--- old/src/share/vm/memory/genCollectedHeap.hpp 2015-05-12 11:41:59.593555984 +0200 +++ /dev/null 2015-03-18 17:10:38.111854831 +0100 @@ -1,518 +0,0 @@ -/* - * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved. - * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. - * - * This code is free software; you can redistribute it and/or modify it - * under the terms of the GNU General Public License version 2 only, as - * published by the Free Software Foundation. - * - * This code is distributed in the hope that it will be useful, but WITHOUT - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License - * version 2 for more details (a copy is included in the LICENSE file that - * accompanied this code). - * - * You should have received a copy of the GNU General Public License version - * 2 along with this work; if not, write to the Free Software Foundation, - * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. - * - * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA - * or visit www.oracle.com if you need additional information or have any - * questions. - * - */ - -#ifndef SHARE_VM_MEMORY_GENCOLLECTEDHEAP_HPP -#define SHARE_VM_MEMORY_GENCOLLECTEDHEAP_HPP - -#include "gc_implementation/shared/adaptiveSizePolicy.hpp" -#include "gc_interface/collectedHeap.hpp" -#include "memory/collectorPolicy.hpp" -#include "memory/generation.hpp" - -class SubTasksDone; -class FlexibleWorkGang; - -// A "GenCollectedHeap" is a CollectedHeap that uses generational -// collection. It has two generations, young and old. -class GenCollectedHeap : public CollectedHeap { - friend class GenCollectorPolicy; - friend class Generation; - friend class DefNewGeneration; - friend class TenuredGeneration; - friend class ConcurrentMarkSweepGeneration; - friend class CMSCollector; - friend class GenMarkSweep; - friend class VM_GenCollectForAllocation; - friend class VM_GenCollectFull; - friend class VM_GenCollectFullConcurrent; - friend class VM_GC_HeapInspection; - friend class VM_HeapDumper; - friend class HeapInspection; - friend class GCCauseSetter; - friend class VMStructs; -public: - friend class VM_PopulateDumpSharedSpace; - -private: - Generation* _young_gen; - Generation* _old_gen; - - // The singleton Gen Remembered Set. - GenRemSet* _rem_set; - - // The generational collector policy. - GenCollectorPolicy* _gen_policy; - - // Indicates that the most recent previous incremental collection failed. - // The flag is cleared when an action is taken that might clear the - // condition that caused that incremental collection to fail. - bool _incremental_collection_failed; - - // In support of ExplicitGCInvokesConcurrent functionality - unsigned int _full_collections_completed; - - // Data structure for claiming the (potentially) parallel tasks in - // (gen-specific) roots processing. - SubTasksDone* _process_strong_tasks; - - // Collects the given generation. - void collect_generation(Generation* gen, bool full, size_t size, bool is_tlab, - bool run_verification, bool clear_soft_refs, - bool restore_marks_for_biased_locking); - - // In block contents verification, the number of header words to skip - NOT_PRODUCT(static size_t _skip_header_HeapWords;) - - FlexibleWorkGang* _workers; - -protected: - // Helper functions for allocation - HeapWord* attempt_allocation(size_t size, - bool is_tlab, - bool first_only); - - // Helper function for two callbacks below. - // Considers collection of the first max_level+1 generations. - void do_collection(bool full, - bool clear_all_soft_refs, - size_t size, - bool is_tlab, - int max_level); - - // Callback from VM_GenCollectForAllocation operation. - // This function does everything necessary/possible to satisfy an - // allocation request that failed in the youngest generation that should - // have handled it (including collection, expansion, etc.) - HeapWord* satisfy_failed_allocation(size_t size, bool is_tlab); - - // Callback from VM_GenCollectFull operation. - // Perform a full collection of the first max_level+1 generations. - virtual void do_full_collection(bool clear_all_soft_refs); - void do_full_collection(bool clear_all_soft_refs, int max_level); - - // Does the "cause" of GC indicate that - // we absolutely __must__ clear soft refs? - bool must_clear_all_soft_refs(); - -public: - GenCollectedHeap(GenCollectorPolicy *policy); - - FlexibleWorkGang* workers() const { return _workers; } - - GCStats* gc_stats(int level) const; - - // Returns JNI_OK on success - virtual jint initialize(); - - // Reserve aligned space for the heap as needed by the contained generations. - char* allocate(size_t alignment, ReservedSpace* heap_rs); - - // Does operations required after initialization has been done. - void post_initialize(); - - // Initialize ("weak") refs processing support - virtual void ref_processing_init(); - - virtual Name kind() const { - return CollectedHeap::GenCollectedHeap; - } - - Generation* young_gen() const { return _young_gen; } - Generation* old_gen() const { return _old_gen; } - - // The generational collector policy. - GenCollectorPolicy* gen_policy() const { return _gen_policy; } - - virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) gen_policy(); } - - // Adaptive size policy - virtual AdaptiveSizePolicy* size_policy() { - return gen_policy()->size_policy(); - } - - // Return the (conservative) maximum heap alignment - static size_t conservative_max_heap_alignment() { - return Generation::GenGrain; - } - - size_t capacity() const; - size_t used() const; - - // Save the "used_region" for generations level and lower. - void save_used_regions(int level); - - size_t max_capacity() const; - - HeapWord* mem_allocate(size_t size, - bool* gc_overhead_limit_was_exceeded); - - // We may support a shared contiguous allocation area, if the youngest - // generation does. - bool supports_inline_contig_alloc() const; - HeapWord** top_addr() const; - HeapWord** end_addr() const; - - // Perform a full collection of the heap; intended for use in implementing - // "System.gc". This implies as full a collection as the CollectedHeap - // supports. Caller does not hold the Heap_lock on entry. - void collect(GCCause::Cause cause); - - // The same as above but assume that the caller holds the Heap_lock. - void collect_locked(GCCause::Cause cause); - - // Perform a full collection of the first max_level+1 generations. - // Mostly used for testing purposes. Caller does not hold the Heap_lock on entry. - void collect(GCCause::Cause cause, int max_level); - - // Returns "TRUE" iff "p" points into the committed areas of the heap. - // The methods is_in(), is_in_closed_subset() and is_in_youngest() may - // be expensive to compute in general, so, to prevent - // their inadvertent use in product jvm's, we restrict their use to - // assertion checking or verification only. - bool is_in(const void* p) const; - - // override - bool is_in_closed_subset(const void* p) const { - if (UseConcMarkSweepGC) { - return is_in_reserved(p); - } else { - return is_in(p); - } - } - - // Returns true if the reference is to an object in the reserved space - // for the young generation. - // Assumes the the young gen address range is less than that of the old gen. - bool is_in_young(oop p); - -#ifdef ASSERT - bool is_in_partial_collection(const void* p); -#endif - - virtual bool is_scavengable(const void* addr) { - return is_in_young((oop)addr); - } - - // Iteration functions. - void oop_iterate_no_header(OopClosure* cl); - void oop_iterate(ExtendedOopClosure* cl); - void object_iterate(ObjectClosure* cl); - void safe_object_iterate(ObjectClosure* cl); - Space* space_containing(const void* addr) const; - - // A CollectedHeap is divided into a dense sequence of "blocks"; that is, - // each address in the (reserved) heap is a member of exactly - // one block. The defining characteristic of a block is that it is - // possible to find its size, and thus to progress forward to the next - // block. (Blocks may be of different sizes.) Thus, blocks may - // represent Java objects, or they might be free blocks in a - // free-list-based heap (or subheap), as long as the two kinds are - // distinguishable and the size of each is determinable. - - // Returns the address of the start of the "block" that contains the - // address "addr". We say "blocks" instead of "object" since some heaps - // may not pack objects densely; a chunk may either be an object or a - // non-object. - virtual HeapWord* block_start(const void* addr) const; - - // Requires "addr" to be the start of a chunk, and returns its size. - // "addr + size" is required to be the start of a new chunk, or the end - // of the active area of the heap. Assumes (and verifies in non-product - // builds) that addr is in the allocated part of the heap and is - // the start of a chunk. - virtual size_t block_size(const HeapWord* addr) const; - - // Requires "addr" to be the start of a block, and returns "TRUE" iff - // the block is an object. Assumes (and verifies in non-product - // builds) that addr is in the allocated part of the heap and is - // the start of a chunk. - virtual bool block_is_obj(const HeapWord* addr) const; - - // Section on TLAB's. - virtual bool supports_tlab_allocation() const; - virtual size_t tlab_capacity(Thread* thr) const; - virtual size_t tlab_used(Thread* thr) const; - virtual size_t unsafe_max_tlab_alloc(Thread* thr) const; - virtual HeapWord* allocate_new_tlab(size_t size); - - // Can a compiler initialize a new object without store barriers? - // This permission only extends from the creation of a new object - // via a TLAB up to the first subsequent safepoint. - virtual bool can_elide_tlab_store_barriers() const { - return true; - } - - virtual bool card_mark_must_follow_store() const { - return UseConcMarkSweepGC; - } - - // We don't need barriers for stores to objects in the - // young gen and, a fortiori, for initializing stores to - // objects therein. This applies to DefNew+Tenured and ParNew+CMS - // only and may need to be re-examined in case other - // kinds of collectors are implemented in the future. - virtual bool can_elide_initializing_store_barrier(oop new_obj) { - return is_in_young(new_obj); - } - - // The "requestor" generation is performing some garbage collection - // action for which it would be useful to have scratch space. The - // requestor promises to allocate no more than "max_alloc_words" in any - // older generation (via promotion say.) Any blocks of space that can - // be provided are returned as a list of ScratchBlocks, sorted by - // decreasing size. - ScratchBlock* gather_scratch(Generation* requestor, size_t max_alloc_words); - // Allow each generation to reset any scratch space that it has - // contributed as it needs. - void release_scratch(); - - // Ensure parsability: override - virtual void ensure_parsability(bool retire_tlabs); - - // Time in ms since the longest time a collector ran in - // in any generation. - virtual jlong millis_since_last_gc(); - - // Total number of full collections completed. - unsigned int total_full_collections_completed() { - assert(_full_collections_completed <= _total_full_collections, - "Can't complete more collections than were started"); - return _full_collections_completed; - } - - // Update above counter, as appropriate, at the end of a stop-world GC cycle - unsigned int update_full_collections_completed(); - // Update above counter, as appropriate, at the end of a concurrent GC cycle - unsigned int update_full_collections_completed(unsigned int count); - - // Update "time of last gc" for all generations to "now". - void update_time_of_last_gc(jlong now) { - _young_gen->update_time_of_last_gc(now); - _old_gen->update_time_of_last_gc(now); - } - - // Update the gc statistics for each generation. - // "level" is the level of the latest collection. - void update_gc_stats(int current_level, bool full) { - _young_gen->update_gc_stats(current_level, full); - _old_gen->update_gc_stats(current_level, full); - } - - bool no_gc_in_progress() { return !is_gc_active(); } - - // Override. - void prepare_for_verify(); - - // Override. - void verify(bool silent, VerifyOption option); - - // Override. - virtual void print_on(outputStream* st) const; - virtual void print_gc_threads_on(outputStream* st) const; - virtual void gc_threads_do(ThreadClosure* tc) const; - virtual void print_tracing_info() const; - virtual void print_on_error(outputStream* st) const; - - // PrintGC, PrintGCDetails support - void print_heap_change(size_t prev_used) const; - - // The functions below are helper functions that a subclass of - // "CollectedHeap" can use in the implementation of its virtual - // functions. - - class GenClosure : public StackObj { - public: - virtual void do_generation(Generation* gen) = 0; - }; - - // Apply "cl.do_generation" to all generations in the heap - // If "old_to_young" determines the order. - void generation_iterate(GenClosure* cl, bool old_to_young); - - // Return "true" if all generations have reached the - // maximal committed limit that they can reach, without a garbage - // collection. - virtual bool is_maximal_no_gc() const; - - // This function returns the "GenRemSet" object that allows us to scan - // generations in a fully generational heap. - GenRemSet* rem_set() { return _rem_set; } - - // Convenience function to be used in situations where the heap type can be - // asserted to be this type. - static GenCollectedHeap* heap(); - - void set_par_threads(uint t); - void set_n_termination(uint t); - - // Invoke the "do_oop" method of one of the closures "not_older_gens" - // or "older_gens" on root locations for the generation at - // "level". (The "older_gens" closure is used for scanning references - // from older generations; "not_older_gens" is used everywhere else.) - // If "younger_gens_as_roots" is false, younger generations are - // not scanned as roots; in this case, the caller must be arranging to - // scan the younger generations itself. (For example, a generation might - // explicitly mark reachable objects in younger generations, to avoid - // excess storage retention.) - // The "so" argument determines which of the roots - // the closure is applied to: - // "SO_None" does none; - enum ScanningOption { - SO_None = 0x0, - SO_AllCodeCache = 0x8, - SO_ScavengeCodeCache = 0x10 - }; - - private: - void process_roots(bool activate_scope, - ScanningOption so, - OopClosure* strong_roots, - OopClosure* weak_roots, - CLDClosure* strong_cld_closure, - CLDClosure* weak_cld_closure, - CodeBlobClosure* code_roots); - - void gen_process_roots(int level, - bool younger_gens_as_roots, - bool activate_scope, - ScanningOption so, - OopsInGenClosure* not_older_gens, - OopsInGenClosure* weak_roots, - OopsInGenClosure* older_gens, - CLDClosure* cld_closure, - CLDClosure* weak_cld_closure, - CodeBlobClosure* code_closure); - - public: - static const bool StrongAndWeakRoots = false; - static const bool StrongRootsOnly = true; - - void gen_process_roots(int level, - bool younger_gens_as_roots, - bool activate_scope, - ScanningOption so, - bool only_strong_roots, - OopsInGenClosure* not_older_gens, - OopsInGenClosure* older_gens, - CLDClosure* cld_closure); - - // Apply "root_closure" to all the weak roots of the system. - // These include JNI weak roots, string table, - // and referents of reachable weak refs. - void gen_process_weak_roots(OopClosure* root_closure); - - // Set the saved marks of generations, if that makes sense. - // In particular, if any generation might iterate over the oops - // in other generations, it should call this method. - void save_marks(); - - // Apply "cur->do_oop" or "older->do_oop" to all the oops in objects - // allocated since the last call to save_marks in generations at or above - // "level". The "cur" closure is - // applied to references in the generation at "level", and the "older" - // closure to older generations. -#define GCH_SINCE_SAVE_MARKS_ITERATE_DECL(OopClosureType, nv_suffix) \ - void oop_since_save_marks_iterate(int level, \ - OopClosureType* cur, \ - OopClosureType* older); - - ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DECL) - -#undef GCH_SINCE_SAVE_MARKS_ITERATE_DECL - - // Returns "true" iff no allocations have occurred in any generation at - // "level" or above since the last - // call to "save_marks". - bool no_allocs_since_save_marks(int level); - - // Returns true if an incremental collection is likely to fail. - // We optionally consult the young gen, if asked to do so; - // otherwise we base our answer on whether the previous incremental - // collection attempt failed with no corrective action as of yet. - bool incremental_collection_will_fail(bool consult_young) { - // Assumes a 2-generation system; the first disjunct remembers if an - // incremental collection failed, even when we thought (second disjunct) - // that it would not. - assert(heap()->collector_policy()->is_generation_policy(), - "the following definition may not be suitable for an n(>2)-generation system"); - return incremental_collection_failed() || - (consult_young && !_young_gen->collection_attempt_is_safe()); - } - - // If a generation bails out of an incremental collection, - // it sets this flag. - bool incremental_collection_failed() const { - return _incremental_collection_failed; - } - void set_incremental_collection_failed() { - _incremental_collection_failed = true; - } - void clear_incremental_collection_failed() { - _incremental_collection_failed = false; - } - - // Promotion of obj into gen failed. Try to promote obj to higher - // gens in ascending order; return the new location of obj if successful. - // Otherwise, try expand-and-allocate for obj in both the young and old - // generation; return the new location of obj if successful. Otherwise, return NULL. - oop handle_failed_promotion(Generation* old_gen, - oop obj, - size_t obj_size); - -private: - // Accessor for memory state verification support - NOT_PRODUCT( - static size_t skip_header_HeapWords() { return _skip_header_HeapWords; } - ) - - // Override - void check_for_non_bad_heap_word_value(HeapWord* addr, - size_t size) PRODUCT_RETURN; - - // For use by mark-sweep. As implemented, mark-sweep-compact is global - // in an essential way: compaction is performed across generations, by - // iterating over spaces. - void prepare_for_compaction(); - - // Perform a full collection of the first max_level+1 generations. - // This is the low level interface used by the public versions of - // collect() and collect_locked(). Caller holds the Heap_lock on entry. - void collect_locked(GCCause::Cause cause, int max_level); - - // Returns success or failure. - bool create_cms_collector(); - - // In support of ExplicitGCInvokesConcurrent functionality - bool should_do_concurrent_full_gc(GCCause::Cause cause); - void collect_mostly_concurrent(GCCause::Cause cause); - - // Save the tops of the spaces in all generations - void record_gen_tops_before_GC() PRODUCT_RETURN; - -protected: - void gc_prologue(bool full); - void gc_epilogue(bool full); -}; - -#endif // SHARE_VM_MEMORY_GENCOLLECTEDHEAP_HPP --- /dev/null 2015-03-18 17:10:38.111854831 +0100 +++ new/src/share/vm/gc/shared/genCollectedHeap.hpp 2015-05-12 11:41:59.368546613 +0200 @@ -0,0 +1,518 @@ +/* + * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + * + */ + +#ifndef SHARE_VM_GC_SHARED_GENCOLLECTEDHEAP_HPP +#define SHARE_VM_GC_SHARED_GENCOLLECTEDHEAP_HPP + +#include "gc/shared/adaptiveSizePolicy.hpp" +#include "gc/shared/collectedHeap.hpp" +#include "gc/shared/collectorPolicy.hpp" +#include "gc/shared/generation.hpp" + +class SubTasksDone; +class FlexibleWorkGang; + +// A "GenCollectedHeap" is a CollectedHeap that uses generational +// collection. It has two generations, young and old. +class GenCollectedHeap : public CollectedHeap { + friend class GenCollectorPolicy; + friend class Generation; + friend class DefNewGeneration; + friend class TenuredGeneration; + friend class ConcurrentMarkSweepGeneration; + friend class CMSCollector; + friend class GenMarkSweep; + friend class VM_GenCollectForAllocation; + friend class VM_GenCollectFull; + friend class VM_GenCollectFullConcurrent; + friend class VM_GC_HeapInspection; + friend class VM_HeapDumper; + friend class HeapInspection; + friend class GCCauseSetter; + friend class VMStructs; +public: + friend class VM_PopulateDumpSharedSpace; + +private: + Generation* _young_gen; + Generation* _old_gen; + + // The singleton Gen Remembered Set. + GenRemSet* _rem_set; + + // The generational collector policy. + GenCollectorPolicy* _gen_policy; + + // Indicates that the most recent previous incremental collection failed. + // The flag is cleared when an action is taken that might clear the + // condition that caused that incremental collection to fail. + bool _incremental_collection_failed; + + // In support of ExplicitGCInvokesConcurrent functionality + unsigned int _full_collections_completed; + + // Data structure for claiming the (potentially) parallel tasks in + // (gen-specific) roots processing. + SubTasksDone* _process_strong_tasks; + + // Collects the given generation. + void collect_generation(Generation* gen, bool full, size_t size, bool is_tlab, + bool run_verification, bool clear_soft_refs, + bool restore_marks_for_biased_locking); + + // In block contents verification, the number of header words to skip + NOT_PRODUCT(static size_t _skip_header_HeapWords;) + + FlexibleWorkGang* _workers; + +protected: + // Helper functions for allocation + HeapWord* attempt_allocation(size_t size, + bool is_tlab, + bool first_only); + + // Helper function for two callbacks below. + // Considers collection of the first max_level+1 generations. + void do_collection(bool full, + bool clear_all_soft_refs, + size_t size, + bool is_tlab, + int max_level); + + // Callback from VM_GenCollectForAllocation operation. + // This function does everything necessary/possible to satisfy an + // allocation request that failed in the youngest generation that should + // have handled it (including collection, expansion, etc.) + HeapWord* satisfy_failed_allocation(size_t size, bool is_tlab); + + // Callback from VM_GenCollectFull operation. + // Perform a full collection of the first max_level+1 generations. + virtual void do_full_collection(bool clear_all_soft_refs); + void do_full_collection(bool clear_all_soft_refs, int max_level); + + // Does the "cause" of GC indicate that + // we absolutely __must__ clear soft refs? + bool must_clear_all_soft_refs(); + +public: + GenCollectedHeap(GenCollectorPolicy *policy); + + FlexibleWorkGang* workers() const { return _workers; } + + GCStats* gc_stats(int level) const; + + // Returns JNI_OK on success + virtual jint initialize(); + + // Reserve aligned space for the heap as needed by the contained generations. + char* allocate(size_t alignment, ReservedSpace* heap_rs); + + // Does operations required after initialization has been done. + void post_initialize(); + + // Initialize ("weak") refs processing support + virtual void ref_processing_init(); + + virtual Name kind() const { + return CollectedHeap::GenCollectedHeap; + } + + Generation* young_gen() const { return _young_gen; } + Generation* old_gen() const { return _old_gen; } + + // The generational collector policy. + GenCollectorPolicy* gen_policy() const { return _gen_policy; } + + virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) gen_policy(); } + + // Adaptive size policy + virtual AdaptiveSizePolicy* size_policy() { + return gen_policy()->size_policy(); + } + + // Return the (conservative) maximum heap alignment + static size_t conservative_max_heap_alignment() { + return Generation::GenGrain; + } + + size_t capacity() const; + size_t used() const; + + // Save the "used_region" for generations level and lower. + void save_used_regions(int level); + + size_t max_capacity() const; + + HeapWord* mem_allocate(size_t size, + bool* gc_overhead_limit_was_exceeded); + + // We may support a shared contiguous allocation area, if the youngest + // generation does. + bool supports_inline_contig_alloc() const; + HeapWord** top_addr() const; + HeapWord** end_addr() const; + + // Perform a full collection of the heap; intended for use in implementing + // "System.gc". This implies as full a collection as the CollectedHeap + // supports. Caller does not hold the Heap_lock on entry. + void collect(GCCause::Cause cause); + + // The same as above but assume that the caller holds the Heap_lock. + void collect_locked(GCCause::Cause cause); + + // Perform a full collection of the first max_level+1 generations. + // Mostly used for testing purposes. Caller does not hold the Heap_lock on entry. + void collect(GCCause::Cause cause, int max_level); + + // Returns "TRUE" iff "p" points into the committed areas of the heap. + // The methods is_in(), is_in_closed_subset() and is_in_youngest() may + // be expensive to compute in general, so, to prevent + // their inadvertent use in product jvm's, we restrict their use to + // assertion checking or verification only. + bool is_in(const void* p) const; + + // override + bool is_in_closed_subset(const void* p) const { + if (UseConcMarkSweepGC) { + return is_in_reserved(p); + } else { + return is_in(p); + } + } + + // Returns true if the reference is to an object in the reserved space + // for the young generation. + // Assumes the the young gen address range is less than that of the old gen. + bool is_in_young(oop p); + +#ifdef ASSERT + bool is_in_partial_collection(const void* p); +#endif + + virtual bool is_scavengable(const void* addr) { + return is_in_young((oop)addr); + } + + // Iteration functions. + void oop_iterate_no_header(OopClosure* cl); + void oop_iterate(ExtendedOopClosure* cl); + void object_iterate(ObjectClosure* cl); + void safe_object_iterate(ObjectClosure* cl); + Space* space_containing(const void* addr) const; + + // A CollectedHeap is divided into a dense sequence of "blocks"; that is, + // each address in the (reserved) heap is a member of exactly + // one block. The defining characteristic of a block is that it is + // possible to find its size, and thus to progress forward to the next + // block. (Blocks may be of different sizes.) Thus, blocks may + // represent Java objects, or they might be free blocks in a + // free-list-based heap (or subheap), as long as the two kinds are + // distinguishable and the size of each is determinable. + + // Returns the address of the start of the "block" that contains the + // address "addr". We say "blocks" instead of "object" since some heaps + // may not pack objects densely; a chunk may either be an object or a + // non-object. + virtual HeapWord* block_start(const void* addr) const; + + // Requires "addr" to be the start of a chunk, and returns its size. + // "addr + size" is required to be the start of a new chunk, or the end + // of the active area of the heap. Assumes (and verifies in non-product + // builds) that addr is in the allocated part of the heap and is + // the start of a chunk. + virtual size_t block_size(const HeapWord* addr) const; + + // Requires "addr" to be the start of a block, and returns "TRUE" iff + // the block is an object. Assumes (and verifies in non-product + // builds) that addr is in the allocated part of the heap and is + // the start of a chunk. + virtual bool block_is_obj(const HeapWord* addr) const; + + // Section on TLAB's. + virtual bool supports_tlab_allocation() const; + virtual size_t tlab_capacity(Thread* thr) const; + virtual size_t tlab_used(Thread* thr) const; + virtual size_t unsafe_max_tlab_alloc(Thread* thr) const; + virtual HeapWord* allocate_new_tlab(size_t size); + + // Can a compiler initialize a new object without store barriers? + // This permission only extends from the creation of a new object + // via a TLAB up to the first subsequent safepoint. + virtual bool can_elide_tlab_store_barriers() const { + return true; + } + + virtual bool card_mark_must_follow_store() const { + return UseConcMarkSweepGC; + } + + // We don't need barriers for stores to objects in the + // young gen and, a fortiori, for initializing stores to + // objects therein. This applies to DefNew+Tenured and ParNew+CMS + // only and may need to be re-examined in case other + // kinds of collectors are implemented in the future. + virtual bool can_elide_initializing_store_barrier(oop new_obj) { + return is_in_young(new_obj); + } + + // The "requestor" generation is performing some garbage collection + // action for which it would be useful to have scratch space. The + // requestor promises to allocate no more than "max_alloc_words" in any + // older generation (via promotion say.) Any blocks of space that can + // be provided are returned as a list of ScratchBlocks, sorted by + // decreasing size. + ScratchBlock* gather_scratch(Generation* requestor, size_t max_alloc_words); + // Allow each generation to reset any scratch space that it has + // contributed as it needs. + void release_scratch(); + + // Ensure parsability: override + virtual void ensure_parsability(bool retire_tlabs); + + // Time in ms since the longest time a collector ran in + // in any generation. + virtual jlong millis_since_last_gc(); + + // Total number of full collections completed. + unsigned int total_full_collections_completed() { + assert(_full_collections_completed <= _total_full_collections, + "Can't complete more collections than were started"); + return _full_collections_completed; + } + + // Update above counter, as appropriate, at the end of a stop-world GC cycle + unsigned int update_full_collections_completed(); + // Update above counter, as appropriate, at the end of a concurrent GC cycle + unsigned int update_full_collections_completed(unsigned int count); + + // Update "time of last gc" for all generations to "now". + void update_time_of_last_gc(jlong now) { + _young_gen->update_time_of_last_gc(now); + _old_gen->update_time_of_last_gc(now); + } + + // Update the gc statistics for each generation. + // "level" is the level of the latest collection. + void update_gc_stats(int current_level, bool full) { + _young_gen->update_gc_stats(current_level, full); + _old_gen->update_gc_stats(current_level, full); + } + + bool no_gc_in_progress() { return !is_gc_active(); } + + // Override. + void prepare_for_verify(); + + // Override. + void verify(bool silent, VerifyOption option); + + // Override. + virtual void print_on(outputStream* st) const; + virtual void print_gc_threads_on(outputStream* st) const; + virtual void gc_threads_do(ThreadClosure* tc) const; + virtual void print_tracing_info() const; + virtual void print_on_error(outputStream* st) const; + + // PrintGC, PrintGCDetails support + void print_heap_change(size_t prev_used) const; + + // The functions below are helper functions that a subclass of + // "CollectedHeap" can use in the implementation of its virtual + // functions. + + class GenClosure : public StackObj { + public: + virtual void do_generation(Generation* gen) = 0; + }; + + // Apply "cl.do_generation" to all generations in the heap + // If "old_to_young" determines the order. + void generation_iterate(GenClosure* cl, bool old_to_young); + + // Return "true" if all generations have reached the + // maximal committed limit that they can reach, without a garbage + // collection. + virtual bool is_maximal_no_gc() const; + + // This function returns the "GenRemSet" object that allows us to scan + // generations in a fully generational heap. + GenRemSet* rem_set() { return _rem_set; } + + // Convenience function to be used in situations where the heap type can be + // asserted to be this type. + static GenCollectedHeap* heap(); + + void set_par_threads(uint t); + void set_n_termination(uint t); + + // Invoke the "do_oop" method of one of the closures "not_older_gens" + // or "older_gens" on root locations for the generation at + // "level". (The "older_gens" closure is used for scanning references + // from older generations; "not_older_gens" is used everywhere else.) + // If "younger_gens_as_roots" is false, younger generations are + // not scanned as roots; in this case, the caller must be arranging to + // scan the younger generations itself. (For example, a generation might + // explicitly mark reachable objects in younger generations, to avoid + // excess storage retention.) + // The "so" argument determines which of the roots + // the closure is applied to: + // "SO_None" does none; + enum ScanningOption { + SO_None = 0x0, + SO_AllCodeCache = 0x8, + SO_ScavengeCodeCache = 0x10 + }; + + private: + void process_roots(bool activate_scope, + ScanningOption so, + OopClosure* strong_roots, + OopClosure* weak_roots, + CLDClosure* strong_cld_closure, + CLDClosure* weak_cld_closure, + CodeBlobClosure* code_roots); + + void gen_process_roots(int level, + bool younger_gens_as_roots, + bool activate_scope, + ScanningOption so, + OopsInGenClosure* not_older_gens, + OopsInGenClosure* weak_roots, + OopsInGenClosure* older_gens, + CLDClosure* cld_closure, + CLDClosure* weak_cld_closure, + CodeBlobClosure* code_closure); + + public: + static const bool StrongAndWeakRoots = false; + static const bool StrongRootsOnly = true; + + void gen_process_roots(int level, + bool younger_gens_as_roots, + bool activate_scope, + ScanningOption so, + bool only_strong_roots, + OopsInGenClosure* not_older_gens, + OopsInGenClosure* older_gens, + CLDClosure* cld_closure); + + // Apply "root_closure" to all the weak roots of the system. + // These include JNI weak roots, string table, + // and referents of reachable weak refs. + void gen_process_weak_roots(OopClosure* root_closure); + + // Set the saved marks of generations, if that makes sense. + // In particular, if any generation might iterate over the oops + // in other generations, it should call this method. + void save_marks(); + + // Apply "cur->do_oop" or "older->do_oop" to all the oops in objects + // allocated since the last call to save_marks in generations at or above + // "level". The "cur" closure is + // applied to references in the generation at "level", and the "older" + // closure to older generations. +#define GCH_SINCE_SAVE_MARKS_ITERATE_DECL(OopClosureType, nv_suffix) \ + void oop_since_save_marks_iterate(int level, \ + OopClosureType* cur, \ + OopClosureType* older); + + ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DECL) + +#undef GCH_SINCE_SAVE_MARKS_ITERATE_DECL + + // Returns "true" iff no allocations have occurred in any generation at + // "level" or above since the last + // call to "save_marks". + bool no_allocs_since_save_marks(int level); + + // Returns true if an incremental collection is likely to fail. + // We optionally consult the young gen, if asked to do so; + // otherwise we base our answer on whether the previous incremental + // collection attempt failed with no corrective action as of yet. + bool incremental_collection_will_fail(bool consult_young) { + // Assumes a 2-generation system; the first disjunct remembers if an + // incremental collection failed, even when we thought (second disjunct) + // that it would not. + assert(heap()->collector_policy()->is_generation_policy(), + "the following definition may not be suitable for an n(>2)-generation system"); + return incremental_collection_failed() || + (consult_young && !_young_gen->collection_attempt_is_safe()); + } + + // If a generation bails out of an incremental collection, + // it sets this flag. + bool incremental_collection_failed() const { + return _incremental_collection_failed; + } + void set_incremental_collection_failed() { + _incremental_collection_failed = true; + } + void clear_incremental_collection_failed() { + _incremental_collection_failed = false; + } + + // Promotion of obj into gen failed. Try to promote obj to higher + // gens in ascending order; return the new location of obj if successful. + // Otherwise, try expand-and-allocate for obj in both the young and old + // generation; return the new location of obj if successful. Otherwise, return NULL. + oop handle_failed_promotion(Generation* old_gen, + oop obj, + size_t obj_size); + +private: + // Accessor for memory state verification support + NOT_PRODUCT( + static size_t skip_header_HeapWords() { return _skip_header_HeapWords; } + ) + + // Override + void check_for_non_bad_heap_word_value(HeapWord* addr, + size_t size) PRODUCT_RETURN; + + // For use by mark-sweep. As implemented, mark-sweep-compact is global + // in an essential way: compaction is performed across generations, by + // iterating over spaces. + void prepare_for_compaction(); + + // Perform a full collection of the first max_level+1 generations. + // This is the low level interface used by the public versions of + // collect() and collect_locked(). Caller holds the Heap_lock on entry. + void collect_locked(GCCause::Cause cause, int max_level); + + // Returns success or failure. + bool create_cms_collector(); + + // In support of ExplicitGCInvokesConcurrent functionality + bool should_do_concurrent_full_gc(GCCause::Cause cause); + void collect_mostly_concurrent(GCCause::Cause cause); + + // Save the tops of the spaces in all generations + void record_gen_tops_before_GC() PRODUCT_RETURN; + +protected: + void gc_prologue(bool full); + void gc_epilogue(bool full); +}; + +#endif // SHARE_VM_GC_SHARED_GENCOLLECTEDHEAP_HPP