Mercurial > hg > truffle
annotate src/share/vm/gc_interface/collectedHeap.hpp @ 845:df6caf649ff7
6700789: G1: Enable use of compressed oops with G1 heaps
Summary: Modifications to G1 so as to allow the use of compressed oops.
Reviewed-by: apetrusenko, coleenp, jmasa, kvn, never, phh, tonyp
| author | ysr |
|---|---|
| date | Tue, 14 Jul 2009 15:40:39 -0700 |
| parents | 7bb995fbd3c0 |
| children | 8b46c4d82093 148e5441d916 |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 579 | 2 * Copyright 2001-2009 Sun Microsystems, Inc. All Rights Reserved. |
| 0 | 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 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This | |
| 26 // is an abstract class: there may be many different kinds of heaps. This | |
| 27 // class defines the functions that a heap must implement, and contains | |
| 28 // infrastructure common to all heaps. | |
| 29 | |
| 30 class BarrierSet; | |
| 31 class ThreadClosure; | |
| 32 class AdaptiveSizePolicy; | |
| 33 class Thread; | |
| 34 | |
| 35 // | |
| 36 // CollectedHeap | |
| 37 // SharedHeap | |
| 38 // GenCollectedHeap | |
| 39 // G1CollectedHeap | |
| 40 // ParallelScavengeHeap | |
| 41 // | |
| 42 class CollectedHeap : public CHeapObj { | |
| 43 friend class VMStructs; | |
| 44 friend class IsGCActiveMark; // Block structured external access to _is_gc_active | |
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45 friend class constantPoolCacheKlass; // allocate() method inserts is_conc_safe |
| 0 | 46 |
| 47 #ifdef ASSERT | |
| 48 static int _fire_out_of_memory_count; | |
| 49 #endif | |
| 50 | |
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51 // Used for filler objects (static, but initialized in ctor). |
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52 static size_t _filler_array_max_size; |
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53 |
| 0 | 54 protected: |
| 55 MemRegion _reserved; | |
| 56 BarrierSet* _barrier_set; | |
| 57 bool _is_gc_active; | |
| 58 unsigned int _total_collections; // ... started | |
| 59 unsigned int _total_full_collections; // ... started | |
| 60 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;) | |
| 61 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;) | |
| 62 | |
| 63 // Reason for current garbage collection. Should be set to | |
| 64 // a value reflecting no collection between collections. | |
| 65 GCCause::Cause _gc_cause; | |
| 66 GCCause::Cause _gc_lastcause; | |
| 67 PerfStringVariable* _perf_gc_cause; | |
| 68 PerfStringVariable* _perf_gc_lastcause; | |
| 69 | |
| 70 // Constructor | |
| 71 CollectedHeap(); | |
| 72 | |
| 73 // Create a new tlab | |
| 74 virtual HeapWord* allocate_new_tlab(size_t size); | |
| 75 | |
| 76 // Fix up tlabs to make the heap well-formed again, | |
| 77 // optionally retiring the tlabs. | |
| 78 virtual void fill_all_tlabs(bool retire); | |
| 79 | |
| 80 // Accumulate statistics on all tlabs. | |
| 81 virtual void accumulate_statistics_all_tlabs(); | |
| 82 | |
| 83 // Reinitialize tlabs before resuming mutators. | |
| 84 virtual void resize_all_tlabs(); | |
| 85 | |
| 86 protected: | |
| 87 // Allocate from the current thread's TLAB, with broken-out slow path. | |
| 88 inline static HeapWord* allocate_from_tlab(Thread* thread, size_t size); | |
| 89 static HeapWord* allocate_from_tlab_slow(Thread* thread, size_t size); | |
| 90 | |
| 91 // Allocate an uninitialized block of the given size, or returns NULL if | |
| 92 // this is impossible. | |
| 93 inline static HeapWord* common_mem_allocate_noinit(size_t size, bool is_noref, TRAPS); | |
| 94 | |
| 95 // Like allocate_init, but the block returned by a successful allocation | |
| 96 // is guaranteed initialized to zeros. | |
| 97 inline static HeapWord* common_mem_allocate_init(size_t size, bool is_noref, TRAPS); | |
| 98 | |
| 99 // Same as common_mem version, except memory is allocated in the permanent area | |
| 100 // If there is no permanent area, revert to common_mem_allocate_noinit | |
| 101 inline static HeapWord* common_permanent_mem_allocate_noinit(size_t size, TRAPS); | |
| 102 | |
| 103 // Same as common_mem version, except memory is allocated in the permanent area | |
| 104 // If there is no permanent area, revert to common_mem_allocate_init | |
| 105 inline static HeapWord* common_permanent_mem_allocate_init(size_t size, TRAPS); | |
| 106 | |
| 107 // Helper functions for (VM) allocation. | |
| 108 inline static void post_allocation_setup_common(KlassHandle klass, | |
| 109 HeapWord* obj, size_t size); | |
| 110 inline static void post_allocation_setup_no_klass_install(KlassHandle klass, | |
| 111 HeapWord* objPtr, | |
| 112 size_t size); | |
| 113 | |
| 114 inline static void post_allocation_setup_obj(KlassHandle klass, | |
| 115 HeapWord* obj, size_t size); | |
| 116 | |
| 117 inline static void post_allocation_setup_array(KlassHandle klass, | |
| 118 HeapWord* obj, size_t size, | |
| 119 int length); | |
| 120 | |
| 121 // Clears an allocated object. | |
| 122 inline static void init_obj(HeapWord* obj, size_t size); | |
| 123 | |
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124 // Filler object utilities. |
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125 static inline size_t filler_array_hdr_size(); |
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126 static inline size_t filler_array_min_size(); |
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127 static inline size_t filler_array_max_size(); |
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128 |
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129 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) |
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130 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words);) |
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131 |
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132 // Fill with a single array; caller must ensure filler_array_min_size() <= |
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133 // words <= filler_array_max_size(). |
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134 static inline void fill_with_array(HeapWord* start, size_t words); |
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135 |
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136 // Fill with a single object (either an int array or a java.lang.Object). |
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137 static inline void fill_with_object_impl(HeapWord* start, size_t words); |
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138 |
| 0 | 139 // Verification functions |
| 140 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size) | |
| 141 PRODUCT_RETURN; | |
| 142 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) | |
| 143 PRODUCT_RETURN; | |
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144 debug_only(static void check_for_valid_allocation_state();) |
| 0 | 145 |
| 146 public: | |
| 147 enum Name { | |
| 148 Abstract, | |
| 149 SharedHeap, | |
| 150 GenCollectedHeap, | |
| 151 ParallelScavengeHeap, | |
| 152 G1CollectedHeap | |
| 153 }; | |
| 154 | |
| 155 virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; } | |
| 156 | |
| 157 /** | |
| 158 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, | |
| 159 * and JNI_OK on success. | |
| 160 */ | |
| 161 virtual jint initialize() = 0; | |
| 162 | |
| 163 // In many heaps, there will be a need to perform some initialization activities | |
| 164 // after the Universe is fully formed, but before general heap allocation is allowed. | |
| 165 // This is the correct place to place such initialization methods. | |
| 166 virtual void post_initialize() = 0; | |
| 167 | |
| 168 MemRegion reserved_region() const { return _reserved; } | |
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169 address base() const { return (address)reserved_region().start(); } |
| 0 | 170 |
| 171 // Future cleanup here. The following functions should specify bytes or | |
| 172 // heapwords as part of their signature. | |
| 173 virtual size_t capacity() const = 0; | |
| 174 virtual size_t used() const = 0; | |
| 175 | |
| 176 // Return "true" if the part of the heap that allocates Java | |
| 177 // objects has reached the maximal committed limit that it can | |
| 178 // reach, without a garbage collection. | |
| 179 virtual bool is_maximal_no_gc() const = 0; | |
| 180 | |
| 181 virtual size_t permanent_capacity() const = 0; | |
| 182 virtual size_t permanent_used() const = 0; | |
| 183 | |
| 184 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of | |
| 185 // memory that the vm could make available for storing 'normal' java objects. | |
| 186 // This is based on the reserved address space, but should not include space | |
| 187 // that the vm uses internally for bookkeeping or temporary storage (e.g., | |
| 188 // perm gen space or, in the case of the young gen, one of the survivor | |
| 189 // spaces). | |
| 190 virtual size_t max_capacity() const = 0; | |
| 191 | |
| 192 // Returns "TRUE" if "p" points into the reserved area of the heap. | |
| 193 bool is_in_reserved(const void* p) const { | |
| 194 return _reserved.contains(p); | |
| 195 } | |
| 196 | |
| 197 bool is_in_reserved_or_null(const void* p) const { | |
| 198 return p == NULL || is_in_reserved(p); | |
| 199 } | |
| 200 | |
| 201 // Returns "TRUE" if "p" points to the head of an allocated object in the | |
| 202 // heap. Since this method can be expensive in general, we restrict its | |
| 203 // use to assertion checking only. | |
| 204 virtual bool is_in(const void* p) const = 0; | |
| 205 | |
| 206 bool is_in_or_null(const void* p) const { | |
| 207 return p == NULL || is_in(p); | |
| 208 } | |
| 209 | |
| 210 // Let's define some terms: a "closed" subset of a heap is one that | |
| 211 // | |
| 212 // 1) contains all currently-allocated objects, and | |
| 213 // | |
| 214 // 2) is closed under reference: no object in the closed subset | |
| 215 // references one outside the closed subset. | |
| 216 // | |
| 217 // Membership in a heap's closed subset is useful for assertions. | |
| 218 // Clearly, the entire heap is a closed subset, so the default | |
| 219 // implementation is to use "is_in_reserved". But this may not be too | |
| 220 // liberal to perform useful checking. Also, the "is_in" predicate | |
| 221 // defines a closed subset, but may be too expensive, since "is_in" | |
| 222 // verifies that its argument points to an object head. The | |
| 223 // "closed_subset" method allows a heap to define an intermediate | |
| 224 // predicate, allowing more precise checking than "is_in_reserved" at | |
| 225 // lower cost than "is_in." | |
| 226 | |
| 227 // One important case is a heap composed of disjoint contiguous spaces, | |
| 228 // such as the Garbage-First collector. Such heaps have a convenient | |
| 229 // closed subset consisting of the allocated portions of those | |
| 230 // contiguous spaces. | |
| 231 | |
| 232 // Return "TRUE" iff the given pointer points into the heap's defined | |
| 233 // closed subset (which defaults to the entire heap). | |
| 234 virtual bool is_in_closed_subset(const void* p) const { | |
| 235 return is_in_reserved(p); | |
| 236 } | |
| 237 | |
| 238 bool is_in_closed_subset_or_null(const void* p) const { | |
| 239 return p == NULL || is_in_closed_subset(p); | |
| 240 } | |
| 241 | |
| 242 // Returns "TRUE" if "p" is allocated as "permanent" data. | |
| 243 // If the heap does not use "permanent" data, returns the same | |
| 244 // value is_in_reserved() would return. | |
| 245 // NOTE: this actually returns true if "p" is in reserved space | |
| 246 // for the space not that it is actually allocated (i.e. in committed | |
| 247 // space). If you need the more conservative answer use is_permanent(). | |
| 248 virtual bool is_in_permanent(const void *p) const = 0; | |
| 249 | |
| 250 // Returns "TRUE" if "p" is in the committed area of "permanent" data. | |
| 251 // If the heap does not use "permanent" data, returns the same | |
| 252 // value is_in() would return. | |
| 253 virtual bool is_permanent(const void *p) const = 0; | |
| 254 | |
| 255 bool is_in_permanent_or_null(const void *p) const { | |
| 256 return p == NULL || is_in_permanent(p); | |
| 257 } | |
| 258 | |
| 259 // Returns "TRUE" if "p" is a method oop in the | |
| 260 // current heap, with high probability. This predicate | |
| 261 // is not stable, in general. | |
| 262 bool is_valid_method(oop p) const; | |
| 263 | |
| 264 void set_gc_cause(GCCause::Cause v) { | |
| 265 if (UsePerfData) { | |
| 266 _gc_lastcause = _gc_cause; | |
| 267 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); | |
| 268 _perf_gc_cause->set_value(GCCause::to_string(v)); | |
| 269 } | |
| 270 _gc_cause = v; | |
| 271 } | |
| 272 GCCause::Cause gc_cause() { return _gc_cause; } | |
| 273 | |
| 274 // Preload classes into the shared portion of the heap, and then dump | |
| 275 // that data to a file so that it can be loaded directly by another | |
| 276 // VM (then terminate). | |
| 277 virtual void preload_and_dump(TRAPS) { ShouldNotReachHere(); } | |
| 278 | |
| 279 // General obj/array allocation facilities. | |
| 280 inline static oop obj_allocate(KlassHandle klass, int size, TRAPS); | |
| 281 inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS); | |
| 282 inline static oop large_typearray_allocate(KlassHandle klass, int size, int length, TRAPS); | |
| 283 | |
| 284 // Special obj/array allocation facilities. | |
| 285 // Some heaps may want to manage "permanent" data uniquely. These default | |
| 286 // to the general routines if the heap does not support such handling. | |
| 287 inline static oop permanent_obj_allocate(KlassHandle klass, int size, TRAPS); | |
| 288 // permanent_obj_allocate_no_klass_install() does not do the installation of | |
| 289 // the klass pointer in the newly created object (as permanent_obj_allocate() | |
| 290 // above does). This allows for a delay in the installation of the klass | |
| 291 // pointer that is needed during the create of klassKlass's. The | |
| 292 // method post_allocation_install_obj_klass() is used to install the | |
| 293 // klass pointer. | |
| 294 inline static oop permanent_obj_allocate_no_klass_install(KlassHandle klass, | |
| 295 int size, | |
| 296 TRAPS); | |
| 297 inline static void post_allocation_install_obj_klass(KlassHandle klass, | |
| 298 oop obj, | |
| 299 int size); | |
| 300 inline static oop permanent_array_allocate(KlassHandle klass, int size, int length, TRAPS); | |
| 301 | |
| 302 // Raw memory allocation facilities | |
| 303 // The obj and array allocate methods are covers for these methods. | |
| 304 // The permanent allocation method should default to mem_allocate if | |
| 305 // permanent memory isn't supported. | |
| 306 virtual HeapWord* mem_allocate(size_t size, | |
| 307 bool is_noref, | |
| 308 bool is_tlab, | |
| 309 bool* gc_overhead_limit_was_exceeded) = 0; | |
| 310 virtual HeapWord* permanent_mem_allocate(size_t size) = 0; | |
| 311 | |
| 312 // The boundary between a "large" and "small" array of primitives, in words. | |
| 313 virtual size_t large_typearray_limit() = 0; | |
| 314 | |
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315 // Utilities for turning raw memory into filler objects. |
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316 // |
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317 // min_fill_size() is the smallest region that can be filled. |
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318 // fill_with_objects() can fill arbitrary-sized regions of the heap using |
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319 // multiple objects. fill_with_object() is for regions known to be smaller |
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320 // than the largest array of integers; it uses a single object to fill the |
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321 // region and has slightly less overhead. |
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322 static size_t min_fill_size() { |
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323 return size_t(align_object_size(oopDesc::header_size())); |
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324 } |
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325 |
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326 static void fill_with_objects(HeapWord* start, size_t words); |
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327 |
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328 static void fill_with_object(HeapWord* start, size_t words); |
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329 static void fill_with_object(MemRegion region) { |
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330 fill_with_object(region.start(), region.word_size()); |
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331 } |
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332 static void fill_with_object(HeapWord* start, HeapWord* end) { |
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333 fill_with_object(start, pointer_delta(end, start)); |
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334 } |
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335 |
| 0 | 336 // Some heaps may offer a contiguous region for shared non-blocking |
| 337 // allocation, via inlined code (by exporting the address of the top and | |
| 338 // end fields defining the extent of the contiguous allocation region.) | |
| 339 | |
| 340 // This function returns "true" iff the heap supports this kind of | |
| 341 // allocation. (Default is "no".) | |
| 342 virtual bool supports_inline_contig_alloc() const { | |
| 343 return false; | |
| 344 } | |
| 345 // These functions return the addresses of the fields that define the | |
| 346 // boundaries of the contiguous allocation area. (These fields should be | |
| 347 // physically near to one another.) | |
| 348 virtual HeapWord** top_addr() const { | |
| 349 guarantee(false, "inline contiguous allocation not supported"); | |
| 350 return NULL; | |
| 351 } | |
| 352 virtual HeapWord** end_addr() const { | |
| 353 guarantee(false, "inline contiguous allocation not supported"); | |
| 354 return NULL; | |
| 355 } | |
| 356 | |
| 357 // Some heaps may be in an unparseable state at certain times between | |
| 358 // collections. This may be necessary for efficient implementation of | |
| 359 // certain allocation-related activities. Calling this function before | |
| 360 // attempting to parse a heap ensures that the heap is in a parsable | |
| 361 // state (provided other concurrent activity does not introduce | |
| 362 // unparsability). It is normally expected, therefore, that this | |
| 363 // method is invoked with the world stopped. | |
| 364 // NOTE: if you override this method, make sure you call | |
| 365 // super::ensure_parsability so that the non-generational | |
| 366 // part of the work gets done. See implementation of | |
| 367 // CollectedHeap::ensure_parsability and, for instance, | |
| 368 // that of GenCollectedHeap::ensure_parsability(). | |
| 369 // The argument "retire_tlabs" controls whether existing TLABs | |
| 370 // are merely filled or also retired, thus preventing further | |
| 371 // allocation from them and necessitating allocation of new TLABs. | |
| 372 virtual void ensure_parsability(bool retire_tlabs); | |
| 373 | |
| 374 // Return an estimate of the maximum allocation that could be performed | |
| 375 // without triggering any collection or expansion activity. In a | |
| 376 // generational collector, for example, this is probably the largest | |
| 377 // allocation that could be supported (without expansion) in the youngest | |
| 378 // generation. It is "unsafe" because no locks are taken; the result | |
| 379 // should be treated as an approximation, not a guarantee, for use in | |
| 380 // heuristic resizing decisions. | |
| 381 virtual size_t unsafe_max_alloc() = 0; | |
| 382 | |
| 383 // Section on thread-local allocation buffers (TLABs) | |
| 384 // If the heap supports thread-local allocation buffers, it should override | |
| 385 // the following methods: | |
| 386 // Returns "true" iff the heap supports thread-local allocation buffers. | |
| 387 // The default is "no". | |
| 388 virtual bool supports_tlab_allocation() const { | |
| 389 return false; | |
| 390 } | |
| 391 // The amount of space available for thread-local allocation buffers. | |
| 392 virtual size_t tlab_capacity(Thread *thr) const { | |
| 393 guarantee(false, "thread-local allocation buffers not supported"); | |
| 394 return 0; | |
| 395 } | |
| 396 // An estimate of the maximum allocation that could be performed | |
| 397 // for thread-local allocation buffers without triggering any | |
| 398 // collection or expansion activity. | |
| 399 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { | |
| 400 guarantee(false, "thread-local allocation buffers not supported"); | |
| 401 return 0; | |
| 402 } | |
| 403 // Can a compiler initialize a new object without store barriers? | |
| 404 // This permission only extends from the creation of a new object | |
| 405 // via a TLAB up to the first subsequent safepoint. | |
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406 virtual bool can_elide_tlab_store_barriers() const = 0; |
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407 |
| 0 | 408 // If a compiler is eliding store barriers for TLAB-allocated objects, |
| 409 // there is probably a corresponding slow path which can produce | |
| 410 // an object allocated anywhere. The compiler's runtime support | |
| 411 // promises to call this function on such a slow-path-allocated | |
| 412 // object before performing initializations that have elided | |
| 413 // store barriers. Returns new_obj, or maybe a safer copy thereof. | |
| 414 virtual oop new_store_barrier(oop new_obj); | |
| 415 | |
| 416 // Can a compiler elide a store barrier when it writes | |
| 417 // a permanent oop into the heap? Applies when the compiler | |
| 418 // is storing x to the heap, where x->is_perm() is true. | |
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419 virtual bool can_elide_permanent_oop_store_barriers() const = 0; |
| 0 | 420 |
| 421 // Does this heap support heap inspection (+PrintClassHistogram?) | |
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422 virtual bool supports_heap_inspection() const = 0; |
| 0 | 423 |
| 424 // Perform a collection of the heap; intended for use in implementing | |
| 425 // "System.gc". This probably implies as full a collection as the | |
| 426 // "CollectedHeap" supports. | |
| 427 virtual void collect(GCCause::Cause cause) = 0; | |
| 428 | |
| 429 // This interface assumes that it's being called by the | |
| 430 // vm thread. It collects the heap assuming that the | |
| 431 // heap lock is already held and that we are executing in | |
| 432 // the context of the vm thread. | |
| 433 virtual void collect_as_vm_thread(GCCause::Cause cause) = 0; | |
| 434 | |
| 435 // Returns the barrier set for this heap | |
| 436 BarrierSet* barrier_set() { return _barrier_set; } | |
| 437 | |
| 438 // Returns "true" iff there is a stop-world GC in progress. (I assume | |
| 439 // that it should answer "false" for the concurrent part of a concurrent | |
| 440 // collector -- dld). | |
| 441 bool is_gc_active() const { return _is_gc_active; } | |
| 442 | |
| 443 // Total number of GC collections (started) | |
| 444 unsigned int total_collections() const { return _total_collections; } | |
| 445 unsigned int total_full_collections() const { return _total_full_collections;} | |
| 446 | |
| 447 // Increment total number of GC collections (started) | |
| 448 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2 | |
| 449 void increment_total_collections(bool full = false) { | |
| 450 _total_collections++; | |
| 451 if (full) { | |
| 452 increment_total_full_collections(); | |
| 453 } | |
| 454 } | |
| 455 | |
| 456 void increment_total_full_collections() { _total_full_collections++; } | |
| 457 | |
| 458 // Return the AdaptiveSizePolicy for the heap. | |
| 459 virtual AdaptiveSizePolicy* size_policy() = 0; | |
| 460 | |
| 461 // Iterate over all the ref-containing fields of all objects, calling | |
| 462 // "cl.do_oop" on each. This includes objects in permanent memory. | |
| 463 virtual void oop_iterate(OopClosure* cl) = 0; | |
| 464 | |
| 465 // Iterate over all objects, calling "cl.do_object" on each. | |
| 466 // This includes objects in permanent memory. | |
| 467 virtual void object_iterate(ObjectClosure* cl) = 0; | |
| 468 | |
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469 // Similar to object_iterate() except iterates only |
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470 // over live objects. |
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471 virtual void safe_object_iterate(ObjectClosure* cl) = 0; |
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472 |
| 0 | 473 // Behaves the same as oop_iterate, except only traverses |
| 474 // interior pointers contained in permanent memory. If there | |
| 475 // is no permanent memory, does nothing. | |
| 476 virtual void permanent_oop_iterate(OopClosure* cl) = 0; | |
| 477 | |
| 478 // Behaves the same as object_iterate, except only traverses | |
| 479 // object contained in permanent memory. If there is no | |
| 480 // permanent memory, does nothing. | |
| 481 virtual void permanent_object_iterate(ObjectClosure* cl) = 0; | |
| 482 | |
| 483 // NOTE! There is no requirement that a collector implement these | |
| 484 // functions. | |
| 485 // | |
| 486 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, | |
| 487 // each address in the (reserved) heap is a member of exactly | |
| 488 // one block. The defining characteristic of a block is that it is | |
| 489 // possible to find its size, and thus to progress forward to the next | |
| 490 // block. (Blocks may be of different sizes.) Thus, blocks may | |
| 491 // represent Java objects, or they might be free blocks in a | |
| 492 // free-list-based heap (or subheap), as long as the two kinds are | |
| 493 // distinguishable and the size of each is determinable. | |
| 494 | |
| 495 // Returns the address of the start of the "block" that contains the | |
| 496 // address "addr". We say "blocks" instead of "object" since some heaps | |
| 497 // may not pack objects densely; a chunk may either be an object or a | |
| 498 // non-object. | |
| 499 virtual HeapWord* block_start(const void* addr) const = 0; | |
| 500 | |
| 501 // Requires "addr" to be the start of a chunk, and returns its size. | |
| 502 // "addr + size" is required to be the start of a new chunk, or the end | |
| 503 // of the active area of the heap. | |
| 504 virtual size_t block_size(const HeapWord* addr) const = 0; | |
| 505 | |
| 506 // Requires "addr" to be the start of a block, and returns "TRUE" iff | |
| 507 // the block is an object. | |
| 508 virtual bool block_is_obj(const HeapWord* addr) const = 0; | |
| 509 | |
| 510 // Returns the longest time (in ms) that has elapsed since the last | |
| 511 // time that any part of the heap was examined by a garbage collection. | |
| 512 virtual jlong millis_since_last_gc() = 0; | |
| 513 | |
| 514 // Perform any cleanup actions necessary before allowing a verification. | |
| 515 virtual void prepare_for_verify() = 0; | |
| 516 | |
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517 // Generate any dumps preceding or following a full gc |
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518 void pre_full_gc_dump(); |
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519 void post_full_gc_dump(); |
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520 |
| 0 | 521 virtual void print() const = 0; |
| 522 virtual void print_on(outputStream* st) const = 0; | |
| 523 | |
| 524 // Print all GC threads (other than the VM thread) | |
| 525 // used by this heap. | |
| 526 virtual void print_gc_threads_on(outputStream* st) const = 0; | |
| 527 void print_gc_threads() { print_gc_threads_on(tty); } | |
| 528 // Iterator for all GC threads (other than VM thread) | |
| 529 virtual void gc_threads_do(ThreadClosure* tc) const = 0; | |
| 530 | |
| 531 // Print any relevant tracing info that flags imply. | |
| 532 // Default implementation does nothing. | |
| 533 virtual void print_tracing_info() const = 0; | |
| 534 | |
| 535 // Heap verification | |
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536 virtual void verify(bool allow_dirty, bool silent, bool option) = 0; |
| 0 | 537 |
| 538 // Non product verification and debugging. | |
| 539 #ifndef PRODUCT | |
| 540 // Support for PromotionFailureALot. Return true if it's time to cause a | |
| 541 // promotion failure. The no-argument version uses | |
| 542 // this->_promotion_failure_alot_count as the counter. | |
| 543 inline bool promotion_should_fail(volatile size_t* count); | |
| 544 inline bool promotion_should_fail(); | |
| 545 | |
| 546 // Reset the PromotionFailureALot counters. Should be called at the end of a | |
| 547 // GC in which promotion failure ocurred. | |
| 548 inline void reset_promotion_should_fail(volatile size_t* count); | |
| 549 inline void reset_promotion_should_fail(); | |
| 550 #endif // #ifndef PRODUCT | |
| 551 | |
| 552 #ifdef ASSERT | |
| 553 static int fired_fake_oom() { | |
| 554 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt); | |
| 555 } | |
| 556 #endif | |
| 557 }; | |
| 558 | |
| 559 // Class to set and reset the GC cause for a CollectedHeap. | |
| 560 | |
| 561 class GCCauseSetter : StackObj { | |
| 562 CollectedHeap* _heap; | |
| 563 GCCause::Cause _previous_cause; | |
| 564 public: | |
| 565 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { | |
| 566 assert(SafepointSynchronize::is_at_safepoint(), | |
| 567 "This method manipulates heap state without locking"); | |
| 568 _heap = heap; | |
| 569 _previous_cause = _heap->gc_cause(); | |
| 570 _heap->set_gc_cause(cause); | |
| 571 } | |
| 572 | |
| 573 ~GCCauseSetter() { | |
| 574 assert(SafepointSynchronize::is_at_safepoint(), | |
| 575 "This method manipulates heap state without locking"); | |
| 576 _heap->set_gc_cause(_previous_cause); | |
| 577 } | |
| 578 }; |