8079792: GC directory structure cleanup

Reviewed-by: brutisso, stefank, david

hotspot/src/share/vm/gc/cms/concurrentMarkSweepThread.hpp

@@ -0,0 +1,181 @@
+/*
+ * Copyright (c) 2001, 2015, 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_VM_GC_CMS_CONCURRENTMARKSWEEPTHREAD_HPP
+#define SHARE_VM_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;
+ public:
+  virtual void run();
+
+ private:
+  static ConcurrentMarkSweepThread*     _cmst;
+  static CMSCollector*                  _collector;
+  static SurrogateLockerThread*         _slt;
+  static SurrogateLockerThread::SLT_msg_type _sltBuffer;
+  static Monitor*                       _sltMonitor;
+
+  static bool _should_terminate;
+
+  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;
+
+ public:
+  // Constructor
+  ConcurrentMarkSweepThread(CMSCollector* collector);
+
+  static void makeSurrogateLockerThread(TRAPS);
+  static SurrogateLockerThread* slt() { return _slt; }
+
+  // Tester
+  bool is_ConcurrentGC_thread() const { return true;       }
+
+  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);
+  static void stop();
+  static bool should_terminate() { return _should_terminate; }
+
+  // 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) {
+      warning("%s has looped " INTX_FORMAT " times %s", _src, _ticks, _msg);
+    }
+  }
+};
+
+#endif // SHARE_VM_GC_CMS_CONCURRENTMARKSWEEPTHREAD_HPP