Table definition cache, part 2

The table opening process now works the following way:
- Create common TABLE_SHARE object
- Read the .frm file and unpack it into the TABLE_SHARE object
- Create a TABLE object based on the information in the TABLE_SHARE
  object and open a handler to the table object

Other noteworthy changes:
- In TABLE_SHARE the most common strings are now LEX_STRING's
- Better error message when table is not found
- Variable table_cache is now renamed 'table_open_cache'
- New variable 'table_definition_cache' that is the number of table defintions that will be cached
- strxnmov() calls are now fixed to avoid overflows
- strxnmov() will now always add one end \0 to result
- engine objects are now created with a TABLE_SHARE object instead of a TABLE object.
- After creating a field object one must call field->init(table) before using it

- For a busy system this change will give you:
 - Less memory usage for table object
 - Faster opening of tables (if it's has been in use or is in table definition cache)
 - Allow you to cache many table definitions objects
 - Faster drop of table

1 files changed, 19 insertions, 8 deletions

diff --git a/mysys/mf_pack.c b/mysys/mf_pack.c
index 049aa59a578..9dd2a6a8276 100644
--- a/mysys/mf_pack.c
+++ b/mysys/mf_pack.c
@@ -107,16 +107,27 @@ void pack_dirname(my_string to, const char *from)
 } /* pack_dirname */
 
 
-	/* remove unwanted chars from dirname */
-	/* if "/../" removes prev dir; "/~/" removes all before ~ */
-	/* "//" is same as "/", except on Win32 at start of a file  */
-	/* "/./" is removed */
-	/* Unpacks home_dir if "~/.." used */
-	/* Unpacks current dir if if "./.." used */
+/*
+  remove unwanted chars from dirname
 
-uint cleanup_dirname(register my_string to, const char *from)
-						/* to may be == from */
+  SYNOPSIS
+     cleanup_dirname()
+     to		Store result here
+     from	Dirname to fix.  May be same as to
+
+  IMPLEMENTATION
+  "/../" removes prev dir
+  "/~/" removes all before ~
+  //" is same as "/", except on Win32 at start of a file
+  "/./" is removed
+  Unpacks home_dir if "~/.." used
+  Unpacks current dir if if "./.." used
 
+  RETURN
+    #  length of new name   
+*/
+
+uint cleanup_dirname(register my_string to, const char *from)
 {
   reg5 uint length;
   reg2 my_string pos;