1 /*
2 * Copyright (c) 2015, 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 "precompiled.hpp"
26
27 #include <string.h>
28 #include "gc/shared/memset_with_concurrent_readers.hpp"
29 #include "utilities/debug.hpp"
30 #include "utilities/globalDefinitions.hpp"
31 #include "utilities/macros.hpp"
32 #include "utilities/ostream.hpp"
33
34 #if INCLUDE_ALL_GCS
35
36 // Unit test
37 #ifndef PRODUCT
38
39 static unsigned line_byte(const char* line, size_t i) {
40 return unsigned(line[i]) & 0xFF;
41 }
42
43 // Verify memset_with_concurrent_readers mimics memset.
44 // We don't attempt to verify the concurrent reader case.
45 void test_memset_with_concurrent_readers() {
46 const size_t chunk_size = 8 * BytesPerWord;
47 const unsigned chunk_count = 4;
48 const size_t block_size = (chunk_count + 4) * chunk_size;
49 char block[block_size];
50 char clear_block[block_size];
51 char set_block[block_size];
52
53 // block format:
54 // 0: unused leading chunk
55 // 1: chunk written from start index to end of chunk
56 // ... nchunks fully written chunks
57 // N: chunk written from start of chunk to end index
58 // N+1: unused trailing chunk
59
60 const int clear_value = 0;
61 const int set_value = 0xAC;
62
63 memset(clear_block, clear_value, block_size);
64 memset(set_block, set_value, block_size);
65
66 for (unsigned nchunks = 0; nchunks <= chunk_count; ++nchunks) {
67 for (size_t start = 1; start <= chunk_size; ++start) {
68 for (size_t end = 0; end <= chunk_size; ++end) {
69 size_t set_start = chunk_size + start;
70 size_t set_end = (2 + nchunks) * chunk_size + end;
71 size_t set_size = set_end - set_start;
72
73 memset(block, clear_value, block_size);
74 memset_with_concurrent_readers(&block[set_start], set_value, set_size);
75 bool head_clear = !memcmp(clear_block, block, set_start);
76 bool middle_set = !memcmp(set_block, block + set_start, set_size);
77 bool tail_clear = !memcmp(clear_block, block + set_end, block_size - set_end);
78 if (!(head_clear && middle_set && tail_clear)) {
79 tty->print_cr("*** memset_with_concurrent_readers failed: "
80 "set start " SIZE_FORMAT ", set end " SIZE_FORMAT,
81 set_start, set_end);
82 for (unsigned chunk = 0; chunk < (block_size / chunk_size); ++chunk) {
83 for (unsigned line = 0; line < (chunk_size / BytesPerWord); ++line) {
84 const char* lp = &block[chunk * chunk_size + line * BytesPerWord];
85 tty->print_cr("%d,%d: %2x %2x %2x %2x %2x %2x %2x %2x",
86 chunk, line,
87 line_byte(lp, 0), line_byte(lp, 1),
88 line_byte(lp, 2), line_byte(lp, 3),
89 line_byte(lp, 4), line_byte(lp, 5),
90 line_byte(lp, 6), line_byte(lp, 7));
91 }
92 }
93 assert(head_clear, "leading byte not clear");
94 assert(middle_set, "memset byte not set");
95 assert(tail_clear, "trailing bye not clear");
96 }
97 }
98 }
99 }
100 }
101
102 #endif // end unit test
103
104 #endif // INCLUDE_ALL_GCS