| /* |
| * Copyright (c) 2013, 2018, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * 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). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #include "precompiled.hpp" |
| #include "jfr/recorder/service/jfrPostBox.hpp" |
| #include "jfr/utilities/jfrTryLock.hpp" |
| #include "runtime/atomic.hpp" |
| #include "runtime/orderAccess.inline.hpp" |
| #include "runtime/thread.inline.hpp" |
| |
| #define MSG_IS_SYNCHRONOUS ( (MSGBIT(MSG_ROTATE)) | \ |
| (MSGBIT(MSG_STOP)) | \ |
| (MSGBIT(MSG_START)) | \ |
| (MSGBIT(MSG_CLONE_IN_MEMORY)) | \ |
| (MSGBIT(MSG_VM_ERROR)) \ |
| ) |
| |
| static JfrPostBox* _instance = NULL; |
| |
| JfrPostBox& JfrPostBox::instance() { |
| return *_instance; |
| } |
| |
| JfrPostBox* JfrPostBox::create() { |
| assert(_instance == NULL, "invariant"); |
| _instance = new JfrPostBox(); |
| return _instance; |
| } |
| |
| void JfrPostBox::destroy() { |
| assert(_instance != NULL, "invariant"); |
| delete _instance; |
| _instance = NULL; |
| } |
| |
| JfrPostBox::JfrPostBox() : |
| _msg_read_serial(0), |
| _msg_handled_serial(0), |
| _messages(0), |
| _has_waiters(false) {} |
| |
| static bool is_thread_lock_aversive() { |
| Thread* const thread = Thread::current(); |
| return (thread->is_Java_thread() && ((JavaThread*)thread)->thread_state() != _thread_in_vm) || thread->is_VM_thread(); |
| } |
| |
| static bool is_synchronous(int messages) { |
| return ((messages & MSG_IS_SYNCHRONOUS) != 0); |
| } |
| |
| void JfrPostBox::post(JFR_Msg msg) { |
| const int the_message = MSGBIT(msg); |
| if (is_thread_lock_aversive()) { |
| deposit(the_message); |
| return; |
| } |
| if (!is_synchronous(the_message)) { |
| asynchronous_post(the_message); |
| return; |
| } |
| synchronous_post(the_message); |
| } |
| |
| void JfrPostBox::deposit(int new_messages) { |
| while (true) { |
| const int current_msgs = OrderAccess::load_acquire(&_messages); |
| // OR the new message |
| const int exchange_value = current_msgs | new_messages; |
| const int result = Atomic::cmpxchg(exchange_value, &_messages, current_msgs); |
| if (result == current_msgs) { |
| return; |
| } |
| /* Some other thread just set exactly what this thread wanted */ |
| if ((result & new_messages) == new_messages) { |
| return; |
| } |
| } |
| } |
| |
| void JfrPostBox::asynchronous_post(int msg) { |
| assert(!is_synchronous(msg), "invariant"); |
| deposit(msg); |
| JfrMonitorTryLock try_msg_lock(JfrMsg_lock); |
| if (try_msg_lock.acquired()) { |
| JfrMsg_lock->notify_all(); |
| } |
| } |
| |
| void JfrPostBox::synchronous_post(int msg) { |
| assert(is_synchronous(msg), "invariant"); |
| assert(!JfrMsg_lock->owned_by_self(), "should not hold JfrMsg_lock here!"); |
| MutexLockerEx msg_lock(JfrMsg_lock); |
| deposit(msg); |
| // serial_id is used to check when what we send in has been processed. |
| // _msg_read_serial is read under JfrMsg_lock protection. |
| const uintptr_t serial_id = OrderAccess::load_acquire(&_msg_read_serial) + 1; |
| JfrMsg_lock->notify_all(); |
| while (!is_message_processed(serial_id)) { |
| JfrMsg_lock->wait(); |
| } |
| } |
| |
| /* |
| * Check if a synchronous message has been processed. |
| * We avoid racing on _msg_handled_serial by ensuring |
| * that we are holding the JfrMsg_lock when checking |
| * completion status. |
| */ |
| bool JfrPostBox::is_message_processed(uintptr_t serial_id) const { |
| assert(JfrMsg_lock->owned_by_self(), "_msg_handled_serial must be read under JfrMsg_lock protection"); |
| return serial_id <= OrderAccess::load_acquire(&_msg_handled_serial); |
| } |
| |
| bool JfrPostBox::is_empty() const { |
| assert(JfrMsg_lock->owned_by_self(), "not holding JfrMsg_lock!"); |
| return OrderAccess::load_acquire(&_messages) == 0; |
| } |
| |
| int JfrPostBox::collect() { |
| // get pending and reset to 0 |
| const int messages = Atomic::xchg(0, &_messages); |
| if (check_waiters(messages)) { |
| _has_waiters = true; |
| assert(JfrMsg_lock->owned_by_self(), "incrementing _msg_read_serial is protected by JfrMsg_lock"); |
| // Update made visible on release of JfrMsg_lock via fence instruction in Monitor::IUnlock. |
| ++_msg_read_serial; |
| } |
| return messages; |
| } |
| |
| bool JfrPostBox::check_waiters(int messages) const { |
| assert(JfrMsg_lock->owned_by_self(), "not holding JfrMsg_lock!"); |
| assert(!_has_waiters, "invariant"); |
| return is_synchronous(messages); |
| } |
| |
| void JfrPostBox::notify_waiters() { |
| if (!_has_waiters) { |
| return; |
| } |
| _has_waiters = false; |
| assert(JfrMsg_lock->owned_by_self(), "incrementing _msg_handled_serial is protected by JfrMsg_lock."); |
| // Update made visible on release of JfrMsg_lock via fence instruction in Monitor::IUnlock. |
| ++_msg_handled_serial; |
| JfrMsg_lock->notify(); |
| } |
| |
| // safeguard to ensure no threads are left waiting |
| void JfrPostBox::notify_collection_stop() { |
| MutexLockerEx msg_lock(JfrMsg_lock); |
| JfrMsg_lock->notify_all(); |
| } |