1 /* 2 * Copyright (c) 2022, 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 #include "precompiled.hpp" 26 #include "runtime/atomic.hpp" 27 #include "runtime/threadIdentifier.hpp" 28 29 // starting at 3, excluding reserved values defined in ObjectMonitor.hpp 30 static const int64_t INITIAL_TID = 3; 31 static volatile int64_t next_thread_id = INITIAL_TID; 32 33 #ifdef ASSERT 34 int64_t ThreadIdentifier::initial() { 35 return INITIAL_TID; 36 } 37 #endif 38 39 int64_t ThreadIdentifier::unsafe_offset() { 40 return reinterpret_cast<int64_t>(&next_thread_id); 41 } 42 43 int64_t ThreadIdentifier::current() { 44 return Atomic::load(&next_thread_id); 45 } 46 47 int64_t ThreadIdentifier::next() { 48 int64_t next_tid; 49 do { 50 next_tid = Atomic::load(&next_thread_id); 51 } while (Atomic::cmpxchg(&next_thread_id, next_tid, next_tid + 1) != next_tid); 52 return next_tid; 53 }