jdk-24/src/hotspot/share/runtime/safepointMechanism.inline.hpp

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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#ifndef SHARE_RUNTIME_SAFEPOINTMECHANISM_INLINE_HPP
#define SHARE_RUNTIME_SAFEPOINTMECHANISM_INLINE_HPP

#include "runtime/atomic.hpp"
#include "runtime/safepointMechanism.hpp"
#include "runtime/safepoint.hpp"
#include "runtime/thread.inline.hpp"

// Caller is responsible for using a memory barrier if needed.
inline void SafepointMechanism::ThreadData::set_polling_page(uintptr_t poll_value) {
  Atomic::store(&_polling_page, poll_value);
}

// The acquire makes sure reading of polling page is done before
// the reading the handshake operation or the global state
inline uintptr_t SafepointMechanism::ThreadData::get_polling_page() {
  return Atomic::load_acquire(&_polling_page);
}

// Caller is responsible for using a memory barrier if needed.
inline void SafepointMechanism::ThreadData::set_polling_word(uintptr_t poll_value) {
  Atomic::store(&_polling_word, poll_value);
}

// The acquire makes sure reading of polling page is done before
// the reading the handshake operation or the global state
inline uintptr_t SafepointMechanism::ThreadData::get_polling_word() {
  return Atomic::load_acquire(&_polling_word);
}

bool SafepointMechanism::local_poll_armed(JavaThread* thread) {
  return thread->poll_data()->get_polling_word() & poll_bit();
}

bool SafepointMechanism::global_poll() {
  return (SafepointSynchronize::_state != SafepointSynchronize::_not_synchronized);
}

bool SafepointMechanism::local_poll(Thread* thread) {
  if (thread->is_Java_thread()) {
    return local_poll_armed(thread->as_Java_thread());
  } else {
    // If the poll is on a non-java thread we can only check the global state.
    return global_poll();
  }
}

bool SafepointMechanism::should_process(Thread* thread) {
  return local_poll(thread);
}

void SafepointMechanism::process_if_requested(JavaThread *thread) {
  if (!local_poll_armed(thread)) {
    return;
  }
  process_if_requested_slow(thread);
}

void SafepointMechanism::arm_local_poll(JavaThread* thread) {
  thread->poll_data()->set_polling_word(_poll_word_armed_value);
  thread->poll_data()->set_polling_page(_poll_page_armed_value);
}

void SafepointMechanism::disarm_local_poll(JavaThread* thread) {
  thread->poll_data()->set_polling_word(_poll_word_disarmed_value);
  thread->poll_data()->set_polling_page(_poll_page_disarmed_value);
}

void SafepointMechanism::arm_local_poll_release(JavaThread* thread) {
  OrderAccess::release();
  thread->poll_data()->set_polling_word(_poll_word_armed_value);
  thread->poll_data()->set_polling_page(_poll_page_armed_value);
}

#endif // SHARE_RUNTIME_SAFEPOINTMECHANISM_INLINE_HPP