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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 * under the terms of the GNU General Public License version 2 only, as
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 *
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#ifndef SHARE_VM_RUNTIME_SAFEPOINTMECHANISM_INLINE_HPP
#define SHARE_VM_RUNTIME_SAFEPOINTMECHANISM_INLINE_HPP

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

bool SafepointMechanism::local_poll_armed(JavaThread* thread) {
  const intptr_t poll_word = reinterpret_cast<intptr_t>(thread->get_polling_page());
  return mask_bits_are_true(poll_word, poll_bit());
}

bool SafepointMechanism::global_poll() {
  return SafepointSynchronize::do_call_back();
}

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

bool SafepointMechanism::should_block(Thread* thread) {
  if (uses_thread_local_poll()) {
    return local_poll(thread);
  } else {
    return global_poll();
  }
}

void SafepointMechanism::block_if_requested_local_poll(JavaThread *thread) {
  bool armed = local_poll_armed(thread); // load acquire, polling page -> op / global state
  if(armed) {
    // We could be armed for either a handshake operation or a safepoint
    if (global_poll()) {
      SafepointSynchronize::block(thread);
    }
    if (thread->has_handshake()) {
      thread->handshake_process_by_self();
    }
  }
}

void SafepointMechanism::block_if_requested(JavaThread *thread) {
  if (uses_thread_local_poll()) {
    block_if_requested_local_poll(thread);
  } else {
    // If we don't have per thread poll this could a handshake or a safepoint
    if (global_poll()) {
      SafepointSynchronize::block(thread);
    }
  }
}

void SafepointMechanism::arm_local_poll(JavaThread* thread) {
  thread->set_polling_page(poll_armed_value());
}

void SafepointMechanism::disarm_local_poll(JavaThread* thread) {
  thread->set_polling_page(poll_disarmed_value());
}

void SafepointMechanism::arm_local_poll_release(JavaThread* thread) {
  thread->set_polling_page_release(poll_armed_value());
}

void SafepointMechanism::disarm_local_poll_release(JavaThread* thread) {
  thread->set_polling_page_release(poll_disarmed_value());
}

#endif // SHARE_VM_RUNTIME_SAFEPOINTMECHANISM_INLINE_HPP