1 /*
   2  * Copyright (c) 1997, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_RUNTIME_SWEEPER_HPP
  26 #define SHARE_VM_RUNTIME_SWEEPER_HPP
  27 
  28 // An NmethodSweeper is an incremental cleaner for:
  29 //    - cleanup inline caches
  30 //    - reclamation of unreferences zombie nmethods
  31 //
  32 
  33 class NMethodSweeper : public AllStatic {
  34   static long      _traversals;      // Stack scan count, also sweep ID.
  35   static nmethod*  _current;         // Current nmethod
  36   static int       _seen;            // Nof. nmethod we have currently processed in current pass of CodeCache
  37   static int       _flushed_count;   // Nof. nmethods flushed in current sweep
  38   static int       _zombified_count; // Nof. nmethods made zombie in current sweep
  39   static int       _marked_count;    // Nof. nmethods marked for reclaim in current sweep
  40 
  41   static volatile int      _invocations;   // No. of invocations left until we are completed with this pass
  42   static volatile int      _sweep_started; // Flag to control conc sweeper
  43 
  44   static bool      _rescan;          // Indicates that we should do a full rescan of the
  45                                      // of the code cache looking for work to do.
  46   static bool      _do_sweep;        // Flag to skip the conc sweep if no stack scan happened
  47   static int       _locked_seen;     // Number of locked nmethods encountered during the scan
  48   static int       _not_entrant_seen_on_stack; // Number of not entrant nmethod were are still on stack
  49 
  50   static bool      _was_full;        // remember if we did emergency unloading
  51   static jint      _advise_to_sweep; // flag to indicate code cache getting full
  52   static jlong     _last_was_full;   // timestamp of last emergency unloading
  53   static uint      _highest_marked;   // highest compile id dumped at last emergency unloading
  54   static long      _was_full_traversal;   // trav number at last emergency unloading
  55 
  56   // Stat counters
  57   static int       _number_of_flushes;           // Total of full traversals caused by full cache
  58   static int       _total_nof_methods_reclaimed; // Accumulated nof methods flushed
  59   static long      _total_time_sweeping;         // Accumulated time sweeping
  60   static long      _total_time_this_sweep;       // Total time this sweep
  61   static long      _peak_sweep_time;             // Peak time for a full sweep
  62   static long      _peak_sweep_fraction_time;    // Peak time sweeping one fraction
  63   static long      _total_disconnect_time;       // Total time cleaning code mem
  64   static long      _peak_disconnect_time;        // Peak time cleaning code mem
  65 
  66   static void process_nmethod(nmethod *nm);
  67 
  68   static void log_sweep(const char* msg, const char* format = NULL, ...);
  69 
  70  public:
  71   static long traversal_count()             { return _traversals; }
  72   static int  number_of_flushes()           { return _number_of_flushes; }
  73   static int  total_nof_methods_reclaimed() { return _total_nof_methods_reclaimed; }
  74   static long total_time_sweeping()         { return _total_time_sweeping; }
  75   static long peak_sweep_time()             { return _peak_sweep_time; }
  76   static long peak_sweep_fraction_time()    { return _peak_sweep_fraction_time; }
  77   static long total_disconnect_time()       { return _total_disconnect_time; }
  78   static long peak_disconnect_time()        { return _peak_disconnect_time; }
  79 
  80 #ifdef ASSERT
  81   // Keep track of sweeper activity in the ring buffer
  82   static void record_sweep(nmethod* nm, int line);
  83   static void report_events(int id, address entry);
  84   static void report_events();
  85 #endif
  86 
  87   static void scan_stacks();      // Invoked at the end of each safepoint
  88   static void sweep_code_cache(); // Concurrent part of sweep job
  89   static void possibly_sweep();   // Compiler threads call this to sweep
  90 
  91   static void notify(nmethod* nm) {
  92     // Perform a full scan of the code cache from the beginning.  No
  93     // need to synchronize the setting of this flag since it only
  94     // changes to false at safepoint so we can never overwrite it with false.
  95      _rescan = true;
  96   }
  97 
  98   static void handle_full_code_cache(bool is_full); // Called by compilers who fail to allocate
  99   static void speculative_disconnect_nmethods(bool was_full);   // Called by vm op to deal with alloc failure
 100 
 101   static void set_was_full(bool state) { _was_full = state; }
 102   static bool was_full() { return _was_full; }
 103 };
 104 
 105 #endif // SHARE_VM_RUNTIME_SWEEPER_HPP