--- a/src/hotspot/share/gc/cms/concurrentMarkSweepThread.hpp Fri Nov 08 14:54:17 2019 +0000
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,169 +0,0 @@
-/*
- * Copyright (c) 2001, 2019, 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.
- *
- */
-
-#ifndef SHARE_GC_CMS_CONCURRENTMARKSWEEPTHREAD_HPP
-#define SHARE_GC_CMS_CONCURRENTMARKSWEEPTHREAD_HPP
-
-#include "gc/cms/concurrentMarkSweepGeneration.hpp"
-#include "gc/shared/concurrentGCThread.hpp"
-#include "runtime/thread.hpp"
-
-class ConcurrentMarkSweepGeneration;
-class CMSCollector;
-
-// The Concurrent Mark Sweep GC Thread
-class ConcurrentMarkSweepThread: public ConcurrentGCThread {
- friend class VMStructs;
- friend class ConcurrentMarkSweepGeneration; // XXX should remove friendship
- friend class CMSCollector;
-
- private:
- static ConcurrentMarkSweepThread* _cmst;
- static CMSCollector* _collector;
-
- enum CMS_flag_type {
- CMS_nil = NoBits,
- CMS_cms_wants_token = nth_bit(0),
- CMS_cms_has_token = nth_bit(1),
- CMS_vm_wants_token = nth_bit(2),
- CMS_vm_has_token = nth_bit(3)
- };
-
- static int _CMS_flag;
-
- static bool CMS_flag_is_set(int b) { return (_CMS_flag & b) != 0; }
- static bool set_CMS_flag(int b) { return (_CMS_flag |= b) != 0; }
- static bool clear_CMS_flag(int b) { return (_CMS_flag &= ~b) != 0; }
- void sleepBeforeNextCycle();
-
- // CMS thread should yield for a young gen collection and direct allocations
- static char _pad_1[64 - sizeof(jint)]; // prevent cache-line sharing
- static volatile jint _pending_yields;
- static char _pad_2[64 - sizeof(jint)]; // prevent cache-line sharing
-
- // debugging
- void verify_ok_to_terminate() const PRODUCT_RETURN;
-
- void run_service();
- void stop_service();
-
- public:
- // Constructor
- ConcurrentMarkSweepThread(CMSCollector* collector);
-
- static void threads_do(ThreadClosure* tc);
-
- // Printing
- static void print_all_on(outputStream* st);
- static void print_all() { print_all_on(tty); }
-
- // Returns the CMS Thread
- static ConcurrentMarkSweepThread* cmst() { return _cmst; }
- static CMSCollector* collector() { return _collector; }
-
- // Create and start the CMS Thread, or stop it on shutdown
- static ConcurrentMarkSweepThread* start(CMSCollector* collector);
-
- // Synchronization using CMS token
- static void synchronize(bool is_cms_thread);
- static void desynchronize(bool is_cms_thread);
- static bool vm_thread_has_cms_token() {
- return CMS_flag_is_set(CMS_vm_has_token);
- }
- static bool cms_thread_has_cms_token() {
- return CMS_flag_is_set(CMS_cms_has_token);
- }
- static bool vm_thread_wants_cms_token() {
- return CMS_flag_is_set(CMS_vm_wants_token);
- }
- static bool cms_thread_wants_cms_token() {
- return CMS_flag_is_set(CMS_cms_wants_token);
- }
-
- // Wait on CMS lock until the next synchronous GC
- // or given timeout, whichever is earlier. A timeout value
- // of 0 indicates that there is no upper bound on the wait time.
- // A concurrent full gc request terminates the wait.
- void wait_on_cms_lock(long t_millis);
-
- // Wait on CMS lock until the next synchronous GC
- // or given timeout, whichever is earlier. A timeout value
- // of 0 indicates that there is no upper bound on the wait time.
- // A concurrent full gc request terminates the wait.
- void wait_on_cms_lock_for_scavenge(long t_millis);
-
- // The CMS thread will yield during the work portion of its cycle
- // only when requested to.
- // A synchronous request is used for young gen collections and
- // for direct allocations. The requesting thread increments
- // _pending_yields at the beginning of an operation, and decrements
- // _pending_yields when that operation is completed.
- // In turn, the CMS thread yields when _pending_yields is positive,
- // and continues to yield until the value reverts to 0.
-
- static void increment_pending_yields() {
- Atomic::inc(&_pending_yields);
- assert(_pending_yields >= 0, "can't be negative");
- }
- static void decrement_pending_yields() {
- Atomic::dec(&_pending_yields);
- assert(_pending_yields >= 0, "can't be negative");
- }
- static bool should_yield() { return _pending_yields > 0; }
-};
-
-// For scoped increment/decrement of (synchronous) yield requests
-class CMSSynchronousYieldRequest: public StackObj {
- public:
- CMSSynchronousYieldRequest() {
- ConcurrentMarkSweepThread::increment_pending_yields();
- }
- ~CMSSynchronousYieldRequest() {
- ConcurrentMarkSweepThread::decrement_pending_yields();
- }
-};
-
-// Used to emit a warning in case of unexpectedly excessive
-// looping (in "apparently endless loops") in CMS code.
-class CMSLoopCountWarn: public StackObj {
- private:
- const char* _src;
- const char* _msg;
- const intx _threshold;
- intx _ticks;
-
- public:
- inline CMSLoopCountWarn(const char* src, const char* msg,
- const intx threshold) :
- _src(src), _msg(msg), _threshold(threshold), _ticks(0) { }
-
- inline void tick() {
- _ticks++;
- if (CMSLoopWarn && _ticks % _threshold == 0) {
- log_warning(gc)("%s has looped " INTX_FORMAT " times %s", _src, _ticks, _msg);
- }
- }
-};
-
-#endif // SHARE_GC_CMS_CONCURRENTMARKSWEEPTHREAD_HPP