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 // TLAB allocations
63 virtual bool supports_tlab_allocation() const { return true; }
64 virtual size_t tlab_capacity(Thread *thr) const { return capacity(); }
65 virtual size_t tlab_used(Thread *thr) const { return used(); } // TODO: Should probably record the TLAB?
66 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
67 // TODO: hook up in TLAB policy better. pointer_delta(_current, _end);
68 return HeapWordSize * 128 * K;
69 }
70
71 virtual bool can_elide_tlab_store_barriers() const {
72 return true; // TODO: Really?
73 }
74
75 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
76 return true; // TODO: Really?
77 }
78
79 virtual bool card_mark_must_follow_store() const {
80 return true; // TODO: Really?
81 }
82
83 virtual void collect_as_vm_thread(GCCause::Cause cause);
84 virtual void collect(GCCause::Cause cause);
85 virtual void do_full_collection(bool clear_all_soft_refs);
86
87 virtual AdaptiveSizePolicy *size_policy() {
88 // No such thing for Epsilon
89 return NULL;
90 }
91
92 virtual CollectorPolicy *collector_policy() const {
93 return _policy;
94 }
95
96 virtual void object_iterate(ObjectClosure *cl) {
97 Unimplemented();
98 }
99
100 virtual void safe_object_iterate(ObjectClosure *cl) {
101 // TODO: Enable heap dumps by implementing this.
102 Unimplemented();
103 }
104
105 virtual HeapWord *block_start(const void *addr) const {
106 Unimplemented();
107 return NULL;
108 }
109
110 virtual size_t block_size(const HeapWord *addr) const {
111 Unimplemented();
112 return 0;
113 }
114
115 virtual bool block_is_obj(const HeapWord *addr) const {
116 Unimplemented();
117 return false;
118 }
119
120 virtual jlong millis_since_last_gc() {
121 return os::elapsed_counter(); // since the VM start
122 }
123
124 virtual void prepare_for_verify() {
125 // No heap verification.
126 }
127
128 virtual void print_on(outputStream *st) const {
129 // Print nothing.
130 }
131
132 virtual void print_gc_threads_on(outputStream *st) const {
133 // No GC threads.
134 }
135
136 virtual void gc_threads_do(ThreadClosure *tc) const {
137 // No GC threads.
138 }
139
140 virtual void print_tracing_info() const {
141 Log(gc) log;
142 log.info("Epsilon: yup, we are still alive.");
143 log.info("Allocated " SIZE_FORMAT "K in this session.",
144 pointer_delta((HeapWord*)_current, _start) * HeapWordSize / K);
145 }
146
147 virtual void verify(VerifyOption option) {
148 // No heap verification for Epsilon.
149 }
150
151 };