1 /*
   2  * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  *
  22  */
  23 
  24 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHSTRINGDEDUP_HPP
  25 #define SHARE_GC_SHENANDOAH_SHENANDOAHSTRINGDEDUP_HPP
  26 
  27 #include "classfile/javaClasses.inline.hpp"
  28 #include "gc/shared/stringdedup/stringDedup.hpp"
  29 #include "memory/iterator.hpp"
  30 
  31 class ShenandoahStringDedup : public StringDedup {
  32 public:
  33   // Initialize string deduplication.
  34   static void initialize();
  35 
  36   // Enqueue a string to worker's local string dedup queue
  37   static void enqueue_candidate(oop java_string);
  38 
  39   // Deduplicate a string, the call is lock-free
  40   static void deduplicate(oop java_string);
  41 
  42   static void parallel_oops_do(OopClosure* cl, uint worker_id);
  43   static void oops_do_slow(OopClosure* cl);
  44 
  45   static inline bool is_candidate(oop obj) {
  46     return java_lang_String::is_instance_inlined(obj) &&
  47            java_lang_String::value(obj) != NULL;
  48   }
  49 private:
  50   static void unlink_or_oops_do(BoolObjectClosure* is_alive,
  51                                 OopClosure* keep_alive,
  52                                 bool allow_resize_and_rehash);
  53 
  54 };
  55 
  56 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHSTRINGDEDUP_HPP