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 /*

  * Copyright (c) 1997, 2010, 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

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  */

 // An NmethodSweeper is an incremental cleaner for:

 //    - cleanup inline caches

 //    - reclamation of unreferences zombie nmethods

 //

 class NMethodSweeper : public AllStatic {

   static long      _traversals;   // Stack traversal count

   static nmethod*  _current;      // Current nmethod

   static int       _seen;         // Nof. nmethod we have currently processed in current pass of CodeCache

   static volatile int      _invocations;   // No. of invocations left until we are completed with this pass

   static volatile int      _sweep_started; // Flag to control conc sweeper

   static bool      _rescan;          // Indicates that we should do a full rescan of the

                                      // of the code cache looking for work to do.

   static bool      _do_sweep;        // Flag to skip the conc sweep if no stack scan happened

   static int       _locked_seen;     // Number of locked nmethods encountered during the scan

   static int       _not_entrant_seen_on_stack; // Number of not entrant nmethod were are still on stack

   static bool      _was_full;        // remember if we did emergency unloading

   static jint      _advise_to_sweep; // flag to indicate code cache getting full

   static jlong     _last_was_full;   // timestamp of last emergency unloading

   static uint      _highest_marked;   // highest compile id dumped at last emergency unloading

   static long      _was_full_traversal;   // trav number at last emergency unloading

   static void process_nmethod(nmethod *nm);

   static void log_sweep(const char* msg, const char* format = NULL, ...);

  public:

   static long traversal_count() { return _traversals; }

   static void scan_stacks();      // Invoked at the end of each safepoint

   static void sweep_code_cache(); // Concurrent part of sweep job

   static void possibly_sweep();   // Compiler threads call this to sweep

   static void notify(nmethod* nm) {

     // Perform a full scan of the code cache from the beginning.  No

     // need to synchronize the setting of this flag since it only

     // changes to false at safepoint so we can never overwrite it with false.

      _rescan = true;

   }

   static void handle_full_code_cache(bool is_full); // Called by compilers who fail to allocate

   static void speculative_disconnect_nmethods(bool was_full);   // Called by vm op to deal with alloc failure

   static void set_was_full(bool state) { _was_full = state; }

   static bool was_full() { return _was_full; }

 };