Adding a Drizzle Plugin

I joined about 50 others including a number of core MySQL developers and MySQL community members today for the 2009 Drizzle developers day at Sun Microsystems Santa Clara campus.

In addition to a number of presentations and various group discussions most of my individual hacking time was under the guidance of Drizzle team developer Stewart Smith were Patrick Galbraith and myself started the porting of Patrick’s memcached UDF functions for MySQL .

Leveraging some existing Drizzle plugin’s such as CRC32() and UNCOMPRESS() we were easily able to navigate the src/plugin/memcached directory plug.in, Makefile.am and drizzle_declare_plugin definition in the new get.cc to get a working stub ‘Hello World Example';

plug.in

$ more plug.in
DRIZZLE_PLUGIN(memcached,[memcached UDF],
        [UDF Plugin for memcached])
DRIZZLE_PLUGIN_STATIC(memcached,   [libmemcachedudf.a])
DRIZZLE_PLUGIN_MANDATORY(memcached)  dnl Default
DRIZZLE_PLUGIN_DYNAMIC(memcached,   [libmemcachedudf.la])

Makefile.am

$ more Makefile.am
# Copyright (C) 2006 MySQL AB
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 2 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

EXTRA_LTLIBRARIES =	libmemcachedudf.la
pkgplugin_LTLIBRARIES =	@plugin_memcached_shared_target@
libmemcachedudf_la_LDFLAGS =	-module -avoid-version -rpath $(pkgplugindir)
libmemcachedudf_la_LIBADD =		$(LIBZ)
libmemcachedudf_la_CPPFLAGS=	$(AM_CPPFLAGS) -DDRIZZLE_DYNAMIC_PLUGIN
libmemcachedudf_la_SOURCES =	get.cc


EXTRA_LIBRARIES =	libmemcachedudf.a
noinst_LIBRARIES =	@plugin_memcached_static_target@
libmemcachedudf_a_SOURCES=	$(libmemcachedudf_la_SOURCES)

$ more get.cc
/* Copyright (C) 2009 Patrick Galbraith, Ronald Bradford
...
*/
#include <drizzled/server_includes.h>
#include <drizzled/sql_udf.h>
#include <drizzled/item/func.h>
#include <drizzled/function/str/strfunc.h>

#include <stdio.h>
#include <libmemcached/memcached.h>

using namespace std;

/* memc_get */
class Item_funcmemc_get : public Item_str_func
{
public:
  Item_funcmemc_get() : Item_str_func() {}
  const char *func_name() const { return "memc_get"; }
  bool check_argument_count(int n) { return (n==1); }
  String *val_str(String*);
  void fix_length_and_dec() {
    max_length=32;
    args[0]->collation.set(
      get_charset_by_csname(args[0]->collation.collation->csname,
                            MY_CS_BINSORT), DERIVATION_COERCIBLE);
  }

};


String *Item_funcmemc_get::val_str(String *str)
{
  assert(fixed == 1);
  String * sptr= args[0]->val_str(str);
  str->set_charset(&my_charset_bin);
  if (sptr)
  {
    null_value=0;
    str->set("hello memcached test", 20,system_charset_info);
    return str;
  }
  null_value=1;
  return 0;
}


Create_function<item_funcmemc_get> memc_get_factory(string("memc_get"));

static int memcached_plugin_init(PluginRegistry &registry)
{
  registry.add(&memc_get_factory);
  return 0;
}

drizzle_declare_plugin(memcached)
{
  "memcached",
  "0.1",
  "Patrick Galbraith, Ronald Bradford",
  "memcached plugin",
  PLUGIN_LICENSE_GPL,
  memcached_plugin_init, /* Plugin Init */
  NULL,   /* Plugin Deinit */
  NULL,   /* status variables */
  NULL,   /* system variables */
  NULL    /* config options */
}
drizzle_declare_plugin_end;
</item_funcmemc_get>