--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/logging/logOutputList.cpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,128 @@
+/*
+ * Copyright (c) 2015, 2016, 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 "logging/logLevel.hpp"
+#include "logging/logOutputList.hpp"
+#include "memory/allocation.inline.hpp"
+#include "runtime/atomic.hpp"
+#include "runtime/orderAccess.inline.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+jint LogOutputList::increase_readers() {
+  jint result = Atomic::add(1, &_active_readers);
+  assert(_active_readers > 0, "Ensure we have consistent state");
+  return result;
+}
+
+jint LogOutputList::decrease_readers() {
+  jint result = Atomic::add(-1, &_active_readers);
+  assert(result >= 0, "Ensure we have consistent state");
+  return result;
+}
+
+void LogOutputList::wait_until_no_readers() const {
+  OrderAccess::storeload();
+  while (_active_readers != 0) {
+    // Busy wait
+  }
+}
+
+void LogOutputList::set_output_level(LogOutput* output, LogLevelType level) {
+  LogOutputNode* node = find(output);
+  if (level == LogLevel::Off && node != NULL) {
+    remove_output(node);
+  } else if (level != LogLevel::Off && node == NULL) {
+    add_output(output, level);
+  } else if (node != NULL) {
+    update_output_level(node, level);
+  }
+}
+
+LogOutputList::LogOutputNode* LogOutputList::find(const LogOutput* output) const {
+  for (LogOutputNode* node = _level_start[LogLevel::Last]; node != NULL; node = node->_next) {
+    if (output == node->_value) {
+      return node;
+    }
+  }
+  return NULL;
+}
+
+void LogOutputList::remove_output(LogOutputList::LogOutputNode* node) {
+  assert(node != NULL, "Node must be non-null");
+
+  // Remove node from _level_start first
+  bool found = false;
+  for (uint level = LogLevel::First; level < LogLevel::Count; level++) {
+    if (_level_start[level] == node) {
+      found = true;
+      _level_start[level] = node->_next;
+    }
+  }
+
+  // Now remove it from the linked list
+  for (LogOutputNode* cur = _level_start[LogLevel::Last]; cur != NULL; cur = cur->_next) {
+    if (cur->_next == node) {
+      found = true;
+      cur->_next = node->_next;
+      break;
+    }
+  }
+  assert(found, "Node to be removed should always be found");
+
+  wait_until_no_readers();
+  delete node;
+}
+
+void LogOutputList::add_output(LogOutput* output, LogLevelType level) {
+  LogOutputNode* node = new LogOutputNode();
+  node->_value = output;
+  node->_level = level;
+
+  // Set the next pointer to the first node of a lower level
+  for (node->_next = _level_start[level];
+       node->_next != NULL && node->_next->_level == level;
+       node->_next = node->_next->_next) {
+  }
+
+  // Update the _level_start index
+  for (int l = LogLevel::Last; l >= level; l--) {
+    if (_level_start[l] == NULL || _level_start[l]->_level < level) {
+      _level_start[l] = node;
+    }
+  }
+
+  // Add the node the list
+  for (LogOutputNode* cur = _level_start[LogLevel::Last]; cur != NULL; cur = cur->_next) {
+    if (cur != node && cur->_next == node->_next) {
+      cur->_next = node;
+      break;
+    }
+  }
+}
+
+void LogOutputList::update_output_level(LogOutputList::LogOutputNode* node, LogLevelType level) {
+  add_output(node->_value, level);
+  wait_until_no_readers();
+  remove_output(node);
+}