1 /*
   2  * Copyright (c) 2005, 2015, 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
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  24 
  25 #ifndef SHARE_VM_GC_SHARED_VMGCOPERATIONS_HPP
  26 #define SHARE_VM_GC_SHARED_VMGCOPERATIONS_HPP
  27 
  28 #include "gc/shared/collectedHeap.hpp"
  29 #include "memory/heapInspection.hpp"
  30 #include "prims/jvmtiExport.hpp"
  31 #include "runtime/handles.hpp"
  32 #include "runtime/jniHandles.hpp"
  33 #include "runtime/synchronizer.hpp"
  34 #include "runtime/vm_operations.hpp"
  35 
  36 // The following class hierarchy represents
  37 // a set of operations (VM_Operation) related to GC.
  38 //
  39 //  VM_Operation
  40 //      VM_GC_Operation
  41 //          VM_GC_HeapInspection
  42 //          VM_GenCollectFull
  43 //          VM_GenCollectFullConcurrent
  44 //          VM_ParallelGCSystemGC
  45 //          VM_CollectForAllocation
  46 //              VM_GenCollectForAllocation
  47 //              VM_ParallelGCFailedAllocation
  48 //  VM_GC_Operation
  49 //   - implements methods common to all classes in the hierarchy:
  50 //     prevents multiple gc requests and manages lock on heap;
  51 //
  52 //  VM_GC_HeapInspection
  53 //   - prints class histogram on SIGBREAK if PrintClassHistogram
  54 //     is specified; and also the attach "inspectheap" operation
  55 //
  56 //  VM_CollectForAllocation
  57 //  VM_GenCollectForAllocation
  58 //  VM_ParallelGCFailedAllocation
  59 //   - this operation is invoked when allocation is failed;
  60 //     operation performs garbage collection and tries to
  61 //     allocate afterwards;
  62 //
  63 //  VM_GenCollectFull
  64 //  VM_GenCollectFullConcurrent
  65 //  VM_ParallelGCSystemGC
  66 //   - these operations preform full collection of heaps of
  67 //     different kind
  68 //
  69 
  70 class VM_GC_Operation: public VM_Operation {
  71  protected:
  72   BasicLock      _pending_list_basic_lock; // for refs pending list notification (PLL)
  73   uint           _gc_count_before;         // gc count before acquiring PLL
  74   uint           _full_gc_count_before;    // full gc count before acquiring PLL
  75   bool           _full;                    // whether a "full" collection
  76   bool           _prologue_succeeded;      // whether doit_prologue succeeded
  77   GCCause::Cause _gc_cause;                // the putative cause for this gc op
  78   bool           _gc_locked;               // will be set if gc was locked
  79 
  80   virtual bool skip_operation() const;
  81 
  82   // java.lang.ref.Reference support
  83   void acquire_pending_list_lock();
  84   void release_and_notify_pending_list_lock();
  85 
  86  public:
  87   VM_GC_Operation(uint gc_count_before,
  88                   GCCause::Cause _cause,
  89                   uint full_gc_count_before = 0,
  90                   bool full = false) {
  91     _full = full;
  92     _prologue_succeeded = false;
  93     _gc_count_before    = gc_count_before;
  94 
  95     // A subclass constructor will likely overwrite the following
  96     _gc_cause           = _cause;
  97 
  98     _gc_locked = false;
  99 
 100     _full_gc_count_before = full_gc_count_before;
 101     // In ParallelScavengeHeap::mem_allocate() collections can be
 102     // executed within a loop and _all_soft_refs_clear can be set
 103     // true after they have been cleared by a collection and another
 104     // collection started so that _all_soft_refs_clear can be true
 105     // when this collection is started.  Don't assert that
 106     // _all_soft_refs_clear have to be false here even though
 107     // mutators have run.  Soft refs will be cleared again in this
 108     // collection.
 109   }
 110   ~VM_GC_Operation();
 111 
 112   // Acquire the reference synchronization lock
 113   virtual bool doit_prologue();
 114   // Do notifyAll (if needed) and release held lock
 115   virtual void doit_epilogue();
 116 
 117   virtual bool allow_nested_vm_operations() const  { return true; }
 118   bool prologue_succeeded() const { return _prologue_succeeded; }
 119 
 120   void set_gc_locked() { _gc_locked = true; }
 121   bool gc_locked() const  { return _gc_locked; }
 122 
 123   static void notify_gc_begin(bool full = false);
 124   static void notify_gc_end();
 125 };
 126 
 127 
 128 class VM_GC_HeapInspection: public VM_GC_Operation {
 129  private:
 130   outputStream* _out;
 131   bool _full_gc;
 132   bool _csv_format; // "comma separated values" format for spreadsheet.
 133   bool _print_help;
 134   bool _print_class_stats;
 135   const char* _columns;
 136  public:
 137   VM_GC_HeapInspection(outputStream* out, bool request_full_gc) :
 138     VM_GC_Operation(0 /* total collections,      dummy, ignored */,
 139                     GCCause::_heap_inspection /* GC Cause */,
 140                     0 /* total full collections, dummy, ignored */,
 141                     request_full_gc) {
 142     _out = out;
 143     _full_gc = request_full_gc;
 144     _csv_format = false;
 145     _print_help = false;
 146     _print_class_stats = false;
 147     _columns = NULL;
 148   }
 149 
 150   ~VM_GC_HeapInspection() {}
 151   virtual VMOp_Type type() const { return VMOp_GC_HeapInspection; }
 152   virtual bool skip_operation() const;
 153   virtual void doit();
 154   void set_csv_format(bool value) {_csv_format = value;}
 155   void set_print_help(bool value) {_print_help = value;}
 156   void set_print_class_stats(bool value) {_print_class_stats = value;}
 157   void set_columns(const char* value) {_columns = value;}
 158  protected:
 159   bool collect();
 160 };
 161 
 162 class VM_CollectForAllocation : public VM_GC_Operation {
 163  protected:
 164   size_t    _word_size; // Size of object to be allocated (in number of words)
 165   HeapWord* _result;    // Allocation result (NULL if allocation failed)
 166 
 167  public:
 168   VM_CollectForAllocation(size_t word_size, uint gc_count_before, GCCause::Cause cause)
 169     : VM_GC_Operation(gc_count_before, cause), _result(NULL), _word_size(word_size) {}
 170 
 171   HeapWord* result() const {
 172     return _result;
 173   }
 174 };
 175 
 176 class VM_GenCollectForAllocation : public VM_CollectForAllocation {
 177  private:
 178   bool        _tlab;                       // alloc is of a tlab.
 179  public:
 180   VM_GenCollectForAllocation(size_t word_size,
 181                              bool tlab,
 182                              uint gc_count_before)
 183     : VM_CollectForAllocation(word_size, gc_count_before, GCCause::_allocation_failure),
 184       _tlab(tlab) {
 185     assert(word_size != 0, "An allocation should always be requested with this operation.");
 186   }
 187   ~VM_GenCollectForAllocation()  {}
 188   virtual VMOp_Type type() const { return VMOp_GenCollectForAllocation; }
 189   virtual void doit();
 190 };
 191 
 192 // VM operation to invoke a collection of the heap as a
 193 // GenCollectedHeap heap.
 194 class VM_GenCollectFull: public VM_GC_Operation {
 195  private:
 196   int _max_level;
 197  public:
 198   VM_GenCollectFull(uint gc_count_before,
 199                     uint full_gc_count_before,
 200                     GCCause::Cause gc_cause,
 201                     int max_level)
 202     : VM_GC_Operation(gc_count_before, gc_cause, full_gc_count_before, true /* full */),
 203       _max_level(max_level) { }
 204   ~VM_GenCollectFull() {}
 205   virtual VMOp_Type type() const { return VMOp_GenCollectFull; }
 206   virtual void doit();
 207 };
 208 
 209 class VM_CollectForMetadataAllocation: public VM_GC_Operation {
 210  private:
 211   MetaWord*                _result;
 212   size_t                   _size;     // size of object to be allocated
 213   Metaspace::MetadataType  _mdtype;
 214   ClassLoaderData*         _loader_data;
 215  public:
 216   VM_CollectForMetadataAllocation(ClassLoaderData* loader_data,
 217                                   size_t size, Metaspace::MetadataType mdtype,
 218                                   uint gc_count_before,
 219                                   uint full_gc_count_before,
 220                                   GCCause::Cause gc_cause)
 221     : VM_GC_Operation(gc_count_before, gc_cause, full_gc_count_before, true),
 222       _loader_data(loader_data), _size(size), _mdtype(mdtype), _result(NULL) {
 223   }
 224   virtual VMOp_Type type() const { return VMOp_CollectForMetadataAllocation; }
 225   virtual void doit();
 226   MetaWord* result() const       { return _result; }
 227 
 228   bool initiate_concurrent_GC();
 229 };
 230 
 231 class SvcGCMarker : public StackObj {
 232  private:
 233   JvmtiGCMarker _jgcm;
 234  public:
 235   typedef enum { MINOR, FULL, OTHER } reason_type;
 236 
 237   SvcGCMarker(reason_type reason ) {
 238     VM_GC_Operation::notify_gc_begin(reason == FULL);
 239   }
 240 
 241   ~SvcGCMarker() {
 242     VM_GC_Operation::notify_gc_end();
 243   }
 244 };
 245 
 246 #endif // SHARE_VM_GC_SHARED_VMGCOPERATIONS_HPP