From 99225ef050f4b3795524f641c2f98ade833a3686 Mon Sep 17 00:00:00 2001
From: David Capello <david@igara.com>
Date: Tue, 29 Aug 2023 11:58:27 -0300
Subject: [PATCH] Add functions to set/get the active thread name

---
 base/thread.cpp       | 75 +++++++++++++++++++++++++++++++++++++++++++
 base/thread.h         |  8 +++++
 base/thread_tests.cpp | 50 +++++++++++++++++++++++++++++
 3 files changed, 133 insertions(+)
 create mode 100644 base/thread_tests.cpp

diff --git a/base/thread.cpp b/base/thread.cpp
index 1779ab1ea..093f7966f 100644
--- a/base/thread.cpp
+++ b/base/thread.cpp
@@ -12,13 +12,46 @@
 #include "base/thread.h"
 
 #if LAF_WINDOWS
+  #include "base/dll.h"
+  #include "base/string.h"
+
   #include <windows.h>
   #include <process.h>
+  #include <mutex>
 #else
   #include <pthread.h>     // Use pthread library in Unix-like systems
 
   #include <unistd.h>
   #include <sys/time.h>
+  #include <algorithm>
+#endif
+
+#if LAF_WINDOWS
+namespace {
+
+class KernelBaseApi {
+public:
+  using SetThreadDescription_Func = HRESULT(WINAPI*)(HANDLE, PCWSTR);
+  using GetThreadDescription_Func = HRESULT(WINAPI*)(HANDLE, PWSTR*);
+
+  SetThreadDescription_Func SetThreadDescription = nullptr;
+  GetThreadDescription_Func GetThreadDescription = nullptr;
+
+  KernelBaseApi() {
+    m_dll = base::load_dll("KernelBase.dll");
+    if (m_dll) {
+      SetThreadDescription = base::get_dll_proc<SetThreadDescription_Func>(m_dll, "SetThreadDescription");
+      GetThreadDescription = base::get_dll_proc<GetThreadDescription_Func>(m_dll, "GetThreadDescription");
+    }
+  }
+
+private:
+  base::dll m_dll;
+};
+
+KernelBaseApi kernelBaseApi;
+
+} // anonymous namespace
 #endif
 
 namespace base {
@@ -56,4 +89,46 @@ void this_thread::sleep_for(double seconds)
 #endif
 }
 
+void this_thread::set_name(const std::string& name)
+{
+#if LAF_WINDOWS
+  if (kernelBaseApi.SetThreadDescription)
+    kernelBaseApi.SetThreadDescription(GetCurrentThread(),
+                                       base::from_utf8(name).c_str());
+#elif LAF_MACOS
+  // macOS has a non-standard pthread_setname_np() impl
+  pthread_setname_np(name.c_str());
+#else
+  int res = pthread_setname_np(pthread_self(), name.c_str());
+  if (res != 0 && name.size() > 15) {
+    // Try with a shorter string (no more than 16 chars including the
+    // null char, as the spec says).
+    pthread_setname_np(pthread_self(), name.substr(0, 15).c_str());
+  }
+#endif
+}
+
+std::string this_thread::get_name()
+{
+#if LAF_WINDOWS
+  if (kernelBaseApi.GetThreadDescription) {
+    PWSTR desc = nullptr;
+    HRESULT hr = kernelBaseApi.GetThreadDescription(GetCurrentThread(), &desc);
+    if (SUCCEEDED(hr) && desc) {
+      std::string result(base::to_utf8(desc));
+      LocalFree(desc);
+      return result;
+    }
+  }
+#else
+  char name[65];
+  int result = pthread_getname_np(pthread_self(), name, sizeof(name)-1);
+  if (result == 0) { // Returns 0 if it was successful
+    // pthread_getname_np() returns a null terminated name.
+    return std::string(name);
+  }
+#endif
+  return std::string();
+}
+
 } // namespace base
diff --git a/base/thread.h b/base/thread.h
index 91bfc5980..613999575 100644
--- a/base/thread.h
+++ b/base/thread.h
@@ -9,6 +9,8 @@
 #define BASE_THREAD_H_INCLUDED
 #pragma once
 
+#include <string>
+
 namespace base {
 namespace this_thread {
 
@@ -17,6 +19,12 @@ void yield();
 // TODO replace with std::this_thread::sleep_for(std::chrono::seconds(...)) or similar
 void sleep_for(double seconds);
 
+// Associates a name/description to the current thread. Useful for
+// debugging purposes. E.g. When we receive a crash dump from Sentry
+// we can identify a thread by its name.
+void set_name(const std::string& name);
+std::string get_name();
+
 } // this_thread
 } // base
 
diff --git a/base/thread_tests.cpp b/base/thread_tests.cpp
new file mode 100644
index 000000000..60f30e91a
--- /dev/null
+++ b/base/thread_tests.cpp
@@ -0,0 +1,50 @@
+// LAF Base Library
+// Copyright (c) 2023 Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#include <gtest/gtest.h>
+
+#include "base/thread.h"
+
+using namespace base;
+
+TEST(Thread, SetGetName)
+{
+  // Empty string by default
+  EXPECT_EQ("", this_thread::get_name());
+
+  this_thread::set_name("main");
+  EXPECT_EQ("main", this_thread::get_name());
+
+  this_thread::set_name("testing");
+  EXPECT_EQ("testing", this_thread::get_name());
+}
+
+TEST(Thread, NameLimits)
+{
+  const char* fullName = "123456789012345678901234567890"
+                         "123456789012345678901234567890"
+                         "123456789012345678901234567890";
+
+  this_thread::set_name(fullName);
+
+#if LAF_WINDOWS
+  EXPECT_EQ(fullName, this_thread::get_name());
+#elif LAF_APPLE
+  // Limited to 64 chars
+  EXPECT_EQ("123456789012345678901234567890"
+            "123456789012345678901234567890"
+            "1234", this_thread::get_name());
+#else
+  // Limited to 16 chars (including the null char)
+  EXPECT_EQ("123456789012345", this_thread::get_name());
+#endif
+}
+
+int main(int argc, char** argv)
+{
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}