release/src/router/mysql/server-tools/instance-manager/buffer.cc

   1 /*
   2    Copyright (c) 2004-2007 MySQL AB, 2009 Sun Microsystems, Inc.
   3    Use is subject to license terms.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; version 2 of the License.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software
  16    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
  17 */
  18
  19 #if defined(__GNUC__) && defined(USE_PRAGMA_IMPLEMENTATION)
  20 #pragma implementation
  21 #endif
  22
  23 #include "buffer.h"
  24 #include <m_string.h>
  25
  26 const uint Buffer::BUFFER_INITIAL_SIZE= 4096;
  27 const uint Buffer::MAX_BUFFER_SIZE= 16777216;
  28
  29 /*
  30   Puts the given string to the buffer.
  31
  32   SYNOPSIS
  33     append()
  34     position          start position in the buffer
  35     string            string to be put in the buffer
  36     len_arg           the length of the string. This way we can avoid some
  37                       strlens.
  38
  39   DESCRIPTION
  40
  41     The method puts a string into the buffer, starting from position .
  42     In the case when the buffer is too small it reallocs the buffer. The
  43     total size of the buffer is restricted with 16.
  44
  45   RETURN
  46     0 - ok
  47     1 - got an error in reserve()
  48 */
  49
  50 int Buffer::append(size_t position, const char *string, size_t len_arg)
  51 {
  52   if (reserve(position, len_arg))
  53     return 1;
  54
  55   strnmov((char*) buffer + position, string, len_arg);
  56   return 0;
  57 }
  58
  59
  60 /*
  61   Checks whether the current buffer size is ok to put a string of the length
  62   "len_arg" starting from "position" and reallocs it if no.
  63
  64   SYNOPSIS
  65     reserve()
  66     position          the number starting byte on the buffer to store a buffer
  67     len_arg           the length of the string.
  68
  69   DESCRIPTION
  70
  71     The method checks whether it is possible to put a string of the "len_arg"
  72     length into the buffer, starting from "position" byte. In the case when the
  73     buffer is too small it reallocs the buffer. The total size of the buffer is
  74     restricted with 16 Mb.
  75
  76   RETURN
  77     0 - ok
  78     1 - realloc error or we have come to the 16Mb barrier
  79 */
  80
  81 int Buffer::reserve(size_t position, size_t len_arg)
  82 {
  83   if (position + len_arg >= MAX_BUFFER_SIZE)
  84     goto err;
  85
  86   if (position + len_arg >= buffer_size)
  87   {
  88     buffer= (uchar*) my_realloc(buffer,
  89                                 min(MAX_BUFFER_SIZE,
  90                                     max((uint) (buffer_size*1.5),
  91                                         position + len_arg)), MYF(0));
  92     if (!(buffer))
  93       goto err;
  94     buffer_size= (size_t) (buffer_size*1.5);
  95   }
  96   return 0;
  97
  98 err:
  99   error= 1;
 100   return 1;
 101 }
 102
 103
 104 int Buffer::get_size()
 105 {
 106   return (uint) buffer_size;
 107 }
 108
 109
 110 int Buffer::is_error()
 111 {
 112   return error;
 113 }