/*
* Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved.
*
* 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_GC_SHENANDOAH_SHENANDOAHHEAP_HPP
#define SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_HPP
#include "gc/shared/markBitMap.hpp"
#include "gc/shared/softRefPolicy.hpp"
#include "gc/shared/collectedHeap.hpp"
#include "gc/shenandoah/shenandoahAsserts.hpp"
#include "gc/shenandoah/shenandoahAllocRequest.hpp"
#include "gc/shenandoah/shenandoahLock.hpp"
#include "gc/shenandoah/shenandoahEvacOOMHandler.hpp"
#include "gc/shenandoah/shenandoahSharedVariables.hpp"
#include "memory/metaspace.hpp"
#include "services/memoryManager.hpp"
class ConcurrentGCTimer;
class ReferenceProcessor;
class ShenandoahAllocTracker;
class ShenandoahCollectorPolicy;
class ShenandoahControlThread;
class ShenandoahGCSession;
class ShenandoahGCStateResetter;
class ShenandoahHeuristics;
class ShenandoahMarkingContext;
class ShenandoahMarkCompact;
class ShenandoahMode;
class ShenandoahPhaseTimings;
class ShenandoahHeap;
class ShenandoahHeapRegion;
class ShenandoahHeapRegionClosure;
class ShenandoahCollectionSet;
class ShenandoahFreeSet;
class ShenandoahConcurrentMark;
class ShenandoahMarkCompact;
class ShenandoahMonitoringSupport;
class ShenandoahPacer;
class ShenandoahTraversalGC;
class ShenandoahVerifier;
class ShenandoahWorkGang;
class VMStructs;
class ShenandoahRegionIterator : public StackObj {
private:
ShenandoahHeap* _heap;
DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
volatile size_t _index;
DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
// No implicit copying: iterators should be passed by reference to capture the state
ShenandoahRegionIterator(const ShenandoahRegionIterator& that);
ShenandoahRegionIterator& operator=(const ShenandoahRegionIterator& o);
public:
ShenandoahRegionIterator();
ShenandoahRegionIterator(ShenandoahHeap* heap);
// Reset iterator to default state
void reset();
// Returns next region, or NULL if there are no more regions.
// This is multi-thread-safe.
inline ShenandoahHeapRegion* next();
// This is *not* MT safe. However, in the absence of multithreaded access, it
// can be used to determine if there is more work to do.
bool has_next() const;
};
class ShenandoahHeapRegionClosure : public StackObj {
public:
virtual void heap_region_do(ShenandoahHeapRegion* r) = 0;
virtual bool is_thread_safe() { return false; }
};
#ifdef ASSERT
class ShenandoahAssertToSpaceClosure : public OopClosure {
private:
template <class T>
void do_oop_work(T* p);
public:
void do_oop(narrowOop* p);
void do_oop(oop* p);
};
#endif
typedef ShenandoahLock ShenandoahHeapLock;
typedef ShenandoahLocker ShenandoahHeapLocker;
// Shenandoah GC is low-pause concurrent GC that uses Brooks forwarding pointers
// to encode forwarding data. See BrooksPointer for details on forwarding data encoding.
// See ShenandoahControlThread for GC cycle structure.
//
class ShenandoahHeap : public CollectedHeap {
friend class ShenandoahAsserts;
friend class VMStructs;
friend class ShenandoahGCSession;
friend class ShenandoahGCStateResetter;
// ---------- Locks that guard important data structures in Heap
//
private:
ShenandoahHeapLock _lock;
public:
ShenandoahHeapLock* lock() {
return &_lock;
}
void assert_heaplock_owned_by_current_thread() NOT_DEBUG_RETURN;
void assert_heaplock_not_owned_by_current_thread() NOT_DEBUG_RETURN;
void assert_heaplock_or_safepoint() NOT_DEBUG_RETURN;
// ---------- Initialization, termination, identification, printing routines
//
public:
static ShenandoahHeap* heap();
static ShenandoahHeap* heap_no_check();
const char* name() const { return "Shenandoah"; }
ShenandoahHeap::Name kind() const { return CollectedHeap::Shenandoah; }
ShenandoahHeap(ShenandoahCollectorPolicy* policy);
jint initialize();
void post_initialize();
void initialize_heuristics();
void initialize_serviceability();
void print_on(outputStream* st) const;
void print_extended_on(outputStream *st) const;
void print_tracing_info() const;
void print_gc_threads_on(outputStream* st) const;
void print_heap_regions_on(outputStream* st) const;
void stop();
void prepare_for_verify();
void verify(VerifyOption vo);
// ---------- Heap counters and metrics
//
private:
size_t _initial_size;
size_t _minimum_size;
DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
volatile size_t _used;
volatile size_t _committed;
volatile size_t _bytes_allocated_since_gc_start;
DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
public:
void increase_used(size_t bytes);
void decrease_used(size_t bytes);
void set_used(size_t bytes);
void increase_committed(size_t bytes);
void decrease_committed(size_t bytes);
void increase_allocated(size_t bytes);
size_t bytes_allocated_since_gc_start();
void reset_bytes_allocated_since_gc_start();
size_t min_capacity() const;
size_t max_capacity() const;
size_t initial_capacity() const;
size_t capacity() const;
size_t used() const;
size_t committed() const;
// ---------- Workers handling
//
private:
uint _max_workers;
ShenandoahWorkGang* _workers;
ShenandoahWorkGang* _safepoint_workers;
public:
uint max_workers();
void assert_gc_workers(uint nworker) NOT_DEBUG_RETURN;
WorkGang* workers() const;
WorkGang* get_safepoint_workers();
void gc_threads_do(ThreadClosure* tcl) const;
// ---------- Heap regions handling machinery
//
private:
MemRegion _heap_region;
bool _heap_region_special;
size_t _num_regions;
ShenandoahHeapRegion** _regions;
ShenandoahRegionIterator _update_refs_iterator;
public:
inline HeapWord* base() const { return _heap_region.start(); }
inline size_t num_regions() const { return _num_regions; }
inline bool is_heap_region_special() { return _heap_region_special; }
inline ShenandoahHeapRegion* const heap_region_containing(const void* addr) const;
inline size_t heap_region_index_containing(const void* addr) const;
inline ShenandoahHeapRegion* const get_region(size_t region_idx) const;
void heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
void parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
// ---------- GC state machinery
//
// GC state describes the important parts of collector state, that may be
// used to make barrier selection decisions in the native and generated code.
// Multiple bits can be set at once.
//
// Important invariant: when GC state is zero, the heap is stable, and no barriers
// are required.
//
public:
enum GCStateBitPos {
// Heap has forwarded objects: needs LRB barriers.
HAS_FORWARDED_BITPOS = 0,
// Heap is under marking: needs SATB barriers.
MARKING_BITPOS = 1,
// Heap is under evacuation: needs LRB barriers. (Set together with HAS_FORWARDED)
EVACUATION_BITPOS = 2,
// Heap is under updating: needs no additional barriers.
UPDATEREFS_BITPOS = 3,
// Heap is under traversal collection
TRAVERSAL_BITPOS = 4
};
enum GCState {
STABLE = 0,
HAS_FORWARDED = 1 << HAS_FORWARDED_BITPOS,
MARKING = 1 << MARKING_BITPOS,
EVACUATION = 1 << EVACUATION_BITPOS,
UPDATEREFS = 1 << UPDATEREFS_BITPOS,
TRAVERSAL = 1 << TRAVERSAL_BITPOS
};
private:
ShenandoahSharedBitmap _gc_state;
ShenandoahSharedFlag _degenerated_gc_in_progress;
ShenandoahSharedFlag _full_gc_in_progress;
ShenandoahSharedFlag _full_gc_move_in_progress;
ShenandoahSharedFlag _progress_last_gc;
void set_gc_state_all_threads(char state);
void set_gc_state_mask(uint mask, bool value);
public:
char gc_state() const;
static address gc_state_addr();
void set_concurrent_mark_in_progress(bool in_progress);
void set_evacuation_in_progress(bool in_progress);
void set_update_refs_in_progress(bool in_progress);
void set_degenerated_gc_in_progress(bool in_progress);
void set_full_gc_in_progress(bool in_progress);
void set_full_gc_move_in_progress(bool in_progress);
void set_concurrent_traversal_in_progress(bool in_progress);
void set_has_forwarded_objects(bool cond);
inline bool is_stable() const;
inline bool is_idle() const;
inline bool is_concurrent_mark_in_progress() const;
inline bool is_update_refs_in_progress() const;
inline bool is_evacuation_in_progress() const;
inline bool is_degenerated_gc_in_progress() const;
inline bool is_full_gc_in_progress() const;
inline bool is_full_gc_move_in_progress() const;
inline bool is_concurrent_traversal_in_progress() const;
inline bool has_forwarded_objects() const;
inline bool is_gc_in_progress_mask(uint mask) const;
// ---------- GC cancellation and degeneration machinery
//
// Cancelled GC flag is used to notify concurrent phases that they should terminate.
//
public:
enum ShenandoahDegenPoint {
_degenerated_unset,
_degenerated_traversal,
_degenerated_outside_cycle,
_degenerated_mark,
_degenerated_evac,
_degenerated_updaterefs,
_DEGENERATED_LIMIT
};
static const char* degen_point_to_string(ShenandoahDegenPoint point) {
switch (point) {
case _degenerated_unset:
return "<UNSET>";
case _degenerated_traversal:
return "Traversal";
case _degenerated_outside_cycle:
return "Outside of Cycle";
case _degenerated_mark:
return "Mark";
case _degenerated_evac:
return "Evacuation";
case _degenerated_updaterefs:
return "Update Refs";
default:
ShouldNotReachHere();
return "ERROR";
}
};
private:
enum CancelState {
// Normal state. GC has not been cancelled and is open for cancellation.
// Worker threads can suspend for safepoint.
CANCELLABLE,
// GC has been cancelled. Worker threads can not suspend for
// safepoint but must finish their work as soon as possible.
CANCELLED,
// GC has not been cancelled and must not be cancelled. At least
// one worker thread checks for pending safepoint and may suspend
// if a safepoint is pending.
NOT_CANCELLED
};
ShenandoahSharedEnumFlag<CancelState> _cancelled_gc;
bool try_cancel_gc();
public:
static address cancelled_gc_addr();
inline bool cancelled_gc() const;
inline bool check_cancelled_gc_and_yield(bool sts_active = true);
inline void clear_cancelled_gc();
void cancel_gc(GCCause::Cause cause);
// ---------- GC operations entry points
//
public:
// Entry points to STW GC operations, these cause a related safepoint, that then
// call the entry method below
void vmop_entry_init_mark();
void vmop_entry_final_mark();
void vmop_entry_final_evac();
void vmop_entry_init_updaterefs();
void vmop_entry_final_updaterefs();
void vmop_entry_init_traversal();
void vmop_entry_final_traversal();
void vmop_entry_full(GCCause::Cause cause);
void vmop_degenerated(ShenandoahDegenPoint point);
// Entry methods to normally STW GC operations. These set up logging, monitoring
// and workers for net VM operation
void entry_init_mark();
void entry_final_mark();
void entry_final_evac();
void entry_init_updaterefs();
void entry_final_updaterefs();
void entry_init_traversal();
void entry_final_traversal();
void entry_full(GCCause::Cause cause);
void entry_degenerated(int point);
// Entry methods to normally concurrent GC operations. These set up logging, monitoring
// for concurrent operation.
void entry_reset();
void entry_mark();
void entry_preclean();
void entry_roots();
void entry_cleanup();
void entry_evac();
void entry_updaterefs();
void entry_traversal();
void entry_uncommit(double shrink_before);
private:
// Actual work for the phases
void op_init_mark();
void op_final_mark();
void op_final_evac();
void op_init_updaterefs();
void op_final_updaterefs();
void op_init_traversal();
void op_final_traversal();
void op_full(GCCause::Cause cause);
void op_degenerated(ShenandoahDegenPoint point);
void op_degenerated_fail();
void op_degenerated_futile();
void op_reset();
void op_mark();
void op_preclean();
void op_roots();
void op_cleanup();
void op_conc_evac();
void op_stw_evac();
void op_updaterefs();
void op_traversal();
void op_uncommit(double shrink_before);
// Messages for GC trace events, they have to be immortal for
// passing around the logging/tracing systems
const char* init_mark_event_message() const;
const char* final_mark_event_message() const;
const char* conc_mark_event_message() const;
const char* degen_event_message(ShenandoahDegenPoint point) const;
// ---------- GC subsystems
//
private:
ShenandoahControlThread* _control_thread;
ShenandoahCollectorPolicy* _shenandoah_policy;
ShenandoahMode* _gc_mode;
ShenandoahHeuristics* _heuristics;
ShenandoahFreeSet* _free_set;
ShenandoahConcurrentMark* _scm;
ShenandoahTraversalGC* _traversal_gc;
ShenandoahMarkCompact* _full_gc;
ShenandoahPacer* _pacer;
ShenandoahVerifier* _verifier;
ShenandoahAllocTracker* _alloc_tracker;
ShenandoahPhaseTimings* _phase_timings;
ShenandoahControlThread* control_thread() { return _control_thread; }
ShenandoahMarkCompact* full_gc() { return _full_gc; }
public:
ShenandoahCollectorPolicy* shenandoah_policy() const { return _shenandoah_policy; }
ShenandoahHeuristics* heuristics() const { return _heuristics; }
ShenandoahFreeSet* free_set() const { return _free_set; }
ShenandoahConcurrentMark* concurrent_mark() { return _scm; }
ShenandoahTraversalGC* traversal_gc() const { return _traversal_gc; }
bool is_traversal_mode() const { return _traversal_gc != NULL; }
ShenandoahPacer* pacer() const { return _pacer; }
ShenandoahPhaseTimings* phase_timings() const { return _phase_timings; }
ShenandoahAllocTracker* alloc_tracker() const { return _alloc_tracker; }
ShenandoahVerifier* verifier();
// ---------- VM subsystem bindings
//
private:
ShenandoahMonitoringSupport* _monitoring_support;
MemoryPool* _memory_pool;
GCMemoryManager _stw_memory_manager;
GCMemoryManager _cycle_memory_manager;
ConcurrentGCTimer* _gc_timer;
SoftRefPolicy _soft_ref_policy;
// For exporting to SA
int _log_min_obj_alignment_in_bytes;
public:
ShenandoahMonitoringSupport* monitoring_support() { return _monitoring_support; }
GCMemoryManager* cycle_memory_manager() { return &_cycle_memory_manager; }
GCMemoryManager* stw_memory_manager() { return &_stw_memory_manager; }
SoftRefPolicy* soft_ref_policy() { return &_soft_ref_policy; }
GrowableArray<GCMemoryManager*> memory_managers();
GrowableArray<MemoryPool*> memory_pools();
MemoryUsage memory_usage();
GCTracer* tracer();
GCTimer* gc_timer() const;
// ---------- Reference processing
//
private:
AlwaysTrueClosure _subject_to_discovery;
ReferenceProcessor* _ref_processor;
ShenandoahSharedFlag _process_references;
void ref_processing_init();
public:
ReferenceProcessor* ref_processor() { return _ref_processor; }
void set_process_references(bool pr);
bool process_references() const;
// ---------- Class Unloading
//
private:
ShenandoahSharedFlag _unload_classes;
public:
void set_unload_classes(bool uc);
bool unload_classes() const;
// Perform STW class unloading and weak root cleaning
void parallel_cleaning(bool full_gc);
private:
void stw_unload_classes(bool full_gc);
void stw_process_weak_roots(bool full_gc);
// ---------- Generic interface hooks
// Minor things that super-interface expects us to implement to play nice with
// the rest of runtime. Some of the things here are not required to be implemented,
// and can be stubbed out.
//
public:
AdaptiveSizePolicy* size_policy() shenandoah_not_implemented_return(NULL);
bool is_maximal_no_gc() const shenandoah_not_implemented_return(false);
bool is_in(const void* p) const;
MemRegion reserved_region() const { return _reserved; }
bool is_in_reserved(const void* addr) const { return _reserved.contains(addr); }
void collect(GCCause::Cause cause);
void do_full_collection(bool clear_all_soft_refs);
// Used for parsing heap during error printing
HeapWord* block_start(const void* addr) const;
bool block_is_obj(const HeapWord* addr) const;
bool print_location(outputStream* st, void* addr) const;
// Used for native heap walkers: heap dumpers, mostly
void object_iterate(ObjectClosure* cl);
void safe_object_iterate(ObjectClosure* cl);
// Used by RMI
jlong millis_since_last_gc();
// ---------- Safepoint interface hooks
//
public:
void safepoint_synchronize_begin();
void safepoint_synchronize_end();
// ---------- Code roots handling hooks
//
public:
void register_nmethod(nmethod* nm);
void unregister_nmethod(nmethod* nm);
void flush_nmethod(nmethod* nm) {}
void verify_nmethod(nmethod* nm) {}
// ---------- Pinning hooks
//
public:
// Shenandoah supports per-object (per-region) pinning
bool supports_object_pinning() const { return true; }
oop pin_object(JavaThread* thread, oop obj);
void unpin_object(JavaThread* thread, oop obj);
void sync_pinned_region_status();
void assert_pinned_region_status() NOT_DEBUG_RETURN;
// ---------- Allocation support
//
private:
HeapWord* allocate_memory_under_lock(ShenandoahAllocRequest& request, bool& in_new_region);
inline HeapWord* allocate_from_gclab(Thread* thread, size_t size);
HeapWord* allocate_from_gclab_slow(Thread* thread, size_t size);
HeapWord* allocate_new_gclab(size_t min_size, size_t word_size, size_t* actual_size);
void retire_and_reset_gclabs();
public:
HeapWord* allocate_memory(ShenandoahAllocRequest& request);
HeapWord* mem_allocate(size_t size, bool* what);
MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
size_t size,
Metaspace::MetadataType mdtype);
void notify_mutator_alloc_words(size_t words, bool waste);
// Shenandoah supports TLAB allocation
bool supports_tlab_allocation() const { return true; }
HeapWord* allocate_new_tlab(size_t min_size, size_t requested_size, size_t* actual_size);
size_t tlab_capacity(Thread *thr) const;
size_t unsafe_max_tlab_alloc(Thread *thread) const;
size_t max_tlab_size() const;
size_t tlab_used(Thread* ignored) const;
void resize_tlabs();
void ensure_parsability(bool retire_tlabs);
void make_parsable(bool retire_tlabs);
// ---------- Marking support
//
private:
ShenandoahMarkingContext* _marking_context;
MemRegion _bitmap_region;
MemRegion _aux_bitmap_region;
MarkBitMap _verification_bit_map;
MarkBitMap _aux_bit_map;
size_t _bitmap_size;
size_t _bitmap_regions_per_slice;
size_t _bitmap_bytes_per_slice;
bool _bitmap_region_special;
bool _aux_bitmap_region_special;
// Used for buffering per-region liveness data.
// Needed since ShenandoahHeapRegion uses atomics to update liveness.
//
// The array has max-workers elements, each of which is an array of
// jushort * max_regions. The choice of jushort is not accidental:
// there is a tradeoff between static/dynamic footprint that translates
// into cache pressure (which is already high during marking), and
// too many atomic updates. size_t/jint is too large, jbyte is too small.
jushort** _liveness_cache;
public:
inline ShenandoahMarkingContext* complete_marking_context() const;
inline ShenandoahMarkingContext* marking_context() const;
inline void mark_complete_marking_context();
inline void mark_incomplete_marking_context();
template<class T>
inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl);
template<class T>
inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
template<class T>
inline void marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
void reset_mark_bitmap();
// SATB barriers hooks
template<bool RESOLVE>
inline bool requires_marking(const void* entry) const;
void force_satb_flush_all_threads();
// Support for bitmap uncommits
bool commit_bitmap_slice(ShenandoahHeapRegion *r);
bool uncommit_bitmap_slice(ShenandoahHeapRegion *r);
bool is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self = false);
// Liveness caching support
jushort* get_liveness_cache(uint worker_id);
void flush_liveness_cache(uint worker_id);
// ---------- Evacuation support
//
private:
ShenandoahCollectionSet* _collection_set;
ShenandoahEvacOOMHandler _oom_evac_handler;
void evacuate_and_update_roots();
public:
static address in_cset_fast_test_addr();
ShenandoahCollectionSet* collection_set() const { return _collection_set; }
template <class T>
inline bool in_collection_set(T obj) const;
// Avoid accidentally calling the method above with ShenandoahHeapRegion*, which would be *wrong*.
inline bool in_collection_set(ShenandoahHeapRegion* r) shenandoah_not_implemented_return(false);
// Evacuates object src. Returns the evacuated object, either evacuated
// by this thread, or by some other thread.
inline oop evacuate_object(oop src, Thread* thread);
// Call before/after evacuation.
void enter_evacuation();
void leave_evacuation();
// ---------- Helper functions
//
public:
template <class T>
inline oop evac_update_with_forwarded(T* p);
template <class T>
inline oop maybe_update_with_forwarded(T* p);
template <class T>
inline oop maybe_update_with_forwarded_not_null(T* p, oop obj);
template <class T>
inline oop update_with_forwarded_not_null(T* p, oop obj);
static inline oop cas_oop(oop n, narrowOop* addr, oop c);
static inline oop cas_oop(oop n, oop* addr, oop c);
static inline oop cas_oop(oop n, narrowOop* addr, narrowOop c);
void trash_humongous_region_at(ShenandoahHeapRegion *r);
void deduplicate_string(oop str);
private:
void trash_cset_regions();
void update_heap_references(bool concurrent);
// ---------- Testing helpers functions
//
private:
ShenandoahSharedFlag _inject_alloc_failure;
void try_inject_alloc_failure();
bool should_inject_alloc_failure();
};
#endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_HPP