diff -r e45861098f5a -r fec48bf5a827 hotspot/src/share/vm/gc/g1/g1CollectedHeap.hpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/hotspot/src/share/vm/gc/g1/g1CollectedHeap.hpp Wed May 13 15:16:06 2015 +0200 @@ -0,0 +1,1594 @@ +/* + * Copyright (c) 2001, 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_G1_G1COLLECTEDHEAP_HPP +#define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP + +#include "gc/g1/concurrentMark.hpp" +#include "gc/g1/evacuationInfo.hpp" +#include "gc/g1/g1AllocRegion.hpp" +#include "gc/g1/g1AllocationContext.hpp" +#include "gc/g1/g1Allocator.hpp" +#include "gc/g1/g1BiasedArray.hpp" +#include "gc/g1/g1HRPrinter.hpp" +#include "gc/g1/g1InCSetState.hpp" +#include "gc/g1/g1MonitoringSupport.hpp" +#include "gc/g1/g1SATBCardTableModRefBS.hpp" +#include "gc/g1/g1YCTypes.hpp" +#include "gc/g1/hSpaceCounters.hpp" +#include "gc/g1/heapRegionManager.hpp" +#include "gc/g1/heapRegionSet.hpp" +#include "gc/shared/barrierSet.hpp" +#include "gc/shared/collectedHeap.hpp" +#include "memory/memRegion.hpp" +#include "utilities/stack.hpp" + +// A "G1CollectedHeap" is an implementation of a java heap for HotSpot. +// It uses the "Garbage First" heap organization and algorithm, which +// may combine concurrent marking with parallel, incremental compaction of +// heap subsets that will yield large amounts of garbage. + +// Forward declarations +class HeapRegion; +class HRRSCleanupTask; +class GenerationSpec; +class OopsInHeapRegionClosure; +class G1KlassScanClosure; +class G1ParScanThreadState; +class ObjectClosure; +class SpaceClosure; +class CompactibleSpaceClosure; +class Space; +class G1CollectorPolicy; +class GenRemSet; +class G1RemSet; +class HeapRegionRemSetIterator; +class ConcurrentMark; +class ConcurrentMarkThread; +class ConcurrentG1Refine; +class ConcurrentGCTimer; +class GenerationCounters; +class STWGCTimer; +class G1NewTracer; +class G1OldTracer; +class EvacuationFailedInfo; +class nmethod; +class Ticks; +class FlexibleWorkGang; + +typedef OverflowTaskQueue RefToScanQueue; +typedef GenericTaskQueueSet RefToScanQueueSet; + +typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) +typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) + +class YoungList : public CHeapObj { +private: + G1CollectedHeap* _g1h; + + HeapRegion* _head; + + HeapRegion* _survivor_head; + HeapRegion* _survivor_tail; + + HeapRegion* _curr; + + uint _length; + uint _survivor_length; + + size_t _last_sampled_rs_lengths; + size_t _sampled_rs_lengths; + + void empty_list(HeapRegion* list); + +public: + YoungList(G1CollectedHeap* g1h); + + void push_region(HeapRegion* hr); + void add_survivor_region(HeapRegion* hr); + + void empty_list(); + bool is_empty() { return _length == 0; } + uint length() { return _length; } + uint eden_length() { return length() - survivor_length(); } + uint survivor_length() { return _survivor_length; } + + // Currently we do not keep track of the used byte sum for the + // young list and the survivors and it'd be quite a lot of work to + // do so. When we'll eventually replace the young list with + // instances of HeapRegionLinkedList we'll get that for free. So, + // we'll report the more accurate information then. + size_t eden_used_bytes() { + assert(length() >= survivor_length(), "invariant"); + return (size_t) eden_length() * HeapRegion::GrainBytes; + } + size_t survivor_used_bytes() { + return (size_t) survivor_length() * HeapRegion::GrainBytes; + } + + void rs_length_sampling_init(); + bool rs_length_sampling_more(); + void rs_length_sampling_next(); + + void reset_sampled_info() { + _last_sampled_rs_lengths = 0; + } + size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } + + // for development purposes + void reset_auxilary_lists(); + void clear() { _head = NULL; _length = 0; } + + void clear_survivors() { + _survivor_head = NULL; + _survivor_tail = NULL; + _survivor_length = 0; + } + + HeapRegion* first_region() { return _head; } + HeapRegion* first_survivor_region() { return _survivor_head; } + HeapRegion* last_survivor_region() { return _survivor_tail; } + + // debugging + bool check_list_well_formed(); + bool check_list_empty(bool check_sample = true); + void print(); +}; + +// The G1 STW is alive closure. +// An instance is embedded into the G1CH and used as the +// (optional) _is_alive_non_header closure in the STW +// reference processor. It is also extensively used during +// reference processing during STW evacuation pauses. +class G1STWIsAliveClosure: public BoolObjectClosure { + G1CollectedHeap* _g1; +public: + G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} + bool do_object_b(oop p); +}; + +class RefineCardTableEntryClosure; + +class G1RegionMappingChangedListener : public G1MappingChangedListener { + private: + void reset_from_card_cache(uint start_idx, size_t num_regions); + public: + virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); +}; + +class G1CollectedHeap : public CollectedHeap { + friend class VM_CollectForMetadataAllocation; + friend class VM_G1CollectForAllocation; + friend class VM_G1CollectFull; + friend class VM_G1IncCollectionPause; + friend class VMStructs; + friend class MutatorAllocRegion; + friend class SurvivorGCAllocRegion; + friend class OldGCAllocRegion; + friend class G1Allocator; + + // Closures used in implementation. + friend class G1ParScanThreadState; + friend class G1ParTask; + friend class G1ParGCAllocator; + friend class G1PrepareCompactClosure; + + // Other related classes. + friend class HeapRegionClaimer; + + // Testing classes. + friend class G1CheckCSetFastTableClosure; + +private: + FlexibleWorkGang* _workers; + + static size_t _humongous_object_threshold_in_words; + + // The secondary free list which contains regions that have been + // freed up during the cleanup process. This will be appended to + // the master free list when appropriate. + FreeRegionList _secondary_free_list; + + // It keeps track of the old regions. + HeapRegionSet _old_set; + + // It keeps track of the humongous regions. + HeapRegionSet _humongous_set; + + void eagerly_reclaim_humongous_regions(); + + // The number of regions we could create by expansion. + uint _expansion_regions; + + // The block offset table for the G1 heap. + G1BlockOffsetSharedArray* _bot_shared; + + // Tears down the region sets / lists so that they are empty and the + // regions on the heap do not belong to a region set / list. The + // only exception is the humongous set which we leave unaltered. If + // free_list_only is true, it will only tear down the master free + // list. It is called before a Full GC (free_list_only == false) or + // before heap shrinking (free_list_only == true). + void tear_down_region_sets(bool free_list_only); + + // Rebuilds the region sets / lists so that they are repopulated to + // reflect the contents of the heap. The only exception is the + // humongous set which was not torn down in the first place. If + // free_list_only is true, it will only rebuild the master free + // list. It is called after a Full GC (free_list_only == false) or + // after heap shrinking (free_list_only == true). + void rebuild_region_sets(bool free_list_only); + + // Callback for region mapping changed events. + G1RegionMappingChangedListener _listener; + + // The sequence of all heap regions in the heap. + HeapRegionManager _hrm; + + // Class that handles the different kinds of allocations. + G1Allocator* _allocator; + + // Statistics for each allocation context + AllocationContextStats _allocation_context_stats; + + // PLAB sizing policy for survivors. + PLABStats _survivor_plab_stats; + + // PLAB sizing policy for tenured objects. + PLABStats _old_plab_stats; + + // It specifies whether we should attempt to expand the heap after a + // region allocation failure. If heap expansion fails we set this to + // false so that we don't re-attempt the heap expansion (it's likely + // that subsequent expansion attempts will also fail if one fails). + // Currently, it is only consulted during GC and it's reset at the + // start of each GC. + bool _expand_heap_after_alloc_failure; + + // It resets the mutator alloc region before new allocations can take place. + void init_mutator_alloc_region(); + + // It releases the mutator alloc region. + void release_mutator_alloc_region(); + + // It initializes the GC alloc regions at the start of a GC. + void init_gc_alloc_regions(EvacuationInfo& evacuation_info); + + // It releases the GC alloc regions at the end of a GC. + void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info); + + // It does any cleanup that needs to be done on the GC alloc regions + // before a Full GC. + void abandon_gc_alloc_regions(); + + // Helper for monitoring and management support. + G1MonitoringSupport* _g1mm; + + // Records whether the region at the given index is (still) a + // candidate for eager reclaim. Only valid for humongous start + // regions; other regions have unspecified values. Humongous start + // regions are initialized at start of collection pause, with + // candidates removed from the set as they are found reachable from + // roots or the young generation. + class HumongousReclaimCandidates : public G1BiasedMappedArray { + protected: + bool default_value() const { return false; } + public: + void clear() { G1BiasedMappedArray::clear(); } + void set_candidate(uint region, bool value) { + set_by_index(region, value); + } + bool is_candidate(uint region) { + return get_by_index(region); + } + }; + + HumongousReclaimCandidates _humongous_reclaim_candidates; + // Stores whether during humongous object registration we found candidate regions. + // If not, we can skip a few steps. + bool _has_humongous_reclaim_candidates; + + volatile unsigned _gc_time_stamp; + + size_t* _surviving_young_words; + + G1HRPrinter _hr_printer; + + void setup_surviving_young_words(); + void update_surviving_young_words(size_t* surv_young_words); + void cleanup_surviving_young_words(); + + // It decides whether an explicit GC should start a concurrent cycle + // instead of doing a STW GC. Currently, a concurrent cycle is + // explicitly started if: + // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or + // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. + // (c) cause == _g1_humongous_allocation + bool should_do_concurrent_full_gc(GCCause::Cause cause); + + // Keeps track of how many "old marking cycles" (i.e., Full GCs or + // concurrent cycles) we have started. + volatile uint _old_marking_cycles_started; + + // Keeps track of how many "old marking cycles" (i.e., Full GCs or + // concurrent cycles) we have completed. + volatile uint _old_marking_cycles_completed; + + bool _concurrent_cycle_started; + bool _heap_summary_sent; + + // This is a non-product method that is helpful for testing. It is + // called at the end of a GC and artificially expands the heap by + // allocating a number of dead regions. This way we can induce very + // frequent marking cycles and stress the cleanup / concurrent + // cleanup code more (as all the regions that will be allocated by + // this method will be found dead by the marking cycle). + void allocate_dummy_regions() PRODUCT_RETURN; + + // Clear RSets after a compaction. It also resets the GC time stamps. + void clear_rsets_post_compaction(); + + // If the HR printer is active, dump the state of the regions in the + // heap after a compaction. + void print_hrm_post_compaction(); + + // Create a memory mapper for auxiliary data structures of the given size and + // translation factor. + static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, + size_t size, + size_t translation_factor); + + double verify(bool guard, const char* msg); + void verify_before_gc(); + void verify_after_gc(); + + void log_gc_header(); + void log_gc_footer(double pause_time_sec); + + // These are macros so that, if the assert fires, we get the correct + // line number, file, etc. + +#define heap_locking_asserts_err_msg(_extra_message_) \ + err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ + (_extra_message_), \ + BOOL_TO_STR(Heap_lock->owned_by_self()), \ + BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ + BOOL_TO_STR(Thread::current()->is_VM_thread())) + +#define assert_heap_locked() \ + do { \ + assert(Heap_lock->owned_by_self(), \ + heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ + } while (0) + +#define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ + do { \ + assert(Heap_lock->owned_by_self() || \ + (SafepointSynchronize::is_at_safepoint() && \ + ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ + heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ + "should be at a safepoint")); \ + } while (0) + +#define assert_heap_locked_and_not_at_safepoint() \ + do { \ + assert(Heap_lock->owned_by_self() && \ + !SafepointSynchronize::is_at_safepoint(), \ + heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ + "should not be at a safepoint")); \ + } while (0) + +#define assert_heap_not_locked() \ + do { \ + assert(!Heap_lock->owned_by_self(), \ + heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ + } while (0) + +#define assert_heap_not_locked_and_not_at_safepoint() \ + do { \ + assert(!Heap_lock->owned_by_self() && \ + !SafepointSynchronize::is_at_safepoint(), \ + heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ + "should not be at a safepoint")); \ + } while (0) + +#define assert_at_safepoint(_should_be_vm_thread_) \ + do { \ + assert(SafepointSynchronize::is_at_safepoint() && \ + ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ + heap_locking_asserts_err_msg("should be at a safepoint")); \ + } while (0) + +#define assert_not_at_safepoint() \ + do { \ + assert(!SafepointSynchronize::is_at_safepoint(), \ + heap_locking_asserts_err_msg("should not be at a safepoint")); \ + } while (0) + +protected: + + // The young region list. + YoungList* _young_list; + + // The current policy object for the collector. + G1CollectorPolicy* _g1_policy; + + // This is the second level of trying to allocate a new region. If + // new_region() didn't find a region on the free_list, this call will + // check whether there's anything available on the + // secondary_free_list and/or wait for more regions to appear on + // that list, if _free_regions_coming is set. + HeapRegion* new_region_try_secondary_free_list(bool is_old); + + // Try to allocate a single non-humongous HeapRegion sufficient for + // an allocation of the given word_size. If do_expand is true, + // attempt to expand the heap if necessary to satisfy the allocation + // request. If the region is to be used as an old region or for a + // humongous object, set is_old to true. If not, to false. + HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); + + // Initialize a contiguous set of free regions of length num_regions + // and starting at index first so that they appear as a single + // humongous region. + HeapWord* humongous_obj_allocate_initialize_regions(uint first, + uint num_regions, + size_t word_size, + AllocationContext_t context); + + // Attempt to allocate a humongous object of the given size. Return + // NULL if unsuccessful. + HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); + + // The following two methods, allocate_new_tlab() and + // mem_allocate(), are the two main entry points from the runtime + // into the G1's allocation routines. They have the following + // assumptions: + // + // * They should both be called outside safepoints. + // + // * They should both be called without holding the Heap_lock. + // + // * All allocation requests for new TLABs should go to + // allocate_new_tlab(). + // + // * All non-TLAB allocation requests should go to mem_allocate(). + // + // * If either call cannot satisfy the allocation request using the + // current allocating region, they will try to get a new one. If + // this fails, they will attempt to do an evacuation pause and + // retry the allocation. + // + // * If all allocation attempts fail, even after trying to schedule + // an evacuation pause, allocate_new_tlab() will return NULL, + // whereas mem_allocate() will attempt a heap expansion and/or + // schedule a Full GC. + // + // * We do not allow humongous-sized TLABs. So, allocate_new_tlab + // should never be called with word_size being humongous. All + // humongous allocation requests should go to mem_allocate() which + // will satisfy them with a special path. + + virtual HeapWord* allocate_new_tlab(size_t word_size); + + virtual HeapWord* mem_allocate(size_t word_size, + bool* gc_overhead_limit_was_exceeded); + + // The following three methods take a gc_count_before_ret + // parameter which is used to return the GC count if the method + // returns NULL. Given that we are required to read the GC count + // while holding the Heap_lock, and these paths will take the + // Heap_lock at some point, it's easier to get them to read the GC + // count while holding the Heap_lock before they return NULL instead + // of the caller (namely: mem_allocate()) having to also take the + // Heap_lock just to read the GC count. + + // First-level mutator allocation attempt: try to allocate out of + // the mutator alloc region without taking the Heap_lock. This + // should only be used for non-humongous allocations. + inline HeapWord* attempt_allocation(size_t word_size, + uint* gc_count_before_ret, + uint* gclocker_retry_count_ret); + + // Second-level mutator allocation attempt: take the Heap_lock and + // retry the allocation attempt, potentially scheduling a GC + // pause. This should only be used for non-humongous allocations. + HeapWord* attempt_allocation_slow(size_t word_size, + AllocationContext_t context, + uint* gc_count_before_ret, + uint* gclocker_retry_count_ret); + + // Takes the Heap_lock and attempts a humongous allocation. It can + // potentially schedule a GC pause. + HeapWord* attempt_allocation_humongous(size_t word_size, + uint* gc_count_before_ret, + uint* gclocker_retry_count_ret); + + // Allocation attempt that should be called during safepoints (e.g., + // at the end of a successful GC). expect_null_mutator_alloc_region + // specifies whether the mutator alloc region is expected to be NULL + // or not. + HeapWord* attempt_allocation_at_safepoint(size_t word_size, + AllocationContext_t context, + bool expect_null_mutator_alloc_region); + + // It dirties the cards that cover the block so that so that the post + // write barrier never queues anything when updating objects on this + // block. It is assumed (and in fact we assert) that the block + // belongs to a young region. + inline void dirty_young_block(HeapWord* start, size_t word_size); + + // Allocate blocks during garbage collection. Will ensure an + // allocation region, either by picking one or expanding the + // heap, and then allocate a block of the given size. The block + // may not be a humongous - it must fit into a single heap region. + inline HeapWord* par_allocate_during_gc(InCSetState dest, + size_t word_size, + AllocationContext_t context); + // Ensure that no further allocations can happen in "r", bearing in mind + // that parallel threads might be attempting allocations. + void par_allocate_remaining_space(HeapRegion* r); + + // Allocation attempt during GC for a survivor object / PLAB. + inline HeapWord* survivor_attempt_allocation(size_t word_size, + AllocationContext_t context); + + // Allocation attempt during GC for an old object / PLAB. + inline HeapWord* old_attempt_allocation(size_t word_size, + AllocationContext_t context); + + // These methods are the "callbacks" from the G1AllocRegion class. + + // For mutator alloc regions. + HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); + void retire_mutator_alloc_region(HeapRegion* alloc_region, + size_t allocated_bytes); + + // For GC alloc regions. + HeapRegion* new_gc_alloc_region(size_t word_size, uint count, + InCSetState dest); + void retire_gc_alloc_region(HeapRegion* alloc_region, + size_t allocated_bytes, InCSetState dest); + + // - if explicit_gc is true, the GC is for a System.gc() or a heap + // inspection request and should collect the entire heap + // - if clear_all_soft_refs is true, all soft references should be + // cleared during the GC + // - if explicit_gc is false, word_size describes the allocation that + // the GC should attempt (at least) to satisfy + // - it returns false if it is unable to do the collection due to the + // GC locker being active, true otherwise + bool do_collection(bool explicit_gc, + bool clear_all_soft_refs, + size_t word_size); + + // Callback from VM_G1CollectFull operation. + // Perform a full collection. + virtual void do_full_collection(bool clear_all_soft_refs); + + // Resize the heap if necessary after a full collection. If this is + // after a collect-for allocation, "word_size" is the allocation size, + // and will be considered part of the used portion of the heap. + void resize_if_necessary_after_full_collection(size_t word_size); + + // Callback from VM_G1CollectForAllocation operation. + // This function does everything necessary/possible to satisfy a + // failed allocation request (including collection, expansion, etc.) + HeapWord* satisfy_failed_allocation(size_t word_size, + AllocationContext_t context, + bool* succeeded); + + // Attempting to expand the heap sufficiently + // to support an allocation of the given "word_size". If + // successful, perform the allocation and return the address of the + // allocated block, or else "NULL". + HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); + + // Process any reference objects discovered during + // an incremental evacuation pause. + void process_discovered_references(uint no_of_gc_workers); + + // Enqueue any remaining discovered references + // after processing. + void enqueue_discovered_references(uint no_of_gc_workers); + +public: + FlexibleWorkGang* workers() const { return _workers; } + + G1Allocator* allocator() { + return _allocator; + } + + G1MonitoringSupport* g1mm() { + assert(_g1mm != NULL, "should have been initialized"); + return _g1mm; + } + + // Expand the garbage-first heap by at least the given size (in bytes!). + // Returns true if the heap was expanded by the requested amount; + // false otherwise. + // (Rounds up to a HeapRegion boundary.) + bool expand(size_t expand_bytes); + + // Returns the PLAB statistics for a given destination. + inline PLABStats* alloc_buffer_stats(InCSetState dest); + + // Determines PLAB size for a given destination. + inline size_t desired_plab_sz(InCSetState dest); + + inline AllocationContextStats& allocation_context_stats(); + + // Do anything common to GC's. + void gc_prologue(bool full); + void gc_epilogue(bool full); + + // Modify the reclaim candidate set and test for presence. + // These are only valid for starts_humongous regions. + inline void set_humongous_reclaim_candidate(uint region, bool value); + inline bool is_humongous_reclaim_candidate(uint region); + + // Remove from the reclaim candidate set. Also remove from the + // collection set so that later encounters avoid the slow path. + inline void set_humongous_is_live(oop obj); + + // Register the given region to be part of the collection set. + inline void register_humongous_region_with_cset(uint index); + // Register regions with humongous objects (actually on the start region) in + // the in_cset_fast_test table. + void register_humongous_regions_with_cset(); + // We register a region with the fast "in collection set" test. We + // simply set to true the array slot corresponding to this region. + void register_young_region_with_cset(HeapRegion* r) { + _in_cset_fast_test.set_in_young(r->hrm_index()); + } + void register_old_region_with_cset(HeapRegion* r) { + _in_cset_fast_test.set_in_old(r->hrm_index()); + } + void clear_in_cset(const HeapRegion* hr) { + _in_cset_fast_test.clear(hr); + } + + void clear_cset_fast_test() { + _in_cset_fast_test.clear(); + } + + // This is called at the start of either a concurrent cycle or a Full + // GC to update the number of old marking cycles started. + void increment_old_marking_cycles_started(); + + // This is called at the end of either a concurrent cycle or a Full + // GC to update the number of old marking cycles completed. Those two + // can happen in a nested fashion, i.e., we start a concurrent + // cycle, a Full GC happens half-way through it which ends first, + // and then the cycle notices that a Full GC happened and ends + // too. The concurrent parameter is a boolean to help us do a bit + // tighter consistency checking in the method. If concurrent is + // false, the caller is the inner caller in the nesting (i.e., the + // Full GC). If concurrent is true, the caller is the outer caller + // in this nesting (i.e., the concurrent cycle). Further nesting is + // not currently supported. The end of this call also notifies + // the FullGCCount_lock in case a Java thread is waiting for a full + // GC to happen (e.g., it called System.gc() with + // +ExplicitGCInvokesConcurrent). + void increment_old_marking_cycles_completed(bool concurrent); + + uint old_marking_cycles_completed() { + return _old_marking_cycles_completed; + } + + void register_concurrent_cycle_start(const Ticks& start_time); + void register_concurrent_cycle_end(); + void trace_heap_after_concurrent_cycle(); + + G1YCType yc_type(); + + G1HRPrinter* hr_printer() { return &_hr_printer; } + + // Frees a non-humongous region by initializing its contents and + // adding it to the free list that's passed as a parameter (this is + // usually a local list which will be appended to the master free + // list later). The used bytes of freed regions are accumulated in + // pre_used. If par is true, the region's RSet will not be freed + // up. The assumption is that this will be done later. + // The locked parameter indicates if the caller has already taken + // care of proper synchronization. This may allow some optimizations. + void free_region(HeapRegion* hr, + FreeRegionList* free_list, + bool par, + bool locked = false); + + // Frees a humongous region by collapsing it into individual regions + // and calling free_region() for each of them. The freed regions + // will be added to the free list that's passed as a parameter (this + // is usually a local list which will be appended to the master free + // list later). The used bytes of freed regions are accumulated in + // pre_used. If par is true, the region's RSet will not be freed + // up. The assumption is that this will be done later. + void free_humongous_region(HeapRegion* hr, + FreeRegionList* free_list, + bool par); +protected: + + // Shrink the garbage-first heap by at most the given size (in bytes!). + // (Rounds down to a HeapRegion boundary.) + virtual void shrink(size_t expand_bytes); + void shrink_helper(size_t expand_bytes); + + #if TASKQUEUE_STATS + static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); + void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; + void reset_taskqueue_stats(); + #endif // TASKQUEUE_STATS + + // Schedule the VM operation that will do an evacuation pause to + // satisfy an allocation request of word_size. *succeeded will + // return whether the VM operation was successful (it did do an + // evacuation pause) or not (another thread beat us to it or the GC + // locker was active). Given that we should not be holding the + // Heap_lock when we enter this method, we will pass the + // gc_count_before (i.e., total_collections()) as a parameter since + // it has to be read while holding the Heap_lock. Currently, both + // methods that call do_collection_pause() release the Heap_lock + // before the call, so it's easy to read gc_count_before just before. + HeapWord* do_collection_pause(size_t word_size, + uint gc_count_before, + bool* succeeded, + GCCause::Cause gc_cause); + + // The guts of the incremental collection pause, executed by the vm + // thread. It returns false if it is unable to do the collection due + // to the GC locker being active, true otherwise + bool do_collection_pause_at_safepoint(double target_pause_time_ms); + + // Actually do the work of evacuating the collection set. + void evacuate_collection_set(EvacuationInfo& evacuation_info); + + // The g1 remembered set of the heap. + G1RemSet* _g1_rem_set; + + // A set of cards that cover the objects for which the Rsets should be updated + // concurrently after the collection. + DirtyCardQueueSet _dirty_card_queue_set; + + // The closure used to refine a single card. + RefineCardTableEntryClosure* _refine_cte_cl; + + // A DirtyCardQueueSet that is used to hold cards that contain + // references into the current collection set. This is used to + // update the remembered sets of the regions in the collection + // set in the event of an evacuation failure. + DirtyCardQueueSet _into_cset_dirty_card_queue_set; + + // After a collection pause, make the regions in the CS into free + // regions. + void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); + + // Abandon the current collection set without recording policy + // statistics or updating free lists. + void abandon_collection_set(HeapRegion* cs_head); + + // The concurrent marker (and the thread it runs in.) + ConcurrentMark* _cm; + ConcurrentMarkThread* _cmThread; + bool _mark_in_progress; + + // The concurrent refiner. + ConcurrentG1Refine* _cg1r; + + // The parallel task queues + RefToScanQueueSet *_task_queues; + + // True iff a evacuation has failed in the current collection. + bool _evacuation_failed; + + EvacuationFailedInfo* _evacuation_failed_info_array; + + // Failed evacuations cause some logical from-space objects to have + // forwarding pointers to themselves. Reset them. + void remove_self_forwarding_pointers(); + + // Together, these store an object with a preserved mark, and its mark value. + Stack _objs_with_preserved_marks; + Stack _preserved_marks_of_objs; + + // Preserve the mark of "obj", if necessary, in preparation for its mark + // word being overwritten with a self-forwarding-pointer. + void preserve_mark_if_necessary(oop obj, markOop m); + + // The stack of evac-failure objects left to be scanned. + GrowableArray* _evac_failure_scan_stack; + // The closure to apply to evac-failure objects. + + OopsInHeapRegionClosure* _evac_failure_closure; + // Set the field above. + void + set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { + _evac_failure_closure = evac_failure_closure; + } + + // Push "obj" on the scan stack. + void push_on_evac_failure_scan_stack(oop obj); + // Process scan stack entries until the stack is empty. + void drain_evac_failure_scan_stack(); + // True iff an invocation of "drain_scan_stack" is in progress; to + // prevent unnecessary recursion. + bool _drain_in_progress; + + // Do any necessary initialization for evacuation-failure handling. + // "cl" is the closure that will be used to process evac-failure + // objects. + void init_for_evac_failure(OopsInHeapRegionClosure* cl); + // Do any necessary cleanup for evacuation-failure handling data + // structures. + void finalize_for_evac_failure(); + + // An attempt to evacuate "obj" has failed; take necessary steps. + oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj); + void handle_evacuation_failure_common(oop obj, markOop m); + +#ifndef PRODUCT + // Support for forcing evacuation failures. Analogous to + // PromotionFailureALot for the other collectors. + + // Records whether G1EvacuationFailureALot should be in effect + // for the current GC + bool _evacuation_failure_alot_for_current_gc; + + // Used to record the GC number for interval checking when + // determining whether G1EvaucationFailureALot is in effect + // for the current GC. + size_t _evacuation_failure_alot_gc_number; + + // Count of the number of evacuations between failures. + volatile size_t _evacuation_failure_alot_count; + + // Set whether G1EvacuationFailureALot should be in effect + // for the current GC (based upon the type of GC and which + // command line flags are set); + inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, + bool during_initial_mark, + bool during_marking); + + inline void set_evacuation_failure_alot_for_current_gc(); + + // Return true if it's time to cause an evacuation failure. + inline bool evacuation_should_fail(); + + // Reset the G1EvacuationFailureALot counters. Should be called at + // the end of an evacuation pause in which an evacuation failure occurred. + inline void reset_evacuation_should_fail(); +#endif // !PRODUCT + + // ("Weak") Reference processing support. + // + // G1 has 2 instances of the reference processor class. One + // (_ref_processor_cm) handles reference object discovery + // and subsequent processing during concurrent marking cycles. + // + // The other (_ref_processor_stw) handles reference object + // discovery and processing during full GCs and incremental + // evacuation pauses. + // + // During an incremental pause, reference discovery will be + // temporarily disabled for _ref_processor_cm and will be + // enabled for _ref_processor_stw. At the end of the evacuation + // pause references discovered by _ref_processor_stw will be + // processed and discovery will be disabled. The previous + // setting for reference object discovery for _ref_processor_cm + // will be re-instated. + // + // At the start of marking: + // * Discovery by the CM ref processor is verified to be inactive + // and it's discovered lists are empty. + // * Discovery by the CM ref processor is then enabled. + // + // At the end of marking: + // * Any references on the CM ref processor's discovered + // lists are processed (possibly MT). + // + // At the start of full GC we: + // * Disable discovery by the CM ref processor and + // empty CM ref processor's discovered lists + // (without processing any entries). + // * Verify that the STW ref processor is inactive and it's + // discovered lists are empty. + // * Temporarily set STW ref processor discovery as single threaded. + // * Temporarily clear the STW ref processor's _is_alive_non_header + // field. + // * Finally enable discovery by the STW ref processor. + // + // The STW ref processor is used to record any discovered + // references during the full GC. + // + // At the end of a full GC we: + // * Enqueue any reference objects discovered by the STW ref processor + // that have non-live referents. This has the side-effect of + // making the STW ref processor inactive by disabling discovery. + // * Verify that the CM ref processor is still inactive + // and no references have been placed on it's discovered + // lists (also checked as a precondition during initial marking). + + // The (stw) reference processor... + ReferenceProcessor* _ref_processor_stw; + + STWGCTimer* _gc_timer_stw; + ConcurrentGCTimer* _gc_timer_cm; + + G1OldTracer* _gc_tracer_cm; + G1NewTracer* _gc_tracer_stw; + + // During reference object discovery, the _is_alive_non_header + // closure (if non-null) is applied to the referent object to + // determine whether the referent is live. If so then the + // reference object does not need to be 'discovered' and can + // be treated as a regular oop. This has the benefit of reducing + // the number of 'discovered' reference objects that need to + // be processed. + // + // Instance of the is_alive closure for embedding into the + // STW reference processor as the _is_alive_non_header field. + // Supplying a value for the _is_alive_non_header field is + // optional but doing so prevents unnecessary additions to + // the discovered lists during reference discovery. + G1STWIsAliveClosure _is_alive_closure_stw; + + // The (concurrent marking) reference processor... + ReferenceProcessor* _ref_processor_cm; + + // Instance of the concurrent mark is_alive closure for embedding + // into the Concurrent Marking reference processor as the + // _is_alive_non_header field. Supplying a value for the + // _is_alive_non_header field is optional but doing so prevents + // unnecessary additions to the discovered lists during reference + // discovery. + G1CMIsAliveClosure _is_alive_closure_cm; + + // Cache used by G1CollectedHeap::start_cset_region_for_worker(). + HeapRegion** _worker_cset_start_region; + + // Time stamp to validate the regions recorded in the cache + // used by G1CollectedHeap::start_cset_region_for_worker(). + // The heap region entry for a given worker is valid iff + // the associated time stamp value matches the current value + // of G1CollectedHeap::_gc_time_stamp. + uint* _worker_cset_start_region_time_stamp; + + volatile bool _free_regions_coming; + +public: + + void set_refine_cte_cl_concurrency(bool concurrent); + + RefToScanQueue *task_queue(uint i) const; + + // A set of cards where updates happened during the GC + DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } + + // A DirtyCardQueueSet that is used to hold cards that contain + // references into the current collection set. This is used to + // update the remembered sets of the regions in the collection + // set in the event of an evacuation failure. + DirtyCardQueueSet& into_cset_dirty_card_queue_set() + { return _into_cset_dirty_card_queue_set; } + + // Create a G1CollectedHeap with the specified policy. + // Must call the initialize method afterwards. + // May not return if something goes wrong. + G1CollectedHeap(G1CollectorPolicy* policy); + + // Initialize the G1CollectedHeap to have the initial and + // maximum sizes and remembered and barrier sets + // specified by the policy object. + jint initialize(); + + virtual void stop(); + + // Return the (conservative) maximum heap alignment for any G1 heap + static size_t conservative_max_heap_alignment(); + + // Does operations required after initialization has been done. + void post_initialize(); + + // Initialize weak reference processing. + void ref_processing_init(); + + // Explicitly import set_par_threads into this scope + using CollectedHeap::set_par_threads; + // Set _n_par_threads according to a policy TBD. + void set_par_threads(); + + virtual Name kind() const { + return CollectedHeap::G1CollectedHeap; + } + + // The current policy object for the collector. + G1CollectorPolicy* g1_policy() const { return _g1_policy; } + + virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } + + // Adaptive size policy. No such thing for g1. + virtual AdaptiveSizePolicy* size_policy() { return NULL; } + + // The rem set and barrier set. + G1RemSet* g1_rem_set() const { return _g1_rem_set; } + + unsigned get_gc_time_stamp() { + return _gc_time_stamp; + } + + inline void reset_gc_time_stamp(); + + void check_gc_time_stamps() PRODUCT_RETURN; + + inline void increment_gc_time_stamp(); + + // Reset the given region's GC timestamp. If it's starts humongous, + // also reset the GC timestamp of its corresponding + // continues humongous regions too. + void reset_gc_time_stamps(HeapRegion* hr); + + void iterate_dirty_card_closure(CardTableEntryClosure* cl, + DirtyCardQueue* into_cset_dcq, + bool concurrent, uint worker_i); + + // The shared block offset table array. + G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } + + // Reference Processing accessors + + // The STW reference processor.... + ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } + + // The Concurrent Marking reference processor... + ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } + + ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } + G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } + + virtual size_t capacity() const; + virtual size_t used() const; + // This should be called when we're not holding the heap lock. The + // result might be a bit inaccurate. + size_t used_unlocked() const; + size_t recalculate_used() const; + + // These virtual functions do the actual allocation. + // Some heaps may offer a contiguous region for shared non-blocking + // allocation, via inlined code (by exporting the address of the top and + // end fields defining the extent of the contiguous allocation region.) + // But G1CollectedHeap doesn't yet support this. + + virtual bool is_maximal_no_gc() const { + return _hrm.available() == 0; + } + + // The current number of regions in the heap. + uint num_regions() const { return _hrm.length(); } + + // The max number of regions in the heap. + uint max_regions() const { return _hrm.max_length(); } + + // The number of regions that are completely free. + uint num_free_regions() const { return _hrm.num_free_regions(); } + + MemoryUsage get_auxiliary_data_memory_usage() const { + return _hrm.get_auxiliary_data_memory_usage(); + } + + // The number of regions that are not completely free. + uint num_used_regions() const { return num_regions() - num_free_regions(); } + + void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; + void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; + void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; + void verify_dirty_young_regions() PRODUCT_RETURN; + +#ifndef PRODUCT + // Make sure that the given bitmap has no marked objects in the + // range [from,limit). If it does, print an error message and return + // false. Otherwise, just return true. bitmap_name should be "prev" + // or "next". + bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, + HeapWord* from, HeapWord* limit); + + // Verify that the prev / next bitmap range [tams,end) for the given + // region has no marks. Return true if all is well, false if errors + // are detected. + bool verify_bitmaps(const char* caller, HeapRegion* hr); +#endif // PRODUCT + + // If G1VerifyBitmaps is set, verify that the marking bitmaps for + // the given region do not have any spurious marks. If errors are + // detected, print appropriate error messages and crash. + void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; + + // If G1VerifyBitmaps is set, verify that the marking bitmaps do not + // have any spurious marks. If errors are detected, print + // appropriate error messages and crash. + void check_bitmaps(const char* caller) PRODUCT_RETURN; + + // Do sanity check on the contents of the in-cset fast test table. + bool check_cset_fast_test() PRODUCT_RETURN_( return true; ); + + // verify_region_sets() performs verification over the region + // lists. It will be compiled in the product code to be used when + // necessary (i.e., during heap verification). + void verify_region_sets(); + + // verify_region_sets_optional() is planted in the code for + // list verification in non-product builds (and it can be enabled in + // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). +#if HEAP_REGION_SET_FORCE_VERIFY + void verify_region_sets_optional() { + verify_region_sets(); + } +#else // HEAP_REGION_SET_FORCE_VERIFY + void verify_region_sets_optional() { } +#endif // HEAP_REGION_SET_FORCE_VERIFY + +#ifdef ASSERT + bool is_on_master_free_list(HeapRegion* hr) { + return _hrm.is_free(hr); + } +#endif // ASSERT + + // Wrapper for the region list operations that can be called from + // methods outside this class. + + void secondary_free_list_add(FreeRegionList* list) { + _secondary_free_list.add_ordered(list); + } + + void append_secondary_free_list() { + _hrm.insert_list_into_free_list(&_secondary_free_list); + } + + void append_secondary_free_list_if_not_empty_with_lock() { + // If the secondary free list looks empty there's no reason to + // take the lock and then try to append it. + if (!_secondary_free_list.is_empty()) { + MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); + append_secondary_free_list(); + } + } + + inline void old_set_remove(HeapRegion* hr); + + size_t non_young_capacity_bytes() { + return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); + } + + void set_free_regions_coming(); + void reset_free_regions_coming(); + bool free_regions_coming() { return _free_regions_coming; } + void wait_while_free_regions_coming(); + + // Determine whether the given region is one that we are using as an + // old GC alloc region. + bool is_old_gc_alloc_region(HeapRegion* hr) { + return _allocator->is_retained_old_region(hr); + } + + // Perform a collection of the heap; intended for use in implementing + // "System.gc". This probably implies as full a collection as the + // "CollectedHeap" supports. + virtual void collect(GCCause::Cause cause); + + // The same as above but assume that the caller holds the Heap_lock. + void collect_locked(GCCause::Cause cause); + + virtual bool copy_allocation_context_stats(const jint* contexts, + jlong* totals, + jbyte* accuracy, + jint len); + + // True iff an evacuation has failed in the most-recent collection. + bool evacuation_failed() { return _evacuation_failed; } + + void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); + void prepend_to_freelist(FreeRegionList* list); + void decrement_summary_bytes(size_t bytes); + + // Returns "TRUE" iff "p" points into the committed areas of the heap. + virtual bool is_in(const void* p) const; +#ifdef ASSERT + // Returns whether p is in one of the available areas of the heap. Slow but + // extensive version. + bool is_in_exact(const void* p) const; +#endif + + // Return "TRUE" iff the given object address is within the collection + // set. Slow implementation. + inline bool obj_in_cs(oop obj); + + inline bool is_in_cset(const HeapRegion *hr); + inline bool is_in_cset(oop obj); + + inline bool is_in_cset_or_humongous(const oop obj); + + private: + // This array is used for a quick test on whether a reference points into + // the collection set or not. Each of the array's elements denotes whether the + // corresponding region is in the collection set or not. + G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; + + public: + + inline InCSetState in_cset_state(const oop obj); + + // Return "TRUE" iff the given object address is in the reserved + // region of g1. + bool is_in_g1_reserved(const void* p) const { + return _hrm.reserved().contains(p); + } + + // Returns a MemRegion that corresponds to the space that has been + // reserved for the heap + MemRegion g1_reserved() const { + return _hrm.reserved(); + } + + virtual bool is_in_closed_subset(const void* p) const; + + G1SATBCardTableLoggingModRefBS* g1_barrier_set() { + return barrier_set_cast(barrier_set()); + } + + // This resets the card table to all zeros. It is used after + // a collection pause which used the card table to claim cards. + void cleanUpCardTable(); + + // Iteration functions. + + // Iterate over all objects, calling "cl.do_object" on each. + virtual void object_iterate(ObjectClosure* cl); + + virtual void safe_object_iterate(ObjectClosure* cl) { + object_iterate(cl); + } + + // Iterate over heap regions, in address order, terminating the + // iteration early if the "doHeapRegion" method returns "true". + void heap_region_iterate(HeapRegionClosure* blk) const; + + // Return the region with the given index. It assumes the index is valid. + inline HeapRegion* region_at(uint index) const; + + // Calculate the region index of the given address. Given address must be + // within the heap. + inline uint addr_to_region(HeapWord* addr) const; + + inline HeapWord* bottom_addr_for_region(uint index) const; + + // Iterate over the heap regions in parallel. Assumes that this will be called + // in parallel by ParallelGCThreads worker threads with distinct worker ids + // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" + // to each of the regions, by attempting to claim the region using the + // HeapRegionClaimer and, if successful, applying the closure to the claimed + // region. The concurrent argument should be set to true if iteration is + // performed concurrently, during which no assumptions are made for consistent + // attributes of the heap regions (as they might be modified while iterating). + void heap_region_par_iterate(HeapRegionClosure* cl, + uint worker_id, + HeapRegionClaimer* hrclaimer, + bool concurrent = false) const; + + // Clear the cached cset start regions and (more importantly) + // the time stamps. Called when we reset the GC time stamp. + void clear_cset_start_regions(); + + // Given the id of a worker, obtain or calculate a suitable + // starting region for iterating over the current collection set. + HeapRegion* start_cset_region_for_worker(uint worker_i); + + // Iterate over the regions (if any) in the current collection set. + void collection_set_iterate(HeapRegionClosure* blk); + + // As above but starting from region r + void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); + + HeapRegion* next_compaction_region(const HeapRegion* from) const; + + // Returns the HeapRegion that contains addr. addr must not be NULL. + template + inline HeapRegion* heap_region_containing_raw(const T addr) const; + + // Returns the HeapRegion that contains addr. addr must not be NULL. + // If addr is within a humongous continues region, it returns its humongous start region. + template + inline HeapRegion* heap_region_containing(const T 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. + 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. + virtual bool block_is_obj(const HeapWord* addr) const; + + // Section on thread-local allocation buffers (TLABs) + // See CollectedHeap for semantics. + + bool supports_tlab_allocation() const; + size_t tlab_capacity(Thread* ignored) const; + size_t tlab_used(Thread* ignored) const; + size_t max_tlab_size() const; + size_t unsafe_max_tlab_alloc(Thread* ignored) const; + + // 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. If such permission + // is granted for this heap type, the compiler promises to call + // defer_store_barrier() below on any slow path allocation of + // a new object for which such initializing store barriers will + // have been elided. G1, like CMS, allows this, but should be + // ready to provide a compensating write barrier as necessary + // if that storage came out of a non-young region. The efficiency + // of this implementation depends crucially on being able to + // answer very efficiently in constant time whether a piece of + // storage in the heap comes from a young region or not. + // See ReduceInitialCardMarks. + virtual bool can_elide_tlab_store_barriers() const { + return true; + } + + virtual bool card_mark_must_follow_store() const { + return true; + } + + inline bool is_in_young(const oop obj); + + virtual bool is_scavengable(const void* addr); + + // We don't need barriers for initializing stores to objects + // in the young gen: for the SATB pre-barrier, there is no + // pre-value that needs to be remembered; for the remembered-set + // update logging post-barrier, we don't maintain remembered set + // information for young gen objects. + virtual inline bool can_elide_initializing_store_barrier(oop new_obj); + + // Returns "true" iff the given word_size is "very large". + static bool is_humongous(size_t word_size) { + // Note this has to be strictly greater-than as the TLABs + // are capped at the humongous threshold and we want to + // ensure that we don't try to allocate a TLAB as + // humongous and that we don't allocate a humongous + // object in a TLAB. + return word_size > _humongous_object_threshold_in_words; + } + + // Update mod union table with the set of dirty cards. + void updateModUnion(); + + // Set the mod union bits corresponding to the given memRegion. Note + // that this is always a safe operation, since it doesn't clear any + // bits. + void markModUnionRange(MemRegion mr); + + // Records the fact that a marking phase is no longer in progress. + void set_marking_complete() { + _mark_in_progress = false; + } + void set_marking_started() { + _mark_in_progress = true; + } + bool mark_in_progress() { + return _mark_in_progress; + } + + // Print the maximum heap capacity. + virtual size_t max_capacity() const; + + virtual jlong millis_since_last_gc(); + + + // Convenience function to be used in situations where the heap type can be + // asserted to be this type. + static G1CollectedHeap* heap(); + + void set_region_short_lived_locked(HeapRegion* hr); + // add appropriate methods for any other surv rate groups + + YoungList* young_list() const { return _young_list; } + + // debugging + bool check_young_list_well_formed() { + return _young_list->check_list_well_formed(); + } + + bool check_young_list_empty(bool check_heap, + bool check_sample = true); + + // *** Stuff related to concurrent marking. It's not clear to me that so + // many of these need to be public. + + // The functions below are helper functions that a subclass of + // "CollectedHeap" can use in the implementation of its virtual + // functions. + // This performs a concurrent marking of the live objects in a + // bitmap off to the side. + void doConcurrentMark(); + + bool isMarkedPrev(oop obj) const; + bool isMarkedNext(oop obj) const; + + // Determine if an object is dead, given the object and also + // the region to which the object belongs. An object is dead + // iff a) it was not allocated since the last mark and b) it + // is not marked. + bool is_obj_dead(const oop obj, const HeapRegion* hr) const { + return + !hr->obj_allocated_since_prev_marking(obj) && + !isMarkedPrev(obj); + } + + // This function returns true when an object has been + // around since the previous marking and hasn't yet + // been marked during this marking. + bool is_obj_ill(const oop obj, const HeapRegion* hr) const { + return + !hr->obj_allocated_since_next_marking(obj) && + !isMarkedNext(obj); + } + + // Determine if an object is dead, given only the object itself. + // This will find the region to which the object belongs and + // then call the region version of the same function. + + // Added if it is NULL it isn't dead. + + inline bool is_obj_dead(const oop obj) const; + + inline bool is_obj_ill(const oop obj) const; + + bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); + HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); + bool is_marked(oop obj, VerifyOption vo); + const char* top_at_mark_start_str(VerifyOption vo); + + ConcurrentMark* concurrent_mark() const { return _cm; } + + // Refinement + + ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } + + // The dirty cards region list is used to record a subset of regions + // whose cards need clearing. The list if populated during the + // remembered set scanning and drained during the card table + // cleanup. Although the methods are reentrant, population/draining + // phases must not overlap. For synchronization purposes the last + // element on the list points to itself. + HeapRegion* _dirty_cards_region_list; + void push_dirty_cards_region(HeapRegion* hr); + HeapRegion* pop_dirty_cards_region(); + + // Optimized nmethod scanning support routines + + // Register the given nmethod with the G1 heap. + virtual void register_nmethod(nmethod* nm); + + // Unregister the given nmethod from the G1 heap. + virtual void unregister_nmethod(nmethod* nm); + + // Free up superfluous code root memory. + void purge_code_root_memory(); + + // Rebuild the strong code root lists for each region + // after a full GC. + void rebuild_strong_code_roots(); + + // Delete entries for dead interned string and clean up unreferenced symbols + // in symbol table, possibly in parallel. + void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); + + // Parallel phase of unloading/cleaning after G1 concurrent mark. + void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); + + // Redirty logged cards in the refinement queue. + void redirty_logged_cards(); + // Verification + + // The following is just to alert the verification code + // that a full collection has occurred and that the + // remembered sets are no longer up to date. + bool _full_collection; + void set_full_collection() { _full_collection = true;} + void clear_full_collection() {_full_collection = false;} + bool full_collection() {return _full_collection;} + + // Perform any cleanup actions necessary before allowing a verification. + virtual void prepare_for_verify(); + + // Perform verification. + + // vo == UsePrevMarking -> use "prev" marking information, + // vo == UseNextMarking -> use "next" marking information + // vo == UseMarkWord -> use the mark word in the object header + // + // NOTE: Only the "prev" marking information is guaranteed to be + // consistent most of the time, so most calls to this should use + // vo == UsePrevMarking. + // Currently, there is only one case where this is called with + // vo == UseNextMarking, which is to verify the "next" marking + // information at the end of remark. + // Currently there is only one place where this is called with + // vo == UseMarkWord, which is to verify the marking during a + // full GC. + void verify(bool silent, VerifyOption vo); + + // Override; it uses the "prev" marking information + virtual void verify(bool silent); + + // The methods below are here for convenience and dispatch the + // appropriate method depending on value of the given VerifyOption + // parameter. The values for that parameter, and their meanings, + // are the same as those above. + + bool is_obj_dead_cond(const oop obj, + const HeapRegion* hr, + const VerifyOption vo) const; + + bool is_obj_dead_cond(const oop obj, + const VerifyOption vo) const; + + // Printing + + virtual void print_on(outputStream* st) const; + virtual void print_extended_on(outputStream* st) const; + virtual void print_on_error(outputStream* st) const; + + virtual void print_gc_threads_on(outputStream* st) const; + virtual void gc_threads_do(ThreadClosure* tc) const; + + // Override + void print_tracing_info() const; + + // The following two methods are helpful for debugging RSet issues. + void print_cset_rsets() PRODUCT_RETURN; + void print_all_rsets() PRODUCT_RETURN; + +public: + size_t pending_card_num(); + size_t cards_scanned(); + +protected: + size_t _max_heap_capacity; +}; + +#endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP