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