1 /*
2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "incls/_precompiled.incl"
26 #include "incls/_stubs.cpp.incl"
27
28
29 // Implementation of StubQueue
30 //
31 // Standard wrap-around queue implementation; the queue dimensions
32 // are specified by the _queue_begin & _queue_end indices. The queue
33 // can be in two states (transparent to the outside):
34 //
35 // a) contiguous state: all queue entries in one block (or empty)
36 //
37 // Queue: |...|XXXXXXX|...............|
38 // ^0 ^begin ^end ^size = limit
39 // |_______|
40 // one block
41 //
42 // b) non-contiguous state: queue entries in two blocks
43 //
44 // Queue: |XXX|.......|XXXXXXX|.......|
45 // ^0 ^end ^begin ^limit ^size
46 // |___| |_______|
47 // 1st block 2nd block
48 //
49 // In the non-contiguous state, the wrap-around point is
50 // indicated via the _buffer_limit index since the last
51 // queue entry may not fill up the queue completely in
52 // which case we need to know where the 2nd block's end
53 // is to do the proper wrap-around. When removing the
54 // last entry of the 2nd block, _buffer_limit is reset
55 // to _buffer_size.
56 //
57 // CAUTION: DO NOT MESS WITH THIS CODE IF YOU CANNOT PROVE
58 // ITS CORRECTNESS! THIS CODE IS MORE SUBTLE THAN IT LOOKS!
59
60
61 StubQueue::StubQueue(StubInterface* stub_interface, int buffer_size,
62 Mutex* lock, const char* name) : _mutex(lock) {
63 intptr_t size = round_to(buffer_size, 2*BytesPerWord);
64 BufferBlob* blob = BufferBlob::create(name, size);
65 if( blob == NULL) {
66 vm_exit_out_of_memory(size, err_msg("CodeCache: no room for %s", name));
67 }
68 _stub_interface = stub_interface;
69 _buffer_size = blob->content_size();
70 _buffer_limit = blob->content_size();
71 _stub_buffer = blob->content_begin();
72 _queue_begin = 0;
73 _queue_end = 0;
74 _number_of_stubs = 0;
75 register_queue(this);
76 }
77
78
79 StubQueue::~StubQueue() {
80 // Note: Currently StubQueues are never destroyed so nothing needs to be done here.
81 // If we want to implement the destructor, we need to release the BufferBlob
82 // allocated in the constructor (i.e., we need to keep it around or look it
83 // up via CodeCache::find_blob(...).
84 Unimplemented();
85 }
86
87
88 Stub* StubQueue::stub_containing(address pc) const {
89 if (contains(pc)) {
90 for (Stub* s = first(); s != NULL; s = next(s)) {
91 if (stub_contains(s, pc)) return s;
92 }
93 }
94 return NULL;
95 }
96
97
98 Stub* StubQueue::request_committed(int code_size) {
99 Stub* s = request(code_size);
100 if (s != NULL) commit(code_size);
101 return s;
102 }
103
104
105 Stub* StubQueue::request(int requested_code_size) {
106 assert(requested_code_size > 0, "requested_code_size must be > 0");
107 if (_mutex != NULL) _mutex->lock();
108 Stub* s = current_stub();
109 int requested_size = round_to(stub_code_size_to_size(requested_code_size), CodeEntryAlignment);
110 if (requested_size <= available_space()) {
111 if (is_contiguous()) {
112 // Queue: |...|XXXXXXX|.............|
113 // ^0 ^begin ^end ^size = limit
114 assert(_buffer_limit == _buffer_size, "buffer must be fully usable");
115 if (_queue_end + requested_size <= _buffer_size) {
116 // code fits in at the end => nothing to do
117 stub_initialize(s, requested_size);
118 return s;
119 } else {
120 // stub doesn't fit in at the queue end
121 // => reduce buffer limit & wrap around
122 assert(!is_empty(), "just checkin'");
123 _buffer_limit = _queue_end;
124 _queue_end = 0;
125 }
126 }
127 }
128 if (requested_size <= available_space()) {
129 assert(!is_contiguous(), "just checkin'");
130 assert(_buffer_limit <= _buffer_size, "queue invariant broken");
131 // Queue: |XXX|.......|XXXXXXX|.......|
132 // ^0 ^end ^begin ^limit ^size
133 s = current_stub();
134 stub_initialize(s, requested_size);
135 return s;
136 }
137 // Not enough space left
138 if (_mutex != NULL) _mutex->unlock();
139 return NULL;
140 }
141
142
143 void StubQueue::commit(int committed_code_size) {
144 assert(committed_code_size > 0, "committed_code_size must be > 0");
145 int committed_size = round_to(stub_code_size_to_size(committed_code_size), CodeEntryAlignment);
146 Stub* s = current_stub();
147 assert(committed_size <= stub_size(s), "committed size must not exceed requested size");
148 stub_initialize(s, committed_size);
149 _queue_end += committed_size;
150 _number_of_stubs++;
151 if (_mutex != NULL) _mutex->unlock();
152 debug_only(stub_verify(s);)
153 }
154
155
156 void StubQueue::remove_first() {
157 if (number_of_stubs() == 0) return;
158 Stub* s = first();
159 debug_only(stub_verify(s);)
160 stub_finalize(s);
161 _queue_begin += stub_size(s);
162 assert(_queue_begin <= _buffer_limit, "sanity check");
163 if (_queue_begin == _queue_end) {
164 // buffer empty
165 // => reset queue indices
166 _queue_begin = 0;
167 _queue_end = 0;
168 _buffer_limit = _buffer_size;
169 } else if (_queue_begin == _buffer_limit) {
170 // buffer limit reached
171 // => reset buffer limit & wrap around
172 _buffer_limit = _buffer_size;
173 _queue_begin = 0;
174 }
175 _number_of_stubs--;
176 }
177
178
179 void StubQueue::remove_first(int n) {
180 int i = MIN2(n, number_of_stubs());
181 while (i-- > 0) remove_first();
182 }
183
184
185 void StubQueue::remove_all(){
186 debug_only(verify();)
187 remove_first(number_of_stubs());
188 assert(number_of_stubs() == 0, "sanity check");
189 }
190
191
192 enum { StubQueueLimit = 10 }; // there are only a few in the world
193 static StubQueue* registered_stub_queues[StubQueueLimit];
194
195 void StubQueue::register_queue(StubQueue* sq) {
196 for (int i = 0; i < StubQueueLimit; i++) {
197 if (registered_stub_queues[i] == NULL) {
198 registered_stub_queues[i] = sq;
199 return;
200 }
201 }
202 ShouldNotReachHere();
203 }
204
205
206 void StubQueue::queues_do(void f(StubQueue* sq)) {
207 for (int i = 0; i < StubQueueLimit; i++) {
208 if (registered_stub_queues[i] != NULL) {
209 f(registered_stub_queues[i]);
210 }
211 }
212 }
213
214
215 void StubQueue::stubs_do(void f(Stub* s)) {
216 debug_only(verify();)
217 MutexLockerEx lock(_mutex);
218 for (Stub* s = first(); s != NULL; s = next(s)) f(s);
219 }
220
221
222 void StubQueue::verify() {
223 // verify only if initialized
224 if (_stub_buffer == NULL) return;
225 MutexLockerEx lock(_mutex);
226 // verify index boundaries
227 guarantee(0 <= _buffer_size, "buffer size must be positive");
228 guarantee(0 <= _buffer_limit && _buffer_limit <= _buffer_size , "_buffer_limit out of bounds");
229 guarantee(0 <= _queue_begin && _queue_begin < _buffer_limit, "_queue_begin out of bounds");
230 guarantee(0 <= _queue_end && _queue_end <= _buffer_limit, "_queue_end out of bounds");
231 // verify alignment
232 guarantee(_buffer_size % CodeEntryAlignment == 0, "_buffer_size not aligned");
233 guarantee(_buffer_limit % CodeEntryAlignment == 0, "_buffer_limit not aligned");
234 guarantee(_queue_begin % CodeEntryAlignment == 0, "_queue_begin not aligned");
235 guarantee(_queue_end % CodeEntryAlignment == 0, "_queue_end not aligned");
236 // verify buffer limit/size relationship
237 if (is_contiguous()) {
238 guarantee(_buffer_limit == _buffer_size, "_buffer_limit must equal _buffer_size");
239 }
240 // verify contents
241 int n = 0;
242 for (Stub* s = first(); s != NULL; s = next(s)) {
243 stub_verify(s);
244 n++;
245 }
246 guarantee(n == number_of_stubs(), "number of stubs inconsistent");
247 guarantee(_queue_begin != _queue_end || n == 0, "buffer indices must be the same");
248 }
249
250
251 void StubQueue::print() {
252 MutexLockerEx lock(_mutex);
253 for (Stub* s = first(); s != NULL; s = next(s)) {
254 stub_print(s);
255 }
256 }