From f53b8200613ca440b6aec6ef5951d975db46160d Mon Sep 17 00:00:00 2001
From: David CARLIER <devnexen@gmail.com>
Date: Sat, 15 Jul 2023 07:34:49 +0100
Subject: [PATCH] thead pool debugging support proposal using native
 capabilities if possible.

---
 src/lib/utils/os_utils.cpp                 | 43 ++++++++++++++++++++--
 src/lib/utils/os_utils.h                   |  8 ++++
 src/lib/utils/thread_utils/thread_pool.cpp |  7 +++-
 3 files changed, 53 insertions(+), 5 deletions(-)

diff --git a/src/lib/utils/os_utils.cpp b/src/lib/utils/os_utils.cpp
index bab3c776dbf..f96683bc25b 100644
--- a/src/lib/utils/os_utils.cpp
+++ b/src/lib/utils/os_utils.cpp
@@ -16,16 +16,13 @@
 #include <chrono>
 #include <cstdlib>
 
-#if defined(BOTAN_TARGET_OS_HAS_THREADS)
-   #include <thread>
-#endif
-
 #if defined(BOTAN_TARGET_OS_HAS_EXPLICIT_BZERO)
    #include <string.h>
 #endif
 
 #if defined(BOTAN_TARGET_OS_HAS_POSIX1)
    #include <errno.h>
+   #include <pthread.h>
    #include <setjmp.h>
    #include <signal.h>
    #include <stdlib.h>
@@ -72,6 +69,15 @@ extern "C" char** environ;
    #include <sys/prctl.h>
 #endif
 
+#if defined(BOTAN_TARGET_IS_FREEBSD) || defined(BOTAN_TARGET_IS_OPENBSD)
+   #include <pthread_np.h>
+#endif
+
+#if defined(BOTAN_TARGET_OS_HAS_WIN32) && defined(BOTAN_BUILD_COMPILER_IS_MSVC)
+   #include <processthreadsapi.h>
+   #include <stringapiset.h>
+#endif
+
 namespace Botan {
 
 // Not defined in OS namespace for historical reasons
@@ -614,6 +620,35 @@ void OS::page_named(void* page, size_t size) {
 #endif
 }
 
+#if defined(BOTAN_TARGET_OS_HAS_THREADS)
+void OS::set_thread_name(std::thread& thread, const char* const name) {
+   int r;
+   auto hdl = thread.native_handle();
+   #if defined(BOTAN_TARGET_OS_IS_LINUX)
+   r = pthread_setname_np(hdl, name);
+   #elif defined(BOTAN_TARGET_OS_IS_FREEBSD)
+   r = pthread_set_name_np(hdl, name);
+   #elif defined(BOTAN_TARGET_OS_IS_OPENBSD)
+   r = pthread_set_name_np(hdl, const_cast<char*>(name));
+   #elif defined(BOTAN_TARGET_OS_IS_NETBSD)
+   r = pthread_set_name_np(hdl, "%s", const_cast<char*>(name));
+   #elif defined(BOTAN_TARGET_OS_HAS_WIN32) && defined(BOTAN_BUILD_COMPILER_IS_MSVC)
+   // This approach (as opposed to trigger an exception) is simpler
+   // also gives a chance to be in coredumps.
+   wchar_t val[16];
+   if(MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, name, -1, val, 16) > 0) {
+      r = SetThreadDescription(hdl, val);
+   }
+   #else
+   // TODO other possible oses ?
+   // macOs does not seem to allow to name threads other than the current one.
+   BOTAN_UNUSED(hdl);
+   BOTAN_UNUSED(name);
+   #endif
+   BOTAN_UNUSED(r);
+}
+#endif
+
 #if defined(BOTAN_TARGET_OS_HAS_POSIX1) && !defined(BOTAN_TARGET_OS_IS_EMSCRIPTEN)
 
 namespace {
diff --git a/src/lib/utils/os_utils.h b/src/lib/utils/os_utils.h
index 85bf8407c29..754456b5d37 100644
--- a/src/lib/utils/os_utils.h
+++ b/src/lib/utils/os_utils.h
@@ -13,6 +13,10 @@
 #include <string>
 #include <vector>
 
+#if defined(BOTAN_TARGET_OS_HAS_THREADS)
+   #include <thread>
+#endif
+
 namespace Botan::OS {
 
 /*
@@ -148,6 +152,10 @@ void page_allow_access(void* page);
 */
 void page_named(void* page, size_t size);
 
+#if defined(BOTAN_TARGET_OS_HAS_THREADS)
+void set_thread_name(std::thread& thread, const char* const name);
+#endif
+
 /**
 * Run a probe instruction to test for support for a CPU instruction.
 * Runs in system-specific env that catches illegal instructions; this
diff --git a/src/lib/utils/thread_utils/thread_pool.cpp b/src/lib/utils/thread_utils/thread_pool.cpp
index d12eb874541..3243f3445e0 100644
--- a/src/lib/utils/thread_utils/thread_pool.cpp
+++ b/src/lib/utils/thread_utils/thread_pool.cpp
@@ -41,6 +41,8 @@ Thread_Pool& Thread_Pool::global_instance() {
 
 Thread_Pool::Thread_Pool(std::optional<size_t> opt_pool_size) {
    m_shutdown = false;
+   // On Linux, it is 16 length max, including terminator
+   static constexpr char tname[] = "Botan thread";
 
    if(!opt_pool_size.has_value()) {
       return;
@@ -65,8 +67,11 @@ Thread_Pool::Thread_Pool(std::optional<size_t> opt_pool_size) {
       }
    }
 
+   m_workers.resize(pool_size);
+
    for(size_t i = 0; i != pool_size; ++i) {
-      m_workers.push_back(std::thread(&Thread_Pool::worker_thread, this));
+      m_workers[i] = std::thread(&Thread_Pool::worker_thread, this);
+      OS::set_thread_name(m_workers[i], tname);
    }
 }