vmGCOperations.hpp revision 8413:92457dfb91bd 
1/*
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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
70class 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
128class 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
162class 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
176class 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.
194class 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
209class 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
231class 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
247