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/softRefPolicy.hpp"
29 #include "gc/shared/space.hpp"
30 #include "services/memoryManager.hpp"
31 #include "gc/epsilon/epsilonCollectorPolicy.hpp"
32 #include "gc/epsilon/epsilonMonitoringSupport.hpp"
33 #include "gc/epsilon/epsilonBarrierSet.hpp"
34 #include "gc/epsilon/epsilon_globals.hpp"
35
36 class EpsilonHeap : public CollectedHeap {
37 friend class VMStructs;
38 private:
39 EpsilonCollectorPolicy* _policy;
40 SoftRefPolicy _soft_ref_policy;
41 EpsilonMonitoringSupport* _monitoring_support;
42 MemoryPool* _pool;
43 GCMemoryManager _memory_manager;
44 ContiguousSpace* _space;
45 VirtualSpace _virtual_space;
46 size_t _max_tlab_size;
47 size_t _step_counter_update;
48 size_t _step_heap_print;
49 int64_t _decay_time_ns;
50 volatile size_t _last_counter_update;
51 volatile size_t _last_heap_print;
52
53 public:
54 static EpsilonHeap* heap();
55
56 EpsilonHeap(EpsilonCollectorPolicy* p) :
57 _policy(p),
58 _memory_manager("Epsilon Heap", "") {};
59
60 virtual Name kind() const {
61 return CollectedHeap::Epsilon;
62 }
63
64 virtual const char* name() const {
65 return "Epsilon";
66 }
67
68 virtual CollectorPolicy* collector_policy() const {
69 return _policy;
70 }
71
72 virtual SoftRefPolicy* soft_ref_policy() {
73 return &_soft_ref_policy;
74 }
75
76 virtual jint initialize();
77 virtual void post_initialize();
78 virtual void initialize_serviceability();
79
80 virtual GrowableArray<GCMemoryManager*> memory_managers();
81 virtual GrowableArray<MemoryPool*> memory_pools();
82
83 virtual size_t max_capacity() const { return _virtual_space.reserved_size(); }
84 virtual size_t capacity() const { return _virtual_space.committed_size(); }
85 virtual size_t used() const { return _space->used(); }
86
87 virtual bool is_in(const void* p) const {
88 return _space->is_in(p);
89 }
90
91 virtual bool is_scavengable(oop obj) {
92 // No GC is going to happen, therefore no objects ever move.
93 // Or are they... (evil laugh).
94 return EpsilonWhyNotGCAnyway;
95 }
96
97 virtual bool is_maximal_no_gc() const {
98 // No GC is going to happen. Return "we are at max", when we are about to fail.
99 return used() == capacity();
100 }
101
102 // Allocation
103 HeapWord* allocate_work(size_t size);
104 HeapWord* allocate_or_collect_work(size_t size);
105 virtual HeapWord* mem_allocate(size_t size, bool* gc_overhead_limit_was_exceeded);
106 virtual HeapWord* allocate_new_tlab(size_t min_size,
107 size_t requested_size,
108 size_t* actual_size);
109
110 // TLAB allocation
111 virtual bool supports_tlab_allocation() const { return true; }
112 virtual size_t tlab_capacity(Thread* thr) const { return capacity(); }
113 virtual size_t tlab_used(Thread* thr) const { return used(); }
114 virtual size_t max_tlab_size() const { return _max_tlab_size; }
115 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
116
117 virtual void collect(GCCause::Cause cause);
118 virtual void do_full_collection(bool clear_all_soft_refs);
119
120 // Heap walking support
121 virtual void safe_object_iterate(ObjectClosure* cl);
122 virtual void object_iterate(ObjectClosure* cl) {
123 safe_object_iterate(cl);
124 }
125
126 // Object pinning support: every object is implicitly pinned
127 // Or is it... (evil laugh)
128 virtual bool supports_object_pinning() const { return !EpsilonWhyNotGCAnyway; }
129 virtual oop pin_object(JavaThread* thread, oop obj) { return obj; }
130 virtual void unpin_object(JavaThread* thread, oop obj) { }
131
132 // No support for block parsing.
133 virtual HeapWord* block_start(const void* addr) const { return NULL; }
134 virtual size_t block_size(const HeapWord* addr) const { return 0; }
135 virtual bool block_is_obj(const HeapWord* addr) const { return false; }
136
137 // No GC threads
138 virtual void print_gc_threads_on(outputStream* st) const {}
139 virtual void gc_threads_do(ThreadClosure* tc) const {}
140
141 // No heap verification
142 virtual void prepare_for_verify() {}
143 virtual void verify(VerifyOption option) {}
144
145 virtual jlong millis_since_last_gc() {
146 // Report time since the VM start
147 return os::elapsed_counter() / NANOSECS_PER_MILLISEC;
148 }
149
150 virtual void print_on(outputStream* st) const;
151 virtual void print_tracing_info() const;
152
153 void entry_collect(GCCause::Cause cause);
154
155 private:
156 void print_heap_info(size_t used) const;
157 void print_metaspace_info() const;
158
159 void vmentry_collect(GCCause::Cause cause);
160
161 void do_roots(OopClosure* cl, bool everything);
162 void process_roots(OopClosure* cl) { do_roots(cl, false); }
163 void process_all_roots(OopClosure* cl) { do_roots(cl, true); }
164 void walk_heap(ObjectClosure* cl, bool only_marked);
165
166 };
167
168 #endif // SHARE_GC_EPSILON_EPSILONHEAP_HPP