Implement set_thread_name and get_thread_name for debugging purposes

appveyor.yml

@@ -36,7 +36,8 @@ build_script:
   - cmd: cmake .. -G "Ninja" -DBUILD_TESTING=on -DBOOST_ROOT="C:/Libraries/boost_1_65_1" -DDOKAN_PATH="C:/Program Files/Dokan/DokanLibrary-1.1.0"
   - cmd: cmake --build . --config %CONFIGURATION%
   - cmd: .\test\gitversion\gitversion-test.exe
-  - cmd: cd .\test\cpp-utils\ && .\cpp-utils-test.exe && cd ..\..
+  # cpp-utils-test disables ThreadDebuggingTest_ThreadName.*_thenIsCorrect because the appveyor image is too old to support the API needed for that
+  - cmd: cd .\test\cpp-utils\ && .\cpp-utils-test.exe --gtest_filter=-ThreadDebuggingTest_ThreadName.*_thenIsCorrect && cd ..\..
   #- cmd: .\test\fspp\fspp-test.exe
   - cmd: .\test\parallelaccessstore\parallelaccessstore-test.exe
   - cmd: .\test\blockstore\blockstore-test.exe

src/cpp-utils/CMakeLists.txt

@@ -24,6 +24,8 @@ set(SOURCES
         io/pipestream.cpp
         thread/LoopThread.cpp
         thread/ThreadSystem.cpp
+        thread/debugging_nonwindows.cpp
+        thread/debugging_windows.cpp
         random/Random.cpp
         random/RandomGeneratorThread.cpp
         random/OSRandomGenerator.cpp

src/cpp-utils/thread/debugging.h

@@ -0,0 +1,16 @@
+#pragma once
+#ifndef MESSMER_CPPUTILS_DEBUGGING_H
+#define MESSMER_CPPUTILS_DEBUGGING_H
+
+#include <string>
+#include <thread>
+
+namespace cpputils {
+
+void set_thread_name(const char* name);
+std::string get_thread_name();
+std::string get_thread_name(std::thread* thread);
+
+}
+
+#endif

src/cpp-utils/thread/debugging_nonwindows.cpp

@@ -0,0 +1,55 @@
+#if !defined(_MSC_VER)
+
+#include "debugging.h"
+#include <stdexcept>
+#include <thread>
+#include <pthread.h>
+#include <cpp-utils/assert/assert.h>
+
+namespace cpputils {
+
+namespace {
+constexpr size_t MAX_NAME_LEN = 16; // this length includes the terminating null character at the end
+}
+
+void set_thread_name(const char* name) {
+  std::string name_(name);
+  if (name_.size() > MAX_NAME_LEN - 1) {
+    name_.resize(MAX_NAME_LEN - 1);
+  }
+#if defined(__APPLE__)
+  int result = pthread_setname_np(name_.c_str());
+#else
+  int result = pthread_setname_np(pthread_self(), name_.c_str());
+#endif
+  if (0 != result) {
+    throw std::runtime_error("Error setting thread name with pthread_setname_np. Code: " + std::to_string(result));
+  }
+}
+
+namespace {
+std::string get_thread_name(pthread_t thread) {
+  char name[MAX_NAME_LEN];
+  int result = pthread_getname_np(thread, name, MAX_NAME_LEN);
+  if (0 != result) {
+    throw std::runtime_error("Error getting thread name with pthread_getname_np. Code: " + std::to_string(result));
+  }
+  // pthread_getname_np returns a null terminated string with maximum 16 bytes.
+  // but just to be safe against a buggy implementation, let's set the last byte to zero.
+  name[MAX_NAME_LEN - 1] = '\0';
+  return name;
+}
+}
+
+std::string get_thread_name() {
+  return get_thread_name(pthread_self());
+}
+
+std::string get_thread_name(std::thread* thread) {
+  ASSERT(thread->joinable(), "Thread not running");
+  return get_thread_name(thread->native_handle());
+}
+
+}
+
+#endif

src/cpp-utils/thread/debugging_windows.cpp

@@ -0,0 +1,111 @@
+#if defined(_MSC_VER)
+
+#include <Windows.h>
+#include "debugging.h"
+#include <codecvt>
+#include <cpp-utils/assert/assert.h>
+
+using std::string;
+using std::wstring;
+using std::wstring_convert;
+
+namespace cpputils {
+
+namespace {
+struct NameData final {
+  wchar_t *name = nullptr;
+
+  ~NameData() {
+    if (nullptr != LocalFree(name)) {
+      throw std::runtime_error("Error releasing thread description memory. Error code: " + std::to_string(GetLastError()));
+    }
+  }
+};
+
+struct ModuleHandle final {
+	HMODULE module;
+
+	ModuleHandle(const char* dll) {
+		bool success = GetModuleHandleExA(0, dll, &module);
+		if (!success) {
+			throw std::runtime_error(string() + "Error loading dll: " + dll + ". Error code: " + std::to_string(GetLastError()));
+		}
+	}
+
+	~ModuleHandle() {
+		bool success = FreeLibrary(module);
+		if (!success) {
+			throw std::runtime_error("Error unloading dll. Error code: " + std::to_string(GetLastError()));
+		}
+	}
+};
+template<class Fn>
+class APIFunction final {
+private:
+	ModuleHandle module_;
+	Fn func_;
+
+public:
+	APIFunction(const char* dll, const char* function)
+	: module_(dll), func_(reinterpret_cast<Fn>(GetProcAddress(module_.module, function))) {
+	}
+
+	bool valid() const {
+		return func_ != nullptr;
+	}
+
+	Fn func() const {
+		return func_;
+	}
+};
+
+std::string get_thread_name(HANDLE thread) {
+  // The GetThreadDescription API was brought in version 1607 of Windows 10.
+  typedef HRESULT(WINAPI* GetThreadDescriptionFn)(HANDLE hThread, PWSTR* ppszThreadDescription);
+  static APIFunction<GetThreadDescriptionFn> get_thread_description_func("Kernel32.dll", "GetThreadDescription");
+
+  if (get_thread_description_func.valid()) {
+	  NameData name_data;
+
+	  HRESULT status = get_thread_description_func.func()(thread, &name_data.name);
+	  if (FAILED(status)) {
+		throw std::runtime_error("Error getting thread description. Error code: " + std::to_string(status));
+	  }
+	  return wstring_convert<std::codecvt_utf8_utf16<wchar_t>>().to_bytes(name_data.name);
+  }
+  else {
+	  // GetThreadDescription API is not available.
+	  return "";
+  }
+}
+}
+
+void set_thread_name(const char* name) {
+  // The GetThreadDescription API was brought in version 1607 of Windows 10.
+  typedef HRESULT(WINAPI* SetThreadDescriptionFn)(HANDLE hThread, PCWSTR lpThreadDescription);
+  static APIFunction<SetThreadDescriptionFn> set_thread_description_func("Kernel32.dll", "SetThreadDescription");
+
+  if (set_thread_description_func.valid()) {
+	  wstring wname = wstring_convert<std::codecvt_utf8_utf16<wchar_t>>().from_bytes(name);
+	  HRESULT status = set_thread_description_func.func()(GetCurrentThread(), wname.c_str());
+	  if (FAILED(status)) {
+		  throw std::runtime_error("Error setting thread description. Error code: " + std::to_string(status));
+	  }
+  }
+  else {
+	  // intentionally empty. SetThreadDescription API is not available.
+  }
+}
+
+std::string get_thread_name() {
+  return get_thread_name(GetCurrentThread());
+}
+
+std::string get_thread_name(std::thread* thread) {
+  ASSERT(thread->joinable(), "Thread not running");
+  return get_thread_name(static_cast<HANDLE>(thread->native_handle()));
+}
+
+}
+
+#endif

test/cpp-utils/CMakeLists.txt

@@ -54,6 +54,7 @@ set(SOURCES
     system/MemoryTest.cpp
     system/HomedirTest.cpp
 	system/EnvTest.cpp
+	thread/debugging_test.cpp
     value_type/ValueTypeTest.cpp
 )
 

test/cpp-utils/thread/debugging_test.cpp

@@ -0,0 +1,62 @@
+#include <cpp-utils/thread/debugging.h>
+#include <cpp-utils/assert/assert.h>
+#include <cpp-utils/lock/ConditionBarrier.h>
+#include <gtest/gtest.h>
+
+using namespace cpputils;
+using std::string;
+
+TEST(ThreadDebuggingTest_ThreadName, givenMainThread_whenSettingAndGetting_thenDoesntCrash) {
+	set_thread_name("my_thread_name");
+	get_thread_name();
+}
+
+TEST(ThreadDebuggingTest_ThreadName, givenChildThread_whenSettingAndGetting_thenDoesntCrash) {
+    ConditionBarrier nameIsChecked;
+
+	bool child_didnt_crash = false;
+	std::thread child([&] {
+		set_thread_name("my_thread_name");
+		get_thread_name();
+		child_didnt_crash = true;
+		nameIsChecked.wait();
+	});
+	get_thread_name(&child);
+	nameIsChecked.release(); // getting the name of a not-running thread would cause errors, so let's make sure we only exit after getting the name
+	child.join();
+	EXPECT_TRUE(child_didnt_crash);
+}
+
+TEST(ThreadDebuggingTest_ThreadName, givenMainThread_whenGettingFromInside_thenIsCorrect) {
+    set_thread_name("my_thread_name");
+    string name = get_thread_name();
+    EXPECT_EQ("my_thread_name", name);
+}
+
+TEST(ThreadDebuggingTest_ThreadName, givenChildThread_whenGettingFromInside_thenIsCorrect) {
+  std::thread child([] {
+    set_thread_name("my_thread_name");
+    string name = get_thread_name();
+    EXPECT_EQ("my_thread_name", name);
+  });
+  child.join();
+}
+
+TEST(ThreadDebuggingTest_ThreadName, givenChildThread_whenGettingFromOutside_thenIsCorrect) {
+  ConditionBarrier nameIsSet;
+  ConditionBarrier nameIsChecked;
+
+  std::thread child([&] {
+    set_thread_name("my_thread_name");
+    nameIsSet.release();
+    nameIsChecked.wait();
+  });
+
+  nameIsSet.wait();
+  string name = get_thread_name(&child);
+  EXPECT_EQ("my_thread_name", name);
+
+  nameIsChecked.release();
+  child.join();
+}
+