All changes are to allow someone to compile the example storage engine and use it.

acconfig.h:
  Default undef for example storage engine.
acinclude.m4:
  Build macro additions for example engine.
configure.in:
  Configure changes for it to be listed in --help
sql/Makefile.am:
  Added in paths to build example.
sql/examples/ha_example.cc:
  Correction in indention and a few minor other corrections. It now lets you create/open/drop example engine.
sql/handler.cc:
  Added definition for the example storage engine. Added case for it to be created.
sql/handler.h:
  Added example storage engine type.
sql/mysql_priv.h:
  Added flag for optional build of example storage engine.
sql/mysqld.cc:
  Pieces to build example storage engine.

acconfig.h

@@ -112,6 +112,9 @@
 /* Define if we are using OSF1 DEC threads on 3.2 */
 #undef HAVE_DEC_3_2_THREADS
 
+/* Builds Example DB */
+#undef HAVE_EXAMPLE_DB
+
 /* fp_except from ieeefp.h */
 #undef HAVE_FP_EXCEPT
 

acinclude.m4

@@ -1302,6 +1302,36 @@ dnl ---------------------------------------------------------------------------
 dnl END OF MYSQL_CHECK_INNODB SECTION
 dnl ---------------------------------------------------------------------------
 
+dnl ---------------------------------------------------------------------------
+dnl Macro: MYSQL_CHECK_EXAMPLEDB
+dnl Sets HAVE_EXAMPLE_DB if --with-example-storage-engine is used
+dnl ---------------------------------------------------------------------------
+AC_DEFUN([MYSQL_CHECK_EXAMPLEDB], [
+  AC_ARG_WITH([example-storage-engine],
+              [
+  --with-example-storage-engine
+                          Enable the Example Storge Engine],
+              [exampledb="$withval"],
+              [exampledb=no])
+  AC_MSG_CHECKING([for example storage engine])
+
+  case "$exampledb" in
+    yes )
+      AC_DEFINE(HAVE_EXAMPLE_DB)
+      AC_MSG_RESULT([yes])
+      [exampledb=yes])
+      ;;
+    * )
+      AC_MSG_RESULT([no])
+      [exampledb=no])
+      ;;
+  esac
+
+])
+dnl ---------------------------------------------------------------------------
+dnl END OF MYSQL_CHECK_EXAMPLE SECTION
+dnl ---------------------------------------------------------------------------
+
 dnl By default, many hosts won't let programs access large files;
 dnl one must use special compiler options to get large-file access to work.
 dnl For more details about this brain damage please see:

configure.in

@@ -2618,6 +2618,7 @@ AC_DEFINE_UNQUOTED(MYSQL_DEFAULT_COLLATION_NAME,"$default_collation")
 MYSQL_CHECK_ISAM
 MYSQL_CHECK_BDB
 MYSQL_CHECK_INNODB
+MYSQL_CHECK_EXAMPLEDB
 
 # If we have threads generate some library functions and test programs
 sql_server_dirs=

sql/Makefile.am

@@ -37,7 +37,7 @@ LDADD =			@isam_libs@ \
 			../mysys/libmysys.a \
 			../dbug/libdbug.a \
 			../regex/libregex.a \
-			../strings/libmystrings.a
+			../strings/libmystrings.a 
 
 mysqld_LDADD =		@MYSQLD_EXTRA_LDFLAGS@ \
 			@bdb_libs@ @innodb_libs@ @pstack_libs@ \
@@ -57,7 +57,8 @@ noinst_HEADERS =	item.h item_func.h item_sum.h item_cmpfunc.h \
 			lex.h lex_symbol.h sql_acl.h sql_crypt.h  \
 			log_event.h sql_repl.h slave.h \
 			stacktrace.h sql_sort.h sql_cache.h set_var.h \
-			spatial.h gstream.h client_settings.h
+			spatial.h gstream.h client_settings.h \
+			examples/ha_example.h
 mysqld_SOURCES =	sql_lex.cc sql_handler.cc \
 			item.cc item_sum.cc item_buff.cc item_func.cc \
 			item_cmpfunc.cc item_strfunc.cc item_timefunc.cc \
@@ -86,7 +87,8 @@ mysqld_SOURCES =	sql_lex.cc sql_handler.cc \
 			slave.cc sql_repl.cc sql_union.cc sql_derived.cc \
 			client.c sql_client.cc mini_client_errors.c pack.c\
 			stacktrace.c repl_failsafe.h repl_failsafe.cc sql_olap.cc\
-			gstream.cc spatial.cc sql_help.cc protocol_cursor.cc
+			gstream.cc spatial.cc sql_help.cc protocol_cursor.cc \
+			examples/ha_example.cc
 gen_lex_hash_SOURCES =	gen_lex_hash.cc
 gen_lex_hash_LDADD =	$(LDADD) $(CXXLDFLAGS)
 

sql/examples/ha_example.cc

@@ -18,11 +18,12 @@
 #pragma implementation        // gcc: Class implementation
 #endif
 
-#include "mysql_priv.h"
+#include <mysql_priv.h>
+
+#ifdef HAVE_EXAMPLE_DB
 #include "ha_example.h"
 
 /* Variables for example share methods */
-extern pthread_mutex_t LOCK_mysql_create_db;
 pthread_mutex_t example_mutex;
 static HASH example_open_tables;
 static int example_init= 0;
@@ -62,7 +63,8 @@ static EXAMPLE_SHARE *get_share(const char *table_name, TABLE *table)
 
   if (!(share=(EXAMPLE_SHARE*) hash_search(&example_open_tables,
                                            (byte*) table_name,
-                                           length))){
+                                           length)))
+  {
     if (!(share=(EXAMPLE_SHARE *)
           my_multi_malloc(MYF(MY_WME | MY_ZEROFILL),
                           &share, sizeof(*share),
@@ -81,9 +83,6 @@ static EXAMPLE_SHARE *get_share(const char *table_name, TABLE *table)
       goto error;
     thr_lock_init(&share->lock);
     pthread_mutex_init(&share->mutex,MY_MUTEX_INIT_FAST);
-
-    if (get_mmap(share, 0) > 0)
-      goto error2;
   }
   share->use_count++;
   pthread_mutex_unlock(&example_mutex);
@@ -224,7 +223,7 @@ void ha_example::position(const byte *record)
 int ha_example::rnd_pos(byte * buf, byte *pos)
 {
   DBUG_ENTER("ha_example::rnd_pos");
-  DBUG_RETURN(HA_ERR_NOT_IMPLEMENTED));
+  DBUG_RETURN(HA_ERR_NOT_IMPLEMENTED);
 }
 
 void ha_example::info(uint flag)
@@ -271,7 +270,8 @@ THR_LOCK_DATA **ha_example::store_lock(THD *thd,
 int ha_example::delete_table(const char *name)
 {
   DBUG_ENTER("ha_example::delete_table");
-  DBUG_RETURN(HA_ERR_NOT_IMPLEMENTED);
+  /* This is not implemented but we want someone to be able that it works. */
+  DBUG_RETURN(0);
 }
 
 int ha_example::rename_table(const char * from, const char * to)
@@ -287,12 +287,14 @@ ha_rows ha_example::records_in_range(int inx,
                                      enum ha_rkey_function end_search_flag)
 {
   DBUG_ENTER("ha_example::records_in_range ");
-  DBUG_RETURN(HA_ERR_NOT_IMPLEMENTED);
+  DBUG_RETURN(records); // HA_ERR_NOT_IMPLEMENTED 
 }
 
 
 int ha_example::create(const char *name, TABLE *table_arg, HA_CREATE_INFO *create_info)
 {
   DBUG_ENTER("ha_example::create");
-  DBUG_RETURN(HA_ERR_NOT_IMPLEMENTED);
+  /* This is not implemented but we want someone to be able that it works. */
+  DBUG_RETURN(0);
 }
+#endif /* HAVE_EXAMPLE_DB */

sql/handler.cc

@@ -32,6 +32,9 @@
 #ifdef HAVE_BERKELEY_DB
 #include "ha_berkeley.h"
 #endif
+#ifdef HAVE_EXAMPLE_DB
+#include "examples/ha_example.h"
+#endif
 #ifdef HAVE_INNOBASE_DB
 #include "ha_innodb.h"
 #else
@@ -76,6 +79,8 @@ struct show_table_type_st sys_table_types[]=
    "Supports transactions and page-level locking", DB_TYPE_BERKELEY_DB},
   {"BERKELEYDB",&have_berkeley_db,
    "Alias for BDB", DB_TYPE_BERKELEY_DB},
+  {"EXAMPLE",&have_example_db,
+   "Example storage engine", DB_TYPE_EXAMPLE_DB},
   {NullS, NULL, NullS, DB_TYPE_UNKNOWN}
 };
 
@@ -171,6 +176,10 @@ handler *get_new_handler(TABLE *table, enum db_type db_type)
 #ifdef HAVE_INNOBASE_DB
   case DB_TYPE_INNODB:
     return new ha_innobase(table);
+#endif
+#ifdef HAVE_EXAMPLE_DB
+  case DB_TYPE_EXAMPLE_DB:
+    return new ha_example(table);
 #endif
   case DB_TYPE_HEAP:
     return new ha_heap(table);

sql/handler.h

@@ -132,7 +132,7 @@ enum db_type { DB_TYPE_UNKNOWN=0,DB_TYPE_DIAB_ISAM=1,
 	       DB_TYPE_RMS_ISAM, DB_TYPE_HEAP, DB_TYPE_ISAM,
 	       DB_TYPE_MRG_ISAM, DB_TYPE_MYISAM, DB_TYPE_MRG_MYISAM,
 	       DB_TYPE_BERKELEY_DB, DB_TYPE_INNODB, DB_TYPE_GEMINI,
-	       DB_TYPE_DEFAULT };
+	       DB_TYPE_EXAMPLE_DB, DB_TYPE_DEFAULT };
 
 struct show_table_type_st {
   const char *type;

sql/mysql_priv.h

@@ -881,7 +881,7 @@ extern struct my_option my_long_options[];
 
 /* optional things, have_* variables */
 
-extern SHOW_COMP_OPTION have_isam, have_innodb, have_berkeley_db;
+extern SHOW_COMP_OPTION have_isam, have_innodb, have_berkeley_db, have_example_db;
 extern SHOW_COMP_OPTION have_raid, have_openssl, have_symlink;
 extern SHOW_COMP_OPTION have_query_cache, have_berkeley_db, have_innodb;
 extern SHOW_COMP_OPTION have_crypt;

sql/mysqld.cc

@@ -370,7 +370,7 @@ KEY_CACHE *sql_key_cache;
 CHARSET_INFO *system_charset_info, *files_charset_info ;
 CHARSET_INFO *national_charset_info, *table_alias_charset;
 
-SHOW_COMP_OPTION have_berkeley_db, have_innodb, have_isam;
+SHOW_COMP_OPTION have_berkeley_db, have_innodb, have_isam, have_example_db;
 SHOW_COMP_OPTION have_raid, have_openssl, have_symlink, have_query_cache;
 SHOW_COMP_OPTION have_crypt, have_compress;
 
@@ -5121,6 +5121,11 @@ static void mysql_init_variables(void)
 #else
   have_isam=SHOW_OPTION_NO;
 #endif
+#ifdef HAVE_EXAMPLE_DB
+  have_example_db= SHOW_OPTION_YES;
+#else
+  have_example_db= SHOW_OPTION_NO;
+#endif
 #ifdef USE_RAID
   have_raid=SHOW_OPTION_YES;
 #else