--- /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<StarTask, mtGC> RefToScanQueue;
+typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
+
+typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
+typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
+
+class YoungList : public CHeapObj<mtGC> {
+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<bool> {
+ protected:
+ bool default_value() const { return false; }
+ public:
+ void clear() { G1BiasedMappedArray<bool>::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<oop, mtGC> _objs_with_preserved_marks;
+ Stack<markOop, mtGC> _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.
+ 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<G1SATBCardTableLoggingModRefBS>(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 <class T>
+ 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 <class T>
+ 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