1 /*
2 * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #ifndef SHARE_GC_EPSILON_EPSILONHEAP_HPP
25 #define SHARE_GC_EPSILON_EPSILONHEAP_HPP
26
27 #include "gc/shared/collectedHeap.hpp"
28 #include "gc/shared/markBitMap.hpp"
29 #include "gc/shared/softRefPolicy.hpp"
30 #include "gc/shared/space.hpp"
31 #include "gc/epsilon/epsilonMonitoringSupport.hpp"
32 #include "gc/epsilon/epsilonBarrierSet.hpp"
33 #include "services/memoryManager.hpp"
34
35 class EpsilonHeap : public CollectedHeap {
36 friend class VMStructs;
37 private:
38 SoftRefPolicy _soft_ref_policy;
39 EpsilonMonitoringSupport* _monitoring_support;
40 MemoryPool* _pool;
41 GCMemoryManager _memory_manager;
42 ContiguousSpace* _space;
43 VirtualSpace _virtual_space;
44 size_t _max_tlab_size;
45 size_t _step_counter_update;
46 size_t _step_heap_print;
47 int64_t _decay_time_ns;
48 volatile size_t _last_counter_update;
49 volatile size_t _last_heap_print;
50 MemRegion _bitmap_region;
51 MarkBitMap _bitmap;
52
53 public:
54 static EpsilonHeap* heap();
55
56 EpsilonHeap() :
57 _memory_manager("Epsilon Heap", "") {};
58
59 virtual Name kind() const {
60 return CollectedHeap::Epsilon;
61 }
62
63 virtual const char* name() const {
64 return "Epsilon";
65 }
66
67 virtual SoftRefPolicy* soft_ref_policy() {
68 return &_soft_ref_policy;
69 }
70
71 virtual jint initialize();
72 virtual void post_initialize();
73 virtual void initialize_serviceability();
74
75 virtual GrowableArray<GCMemoryManager*> memory_managers();
76 virtual GrowableArray<MemoryPool*> memory_pools();
77
78 virtual size_t max_capacity() const { return _virtual_space.reserved_size(); }
79 virtual size_t capacity() const { return _virtual_space.committed_size(); }
80 virtual size_t used() const { return _space->used(); }
81
82 virtual bool is_in(const void* p) const {
83 return _space->is_in(p);
84 }
85
86 virtual bool is_maximal_no_gc() const {
87 // No GC is going to happen. Return "we are at max", when we are about to fail.
88 return used() == capacity();
89 }
90
91 // Allocation
92 HeapWord* allocate_work(size_t size);
93 HeapWord* allocate_or_collect_work(size_t size);
94 virtual HeapWord* mem_allocate(size_t size, bool* gc_overhead_limit_was_exceeded);
95 virtual HeapWord* allocate_new_tlab(size_t min_size,
96 size_t requested_size,
97 size_t* actual_size);
98
99 // TLAB allocation
100 virtual bool supports_tlab_allocation() const { return true; }
101 virtual size_t tlab_capacity(Thread* thr) const { return capacity(); }
102 virtual size_t tlab_used(Thread* thr) const { return used(); }
103 virtual size_t max_tlab_size() const { return _max_tlab_size; }
104 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
105
106 virtual void collect(GCCause::Cause cause);
107 virtual void do_full_collection(bool clear_all_soft_refs);
108
109 // Heap walking support
110 virtual void object_iterate(ObjectClosure* cl);
111
112 // Object pinning support: every object is implicitly pinned
113 // Or is it... (evil laugh)
114 virtual bool supports_object_pinning() const { return !EpsilonSlidingGC; }
115 virtual oop pin_object(JavaThread* thread, oop obj) { return obj; }
116 virtual void unpin_object(JavaThread* thread, oop obj) { }
117
118 // No support for block parsing.
119 HeapWord* block_start(const void* addr) const { return NULL; }
120 bool block_is_obj(const HeapWord* addr) const { return false; }
121
122 // No GC threads
123 virtual void print_gc_threads_on(outputStream* st) const {}
124 virtual void gc_threads_do(ThreadClosure* tc) const {}
125
126 // No nmethod handling
127 virtual void register_nmethod(nmethod* nm) {}
128 virtual void unregister_nmethod(nmethod* nm) {}
129 virtual void flush_nmethod(nmethod* nm) {}
130 virtual void verify_nmethod(nmethod* nm) {}
131
132 // No heap verification
133 virtual void prepare_for_verify() {}
134 virtual void verify(VerifyOption option) {}
135
136 virtual jlong millis_since_last_gc() {
137 // Report time since the VM start
138 return os::elapsed_counter() / NANOSECS_PER_MILLISEC;
139 }
140
141 MemRegion reserved_region() const { return _reserved; }
142 bool is_in_reserved(const void* addr) const { return _reserved.contains(addr); }
143
144 virtual void print_on(outputStream* st) const;
145 virtual void print_tracing_info() const;
146 virtual bool print_location(outputStream* st, void* addr) const;
147
148 void entry_collect(GCCause::Cause cause);
149
150 private:
151 void print_heap_info(size_t used) const;
152 void print_metaspace_info() const;
153
154 void vmentry_collect(GCCause::Cause cause);
155
156 void do_roots(OopClosure* cl, bool everything);
157 void process_roots(OopClosure* cl) { do_roots(cl, false); }
158 void process_all_roots(OopClosure* cl) { do_roots(cl, true); }
159 void walk_bitmap(ObjectClosure* cl);
160
161 };
162
163 #endif // SHARE_GC_EPSILON_EPSILONHEAP_HPP