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 /*

  * Copyright (c) 1997, 2013, 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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  */

 #ifndef SHARE_VM_RUNTIME_SWEEPER_HPP

 #define SHARE_VM_RUNTIME_SWEEPER_HPP

 // An NmethodSweeper is an incremental cleaner for:

 //    - cleanup inline caches

 //    - reclamation of unreferences zombie nmethods

 //

 class NMethodSweeper : public AllStatic {

   static long      _traversals;      // Stack scan count, also sweep ID.

   static nmethod*  _current;         // Current nmethod

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

   static int       _flushed_count;   // Nof. nmethods flushed in current sweep

   static int       _zombified_count; // Nof. nmethods made zombie in current sweep

   static int       _marked_count;    // Nof. nmethods marked for reclaim in current sweep

   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

   //The following are reset in scan_stacks and synchronized by the safepoint

   static bool      _resweep;           // Indicates that a change has happend and we want another sweep,

                                        // always checked and reset at a safepoint so memory will be in sync.

   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 jint      _flush_token;       // token that guards method flushing, making sure it is executed only once.

   // These are set during a flush, a VM-operation

   static long      _last_flush_traversal_id; // trav number at last flush unloading

   static jlong     _last_full_flush_time;    // timestamp of last emergency unloading

   // These are synchronized by the _sweep_started token

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

   static int       _dead_compile_ids; // number of compile ids that where not in the cache last flush

   // Stat counters

   static int       _number_of_flushes;            // Total of full traversals caused by full cache

   static int       _total_nof_methods_reclaimed;  // Accumulated nof methods flushed

   static jlong     _total_time_sweeping;          // Accumulated time sweeping

   static jlong     _total_time_this_sweep;        // Total time this sweep

   static jlong     _peak_sweep_time;              // Peak time for a full sweep

   static jlong     _peak_sweep_fraction_time;     // Peak time sweeping one fraction

   static jlong     _total_disconnect_time;        // Total time cleaning code mem

   static jlong     _peak_disconnect_time;         // Peak time cleaning code mem

   static void process_nmethod(nmethod *nm);

   static void release_nmethod(nmethod* nm);

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

   static bool sweep_in_progress();

  public:

   static long traversal_count()              { return _traversals; }

   static int  number_of_flushes()            { return _number_of_flushes; }

   static int  total_nof_methods_reclaimed()  { return _total_nof_methods_reclaimed; }

   static jlong total_time_sweeping()         { return _total_time_sweeping; }

   static jlong peak_sweep_time()             { return _peak_sweep_time; }

   static jlong peak_sweep_fraction_time()    { return _peak_sweep_fraction_time; }

   static jlong total_disconnect_time()       { return _total_disconnect_time; }

   static jlong peak_disconnect_time()        { return _peak_disconnect_time; }

 #ifdef ASSERT

   static bool is_sweeping(nmethod* which) { return _current == which; }

   // Keep track of sweeper activity in the ring buffer

   static void record_sweep(nmethod* nm, int line);

   static void report_events(int id, address entry);

   static void report_events();

 #endif

   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) {

     // Request a new sweep 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.

      _resweep = 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

 };

 #endif // SHARE_VM_RUNTIME_SWEEPER_HPP