1 /*
2 * Copyright (c) 2017, Red Hat, Inc. and/or its affiliates.
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 #include "gc/shared/collectedHeap.hpp"
25 #include "gc/epsilon/epsilonCollectorPolicy.hpp"
26 #include "gc/epsilon/epsilonBarrierSet.hpp"
27
28 class EpsilonCollectedHeap : public CollectedHeap {
29 private:
30 EpsilonCollectorPolicy* _policy;
31 HeapWord* _start;
32 HeapWord* _end;
33 volatile HeapWord* _current;
34 public:
35 EpsilonCollectedHeap(EpsilonCollectorPolicy* p) : _policy(p) {};
36
37 virtual Name kind() const {
38 return CollectedHeap::EpsilonCollectedHeap;
39 }
40
41 virtual const char *name() const {
42 return "Epsilon GC";
43 }
44
45 virtual jint initialize();
46
47 virtual void post_initialize() {}
48
49 virtual size_t capacity() const { return pointer_delta(_end, _start); }
50 virtual size_t used() const { return pointer_delta((HeapWord*)_current, _start); }
51 virtual size_t max_capacity() const { return capacity(); }
52
53 virtual bool is_maximal_no_gc() const { return used() == capacity(); } // TODO: Really?
54
55 virtual bool is_in(const void *p) const { return (_start <= p) && (p < _end); }
56
57 virtual bool is_scavengable(const void *p) { return true; } // TODO: Why?
58
59 virtual HeapWord* mem_allocate(size_t size, bool *gc_overhead_limit_was_exceeded);
60 virtual HeapWord* allocate_new_tlab(size_t size);
61
62 virtual HeapWord* allocate_work(size_t size);
63
64 // TLAB allocations
65 virtual bool supports_tlab_allocation() const { return true; }
66 virtual size_t tlab_capacity(Thread *thr) const { return capacity(); }
67 virtual size_t tlab_used(Thread *thr) const { return used(); } // TODO: Should probably record the TLAB?
68 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
69 // TODO: hook up in TLAB policy better. pointer_delta(_current, _end);
70 return HeapWordSize * 128 * K;
71 }
72
73 virtual bool can_elide_tlab_store_barriers() const {
74 return true; // TODO: Really?
75 }
76
77 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
78 return true; // TODO: Really?
79 }
80
81 virtual bool card_mark_must_follow_store() const {
82 return true; // TODO: Really?
83 }
84
85 virtual void collect(GCCause::Cause cause);
86 virtual void do_full_collection(bool clear_all_soft_refs);
87
88 virtual AdaptiveSizePolicy *size_policy() {
89 // No such thing for Epsilon
90 return NULL;
91 }
92
93 virtual CollectorPolicy *collector_policy() const {
94 return _policy;
95 }
96
97 virtual void object_iterate(ObjectClosure *cl) {
98 safe_object_iterate(cl);
99 }
100
101 virtual void safe_object_iterate(ObjectClosure *cl);
102
103 virtual HeapWord *block_start(const void *addr) const {
104 Unimplemented();
105 return NULL;
106 }
107
108 virtual size_t block_size(const HeapWord *addr) const {
109 Unimplemented();
110 return 0;
111 }
112
113 virtual bool block_is_obj(const HeapWord *addr) const {
114 Unimplemented();
115 return false;
116 }
117
118 virtual jlong millis_since_last_gc() {
119 return os::elapsed_counter() / NANOSECS_PER_MILLISEC; // since the VM start
120 }
121
122 virtual void prepare_for_verify() {
123 // No heap verification.
124 }
125
126 virtual void print_on(outputStream *st) const {
127 // Print nothing.
128 }
129
130 virtual void print_gc_threads_on(outputStream *st) const {
131 // No GC threads.
132 }
133
134 virtual void gc_threads_do(ThreadClosure *tc) const {
135 // No GC threads.
136 }
137
138 virtual void print_tracing_info() const {
139 Log(gc) log;
140 size_t allocated_kb = pointer_delta((HeapWord*)_current, _start) * HeapWordSize / K;
141 log.info("Total allocated: " SIZE_FORMAT " KB.",
142 allocated_kb);
143 log.info("Average allocation rate: " SIZE_FORMAT " KB/sec",
144 allocated_kb * NANOSECS_PER_SEC / os::elapsed_counter());
145 }
146
147 virtual void verify(VerifyOption option) {
148 // No heap verification for Epsilon.
149 }
150
151 };