From a38633c4534ccd58e285629562f8eadd4662aab8 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Mon, 16 Mar 2026 23:03:02 +0100
Subject: [PATCH] Add basic `WebThread` impl

---
 Source/Engine/Platform/Web/WebPlatform.cpp | 23 ++++++++++
 Source/Engine/Platform/Web/WebThread.h     | 53 ++++++++++++++++++----
 2 files changed, 67 insertions(+), 9 deletions(-)

diff --git a/Source/Engine/Platform/Web/WebPlatform.cpp b/Source/Engine/Platform/Web/WebPlatform.cpp
index cd814af9c..d76ec7dd9 100644
--- a/Source/Engine/Platform/Web/WebPlatform.cpp
+++ b/Source/Engine/Platform/Web/WebPlatform.cpp
@@ -3,6 +3,7 @@
 #if PLATFORM_WEB
 
 #include "WebPlatform.h"
+#include "WebThread.h"
 #include "WebFileSystem.h"
 #include "Engine/Core/Log.h"
 #include "Engine/Core/Types/String.h"
@@ -50,6 +51,28 @@ DialogResult MessageBox::Show(Window* parent, const StringView& text, const Stri
     return DialogResult::None;
 }
 
+WebThread* WebThread::Create(IRunnable* runnable, const String& name, ThreadPriority priority, uint32 stackSize)
+{
+#ifdef __EMSCRIPTEN_PTHREADS__
+    pthread_attr_t attr;
+    pthread_attr_init(&attr);
+    if (stackSize != 0)
+        pthread_attr_setstacksize(&attr, stackSize);
+    auto thread = New<WebThread>(runnable, name, priority);
+    const int result = pthread_create(&thread->_thread, &attr, ThreadProc, thread);
+    if (result != 0)
+    {
+        LOG(Warning, "Failed to spawn a thread. Result code: {0}", result);
+        Delete(thread);
+        return nullptr;
+    }
+    return thread;
+#else
+    LOG(Fatal, "Threading is not supported.");
+    return nullptr;
+#endif
+}
+
 void WebFileSystem::GetSpecialFolderPath(const SpecialFolder type, String& result)
 {
     result = TEXT("/");
diff --git a/Source/Engine/Platform/Web/WebThread.h b/Source/Engine/Platform/Web/WebThread.h
index a5086787b..926567182 100644
--- a/Source/Engine/Platform/Web/WebThread.h
+++ b/Source/Engine/Platform/Web/WebThread.h
@@ -5,6 +5,10 @@
 #if PLATFORM_WEB
 
 #include "../Base/ThreadBase.h"
+#ifdef __EMSCRIPTEN_PTHREADS__
+#include <pthread.h>
+#include <signal.h>
+#endif
 
 /// <summary>
 /// Thread object for Web platform.
@@ -20,6 +24,9 @@ public:
     /// <param name="priority">The thread priority.</param>
     WebThread(IRunnable* runnable, const String& name, ThreadPriority priority)
         : ThreadBase(runnable, name, priority)
+#ifdef __EMSCRIPTEN_PTHREADS__
+        , _thread(0)
+#endif
     {
     }
     
@@ -32,32 +39,60 @@ public:
     /// <param name="priority">Tells the thread whether it needs to adjust its priority or not. Defaults to normal priority</param>
     /// <param name="stackSize">The size of the stack to create. 0 means use the current thread's stack size</param>
     /// <returns>Pointer to the new thread or null if cannot create it</returns>
-    static WebThread* Create(IRunnable* runnable, const String& name, ThreadPriority priority = ThreadPriority::Normal, uint32 stackSize = 0)
-    {
-        return New<WebThread>(runnable, name, priority);
-    }
+    static WebThread* Create(IRunnable* runnable, const String& name, ThreadPriority priority = ThreadPriority::Normal, uint32 stackSize = 0);
 
-public:
+#ifdef __EMSCRIPTEN_PTHREADS__
     // [ThreadBase]
     void Join() override
     {
-        // TOOD: impl this
+        pthread_join(_thread, nullptr);
+        ClearHandleInternal();
     }
 
 protected:
     // [ThreadBase]
     void ClearHandleInternal() override
     {
-        // TOOD: impl this
+        _thread = 0;
     }
     void SetPriorityInternal(ThreadPriority priority) override
     {
-        // TOOD: impl this
+        // Not supported
     }
     void KillInternal(bool waitForJoin) override
     {
-        // TOOD: impl this
+        if (waitForJoin)
+            pthread_join(_thread, nullptr);
+        pthread_kill(_thread, SIGKILL);
     }
+
+private:
+    pthread_t _thread;
+
+    static void* ThreadProc(void* pThis)
+    {
+        auto thread = (WebThread*)pThis;
+        const int32 exitCode = thread->Run();
+        return (void*)(uintptr)exitCode;
+    }
+#else
+    // [ThreadBase]
+    void Join() override
+    {
+    }
+
+protected:
+    // [ThreadBase]
+    void ClearHandleInternal() override
+    {
+    }
+    void SetPriorityInternal(ThreadPriority priority) override
+    {
+    }
+    void KillInternal(bool waitForJoin) override
+    {
+    }
+#endif
 };
 
 #endif