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