 +184,13 @@ static void WorkControl2_3(void* control) {
 }
 
 void TestControl2::ExecuteThread(u32 id) {
-    std::thread::id this_id = std::this_thread::get_id();
+    thread_ids.Register(id);
-    ids[this_id] = id;
     auto thread_fiber = Fiber::ThreadToFiber();
     thread_fibers[id] = thread_fiber;
 }
 
 void TestControl2::Exit() {
-    std::thread::id this_id = std::this_thread::get_id();
+    const u32 id = thread_ids.Get();
-    u32 id = ids[this_id];
     thread_fibers[id]->Exit();
 }
 
@@ -228,24 +242,21 @@ public:
     void DoWork1() {
         value1 += 1;
         Fiber::YieldTo(fiber1, fiber2);
-        std::thread::id this_id = std::this_thread::get_id();
+        const u32 id = thread_ids.Get();
-        u32 id = ids[this_id];
         value3 += 1;
         Fiber::YieldTo(fiber1, thread_fibers[id]);
     }
 
     void DoWork2() {
         value2 += 1;
-        std::thread::id this_id = std::this_thread::get_id();
+        const u32 id = thread_ids.Get();
-        u32 id = ids[this_id];
         Fiber::YieldTo(fiber2, thread_fibers[id]);
     }
 
     void ExecuteThread(u32 id);
 
     void CallFiber1() {
-        std::thread::id this_id = std::this_thread::get_id();
+        const u32 id = thread_ids.Get();
-        u32 id = ids[this_id];
         Fiber::YieldTo(thread_fibers[id], fiber1);
     }
 
@@ -254,7 +265,7 @@ public:
     u32 value1{};
     u32 value2{};
     u32 value3{};
-    std::unordered_map<std::thread::id, u32> ids;
+    ThreadIds thread_ids;
     std::vector<std::shared_ptr<Common::Fiber>> thread_fibers;
     std::shared_ptr<Common::Fiber> fiber1;
     std::shared_ptr<Common::Fiber> fiber2;
@@ -271,15 +282,13 @@ static void WorkControl3_2(void* control) {
 }
 
 void TestControl3::ExecuteThread(u32 id) {
-    std::thread::id this_id = std::this_thread::get_id();
+    thread_ids.Register(id);
-    ids[this_id] = id;
     auto thread_fiber = Fiber::ThreadToFiber();
     thread_fibers[id] = thread_fiber;
 }
 
 void TestControl3::Exit() {
-    std::thread::id this_id = std::this_thread::get_id();
+    const u32 id = thread_ids.Get();
-    u32 id = ids[this_id];
     thread_fibers[id]->Exit();
 }