1 /*
   2  * Copyright 1997-2005 Sun Microsystems, Inc.  All Rights Reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  20  * CA 95054 USA or visit www.sun.com if you need additional information or
  21  * have any questions.
  22  *
  23  */
  24 
  25 // An NmethodSweeper is an incremental cleaner for:
  26 //    - cleanup inline caches
  27 //    - reclamation of unreferences zombie nmethods
  28 //
  29 
  30 class NMethodSweeper : public AllStatic {
  31   static long      _traversals;   // Stack traversal count
  32   static CodeBlob* _current;      // Current nmethod
  33   static int       _seen;         // Nof. nmethod we have currently processed in current pass of CodeCache
  34   static int       _invocations;  // No. of invocations left until we are completed with this pass
  35 
  36   static bool      _rescan;          // Indicates that we should do a full rescan of the
  37                                      // of the code cache looking for work to do.
  38   static int       _locked_seen;     // Number of locked nmethods encountered during the scan
  39   static int       _not_entrant_seen_on_stack; // Number of not entrant nmethod were are still on stack
  40 
  41   static bool      _was_full;        // remember if we did emergency unloading
  42   static jlong     _advise_to_sweep; // flag to indicate code cache getting full
  43   static jlong     _last_was_full;   // timestamp of last emergency unloading
  44   static uint      _highest_marked;   // highest compile id dumped at last emergency unloading
  45   static long      _was_full_traversal;   // trav number at last emergency unloading
  46 
  47   static void process_nmethod(nmethod *nm);
  48  public:
  49   static long traversal_count() { return _traversals; }
  50 
  51   static void sweep();  // Invoked at the end of each safepoint
  52 
  53   static void notify(nmethod* nm) {
  54     // Perform a full scan of the code cache from the beginning.  No
  55     // need to synchronize the setting of this flag since it only
  56     // changes to false at safepoint so we can never overwrite it with false.
  57      _rescan = true;
  58   }
  59 
  60   static void handle_full_code_cache(bool is_full); // Called by compilers who fail to allocate
  61   static void speculative_disconnect_nmethods(bool was_full);   // Called by vm op to deal with alloc failure
  62 
  63   static void set_was_full(bool state) { _was_full = state; }
  64   static bool was_full() { return _was_full; }
  65 };