truffle: src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp comparison

comparison src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp @ 342:37f87013dfd8

6711316: Open source the Garbage-First garbage collector Summary: First mercurial integration of the code for the Garbage-First garbage collector. Reviewed-by: apetrusenko, iveresov, jmasa, sgoldman, tonyp, ysr

author	ysr
date	Thu, 05 Jun 2008 15:57:56 -0700
parents
children	9bb2c10ac07b

comparison

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-:0b27f3512f9e
+:37f87013dfd8
+/*
+* Copyright 2001-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+* CA 95054 USA or visit www.sun.com if you need additional information or
+* have any questions.
+*
+*/
+// 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.
+class HeapRegion;
+class HeapRegionSeq;
+class HeapRegionList;
+class PermanentGenerationSpec;
+class GenerationSpec;
+class OopsInHeapRegionClosure;
+class G1ScanHeapEvacClosure;
+class ObjectClosure;
+class SpaceClosure;
+class CompactibleSpaceClosure;
+class Space;
+class G1CollectorPolicy;
+class GenRemSet;
+class G1RemSet;
+class HeapRegionRemSetIterator;
+class ConcurrentMark;
+class ConcurrentMarkThread;
+class ConcurrentG1Refine;
+class ConcurrentZFThread;
+// If want to accumulate detailed statistics on work queues
+// turn this on.
+#define G1_DETAILED_STATS 0
+#if G1_DETAILED_STATS
+#  define IF_G1_DETAILED_STATS(code) code
+#else
+#  define IF_G1_DETAILED_STATS(code)
+#endif
+typedef GenericTaskQueue<oop*>    RefToScanQueue;
+typedef GenericTaskQueueSet<oop*> RefToScanQueueSet;
+enum G1GCThreadGroups {
+G1CRGroup = 0,
+G1ZFGroup = 1,
+G1CMGroup = 2,
+G1CLGroup = 3
+};
+enum GCAllocPurpose {
+GCAllocForTenured,
+GCAllocForSurvived,
+GCAllocPurposeCount
+};
+class YoungList : public CHeapObj {
+private:
+G1CollectedHeap* _g1h;
+HeapRegion* _head;
+HeapRegion* _scan_only_head;
+HeapRegion* _scan_only_tail;
+size_t      _length;
+size_t      _scan_only_length;
+size_t      _last_sampled_rs_lengths;
+size_t      _sampled_rs_lengths;
+HeapRegion* _curr;
+HeapRegion* _curr_scan_only;
+HeapRegion* _survivor_head;
+HeapRegion* _survivors_tail;
+size_t      _survivor_length;
+void          empty_list(HeapRegion* list);
+public:
+YoungList(G1CollectedHeap* g1h);
+void          push_region(HeapRegion* hr);
+void          add_survivor_region(HeapRegion* hr);
+HeapRegion*   pop_region();
+void          empty_list();
+bool          is_empty() { return _length == 0; }
+size_t        length() { return _length; }
+size_t        scan_only_length() { return _scan_only_length; }
+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();
+HeapRegion* first_region() { return _head; }
+HeapRegion* first_scan_only_region() { return _scan_only_head; }
+HeapRegion* first_survivor_region() { return _survivor_head; }
+HeapRegion* par_get_next_scan_only_region() {
+MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
+HeapRegion* ret = _curr_scan_only;
+if (ret != NULL)
+_curr_scan_only = ret->get_next_young_region();
+return ret;
+}
+// debugging
+bool          check_list_well_formed();
+bool          check_list_empty(bool ignore_scan_only_list,
+bool check_sample = true);
+void          print();
+};
+class RefineCardTableEntryClosure;
+class G1CollectedHeap : public SharedHeap {
+friend class VM_G1CollectForAllocation;
+friend class VM_GenCollectForPermanentAllocation;
+friend class VM_G1CollectFull;
+friend class VM_G1IncCollectionPause;
+friend class VM_G1PopRegionCollectionPause;
+friend class VMStructs;
+// Closures used in implementation.
+friend class G1ParCopyHelper;
+friend class G1IsAliveClosure;
+friend class G1EvacuateFollowersClosure;
+friend class G1ParScanThreadState;
+friend class G1ParScanClosureSuper;
+friend class G1ParEvacuateFollowersClosure;
+friend class G1ParTask;
+friend class G1FreeGarbageRegionClosure;
+friend class RefineCardTableEntryClosure;
+friend class G1PrepareCompactClosure;
+friend class RegionSorter;
+friend class CountRCClosure;
+friend class EvacPopObjClosure;
+// Other related classes.
+friend class G1MarkSweep;
+private:
+enum SomePrivateConstants {
+VeryLargeInBytes = HeapRegion::GrainBytes/2,
+VeryLargeInWords = VeryLargeInBytes/HeapWordSize,
+MinHeapDeltaBytes = 10 * HeapRegion::GrainBytes,      // FIXME
+NumAPIs = HeapRegion::MaxAge
+};
+// The one and only G1CollectedHeap, so static functions can find it.
+static G1CollectedHeap* _g1h;
+// Storage for the G1 heap (excludes the permanent generation).
+VirtualSpace _g1_storage;
+MemRegion    _g1_reserved;
+// The part of _g1_storage that is currently committed.
+MemRegion _g1_committed;
+// The maximum part of _g1_storage that has ever been committed.
+MemRegion _g1_max_committed;
+// The number of regions that are completely free.
+size_t _free_regions;
+// The number of regions we could create by expansion.
+size_t _expansion_regions;
+// Return the number of free regions in the heap (by direct counting.)
+size_t count_free_regions();
+// Return the number of free regions on the free and unclean lists.
+size_t count_free_regions_list();
+// The block offset table for the G1 heap.
+G1BlockOffsetSharedArray* _bot_shared;
+// Move all of the regions off the free lists, then rebuild those free
+// lists, before and after full GC.
+void tear_down_region_lists();
+void rebuild_region_lists();
+// This sets all non-empty regions to need zero-fill (which they will if
+// they are empty after full collection.)
+void set_used_regions_to_need_zero_fill();
+// The sequence of all heap regions in the heap.
+HeapRegionSeq* _hrs;
+// The region from which normal-sized objects are currently being
+// allocated.  May be NULL.
+HeapRegion* _cur_alloc_region;
+// Postcondition: cur_alloc_region == NULL.
+void abandon_cur_alloc_region();
+// The to-space memory regions into which objects are being copied during
+// a GC.
+HeapRegion* _gc_alloc_regions[GCAllocPurposeCount];
+uint _gc_alloc_region_counts[GCAllocPurposeCount];
+// A list of the regions that have been set to be alloc regions in the
+// current collection.
+HeapRegion* _gc_alloc_region_list;
+// When called by par thread, require par_alloc_during_gc_lock() to be held.
+void push_gc_alloc_region(HeapRegion* hr);
+// This should only be called single-threaded.  Undeclares all GC alloc
+// regions.
+void forget_alloc_region_list();
+// Should be used to set an alloc region, because there's other
+// associated bookkeeping.
+void set_gc_alloc_region(int purpose, HeapRegion* r);
+// Check well-formedness of alloc region list.
+bool check_gc_alloc_regions();
+// Outside of GC pauses, the number of bytes used in all regions other
+// than the current allocation region.
+size_t _summary_bytes_used;
+// Summary information about popular objects; method to print it.
+NumberSeq _pop_obj_rc_at_copy;
+void print_popularity_summary_info() const;
+unsigned _gc_time_stamp;
+size_t* _surviving_young_words;
+void setup_surviving_young_words();
+void update_surviving_young_words(size_t* surv_young_words);
+void cleanup_surviving_young_words();
+protected:
+// Returns "true" iff none of the gc alloc regions have any allocations
+// since the last call to "save_marks".
+bool all_alloc_regions_no_allocs_since_save_marks();
+// Calls "note_end_of_copying on all gc alloc_regions.
+void all_alloc_regions_note_end_of_copying();
+// The number of regions allocated to hold humongous objects.
+int         _num_humongous_regions;
+YoungList*  _young_list;
+// The current policy object for the collector.
+G1CollectorPolicy* _g1_policy;
+// Parallel allocation lock to protect the current allocation region.
+Mutex  _par_alloc_during_gc_lock;
+Mutex* par_alloc_during_gc_lock() { return &_par_alloc_during_gc_lock; }
+// If possible/desirable, allocate a new HeapRegion for normal object
+// allocation sufficient for an allocation of the given "word_size".
+// If "do_expand" is true, will attempt to expand the heap if necessary
+// to to satisfy the request.  If "zero_filled" is true, requires a
+// zero-filled region.
+// (Returning NULL will trigger a GC.)
+virtual HeapRegion* newAllocRegion_work(size_t word_size,
+bool do_expand,
+bool zero_filled);
+virtual HeapRegion* newAllocRegion(size_t word_size,
+bool zero_filled = true) {
+return newAllocRegion_work(word_size, false, zero_filled);
+}
+virtual HeapRegion* newAllocRegionWithExpansion(int purpose,
+size_t word_size,
+bool zero_filled = true);
+// Attempt to allocate an object of the given (very large) "word_size".
+// Returns "NULL" on failure.
+virtual HeapWord* humongousObjAllocate(size_t word_size);
+// If possible, allocate a block of the given word_size, else return "NULL".
+// Returning NULL will trigger GC or heap expansion.
+// These two methods have rather awkward pre- and
+// post-conditions. If they are called outside a safepoint, then
+// they assume that the caller is holding the heap lock. Upon return
+// they release the heap lock, if they are returning a non-NULL
+// value. attempt_allocation_slow() also dirties the cards of a
+// newly-allocated young region after it releases the heap
+// lock. This change in interface was the neatest way to achieve
+// this card dirtying without affecting mem_allocate(), which is a
+// more frequently called method. We tried two or three different
+// approaches, but they were even more hacky.
+HeapWord* attempt_allocation(size_t word_size,
+bool permit_collection_pause = true);
+HeapWord* attempt_allocation_slow(size_t word_size,
+bool permit_collection_pause = true);
+// 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.
+HeapWord* allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
+HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
+HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
+HeapRegion*    alloc_region,
+bool           par,
+size_t         word_size);
+// 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);
+// Helper function for two callbacks below.
+// "full", if true, indicates that the GC is for a System.gc() request,
+// and should collect the entire heap.  If "clear_all_soft_refs" is true,
+// all soft references are cleared during the GC.  If "full" is false,
+// "word_size" describes the allocation that the GC should
+// attempt (at least) to satisfy.
+void do_collection(bool full, bool clear_all_soft_refs,
+size_t word_size);
+// Callback from VM_G1CollectFull operation.
+// Perform a full collection.
+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);
+// 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".
+virtual HeapWord* expand_and_allocate(size_t word_size);
+public:
+// Expand the garbage-first heap by at least the given size (in bytes!).
+// (Rounds up to a HeapRegion boundary.)
+virtual void expand(size_t expand_bytes);
+// Do anything common to GC's.
+virtual void gc_prologue(bool full);
+virtual void gc_epilogue(bool full);
+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);
+// Do an incremental collection: identify a collection set, and evacuate
+// its live objects elsewhere.
+virtual void do_collection_pause();
+// The guts of the incremental collection pause, executed by the vm
+// thread.  If "popular_region" is non-NULL, this pause should evacuate
+// this single region whose remembered set has gotten large, moving
+// any popular objects to one of the popular regions.
+virtual void do_collection_pause_at_safepoint(HeapRegion* popular_region);
+// Actually do the work of evacuating the collection set.
+virtual void evacuate_collection_set();
+// If this is an appropriate right time, do a collection pause.
+// The "word_size" argument, if non-zero, indicates the size of an
+// allocation request that is prompting this query.
+void do_collection_pause_if_appropriate(size_t word_size);
+// The g1 remembered set of the heap.
+G1RemSet* _g1_rem_set;
+// And it's mod ref barrier set, used to track updates for the above.
+ModRefBarrierSet* _mr_bs;
+// The Heap Region Rem Set Iterator.
+HeapRegionRemSetIterator** _rem_set_iterator;
+// The closure used to refine a single card.
+RefineCardTableEntryClosure* _refine_cte_cl;
+// A function to check the consistency of dirty card logs.
+void check_ct_logs_at_safepoint();
+// After a collection pause, make the regions in the CS into free
+// regions.
+void free_collection_set(HeapRegion* cs_head);
+// Applies "scan_non_heap_roots" to roots outside the heap,
+// "scan_rs" to roots inside the heap (having done "set_region" to
+// indicate the region in which the root resides), and does "scan_perm"
+// (setting the generation to the perm generation.)  If "scan_rs" is
+// NULL, then this step is skipped.  The "worker_i"
+// param is for use with parallel roots processing, and should be
+// the "i" of the calling parallel worker thread's work(i) function.
+// In the sequential case this param will be ignored.
+void g1_process_strong_roots(bool collecting_perm_gen,
+SharedHeap::ScanningOption so,
+OopClosure* scan_non_heap_roots,
+OopsInHeapRegionClosure* scan_rs,
+OopsInHeapRegionClosure* scan_so,
+OopsInGenClosure* scan_perm,
+int worker_i);
+void scan_scan_only_set(OopsInHeapRegionClosure* oc,
+int worker_i);
+void scan_scan_only_region(HeapRegion* hr,
+OopsInHeapRegionClosure* oc,
+int worker_i);
+// Apply "blk" to all the weak roots of the system.  These include
+// JNI weak roots, the code cache, system dictionary, symbol table,
+// string table, and referents of reachable weak refs.
+void g1_process_weak_roots(OopClosure* root_closure,
+OopClosure* non_root_closure);
+// Invoke "save_marks" on all heap regions.
+void save_marks();
+// Free a heap region.
+void free_region(HeapRegion* hr);
+// A component of "free_region", exposed for 'batching'.
+// All the params after "hr" are out params: the used bytes of the freed
+// region(s), the number of H regions cleared, the number of regions
+// freed, and pointers to the head and tail of a list of freed contig
+// regions, linked throught the "next_on_unclean_list" field.
+void free_region_work(HeapRegion* hr,
+size_t& pre_used,
+size_t& cleared_h,
+size_t& freed_regions,
+UncleanRegionList* list,
+bool par = false);
+// The concurrent marker (and the thread it runs in.)
+ConcurrentMark* _cm;
+ConcurrentMarkThread* _cmThread;
+bool _mark_in_progress;
+// The concurrent refiner.
+ConcurrentG1Refine* _cg1r;
+// The concurrent zero-fill thread.
+ConcurrentZFThread* _czft;
+// The parallel task queues
+RefToScanQueueSet *_task_queues;
+// True iff a evacuation has failed in the current collection.
+bool _evacuation_failed;
+// Set the attribute indicating whether evacuation has failed in the
+// current collection.
+void set_evacuation_failed(bool b) { _evacuation_failed = b; }
+// Failed evacuations cause some logical from-space objects to have
+// forwarding pointers to themselves.  Reset them.
+void remove_self_forwarding_pointers();
+// When one is non-null, so is the other.  Together, they each pair is
+// an object with a preserved mark, and its mark value.
+GrowableArray<oop>*     _objs_with_preserved_marks;
+GrowableArray<markOop>* _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<oop>*    _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.
+void handle_evacuation_failure(oop obj);
+oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
+void handle_evacuation_failure_common(oop obj, markOop m);
+// Ensure that the relevant gc_alloc regions are set.
+void get_gc_alloc_regions();
+// We're done with GC alloc regions; release them, as appropriate.
+void release_gc_alloc_regions();
+// ("Weak") Reference processing support
+ReferenceProcessor* _ref_processor;
+enum G1H_process_strong_roots_tasks {
+G1H_PS_mark_stack_oops_do,
+G1H_PS_refProcessor_oops_do,
+// Leave this one last.
+G1H_PS_NumElements
+};
+SubTasksDone* _process_strong_tasks;
+// Allocate space to hold a popular object.  Result is guaranteed below
+// "popular_object_boundary()".  Note: CURRENTLY halts the system if we
+// run out of space to hold popular objects.
+HeapWord* allocate_popular_object(size_t word_size);
+// The boundary between popular and non-popular objects.
+HeapWord* _popular_object_boundary;
+HeapRegionList* _popular_regions_to_be_evacuated;
+// Compute which objects in "single_region" are popular.  If any are,
+// evacuate them to a popular region, leaving behind forwarding pointers,
+// and select "popular_region" as the single collection set region.
+// Otherwise, leave the collection set null.
+void popularity_pause_preamble(HeapRegion* populer_region);
+// Compute which objects in "single_region" are popular, and evacuate
+// them to a popular region, leaving behind forwarding pointers.
+// Returns "true" if at least one popular object is discovered and
+// evacuated.  In any case, "*max_rc" is set to the maximum reference
+// count of an object in the region.
+bool compute_reference_counts_and_evac_popular(HeapRegion* populer_region,
+size_t* max_rc);
+// Subroutines used in the above.
+bool _rc_region_above;
+size_t _rc_region_diff;
+jint* obj_rc_addr(oop obj) {
+uintptr_t obj_addr = (uintptr_t)obj;
+if (_rc_region_above) {
+jint* res = (jint*)(obj_addr + _rc_region_diff);
+assert((uintptr_t)res > obj_addr, "RC region is above.");
+return res;
+} else {
+jint* res = (jint*)(obj_addr - _rc_region_diff);
+assert((uintptr_t)res < obj_addr, "RC region is below.");
+return res;
+}
+}
+jint obj_rc(oop obj) {
+return *obj_rc_addr(obj);
+}
+void inc_obj_rc(oop obj) {
+(*obj_rc_addr(obj))++;
+}
+void atomic_inc_obj_rc(oop obj);
+// Number of popular objects and bytes (latter is cheaper!).
+size_t pop_object_used_objs();
+size_t pop_object_used_bytes();
+// Index of the popular region in which allocation is currently being
+// done.
+int _cur_pop_hr_index;
+// List of regions which require zero filling.
+UncleanRegionList _unclean_region_list;
+bool _unclean_regions_coming;
+bool check_age_cohort_well_formed_work(int a, HeapRegion* hr);
+public:
+void set_refine_cte_cl_concurrency(bool concurrent);
+RefToScanQueue *task_queue(int i);
+// 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, permanent generation, and remembered and barrier sets
+// specified by the policy object.
+jint initialize();
+void ref_processing_init();
+void set_par_threads(int t) {
+SharedHeap::set_par_threads(t);
+_process_strong_tasks->set_par_threads(t);
+}
+virtual CollectedHeap::Name kind() const {
+return CollectedHeap::G1CollectedHeap;
+}
+// The current policy object for the collector.
+G1CollectorPolicy* g1_policy() const { return _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; }
+ModRefBarrierSet* mr_bs() const { return _mr_bs; }
+// The rem set iterator.
+HeapRegionRemSetIterator* rem_set_iterator(int i) {
+return _rem_set_iterator[i];
+}
+HeapRegionRemSetIterator* rem_set_iterator() {
+return _rem_set_iterator[0];
+}
+unsigned get_gc_time_stamp() {
+return _gc_time_stamp;
+}
+void reset_gc_time_stamp() {
+_gc_time_stamp = 0;
+}
+void iterate_dirty_card_closure(bool concurrent, int worker_i);
+// The shared block offset table array.
+G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
+// Reference Processing accessor
+ReferenceProcessor* ref_processor() { return _ref_processor; }
+// Reserved (g1 only; super method includes perm), capacity and the used
+// portion in bytes.
+size_t g1_reserved_obj_bytes() { return _g1_reserved.byte_size(); }
+virtual size_t capacity() const;
+virtual size_t used() const;
+size_t recalculate_used() const;
+#ifndef PRODUCT
+size_t recalculate_used_regions() const;
+#endif // PRODUCT
+// These virtual functions do the actual allocation.
+virtual HeapWord* mem_allocate(size_t word_size,
+bool   is_noref,
+bool   is_tlab,
+bool* gc_overhead_limit_was_exceeded);
+// 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.
+// Return an estimate of the maximum allocation that could be performed
+// without triggering any collection or expansion activity.  In a
+// generational collector, for example, this is probably the largest
+// allocation that could be supported (without expansion) in the youngest
+// generation.  It is "unsafe" because no locks are taken; the result
+// should be treated as an approximation, not a guarantee, for use in
+// heuristic resizing decisions.
+virtual size_t unsafe_max_alloc();
+virtual bool is_maximal_no_gc() const {
+return _g1_storage.uncommitted_size() == 0;
+}
+// The total number of regions in the heap.
+size_t n_regions();
+// The number of regions that are completely free.
+size_t max_regions();
+// The number of regions that are completely free.
+size_t free_regions();
+// The number of regions that are not completely free.
+size_t used_regions() { return n_regions() - free_regions(); }
+// True iff the ZF thread should run.
+bool should_zf();
+// The number of regions available for "regular" expansion.
+size_t expansion_regions() { return _expansion_regions; }
+#ifndef PRODUCT
+bool regions_accounted_for();
+bool print_region_accounting_info();
+void print_region_counts();
+#endif
+HeapRegion* alloc_region_from_unclean_list(bool zero_filled);
+HeapRegion* alloc_region_from_unclean_list_locked(bool zero_filled);
+void put_region_on_unclean_list(HeapRegion* r);
+void put_region_on_unclean_list_locked(HeapRegion* r);
+void prepend_region_list_on_unclean_list(UncleanRegionList* list);
+void prepend_region_list_on_unclean_list_locked(UncleanRegionList* list);
+void set_unclean_regions_coming(bool b);
+void set_unclean_regions_coming_locked(bool b);
+// Wait for cleanup to be complete.
+void wait_for_cleanup_complete();
+// Like above, but assumes that the calling thread owns the Heap_lock.
+void wait_for_cleanup_complete_locked();
+// Return the head of the unclean list.
+HeapRegion* peek_unclean_region_list_locked();
+// Remove and return the head of the unclean list.
+HeapRegion* pop_unclean_region_list_locked();
+// List of regions which are zero filled and ready for allocation.
+HeapRegion* _free_region_list;
+// Number of elements on the free list.
+size_t _free_region_list_size;
+// If the head of the unclean list is ZeroFilled, move it to the free
+// list.
+bool move_cleaned_region_to_free_list_locked();
+bool move_cleaned_region_to_free_list();
+void put_free_region_on_list_locked(HeapRegion* r);
+void put_free_region_on_list(HeapRegion* r);
+// Remove and return the head element of the free list.
+HeapRegion* pop_free_region_list_locked();
+// If "zero_filled" is true, we first try the free list, then we try the
+// unclean list, zero-filling the result.  If "zero_filled" is false, we
+// first try the unclean list, then the zero-filled list.
+HeapRegion* alloc_free_region_from_lists(bool zero_filled);
+// Verify the integrity of the region lists.
+void remove_allocated_regions_from_lists();
+bool verify_region_lists();
+bool verify_region_lists_locked();
+size_t unclean_region_list_length();
+size_t free_region_list_length();
+// 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);
+// This interface assumes that it's being called by the
+// vm thread. It collects the heap assuming that the
+// heap lock is already held and that we are executing in
+// the context of the vm thread.
+virtual void collect_as_vm_thread(GCCause::Cause cause);
+// True iff a evacuation has failed in the most-recent collection.
+bool evacuation_failed() { return _evacuation_failed; }
+// Free a region if it is totally full of garbage.  Returns the number of
+// bytes freed (0 ==> didn't free it).
+size_t free_region_if_totally_empty(HeapRegion *hr);
+void free_region_if_totally_empty_work(HeapRegion *hr,
+size_t& pre_used,
+size_t& cleared_h_regions,
+size_t& freed_regions,
+UncleanRegionList* list,
+bool par = false);
+// If we've done free region work that yields the given changes, update
+// the relevant global variables.
+void finish_free_region_work(size_t pre_used,
+size_t cleared_h_regions,
+size_t freed_regions,
+UncleanRegionList* list);
+// Returns "TRUE" iff "p" points into the allocated area of the heap.
+virtual bool is_in(const void* p) const;
+// Return "TRUE" iff the given object address is within the collection
+// set.
+inline bool obj_in_cs(oop obj);
+// Return "TRUE" iff the given object address is in the reserved
+// region of g1 (excluding the permanent generation).
+bool is_in_g1_reserved(const void* p) const {
+return _g1_reserved.contains(p);
+}
+// Returns a MemRegion that corresponds to the space that  has been
+// committed in the heap
+MemRegion g1_committed() {
+return _g1_committed;
+}
+NOT_PRODUCT( bool is_in_closed_subset(const void* p) const; )
+// Dirty card table entries covering a list of young regions.
+void dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list);
+// 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 the ref-containing fields of all objects, calling
+// "cl.do_oop" on each.
+virtual void oop_iterate(OopClosure* cl);
+// Same as above, restricted to a memory region.
+virtual void oop_iterate(MemRegion mr, OopClosure* cl);
+// Iterate over all objects, calling "cl.do_object" on each.
+virtual void object_iterate(ObjectClosure* cl);
+// Iterate over all objects allocated since the last collection, calling
+// "cl.do_object" on each.  The heap must have been initialized properly
+// to support this function, or else this call will fail.
+virtual void object_iterate_since_last_GC(ObjectClosure* cl);
+// Iterate over all spaces in use in the heap, in ascending address order.
+virtual void space_iterate(SpaceClosure* cl);
+// Iterate over heap regions, in address order, terminating the
+// iteration early if the "doHeapRegion" method returns "true".
+void heap_region_iterate(HeapRegionClosure* blk);
+// Iterate over heap regions starting with r (or the first region if "r"
+// is NULL), in address order, terminating early if the "doHeapRegion"
+// method returns "true".
+void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk);
+// As above but starting from the region at index idx.
+void heap_region_iterate_from(int idx, HeapRegionClosure* blk);
+HeapRegion* region_at(size_t idx);
+// Divide the heap region sequence into "chunks" of some size (the number
+// of regions divided by the number of parallel threads times some
+// overpartition factor, currently 4).  Assumes that this will be called
+// in parallel by ParallelGCThreads worker threads with discinct worker
+// ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
+// calls will use the same "claim_value", and that that claim value is
+// different from the claim_value of any heap region before the start of
+// the iteration.  Applies "blk->doHeapRegion" to each of the regions, by
+// attempting to claim the first region in each chunk, and, if
+// successful, applying the closure to each region in the chunk (and
+// setting the claim value of the second and subsequent regions of the
+// chunk.)  For now requires that "doHeapRegion" always returns "false",
+// i.e., that a closure never attempt to abort a traversal.
+void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
+int worker,
+jint claim_value);
+// 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);
+// Returns the first (lowest address) compactible space in the heap.
+virtual CompactibleSpace* first_compactible_space();
+// A CollectedHeap will contain some number of spaces.  This finds the
+// space containing a given address, or else returns NULL.
+virtual Space* space_containing(const void* addr) const;
+// A G1CollectedHeap will contain some number of heap regions.  This
+// finds the region containing a given address, or else returns NULL.
+HeapRegion* heap_region_containing(const void* addr) const;
+// Like the above, but requires "addr" to be in the heap (to avoid a
+// null-check), and unlike the above, may return an continuing humongous
+// region.
+HeapRegion* heap_region_containing_raw(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.
+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;
+// Does this heap support heap inspection? (+PrintClassHistogram)
+virtual bool supports_heap_inspection() const { return true; }
+// Section on thread-local allocation buffers (TLABs)
+// See CollectedHeap for semantics.
+virtual bool supports_tlab_allocation() const;
+virtual size_t tlab_capacity(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 {
+// Since G1's TLAB's may, on occasion, come from non-young regions
+// as well. (Is there a flag controlling that? XXX)
+return false;
+}
+// Can a compiler elide a store barrier when it writes
+// a permanent oop into the heap?  Applies when the compiler
+// is storing x to the heap, where x->is_perm() is true.
+virtual bool can_elide_permanent_oop_store_barriers() const {
+// At least until perm gen collection is also G1-ified, at
+// which point this should return false.
+return true;
+}
+virtual bool allocs_are_zero_filled();
+// The boundary between a "large" and "small" array of primitives, in
+// words.
+virtual size_t large_typearray_limit();
+// All popular objects are guaranteed to have addresses below this
+// boundary.
+HeapWord* popular_object_boundary() {
+return _popular_object_boundary;
+}
+// Declare the region as one that should be evacuated because its
+// remembered set is too large.
+void schedule_popular_region_evac(HeapRegion* r);
+// If there is a popular region to evacuate it, remove it from the list
+// and return it.
+HeapRegion* popular_region_to_evac();
+// Evacuate the given popular region.
+void evac_popular_region(HeapRegion* r);
+// Returns "true" iff the given word_size is "very large".
+static bool isHumongous(size_t word_size) {
+return word_size >= VeryLargeInWords;
+}
+// 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();
+// Perform any cleanup actions necessary before allowing a verification.
+virtual void prepare_for_verify();
+// Perform verification.
+virtual void verify(bool allow_dirty, bool silent);
+virtual void print() const;
+virtual void print_on(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;
+// If "addr" is a pointer into the (reserved?) heap, returns a positive
+// number indicating the "arena" within the heap in which "addr" falls.
+// Or else returns 0.
+virtual int addr_to_arena_id(void* addr) const;
+// Convenience function to be used in situations where the heap type can be
+// asserted to be this type.
+static G1CollectedHeap* heap();
+void empty_young_list();
+bool should_set_young_locked();
+void set_region_short_lived_locked(HeapRegion* hr);
+// add appropriate methods for any other surv rate groups
+void young_list_rs_length_sampling_init() {
+_young_list->rs_length_sampling_init();
+}
+bool young_list_rs_length_sampling_more() {
+return _young_list->rs_length_sampling_more();
+}
+void young_list_rs_length_sampling_next() {
+_young_list->rs_length_sampling_next();
+}
+size_t young_list_sampled_rs_lengths() {
+return _young_list->sampled_rs_lengths();
+}
+size_t young_list_length()   { return _young_list->length(); }
+size_t young_list_scan_only_length() {
+return _young_list->scan_only_length(); }
+HeapRegion* pop_region_from_young_list() {
+return _young_list->pop_region();
+}
+HeapRegion* young_list_first_region() {
+return _young_list->first_region();
+}
+// debugging
+bool check_young_list_well_formed() {
+return _young_list->check_list_well_formed();
+}
+bool check_young_list_empty(bool ignore_scan_only_list,
+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();
+// This is called from the marksweep collector which then does
+// a concurrent mark and verifies that the results agree with
+// the stop the world marking.
+void checkConcurrentMark();
+void do_sync_mark();
+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 is used when copying an object to survivor space.
+// If the object is marked live, then we mark the copy live.
+// If the object is allocated since the start of this mark
+// cycle, then we mark the copy live.
+// If the object has been around since the previous mark
+// phase, and hasn't been marked yet during this phase,
+// then we don't mark it, we just wait for the
+// current marking cycle to get to it.
+// 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 in permanent gen it isn't dead.
+// Added if it is NULL it isn't dead.
+bool is_obj_dead(oop obj) {
+HeapRegion* hr = heap_region_containing(obj);
+if (hr == NULL) {
+if (Universe::heap()->is_in_permanent(obj))
+return false;
+else if (obj == NULL) return false;
+else return true;
+}
+else return is_obj_dead(obj, hr);
+}
+bool is_obj_ill(oop obj) {
+HeapRegion* hr = heap_region_containing(obj);
+if (hr == NULL) {
+if (Universe::heap()->is_in_permanent(obj))
+return false;
+else if (obj == NULL) return false;
+else return true;
+}
+else return is_obj_ill(obj, hr);
+}
+// 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;}
+ConcurrentMark* concurrent_mark() const { return _cm; }
+ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
+public:
+void stop_conc_gc_threads();
+// <NEW PREDICTION>
+double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
+void check_if_region_is_too_expensive(double predicted_time_ms);
+size_t pending_card_num();
+size_t max_pending_card_num();
+size_t cards_scanned();
+// </NEW PREDICTION>
+protected:
+size_t _max_heap_capacity;
+//  debug_only(static void check_for_valid_allocation_state();)
+public:
+// Temporary: call to mark things unimplemented for the G1 heap (e.g.,
+// MemoryService).  In productization, we can make this assert false
+// to catch such places (as well as searching for calls to this...)
+static void g1_unimplemented();
+};
+// Local Variables: ***
+// c-indentation-style: gnu ***
+// End: ***

Mercurial > hg > truffle

comparison src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp @ 342:37f87013dfd8