hotspot/src/share/vm/gc_implementation/shared/vmGCOperations.hpp
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     1 /*
       
     2  * Copyright 2005-2006 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 // The following class hierarchy represents
       
    26 // a set of operations (VM_Operation) related to GC.
       
    27 //
       
    28 //  VM_Operation
       
    29 //      VM_GC_Operation
       
    30 //          VM_GC_HeapInspection
       
    31 //          VM_GenCollectForAllocation
       
    32 //          VM_GenCollectFull
       
    33 //          VM_GenCollectFullConcurrent
       
    34 //          VM_ParallelGCFailedAllocation
       
    35 //          VM_ParallelGCFailedPermanentAllocation
       
    36 //          VM_ParallelGCSystemGC
       
    37 //  VM_GC_Operation
       
    38 //   - implements methods common to all classes in the hierarchy:
       
    39 //     prevents multiple gc requests and manages lock on heap;
       
    40 //
       
    41 //  VM_GC_HeapInspection
       
    42 //   - prints class histogram on SIGBREAK if PrintClassHistogram
       
    43 //     is specified; and also the attach "inspectheap" operation
       
    44 //
       
    45 //  VM_GenCollectForAllocation
       
    46 //  VM_ParallelGCFailedAllocation
       
    47 //  VM_ParallelGCFailedPermanentAllocation
       
    48 //   - this operation is invoked when allocation is failed;
       
    49 //     operation performs garbage collection and tries to
       
    50 //     allocate afterwards;
       
    51 //
       
    52 //  VM_GenCollectFull
       
    53 //  VM_GenCollectFullConcurrent
       
    54 //  VM_ParallelGCSystemGC
       
    55 //   - these operations preform full collection of heaps of
       
    56 //     different kind
       
    57 //
       
    58 
       
    59 class VM_GC_Operation: public VM_Operation {
       
    60  protected:
       
    61   BasicLock     _pending_list_basic_lock; // for refs pending list notification (PLL)
       
    62   unsigned int  _gc_count_before;         // gc count before acquiring PLL
       
    63   unsigned int  _full_gc_count_before;    // full gc count before acquiring PLL
       
    64   bool          _full;                    // whether a "full" collection
       
    65   bool          _prologue_succeeded;      // whether doit_prologue succeeded
       
    66   GCCause::Cause _gc_cause;                // the putative cause for this gc op
       
    67   bool          _gc_locked;               // will be set if gc was locked
       
    68 
       
    69   virtual bool skip_operation() const;
       
    70 
       
    71   // java.lang.ref.Reference support
       
    72   void acquire_pending_list_lock();
       
    73   void release_and_notify_pending_list_lock();
       
    74 
       
    75  public:
       
    76   VM_GC_Operation(unsigned int gc_count_before,
       
    77                   unsigned int full_gc_count_before = 0,
       
    78                   bool full = false) {
       
    79     _full = full;
       
    80     _prologue_succeeded = false;
       
    81     _gc_count_before    = gc_count_before;
       
    82 
       
    83     // A subclass constructor will likely overwrite the following
       
    84     _gc_cause           = GCCause::_no_cause_specified;
       
    85 
       
    86     _gc_locked = false;
       
    87 
       
    88     if (full) {
       
    89       _full_gc_count_before = full_gc_count_before;
       
    90     }
       
    91   }
       
    92   ~VM_GC_Operation() {}
       
    93 
       
    94   // Acquire the reference synchronization lock
       
    95   virtual bool doit_prologue();
       
    96   // Do notifyAll (if needed) and release held lock
       
    97   virtual void doit_epilogue();
       
    98 
       
    99   virtual bool allow_nested_vm_operations() const  { return true; }
       
   100   bool prologue_succeeded() const { return _prologue_succeeded; }
       
   101 
       
   102   void set_gc_locked() { _gc_locked = true; }
       
   103   bool gc_locked() const  { return _gc_locked; }
       
   104 
       
   105   static void notify_gc_begin(bool full = false);
       
   106   static void notify_gc_end();
       
   107 };
       
   108 
       
   109 
       
   110 class VM_GC_HeapInspection: public VM_GC_Operation {
       
   111  private:
       
   112   outputStream* _out;
       
   113   bool _full_gc;
       
   114  public:
       
   115   VM_GC_HeapInspection(outputStream* out, bool request_full_gc) :
       
   116     VM_GC_Operation(0 /* total collections,      dummy, ignored */,
       
   117                     0 /* total full collections, dummy, ignored */,
       
   118                     request_full_gc) {
       
   119     _out = out;
       
   120     _full_gc = request_full_gc;
       
   121   }
       
   122 
       
   123   ~VM_GC_HeapInspection() {}
       
   124   virtual VMOp_Type type() const { return VMOp_GC_HeapInspection; }
       
   125   virtual bool skip_operation() const;
       
   126   virtual bool doit_prologue();
       
   127   virtual void doit();
       
   128 };
       
   129 
       
   130 
       
   131 class VM_GenCollectForAllocation: public VM_GC_Operation {
       
   132  private:
       
   133   HeapWord*   _res;
       
   134   size_t      _size;                       // size of object to be allocated.
       
   135   bool        _tlab;                       // alloc is of a tlab.
       
   136  public:
       
   137   VM_GenCollectForAllocation(size_t size,
       
   138                              bool tlab,
       
   139                              unsigned int gc_count_before)
       
   140     : VM_GC_Operation(gc_count_before),
       
   141       _size(size),
       
   142       _tlab(tlab) {
       
   143     _res = NULL;
       
   144   }
       
   145   ~VM_GenCollectForAllocation()  {}
       
   146   virtual VMOp_Type type() const { return VMOp_GenCollectForAllocation; }
       
   147   virtual void doit();
       
   148   HeapWord* result() const       { return _res; }
       
   149 };
       
   150 
       
   151 
       
   152 // VM operation to invoke a collection of the heap as a
       
   153 // GenCollectedHeap heap.
       
   154 class VM_GenCollectFull: public VM_GC_Operation {
       
   155  private:
       
   156   int _max_level;
       
   157  public:
       
   158   VM_GenCollectFull(unsigned int gc_count_before,
       
   159                     unsigned int full_gc_count_before,
       
   160                     GCCause::Cause gc_cause,
       
   161                       int max_level)
       
   162     : VM_GC_Operation(gc_count_before, full_gc_count_before, true /* full */),
       
   163       _max_level(max_level)
       
   164   { _gc_cause = gc_cause; }
       
   165   ~VM_GenCollectFull() {}
       
   166   virtual VMOp_Type type() const { return VMOp_GenCollectFull; }
       
   167   virtual void doit();
       
   168 };