Tue, 10 Jan 2012 18:58:13 -0500
6888336: G1: avoid explicitly marking and pushing objects in survivor spaces
Summary: This change simplifies the interaction between GC and concurrent marking. By disabling survivor spaces during the initial-mark pause we don't need to propagate marks of objects we copy during each GC (since we never need to copy an explicitly marked object).
Reviewed-by: johnc, brutisso
1 /*
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSET_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSET_HPP
28 #include "gc_implementation/g1/heapRegion.hpp"
30 // Large buffer for some cases where the output might be larger than normal.
31 #define HRS_ERR_MSG_BUFSZ 512
32 typedef FormatBuffer<HRS_ERR_MSG_BUFSZ> hrs_err_msg;
34 // Set verification will be forced either if someone defines
35 // HEAP_REGION_SET_FORCE_VERIFY to be 1, or in builds in which
36 // asserts are compiled in.
37 #ifndef HEAP_REGION_SET_FORCE_VERIFY
38 #define HEAP_REGION_SET_FORCE_VERIFY defined(ASSERT)
39 #endif // HEAP_REGION_SET_FORCE_VERIFY
41 //////////////////// HeapRegionSetBase ////////////////////
43 // Base class for all the classes that represent heap region sets. It
44 // contains the basic attributes that each set needs to maintain
45 // (e.g., length, region num, used bytes sum) plus any shared
46 // functionality (e.g., verification).
48 class hrs_ext_msg;
50 typedef enum {
51 HRSPhaseNone,
52 HRSPhaseEvacuation,
53 HRSPhaseCleanup,
54 HRSPhaseFullGC
55 } HRSPhase;
57 class HRSPhaseSetter;
59 class HeapRegionSetBase VALUE_OBJ_CLASS_SPEC {
60 friend class hrs_ext_msg;
61 friend class HRSPhaseSetter;
63 protected:
64 static size_t calculate_region_num(HeapRegion* hr);
66 static size_t _unrealistically_long_length;
68 // The number of regions added to the set. If the set contains
69 // only humongous regions, this reflects only 'starts humongous'
70 // regions and does not include 'continues humongous' ones.
71 size_t _length;
73 // The total number of regions represented by the set. If the set
74 // does not contain humongous regions, this should be the same as
75 // _length. If the set contains only humongous regions, this will
76 // include the 'continues humongous' regions.
77 size_t _region_num;
79 // We don't keep track of the total capacity explicitly, we instead
80 // recalculate it based on _region_num and the heap region size.
82 // The sum of used bytes in the all the regions in the set.
83 size_t _total_used_bytes;
85 const char* _name;
87 bool _verify_in_progress;
88 size_t _calc_length;
89 size_t _calc_region_num;
90 size_t _calc_total_capacity_bytes;
91 size_t _calc_total_used_bytes;
93 // This is here so that it can be used in the subclasses to assert
94 // something different depending on which phase the GC is in. This
95 // can be particularly helpful in the check_mt_safety() methods.
96 static HRSPhase _phase;
98 // Only used by HRSPhaseSetter.
99 static void clear_phase();
100 static void set_phase(HRSPhase phase);
102 // verify_region() is used to ensure that the contents of a region
103 // added to / removed from a set are consistent. Different sets
104 // make different assumptions about the regions added to them. So
105 // each set can override verify_region_extra(), which is called
106 // from verify_region(), and do any extra verification it needs to
107 // perform in that.
108 virtual const char* verify_region_extra(HeapRegion* hr) { return NULL; }
109 bool verify_region(HeapRegion* hr,
110 HeapRegionSetBase* expected_containing_set);
112 // Indicates whether all regions in the set should be humongous or
113 // not. Only used during verification.
114 virtual bool regions_humongous() = 0;
116 // Indicates whether all regions in the set should be empty or
117 // not. Only used during verification.
118 virtual bool regions_empty() = 0;
120 // Subclasses can optionally override this to do MT safety protocol
121 // checks. It is called in an assert from all methods that perform
122 // updates on the set (and subclasses should also call it too).
123 virtual bool check_mt_safety() { return true; }
125 // fill_in_ext_msg() writes the the values of the set's attributes
126 // in the custom err_msg (hrs_ext_msg). fill_in_ext_msg_extra()
127 // allows subclasses to append further information.
128 virtual void fill_in_ext_msg_extra(hrs_ext_msg* msg) { }
129 void fill_in_ext_msg(hrs_ext_msg* msg, const char* message);
131 // It updates the fields of the set to reflect hr being added to
132 // the set.
133 inline void update_for_addition(HeapRegion* hr);
135 // It updates the fields of the set to reflect hr being added to
136 // the set and tags the region appropriately.
137 inline void add_internal(HeapRegion* hr);
139 // It updates the fields of the set to reflect hr being removed
140 // from the set.
141 inline void update_for_removal(HeapRegion* hr);
143 // It updates the fields of the set to reflect hr being removed
144 // from the set and tags the region appropriately.
145 inline void remove_internal(HeapRegion* hr);
147 // It clears all the fields of the sets. Note: it will not iterate
148 // over the set and remove regions from it. It assumes that the
149 // caller has already done so. It will literally just clear the fields.
150 virtual void clear();
152 HeapRegionSetBase(const char* name);
154 public:
155 static void set_unrealistically_long_length(size_t len);
157 const char* name() { return _name; }
159 size_t length() { return _length; }
161 bool is_empty() { return _length == 0; }
163 size_t region_num() { return _region_num; }
165 size_t total_capacity_bytes() {
166 return region_num() << HeapRegion::LogOfHRGrainBytes;
167 }
169 size_t total_used_bytes() { return _total_used_bytes; }
171 virtual void verify();
172 void verify_start();
173 void verify_next_region(HeapRegion* hr);
174 void verify_end();
176 #if HEAP_REGION_SET_FORCE_VERIFY
177 void verify_optional() {
178 verify();
179 }
180 #else // HEAP_REGION_SET_FORCE_VERIFY
181 void verify_optional() { }
182 #endif // HEAP_REGION_SET_FORCE_VERIFY
184 virtual void print_on(outputStream* out, bool print_contents = false);
185 };
187 // Customized err_msg for heap region sets. Apart from a
188 // assert/guarantee-specific message it also prints out the values of
189 // the fields of the associated set. This can be very helpful in
190 // diagnosing failures.
192 class hrs_ext_msg : public hrs_err_msg {
193 public:
194 hrs_ext_msg(HeapRegionSetBase* set, const char* message) : hrs_err_msg("") {
195 set->fill_in_ext_msg(this, message);
196 }
197 };
199 class HRSPhaseSetter {
200 public:
201 HRSPhaseSetter(HRSPhase phase) {
202 HeapRegionSetBase::set_phase(phase);
203 }
204 ~HRSPhaseSetter() {
205 HeapRegionSetBase::clear_phase();
206 }
207 };
209 // These two macros are provided for convenience, to keep the uses of
210 // these two asserts a bit more concise.
212 #define hrs_assert_mt_safety_ok(_set_) \
213 do { \
214 assert((_set_)->check_mt_safety(), hrs_ext_msg((_set_), "MT safety")); \
215 } while (0)
217 #define hrs_assert_region_ok(_set_, _hr_, _expected_) \
218 do { \
219 assert((_set_)->verify_region((_hr_), (_expected_)), \
220 hrs_ext_msg((_set_), "region verification")); \
221 } while (0)
223 //////////////////// HeapRegionSet ////////////////////
225 #define hrs_assert_sets_match(_set1_, _set2_) \
226 do { \
227 assert(((_set1_)->regions_humongous() == \
228 (_set2_)->regions_humongous()) && \
229 ((_set1_)->regions_empty() == (_set2_)->regions_empty()), \
230 hrs_err_msg("the contents of set %s and set %s should match", \
231 (_set1_)->name(), (_set2_)->name())); \
232 } while (0)
234 // This class represents heap region sets whose members are not
235 // explicitly tracked. It's helpful to group regions using such sets
236 // so that we can reason about all the region groups in the heap using
237 // the same interface (namely, the HeapRegionSetBase API).
239 class HeapRegionSet : public HeapRegionSetBase {
240 protected:
241 virtual const char* verify_region_extra(HeapRegion* hr) {
242 if (hr->next() != NULL) {
243 return "next() should always be NULL as we do not link the regions";
244 }
246 return HeapRegionSetBase::verify_region_extra(hr);
247 }
249 HeapRegionSet(const char* name) : HeapRegionSetBase(name) {
250 clear();
251 }
253 public:
254 // It adds hr to the set. The region should not be a member of
255 // another set.
256 inline void add(HeapRegion* hr);
258 // It removes hr from the set. The region should be a member of
259 // this set.
260 inline void remove(HeapRegion* hr);
262 // It removes a region from the set. Instead of updating the fields
263 // of the set to reflect this removal, it accumulates the updates
264 // in proxy_set. The idea is that proxy_set is thread-local to
265 // avoid multiple threads updating the fields of the set
266 // concurrently and having to synchronize. The method
267 // update_from_proxy() will update the fields of the set from the
268 // proxy_set.
269 inline void remove_with_proxy(HeapRegion* hr, HeapRegionSet* proxy_set);
271 // After multiple calls to remove_with_proxy() the updates to the
272 // fields of the set are accumulated in proxy_set. This call
273 // updates the fields of the set from proxy_set.
274 void update_from_proxy(HeapRegionSet* proxy_set);
275 };
277 //////////////////// HeapRegionLinkedList ////////////////////
279 // A set that links all the regions added to it in a singly-linked
280 // list. We should try to avoid doing operations that iterate over
281 // such lists in performance critical paths. Typically we should
282 // add / remove one region at a time or concatenate two lists. All
283 // those operations are done in constant time.
285 class HeapRegionLinkedListIterator;
287 class HeapRegionLinkedList : public HeapRegionSetBase {
288 friend class HeapRegionLinkedListIterator;
290 private:
291 HeapRegion* _head;
292 HeapRegion* _tail;
294 // These are provided for use by the friend classes.
295 HeapRegion* head() { return _head; }
296 HeapRegion* tail() { return _tail; }
298 protected:
299 virtual void fill_in_ext_msg_extra(hrs_ext_msg* msg);
301 // See the comment for HeapRegionSetBase::clear()
302 virtual void clear();
304 HeapRegionLinkedList(const char* name) : HeapRegionSetBase(name) {
305 clear();
306 }
308 public:
309 // It adds hr to the list as the new head. The region should not be
310 // a member of another set.
311 inline void add_as_head(HeapRegion* hr);
313 // It adds hr to the list as the new tail. The region should not be
314 // a member of another set.
315 inline void add_as_tail(HeapRegion* hr);
317 // It removes and returns the head of the list. It assumes that the
318 // list is not empty so it will return a non-NULL value.
319 inline HeapRegion* remove_head();
321 // Convenience method.
322 inline HeapRegion* remove_head_or_null();
324 // It moves the regions from from_list to this list and empties
325 // from_list. The new regions will appear in the same order as they
326 // were in from_list and be linked in the beginning of this list.
327 void add_as_head(HeapRegionLinkedList* from_list);
329 // It moves the regions from from_list to this list and empties
330 // from_list. The new regions will appear in the same order as they
331 // were in from_list and be linked in the end of this list.
332 void add_as_tail(HeapRegionLinkedList* from_list);
334 // It empties the list by removing all regions from it.
335 void remove_all();
337 // It removes all regions in the list that are pending for removal
338 // (i.e., they have been tagged with "pending_removal"). The list
339 // must not be empty, target_count should reflect the exact number
340 // of regions that are pending for removal in the list, and
341 // target_count should be > 1 (currently, we never need to remove a
342 // single region using this).
343 void remove_all_pending(size_t target_count);
345 virtual void verify();
347 virtual void print_on(outputStream* out, bool print_contents = false);
348 };
350 //////////////////// HeapRegionLinkedListIterator ////////////////////
352 // Iterator class that provides a convenient way to iterate over the
353 // regions of a HeapRegionLinkedList instance.
355 class HeapRegionLinkedListIterator : public StackObj {
356 private:
357 HeapRegionLinkedList* _list;
358 HeapRegion* _curr;
360 public:
361 bool more_available() {
362 return _curr != NULL;
363 }
365 HeapRegion* get_next() {
366 assert(more_available(),
367 "get_next() should be called when more regions are available");
369 // If we are going to introduce a count in the iterator we should
370 // do the "cycle" check.
372 HeapRegion* hr = _curr;
373 assert(_list->verify_region(hr, _list), "region verification");
374 _curr = hr->next();
375 return hr;
376 }
378 HeapRegionLinkedListIterator(HeapRegionLinkedList* list)
379 : _curr(NULL), _list(list) {
380 _curr = list->head();
381 }
382 };
384 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSET_HPP