--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/runtime/task.cpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,154 @@
+/*
+ * Copyright (c) 1997, 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.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "memory/allocation.hpp"
+#include "runtime/init.hpp"
+#include "runtime/task.hpp"
+#include "runtime/thread.inline.hpp"
+#include "runtime/timer.hpp"
+
+int PeriodicTask::_num_tasks = 0;
+PeriodicTask* PeriodicTask::_tasks[PeriodicTask::max_tasks];
+#ifndef PRODUCT
+elapsedTimer PeriodicTask::_timer;
+int PeriodicTask::_intervalHistogram[PeriodicTask::max_interval];
+int PeriodicTask::_ticks;
+
+void PeriodicTask::print_intervals() {
+  if (ProfilerCheckIntervals) {
+    for (int i = 0; i < PeriodicTask::max_interval; i++) {
+      int n = _intervalHistogram[i];
+      if (n > 0) tty->print_cr("%3d: %5d (%4.1f%%)", i, n, 100.0 * n / _ticks);
+    }
+  }
+}
+#endif
+
+void PeriodicTask::real_time_tick(int delay_time) {
+  assert(Thread::current()->is_Watcher_thread(), "must be WatcherThread");
+
+#ifndef PRODUCT
+  if (ProfilerCheckIntervals) {
+    _ticks++;
+    _timer.stop();
+    int ms = (int)_timer.milliseconds();
+    _timer.reset();
+    _timer.start();
+    if (ms >= PeriodicTask::max_interval) ms = PeriodicTask::max_interval - 1;
+    _intervalHistogram[ms]++;
+  }
+#endif
+
+  {
+    // The WatcherThread does not participate in the safepoint protocol
+    // for the PeriodicTask_lock because it is not a JavaThread.
+    MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
+    int orig_num_tasks = _num_tasks;
+
+    for(int index = 0; index < _num_tasks; index++) {
+      _tasks[index]->execute_if_pending(delay_time);
+      if (_num_tasks < orig_num_tasks) { // task dis-enrolled itself
+        index--;  // re-do current slot as it has changed
+        orig_num_tasks = _num_tasks;
+      }
+    }
+  }
+}
+
+int PeriodicTask::time_to_wait() {
+  assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
+
+  if (_num_tasks == 0) {
+    return 0; // sleep until shutdown or a task is enrolled
+  }
+
+  int delay = _tasks[0]->time_to_next_interval();
+  for (int index = 1; index < _num_tasks; index++) {
+    delay = MIN2(delay, _tasks[index]->time_to_next_interval());
+  }
+  return delay;
+}
+
+
+PeriodicTask::PeriodicTask(size_t interval_time) :
+  _counter(0), _interval((int) interval_time) {
+  // Sanity check the interval time
+  assert(_interval >= PeriodicTask::min_interval &&
+         _interval %  PeriodicTask::interval_gran == 0,
+              "improper PeriodicTask interval time");
+}
+
+PeriodicTask::~PeriodicTask() {
+  // This PeriodicTask may have already been disenrolled by a call
+  // to disenroll() before the PeriodicTask was deleted.
+  disenroll();
+}
+
+// enroll the current PeriodicTask
+void PeriodicTask::enroll() {
+  // Follow normal safepoint aware lock enter protocol if the caller does
+  // not already own the PeriodicTask_lock. Otherwise, we don't try to
+  // enter it again because VM internal Mutexes do not support recursion.
+  //
+  MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ? NULL
+                                                      : PeriodicTask_lock);
+
+  if (_num_tasks == PeriodicTask::max_tasks) {
+    fatal("Overflow in PeriodicTask table");
+  } else {
+    _tasks[_num_tasks++] = this;
+  }
+
+  WatcherThread* thread = WatcherThread::watcher_thread();
+  if (thread != NULL) {
+    thread->unpark();
+  } else {
+    WatcherThread::start();
+  }
+}
+
+// disenroll the current PeriodicTask
+void PeriodicTask::disenroll() {
+  // Follow normal safepoint aware lock enter protocol if the caller does
+  // not already own the PeriodicTask_lock. Otherwise, we don't try to
+  // enter it again because VM internal Mutexes do not support recursion.
+  //
+  MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ? NULL
+                                                      : PeriodicTask_lock);
+
+  int index;
+  for(index = 0; index < _num_tasks && _tasks[index] != this; index++)
+    ;
+
+  if (index == _num_tasks) {
+    return;
+  }
+
+  _num_tasks--;
+
+  for (; index < _num_tasks; index++) {
+    _tasks[index] = _tasks[index+1];
+  }
+}