mariadb/sql/sp_rcontext.h

/* -*- C++ -*- */
/* Copyright (C) 2002 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; either version 2 of the License, or
   (at your option) any later version.

   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

#ifndef _SP_RCONTEXT_H_
#define _SP_RCONTEXT_H_

#ifdef USE_PRAGMA_INTERFACE
#pragma interface			/* gcc class implementation */
#endif

struct sp_cond_type;
class sp_cursor;
struct sp_pvar;
class sp_lex_keeper;
class sp_instr_cpush;

#define SP_HANDLER_NONE      0
#define SP_HANDLER_EXIT      1
#define SP_HANDLER_CONTINUE  2
#define SP_HANDLER_UNDO      3

typedef struct
{
  struct sp_cond_type *cond;
  uint handler;			// Location of handler
  int type;
  uint foffset;			// Frame offset for the handlers declare level
} sp_handler_t;


/*
  This is a run context? of one SP ?
  THis is 
   - a stack of cursors? 
   - a stack of handlers?
   - a stack of Items ?
   - a stack of instruction locations in SP?
*/

class sp_rcontext : public Sql_alloc
{
  sp_rcontext(const sp_rcontext &); /* Prevent use of these */
  void operator=(sp_rcontext &);

 public:

  /*
    Arena used to (re) allocate items on . E.g. reallocate INOUT/OUT
    SP parameters when they don't fit into prealloced items. This
    is common situation with String items. It is used mainly in
    sp_eval_func_item().
  */
  Query_arena *callers_arena;

  sp_rcontext(sp_rcontext *prev, uint fsize, uint hmax, uint cmax);

  ~sp_rcontext()
  {
    // Not needed?
    //sql_element_free(m_frame);
    //m_saved.empty();
  }

  inline void
  push_item(Item *i)
  {
    if (m_count < m_fsize)
      m_frame[m_count++]= i;
  }

  inline void
  set_item(uint idx, Item *i)
  {
    if (idx < m_count)
      m_frame[idx]= i;
  }

  /* Returns 0 on success, -1 on (eval) failure */
  int
  set_item_eval(THD *thd, uint idx, Item **i, enum_field_types type);

  inline Item *
  get_item(uint idx)
  {
    return m_frame[idx];
  }

  inline Item **
  get_item_addr(uint idx)
  {
    return m_frame + idx;
  }


  inline void
  set_result(Item *it)
  {
    m_result= it;
  }

  inline Item *
  get_result()
  {
    return m_result;
  }

  inline void
  push_handler(struct sp_cond_type *cond, uint h, int type, uint f)
  {
    m_handler[m_hcount].cond= cond;
    m_handler[m_hcount].handler= h;
    m_handler[m_hcount].type= type;
    m_handler[m_hcount].foffset= f;
    m_hcount+= 1;
  }

  inline void
  pop_handlers(uint count)
  {
    m_hcount-= count;
  }

  // Returns 1 if a handler was found, 0 otherwise.
  bool
  find_handler(uint sql_errno,MYSQL_ERROR::enum_warning_level level);

  // Returns handler type and sets *ip to location if one was found
  inline int
  found_handler(uint *ip, uint *fp)
  {
    if (m_hfound < 0)
      return SP_HANDLER_NONE;
    *ip= m_handler[m_hfound].handler;
    *fp= m_handler[m_hfound].foffset;
    return m_handler[m_hfound].type;
  }

  // Returns true if we found a handler in this context
  inline bool
  found_handler_here()
  {
    return (m_hfound >= 0);
  }

  // Clears the handler find state
  inline void
  clear_handler()
  {
    m_hfound= -1;
  }

  inline void
  push_hstack(uint h)
  {
    m_hstack[m_hsp++]= h;
  }

  inline uint
  pop_hstack()
  {
    return m_hstack[--m_hsp];
  }

  inline void
  enter_handler(int hid)
  {
    m_in_handler[m_ihsp++]= hid;
  }

  inline void
  exit_handler()
  {
    m_ihsp-= 1;
  }

  // Save variables starting at fp and up
  void
  save_variables(uint fp);

  // Restore variables down to fp
  void
  restore_variables(uint fp);

  void
  push_cursor(sp_lex_keeper *lex_keeper, sp_instr_cpush *i);

  void
  pop_cursors(uint count);

  void
  pop_all_cursors()
  {
    pop_cursors(m_ccount);
  }

  inline sp_cursor *
  get_cursor(uint i)
  {
    return m_cstack[i];
  }

private:

  uint m_count;
  uint m_fsize;
  Item **m_frame;

  Item *m_result;		// For FUNCTIONs

  sp_handler_t *m_handler;      // Visible handlers
  uint m_hcount;                // Stack pointer for m_handler
  uint *m_hstack;               // Return stack for continue handlers
  uint m_hsp;                   // Stack pointer for m_hstack
  uint *m_in_handler;           // Active handler, for recursion check
  uint m_ihsp;                  // Stack pointer for m_in_handler
  int m_hfound;                 // Set by find_handler; -1 if not found
  List<Item> m_saved;           // Saved variables during handler exec.

  sp_cursor **m_cstack;
  uint m_ccount;

  sp_rcontext *m_prev_ctx;      // Previous context (NULL if none)

}; // class sp_rcontext : public Sql_alloc


/*
  An interceptor of cursor result set used to implement
  FETCH <cname> INTO <varlist>.
*/

class Select_fetch_into_spvars: public select_result_interceptor
{
  List<struct sp_pvar> *spvar_list;
  uint field_count;
public:
  uint get_field_count() { return field_count; }
  void set_spvar_list(List<struct sp_pvar> *vars) { spvar_list= vars; }

  virtual bool send_eof() { return FALSE; }
  virtual bool send_data(List<Item> &items);
  virtual int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
};


/* A mediator between stored procedures and server side cursors */

class sp_cursor : public Sql_alloc
{
public:

  sp_cursor(sp_lex_keeper *lex_keeper, sp_instr_cpush *i);

  virtual ~sp_cursor()
  {
    destroy();
  }

  sp_lex_keeper *
  get_lex_keeper() { return m_lex_keeper; }

  int
  open(THD *thd);

  int
  close(THD *thd);

  inline my_bool
  is_open()
  {
    return test(server_side_cursor);
  }

  int
  fetch(THD *, List<struct sp_pvar> *vars);

  inline sp_instr_cpush *
  get_instr()
  {
    return m_i;
  }

private:

  Select_fetch_into_spvars result;
  sp_lex_keeper *m_lex_keeper;
  Server_side_cursor *server_side_cursor;
  sp_instr_cpush *m_i;		// My push instruction
  void
  destroy();

}; // class sp_cursor : public Sql_alloc

#endif /* _SP_RCONTEXT_H_ */