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 #include "gc/epsilon/epsilon_globals.hpp"
28
29 class EpsilonCollectedHeap : public CollectedHeap {
30 private:
31 EpsilonCollectorPolicy* _policy;
32 HeapWord* _start;
33 HeapWord* _end;
34 volatile HeapWord* _current;
35 public:
36 EpsilonCollectedHeap(EpsilonCollectorPolicy* p) : _policy(p) {};
37
38 virtual Name kind() const {
39 return CollectedHeap::EpsilonCollectedHeap;
40 }
41
42 virtual const char *name() const {
43 return "Epsilon GC";
44 }
45
46 virtual jint initialize();
47
48 virtual void post_initialize() {}
49
50 virtual size_t capacity() const { return pointer_delta(_end, _start); }
51 virtual size_t used() const { return pointer_delta((HeapWord*)_current, _start); }
52 virtual size_t max_capacity() const { return capacity(); }
53
54 virtual bool is_maximal_no_gc() const { return used() == capacity(); } // TODO: Really?
55
56 virtual bool is_in(const void *p) const { return (_start <= p) && (p < _end); }
57
58 virtual bool is_scavengable(const void *p) { return true; } // TODO: Why?
59
60 virtual HeapWord* mem_allocate(size_t size, bool *gc_overhead_limit_was_exceeded);
61 virtual HeapWord* allocate_new_tlab(size_t size);
62
63 virtual HeapWord* allocate_work(size_t size);
64
65 // TLAB allocations
66 virtual bool supports_tlab_allocation() const { return UseTLAB; }
67 virtual size_t tlab_capacity(Thread *thr) const { return capacity(); }
68 virtual size_t tlab_used(Thread *thr) const { return used(); } // TODO: Should probably record the TLAB?
69 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
70 // TODO: hook up in TLAB policy better.
71 return EpsilonTLABSize;
72 }
73
74 virtual bool can_elide_tlab_store_barriers() const {
75 return true; // TODO: Really?
76 }
77
78 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
79 return true; // TODO: Really?
80 }
81
82 virtual bool card_mark_must_follow_store() const {
83 return false; // TODO: Really?
84 }
85
86 virtual void collect(GCCause::Cause cause);
87 virtual void do_full_collection(bool clear_all_soft_refs);
88
89 virtual AdaptiveSizePolicy *size_policy() {
90 // No such thing for Epsilon
91 return NULL;
92 }
93
94 virtual CollectorPolicy *collector_policy() const {
95 return _policy;
96 }
97
98 virtual void object_iterate(ObjectClosure *cl) {
99 safe_object_iterate(cl);
100 }
101
102 virtual void safe_object_iterate(ObjectClosure *cl);
103
104 virtual HeapWord *block_start(const void *addr) const {
105 Unimplemented();
106 return NULL;
107 }
108
109 virtual size_t block_size(const HeapWord *addr) const {
110 Unimplemented();
111 return 0;
112 }
113
114 virtual bool block_is_obj(const HeapWord *addr) const {
115 Unimplemented();
116 return false;
117 }
118
119 virtual jlong millis_since_last_gc() {
120 return os::elapsed_counter() / NANOSECS_PER_MILLISEC; // since the VM start
121 }
122
123 virtual void prepare_for_verify() {
124 // No heap verification.
125 }
126
127 virtual void print_on(outputStream *st) const {
128 // Print nothing.
129 }
130
131 virtual void print_gc_threads_on(outputStream *st) const {
132 // No GC threads.
133 }
134
135 virtual void gc_threads_do(ThreadClosure *tc) const {
136 // No GC threads.
137 }
138
139 virtual void print_tracing_info() const {
140 Log(gc) log;
141 size_t allocated_kb = pointer_delta((HeapWord*)_current, _start) * HeapWordSize / K;
142 log.info("Total allocated: " SIZE_FORMAT " KB.",
143 allocated_kb);
144 log.info("Average allocation rate: " SIZE_FORMAT " KB/sec",
145 allocated_kb * NANOSECS_PER_SEC / os::elapsed_counter());
146 }
147
148 virtual void verify(VerifyOption option) {
149 // No heap verification for Epsilon.
150 }
151
152 };