1 /*
   2  * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_RUNTIME_SAFEPOINTMECHANISM_INLINE_HPP
  26 #define SHARE_VM_RUNTIME_SAFEPOINTMECHANISM_INLINE_HPP
  27 
  28 #include "runtime/safepointMechanism.hpp"
  29 #include "runtime/safepoint.hpp"
  30 #include "runtime/thread.inline.hpp"
  31 
  32 bool SafepointMechanism::local_poll_armed(JavaThread* thread) {
  33   const intptr_t poll_word = reinterpret_cast<intptr_t>(thread->get_polling_page());
  34   return mask_bits_are_true(poll_word, poll_bit());
  35 }
  36 
  37 bool SafepointMechanism::global_poll() {
  38   return SafepointSynchronize::do_call_back();
  39 }
  40 
  41 bool SafepointMechanism::local_poll(Thread* thread) {
  42   // Mutexes can be taken but none JavaThread. These cannot have handshakes
  43   // operation but they must stop for safepoints.
  44   if (thread->is_Java_thread()) {
  45     return local_poll_armed((JavaThread*)thread);
  46   } else {
  47     return global_poll();
  48   }
  49 }
  50 
  51 bool SafepointMechanism::poll(Thread* thread) {
  52   if (uses_thread_local_poll()) {
  53     return local_poll(thread);
  54   } else {
  55     return global_poll();
  56   }
  57 }
  58 
  59 void SafepointMechanism::block_if_requested_local_poll(JavaThread *thread) {
  60   bool armed = local_poll_armed(thread); // load acquire, polling page -> op / global state
  61   if(armed) {
  62     // We could be armed for either a handshake operation or a safepoint
  63     if (thread->has_handshake()) {
  64       thread->handshake_process_by_self();
  65     } else {
  66       if (global_poll()) {
  67         SafepointSynchronize::block(thread);
  68       }
  69     }
  70   }
  71 }
  72 
  73 void SafepointMechanism::block_if_requested(JavaThread *thread) {
  74   if (uses_thread_local_poll()) {
  75     block_if_requested_local_poll(thread);
  76   } else {
  77     // If we don't have per thread poll this could a handshake or a safepoint
  78     if (global_poll()) {
  79       SafepointSynchronize::block(thread);
  80     }
  81   }
  82 }
  83 
  84 void SafepointMechanism::arm_local_poll(JavaThread* thread) {
  85   thread->set_polling_page(poll_armed_value());
  86 }
  87 
  88 void SafepointMechanism::disarm_local_poll(JavaThread* thread) {
  89   thread->set_polling_page(poll_disarmed_value());
  90 }
  91 
  92 #endif // SHARE_VM_RUNTIME_SAFEPOINTMECHANISM_INLINE_HPP