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Drop workaround for glibc<2.25 #211

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Drop workaround for glibc<2.25 #211

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59c5343
Drop workaround for `glibc<2.25`
pentschev Mar 16, 2024
003a7d1
Merge remote-tracking branch 'upstream/branch-0.38' into drop-glibc-w…
pentschev Mar 16, 2024
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61 changes: 14 additions & 47 deletions cpp/src/utils/callback_notifier.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5,68 +5,35 @@
#include <atomic>
#include <features.h>

#ifdef __GLIBC__
#include <gnu/libc-version.h>
#include <string>
#endif

#include <ucxx/log.h>
#include <ucxx/utils/callback_notifier.h>

namespace ucxx {
namespace utils {

#ifdef __GLIBC__
static const bool _useSpinlock = []() {
auto const libcVersion = std::string{gnu_get_libc_version()};
auto const dot = libcVersion.find(".");
if (dot == std::string::npos) {
return false;
} else {
// See https://sourceware.org/bugzilla/show_bug.cgi?id=13165
auto const glibcMajor = std::stoi(libcVersion.substr(0, dot).data());
auto const glibcMinor = std::stoi(libcVersion.substr(dot + 1).data());
auto const use = glibcMajor < 2 || (glibcMajor == 2 && glibcMinor < 25);
ucxx_debug("glibc version %s detected, spinlock use is %d", libcVersion.c_str(), use);
return use;
}
}();
#else
static constexpr bool _useSpinlock = false;
#endif

void CallbackNotifier::set()
{
if (_useSpinlock) {
_flag.store(true, std::memory_order_release);
} else {
{
std::lock_guard lock(_mutex);
// This can be relaxed because the mutex is providing
// ordering.
_flag.store(true, std::memory_order_relaxed);
}
_conditionVariable.notify_one();
{
std::lock_guard lock(_mutex);
// This can be relaxed because the mutex is providing
// ordering.
_flag.store(true, std::memory_order_relaxed);
}
_conditionVariable.notify_one();
}

bool CallbackNotifier::wait(uint64_t period)
{
if (_useSpinlock) {
while (!_flag.load(std::memory_order_acquire)) {}
std::unique_lock lock(_mutex);
// Likewise here, the mutex provides ordering.
if (period > 0) {
return _conditionVariable.wait_for(lock,
std::chrono::duration<uint64_t, std::nano>(period),
[this]() { return _flag.load(std::memory_order_relaxed); });
} else {
std::unique_lock lock(_mutex);
// Likewise here, the mutex provides ordering.
if (period > 0) {
return _conditionVariable.wait_for(
lock, std::chrono::duration<uint64_t, std::nano>(period), [this]() {
return _flag.load(std::memory_order_relaxed);
});
} else {
_conditionVariable.wait(lock, [this]() { return _flag.load(std::memory_order_relaxed); });
}
_conditionVariable.wait(lock, [this]() { return _flag.load(std::memory_order_relaxed); });
return true;
}
return true;
}

} // namespace utils
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