Merge bitcoin/bitcoin#30137: build: Remove --enable-threadlocal

17fe948 build: remove --enable-threadlocal (fanquake)
1e7c20b doc: remove comment about using thread_local (fanquake)
5bba433 build: Enable `thread_local` for MinGW-w64 builds (Hennadii Stepanov)

Pull request description:

  Includes a commit from #30099.
  Closes #29952.

ACKs for top commit:
  laanwj:
    Code review ACK 17fe948
  maflcko:
    utACK 17fe948
  hebasto:
    ACK 17fe948.
  theuni:
    utACK 17fe948

Tree-SHA512: 2aad6d19e79c4d6d7aefd0f41b215ac8d9320f5908808221d78e6ee1c77503832a02759bee2ad397e235b6739e22aca8dcf5c5ef8854deb8c697b18ac56a06da

Author: fanquake

configure.ac

@@ -244,12 +244,6 @@ AC_ARG_ENABLE([lcov-branch-coverage],
   [use_lcov_branch=yes],
   [use_lcov_branch=no])
 
-AC_ARG_ENABLE([threadlocal],
-  [AS_HELP_STRING([--enable-threadlocal],
-  [enable features that depend on the c++ thread_local keyword (currently just thread names in debug logs). (default is to enable if there is platform support)])],
-  [use_thread_local=$enableval],
-  [use_thread_local=auto])
-
 AC_ARG_ENABLE([zmq],
   [AS_HELP_STRING([--disable-zmq],
   [disable ZMQ notifications])],
@@ -1028,40 +1022,6 @@ AC_COMPILE_IFELSE([AC_LANG_SOURCE([
   [AC_MSG_RESULT([no])]
 )
 
-if test "$use_thread_local" = "yes" || test "$use_thread_local" = "auto"; then
-  TEMP_LDFLAGS="$LDFLAGS"
-  LDFLAGS="$TEMP_LDFLAGS $PTHREAD_CFLAGS"
-  AC_MSG_CHECKING([for thread_local support])
-  AC_LINK_IFELSE([AC_LANG_SOURCE([
-    #include <thread>
-    static thread_local int foo = 0;
-    static void run_thread() { foo++;}
-    int main(){
-    for(int i = 0; i < 10; i++) { std::thread(run_thread).detach();}
-    return foo;
-    }
-    ])],
-    [
-     case $host in
-       *mingw*)
-          dnl mingw32's implementation of thread_local has also been shown to behave
-          dnl erroneously under concurrent usage; see:
-          dnl https://gist.github.com/jamesob/fe9a872051a88b2025b1aa37bfa98605
-          AC_MSG_RESULT([no])
-          ;;
-        *)
-          AC_DEFINE([HAVE_THREAD_LOCAL], [1], [Define if thread_local is supported.])
-          AC_MSG_RESULT([yes])
-          ;;
-      esac
-    ],
-    [
-      AC_MSG_RESULT([no])
-    ]
-  )
-  LDFLAGS="$TEMP_LDFLAGS"
-fi
-
 dnl Check for different ways of gathering OS randomness
 AC_MSG_CHECKING([for Linux getrandom function])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[

src/init/common.cpp

@@ -31,11 +31,7 @@ void AddLoggingArgs(ArgsManager& argsman)
     argsman.AddArg("-logips", strprintf("Include IP addresses in debug output (default: %u)", DEFAULT_LOGIPS), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-loglevel=<level>|<category>:<level>", strprintf("Set the global or per-category severity level for logging categories enabled with the -debug configuration option or the logging RPC. Possible values are %s (default=%s). The following levels are always logged: error, warning, info. If <category>:<level> is supplied, the setting will override the global one and may be specified multiple times to set multiple category-specific levels. <category> can be: %s.", LogInstance().LogLevelsString(), LogInstance().LogLevelToStr(BCLog::DEFAULT_LOG_LEVEL), LogInstance().LogCategoriesString()), ArgsManager::DISALLOW_NEGATION | ArgsManager::DISALLOW_ELISION | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-logtimestamps", strprintf("Prepend debug output with timestamp (default: %u)", DEFAULT_LOGTIMESTAMPS), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
-#ifdef HAVE_THREAD_LOCAL
-    argsman.AddArg("-logthreadnames", strprintf("Prepend debug output with name of the originating thread (only available on platforms supporting thread_local) (default: %u)", DEFAULT_LOGTHREADNAMES), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
-#else
-    argsman.AddHiddenArgs({"-logthreadnames"});
-#endif
+    argsman.AddArg("-logthreadnames", strprintf("Prepend debug output with name of the originating thread (default: %u)", DEFAULT_LOGTHREADNAMES), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-logsourcelocations", strprintf("Prepend debug output with name of the originating source location (source file, line number and function name) (default: %u)", DEFAULT_LOGSOURCELOCATIONS), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-logtimemicros", strprintf("Add microsecond precision to debug timestamps (default: %u)", DEFAULT_LOGTIMEMICROS), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-loglevelalways", strprintf("Always prepend a category and level (default: %u)", DEFAULT_LOGLEVELALWAYS), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
@@ -50,9 +46,7 @@ void SetLoggingOptions(const ArgsManager& args)
     LogInstance().m_print_to_console = args.GetBoolArg("-printtoconsole", !args.GetBoolArg("-daemon", false));
     LogInstance().m_log_timestamps = args.GetBoolArg("-logtimestamps", DEFAULT_LOGTIMESTAMPS);
     LogInstance().m_log_time_micros = args.GetBoolArg("-logtimemicros", DEFAULT_LOGTIMEMICROS);
-#ifdef HAVE_THREAD_LOCAL
     LogInstance().m_log_threadnames = args.GetBoolArg("-logthreadnames", DEFAULT_LOGTHREADNAMES);
-#endif
     LogInstance().m_log_sourcelocations = args.GetBoolArg("-logsourcelocations", DEFAULT_LOGSOURCELOCATIONS);
     LogInstance().m_always_print_category_level = args.GetBoolArg("-loglevelalways", DEFAULT_LOGLEVELALWAYS);
 

src/test/util/random.h

@@ -14,9 +14,8 @@
 /**
  * This global and the helpers that use it are not thread-safe.
  *
- * If thread-safety is needed, the global could be made thread_local (given
- * that thread_local is supported on all architectures we support) or a
- * per-thread instance could be used in the multi-threaded test.
+ * If thread-safety is needed, a per-thread instance could be
+ * used in the multi-threaded test.
  */
 extern FastRandomContext g_insecure_rand_ctx;
 

src/test/util_threadnames_tests.cpp

@@ -11,8 +11,6 @@
 #include <thread>
 #include <vector>
 
-#include <config/bitcoin-config.h> // IWYU pragma: keep
-
 #include <boost/test/unit_test.hpp>
 
 BOOST_AUTO_TEST_SUITE(util_threadnames_tests)
@@ -52,11 +50,6 @@ std::set<std::string> RenameEnMasse(int num_threads)
  */
 BOOST_AUTO_TEST_CASE(util_threadnames_test_rename_threaded)
 {
-#if !defined(HAVE_THREAD_LOCAL)
-    // This test doesn't apply to platforms where we don't have thread_local.
-    return;
-#endif
-
     std::set<std::string> names = RenameEnMasse(100);
 
     BOOST_CHECK_EQUAL(names.size(), 100U);

src/util/threadnames.cpp

@@ -37,10 +37,6 @@ static void SetThreadName(const char* name)
 #endif
 }
 
-// If we have thread_local, just keep thread ID and name in a thread_local
-// global.
-#if defined(HAVE_THREAD_LOCAL)
-
 /**
  * The name of the thread. We use char array instead of std::string to avoid
  * complications with running a destructor when the thread exits. Avoid adding
@@ -58,13 +54,6 @@ static void SetInternalName(const std::string& name)
     g_thread_name[copy_bytes] = '\0';
 }
 
-// Without thread_local available, don't handle internal name at all.
-#else
-
-std::string util::ThreadGetInternalName() { return ""; }
-static void SetInternalName(const std::string& name) { }
-#endif
-
 void util::ThreadRename(const std::string& name)
 {
     SetThreadName(("b-" + name).c_str());