Background:

Since long, the compiled code of stored routines has been printed in the trace file
when starting mysqld with the "--debug" flag. (At creation time only, and only in
debug builds of course.) This has been helpful when debugging stored procedure
execution, but it's a bit awkward to use. Also, the printing of some of the
instructions is a bit terse, in particular for sp_instr_stmt where only the command
code was printed.

This improves the printout of several of the instructions, and adds the debugging-
only commands "show procedure code <name>" and "show function code <name>".
(In non-debug builds they are not available.)


sql/lex.h:
  New symbol for debug-only command (e.g. show procedure code).
sql/sp_head.cc:
  Fixed some minor debug-mode bugs in show_create_*().
  New method for debugging: sp_head::show_routine_code() - returns the "assembly code"
  for a stored routine as a result set.
  Improved the print() methods for many sp_instr* classes, particularly for
  sp_instr_stmt where the query string is printed as well (up to a max length, just
  to give a hint of which statement it is). Also print the names of variables and
  cursors in some instruction.
sql/sp_head.h:
  New debugging-only method in sp_head: show_routine_code().
  Added offset member to sp_instr_cpush for improved debug printing.
sql/sp_pcontext.cc:
  Moved find_pvar(uint i) method from sp_pcontext.h, and made it work for all
  frames, not just the first one. (For debugging purposes)
  Added a similar find_cursor(uint i, ...) method, for debugging.
sql/sp_pcontext.h:
  Moved find_pvar(uint i) method to sp_pcontext.cc.
  Added a similar find_cursor(uint i, ...) method, for debugging.
sql/sql_lex.h:
  Added new sql_command codes for debugging.
sql/sql_parse.cc:
  Added new commands for debugging, e.g. "show procedure code".
sql/sql_yacc.yy:
  Added new commands for debugging purposes:
  "show procedure code ..." and "show function code ...".
  These are only enabled in debug builds, otherwise they result in a syntax error.
  (I.e. they don't exist)

sql/lex.h

@@ -110,6 +110,7 @@ static SYMBOL symbols[] = {
   { "CIPHER",		SYM(CIPHER_SYM)},
   { "CLIENT",		SYM(CLIENT_SYM)},
   { "CLOSE",		SYM(CLOSE_SYM)},
+  { "CODE",             SYM(CODE_SYM)},
   { "COLLATE",		SYM(COLLATE_SYM)},
   { "COLLATION",	SYM(COLLATION_SYM)},
   { "COLUMN",		SYM(COLUMN_SYM)},

sql/sp_head.cc

@@ -105,6 +105,8 @@ sp_get_flags_for_command(LEX *lex)
   case SQLCOM_SHOW_TABLES:
   case SQLCOM_SHOW_VARIABLES:
   case SQLCOM_SHOW_WARNS:
+  case SQLCOM_SHOW_PROC_CODE:
+  case SQLCOM_SHOW_FUNC_CODE:
     flags= sp_head::MULTI_RESULTS;
     break;
   /*
@@ -1698,7 +1700,7 @@ sp_head::show_create_procedure(THD *thd)
   LINT_INIT(sql_mode_len);
 
   if (check_show_routine_access(thd, this, &full_access))
-    return 1;
+    DBUG_RETURN(1);
 
   sql_mode_str=
     sys_var_thd_sql_mode::symbolic_mode_representation(thd,
@@ -1711,10 +1713,7 @@ sp_head::show_create_procedure(THD *thd)
 					     max(buffer.length(), 1024)));
   if (protocol->send_fields(&field_list, Protocol::SEND_NUM_ROWS |
                                          Protocol::SEND_EOF))
-  {
-    res= 1;
-    goto done;
-  }
+    DBUG_RETURN(1);
   protocol->prepare_for_resend();
   protocol->store(m_name.str, m_name.length, system_charset_info);
   protocol->store((char*) sql_mode_str, sql_mode_len, system_charset_info);
@@ -1723,7 +1722,6 @@ sp_head::show_create_procedure(THD *thd)
   res= protocol->write();
   send_eof(thd);
 
- done:
   DBUG_RETURN(res);
 }
 
@@ -1768,7 +1766,7 @@ sp_head::show_create_function(THD *thd)
   LINT_INIT(sql_mode_len);
 
   if (check_show_routine_access(thd, this, &full_access))
-    return 1;
+    DBUG_RETURN(1);
 
   sql_mode_str=
     sys_var_thd_sql_mode::symbolic_mode_representation(thd,
@@ -1780,10 +1778,7 @@ sp_head::show_create_function(THD *thd)
 					     max(buffer.length(),1024)));
   if (protocol->send_fields(&field_list,
                             Protocol::SEND_NUM_ROWS | Protocol::SEND_EOF))
-  {
-    res= 1;
-    goto done;
-  }
+    DBUG_RETURN(1);
   protocol->prepare_for_resend();
   protocol->store(m_name.str, m_name.length, system_charset_info);
   protocol->store((char*) sql_mode_str, sql_mode_len, system_charset_info);
@@ -1792,7 +1787,6 @@ sp_head::show_create_function(THD *thd)
   res= protocol->write();
   send_eof(thd);
 
- done:
   DBUG_RETURN(res);
 }
 
@@ -1852,6 +1846,51 @@ sp_head::opt_mark(uint ip)
 }
 
 
+#ifndef DBUG_OFF
+int
+sp_head::show_routine_code(THD *thd)
+{
+  Protocol *protocol= thd->protocol;
+  char buff[2048];
+  String buffer(buff, sizeof(buff), system_charset_info);
+  int res;
+  List<Item> field_list;
+  bool full_access;
+  uint ip;
+  sp_instr *i;
+
+  DBUG_ENTER("sp_head::show_routine_code");
+  DBUG_PRINT("info", ("procedure %s", m_name.str));
+
+  if (check_show_routine_access(thd, this, &full_access) || !full_access)
+    DBUG_RETURN(1);
+
+  field_list.push_back(new Item_uint("Pos", 9));
+  // 1024 is for not to confuse old clients
+  field_list.push_back(new Item_empty_string("Instruction",
+					     max(buffer.length(), 1024)));
+  if (protocol->send_fields(&field_list, Protocol::SEND_NUM_ROWS |
+                                         Protocol::SEND_EOF))
+    DBUG_RETURN(1);
+
+  for (ip= 0; (i = get_instr(ip)) ; ip++)
+  {
+    protocol->prepare_for_resend();
+    protocol->store((longlong)ip);
+
+    buffer.set("", 0, system_charset_info);
+    i->print(&buffer);
+    protocol->store(buffer.c_ptr_quick(), buffer.length(), system_charset_info);
+    if ((res= protocol->write()))
+      break;
+  }
+  send_eof(thd);
+
+  DBUG_RETURN(res);
+}
+#endif // ifndef DBUG_OFF
+
+
 /*
   Prepare LEX and thread for execution of instruction, if requested open
   and lock LEX's tables, execute instruction's core function, perform
@@ -2010,14 +2049,34 @@ sp_instr_stmt::execute(THD *thd, uint *nextp)
   DBUG_RETURN(res);
 }
 
+#define STMT_PRINT_MAXLEN 40
 void
 sp_instr_stmt::print(String *str)
 {
-  str->reserve(12);
+  uint i, len;
+
+  str->reserve(STMT_PRINT_MAXLEN+20);
   str->append("stmt ");
   str->qs_append((uint)m_lex_keeper.sql_command());
+  str->append(" \"");
+  len= m_query.length;
+  /*
+    Print the query string (but not too much of it), just to indicate which
+    statement it is.
+  */
+  if (len > STMT_PRINT_MAXLEN)
+    len= STMT_PRINT_MAXLEN-3;
+  /* Copy the query string and replace '\n' with ' ' in the process */
+  for (i= 0 ; i < len ; i++)
+    if (m_query.str[i] == '\n')
+      str->append(' ');
+    else
+      str->append(m_query.str[i]);
+  if (m_query.length > STMT_PRINT_MAXLEN)
+    str->append("...");        /* Indicate truncated string */
+  str->append('"');
 }
-
+#undef STMT_PRINT_MAXLEN
 
 int
 sp_instr_stmt::exec_core(THD *thd, uint *nextp)
@@ -2054,8 +2113,19 @@ sp_instr_set::exec_core(THD *thd, uint *nextp)
 void
 sp_instr_set::print(String *str)
 {
-  str->reserve(12);
+  int rsrv = 16;
+  sp_pvar_t *var = m_ctx->find_pvar(m_offset);
+
+  /* 'var' should always be non-null, but just in case... */
+  if (var)
+    rsrv+= var->name.length;
+  str->reserve(rsrv);
   str->append("set ");
+  if (var)
+  {
+    str->append(var->name.str, var->name.length);
+    str->append('@');
+  }
   str->qs_append(m_offset);
   str->append(' ');
   m_value->print(str);
@@ -2346,12 +2416,26 @@ sp_instr_hpush_jump::print(String *str)
   str->reserve(32);
   str->append("hpush_jump ");
   str->qs_append(m_dest);
-  str->append(" t=");
-  str->qs_append(m_type);
-  str->append(" f=");
+  str->append(' ');
   str->qs_append(m_frame);
-  str->append(" h=");
-  str->qs_append(m_ip+1);
+  switch (m_type)
+  {
+  case SP_HANDLER_NONE:
+    str->append(" NONE");       // This would be a bug
+    break;
+  case SP_HANDLER_EXIT:
+    str->append(" EXIT");
+    break;
+  case SP_HANDLER_CONTINUE:
+    str->append(" CONTINUE");
+    break;
+  case SP_HANDLER_UNDO:
+    str->append(" UNDO");
+    break;
+  default:
+    str->append(" UNKNOWN:");   // This would be a bug as well
+    str->qs_append(m_type);
+  }
 }
 
 uint
@@ -2474,7 +2558,17 @@ sp_instr_cpush::execute(THD *thd, uint *nextp)
 void
 sp_instr_cpush::print(String *str)
 {
-  str->append("cpush");
+  LEX_STRING n;
+  my_bool found= m_ctx->find_cursor(m_cursor, &n);
+
+  str->reserve(32);
+  str->append("cpush ");
+  if (found)
+  {
+    str->append(n.str, n.length);
+    str->append('@');
+  }
+  str->qs_append(m_cursor);
 }
 
 
@@ -2570,8 +2664,16 @@ sp_instr_copen::exec_core(THD *thd, uint *nextp)
 void
 sp_instr_copen::print(String *str)
 {
-  str->reserve(12);
+  LEX_STRING n;
+  my_bool found= m_ctx->find_cursor(m_cursor, &n);
+
+  str->reserve(32);
   str->append("copen ");
+  if (found)
+  {
+    str->append(n.str, n.length);
+    str->append('@');
+  }
   str->qs_append(m_cursor);
 }
 
@@ -2599,8 +2701,16 @@ sp_instr_cclose::execute(THD *thd, uint *nextp)
 void
 sp_instr_cclose::print(String *str)
 {
-  str->reserve(12);
+  LEX_STRING n;
+  my_bool found= m_ctx->find_cursor(m_cursor, &n);
+
+  str->reserve(32);
   str->append("cclose ");
+  if (found)
+  {
+    str->append(n.str, n.length);
+    str->append('@');
+  }
   str->qs_append(m_cursor);
 }
 
@@ -2629,14 +2739,23 @@ sp_instr_cfetch::print(String *str)
 {
   List_iterator_fast<struct sp_pvar> li(m_varlist);
   sp_pvar_t *pv;
+  LEX_STRING n;
+  my_bool found= m_ctx->find_cursor(m_cursor, &n);
 
-  str->reserve(12);
+  str->reserve(32);
   str->append("cfetch ");
+  if (found)
+  {
+    str->append(n.str, n.length);
+    str->append('@');
+  }
   str->qs_append(m_cursor);
   while ((pv= li++))
   {
-    str->reserve(8);
+    str->reserve(16);
     str->append(' ');
+    str->append(pv->name.str, pv->name.length);
+    str->append('@');
     str->qs_append(pv->offset);
   }
 }

sql/sp_head.h

@@ -295,6 +295,12 @@ class sp_head :private Query_arena
     return test(m_flags &
 		(CONTAINS_DYNAMIC_SQL|MULTI_RESULTS|HAS_SET_AUTOCOMMIT_STMT));
   }
+
+#ifndef DBUG_OFF
+  int show_routine_code(THD *thd);
+#endif
+
+
 private:
 
   MEM_ROOT *m_thd_root;		// Temp. store for thd's mem_root
@@ -856,8 +862,8 @@ class sp_instr_cpush : public sp_instr
 
 public:
 
-  sp_instr_cpush(uint ip, sp_pcontext *ctx, LEX *lex)
-    : sp_instr(ip, ctx), m_lex_keeper(lex, TRUE)
+  sp_instr_cpush(uint ip, sp_pcontext *ctx, LEX *lex, uint offset)
+    : sp_instr(ip, ctx), m_lex_keeper(lex, TRUE), m_cursor(offset)
   {}
 
   virtual ~sp_instr_cpush()
@@ -876,6 +882,7 @@ class sp_instr_cpush : public sp_instr
 private:
 
   sp_lex_keeper m_lex_keeper;
+  uint m_cursor;                /* Frame offset (for debugging) */
 
 }; // class sp_instr_cpush : public sp_instr
 

sql/sp_pcontext.cc

@@ -169,6 +169,29 @@ sp_pcontext::find_pvar(LEX_STRING *name, my_bool scoped)
   return NULL;
 }
 
+/*
+  Find a variable by offset from the top.
+  This used for two things:
+  - When evaluating parameters at the beginning, and setting out parameters
+    at the end, of invokation. (Top frame only, so no recursion then.)
+  - For printing of sp_instr_set. (Debug mode only.)
+ */
+sp_pvar_t *
+sp_pcontext::find_pvar(uint i)
+{
+  if (m_poffset <= i && i < m_poffset + m_pvar.elements)
+  {                           // This frame
+    sp_pvar_t *p;
+
+    get_dynamic(&m_pvar, (gptr)&p, i - m_poffset);
+    return p;
+  }
+  else if (m_parent)
+    return m_parent->find_pvar(i); // Some previous frame
+  else
+    return NULL;              // index out of bounds
+}
+
 void
 sp_pcontext::push_pvar(LEX_STRING *name, enum enum_field_types type,
 		       sp_param_mode_t mode)
@@ -331,3 +354,22 @@ sp_pcontext::find_cursor(LEX_STRING *name, uint *poff, my_bool scoped)
     return m_parent->find_cursor(name, poff, scoped);
   return FALSE;
 }
+
+/*
+  Find a cursor by offset from the top.
+  This is only used for debugging.
+ */
+my_bool
+sp_pcontext::find_cursor(uint i, LEX_STRING *n)
+{
+  if (m_coffset <= i && i < m_coffset + m_cursor.elements)
+  {                           // This frame
+    get_dynamic(&m_cursor, (gptr)n, i - m_poffset);
+    return TRUE;
+  }
+  else if (m_parent)
+    return m_parent->find_cursor(i, n); // Some previous frame
+  else
+    return FALSE;               // index out of bounds
+}
+

sql/sp_pcontext.h

@@ -172,16 +172,7 @@ class sp_pcontext : public Sql_alloc
 
   // Find by index
   sp_pvar_t *
-  find_pvar(uint i)
-  {
-    sp_pvar_t *p;
-
-    if (i < m_pvar.elements)
-      get_dynamic(&m_pvar, (gptr)&p, i);
-    else
-      p= NULL;
-    return p;
-  }
+  find_pvar(uint i);
 
   //
   // Labels
@@ -261,6 +252,10 @@ class sp_pcontext : public Sql_alloc
   my_bool
   find_cursor(LEX_STRING *name, uint *poff, my_bool scoped=0);
 
+  /* Find by index (for debugging only) */
+  my_bool
+  find_cursor(uint i, LEX_STRING *n);
+
   inline uint
   max_cursors()
   {

sql/sql_lex.h

@@ -90,6 +90,7 @@ enum enum_sql_command {
   SQLCOM_CREATE_TRIGGER, SQLCOM_DROP_TRIGGER,
   SQLCOM_XA_START, SQLCOM_XA_END, SQLCOM_XA_PREPARE,
   SQLCOM_XA_COMMIT, SQLCOM_XA_ROLLBACK, SQLCOM_XA_RECOVER,
+  SQLCOM_SHOW_PROC_CODE, SQLCOM_SHOW_FUNC_CODE,
   /* This should be the last !!! */
 
   SQLCOM_END

sql/sql_parse.cc

@@ -4560,6 +4560,30 @@ mysql_execute_command(THD *thd)
 					 lex->wild->ptr() : NullS));
       break;
     }
+#ifndef DBUG_OFF
+  case SQLCOM_SHOW_PROC_CODE:
+  case SQLCOM_SHOW_FUNC_CODE:
+    {
+      sp_head *sp;
+
+      if (lex->spname->m_name.length > NAME_LEN)
+      {
+	my_error(ER_TOO_LONG_IDENT, MYF(0), lex->spname->m_name.str);
+	goto error;
+      }
+      if (lex->sql_command == SQLCOM_SHOW_PROC_CODE)
+        sp= sp_find_procedure(thd, lex->spname);
+      else
+        sp= sp_find_function(thd, lex->spname);
+      if (!sp || !sp->show_routine_code(thd))
+      {                       /* We don't distinguish between errors for now */
+        my_error(ER_SP_DOES_NOT_EXIST, MYF(0),
+                 SP_COM_STRING(lex), lex->spname->m_name.str);
+        goto error;
+      }
+      break;
+    }
+#endif // ifndef DBUG_OFF
   case SQLCOM_CREATE_VIEW:
     {
       if (end_active_trans(thd))

sql/sql_yacc.yy

@@ -175,6 +175,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b, ulong *yystacksize);
 %token  CLIENT_SYM
 %token  CLOSE_SYM
 %token  COALESCE
+%token  CODE_SYM
 %token  COLLATE_SYM
 %token  COLLATION_SYM
 %token  COLUMNS
@@ -1698,7 +1699,8 @@ sp_decl:
 	      delete $5;
 	      YYABORT;
 	    }
-            i= new sp_instr_cpush(sp->instructions(), ctx, $5);
+            i= new sp_instr_cpush(sp->instructions(), ctx, $5,
+                                  ctx->current_cursors());
 	    sp->add_instr(i);
 	    ctx->push_cursor(&$2);
 	    $$.vars= $$.conds= $$.hndlrs= 0;
@@ -6625,7 +6627,28 @@ show_param:
 	      YYABORT;
             if (prepare_schema_table(YYTHD, lex, 0, SCH_PROCEDURES))
               YYABORT;
-	  };
+	  }
+        | PROCEDURE CODE_SYM sp_name
+          {
+#ifdef DBUG_OFF
+            yyerror(ER(ER_SYNTAX_ERROR));
+            YYABORT;
+#else
+            Lex->sql_command= SQLCOM_SHOW_PROC_CODE;
+	    Lex->spname= $3;
+#endif
+          }
+        | FUNCTION_SYM CODE_SYM sp_name
+          {
+#ifdef DBUG_OFF
+            yyerror(ER(ER_SYNTAX_ERROR));
+            YYABORT;
+#else
+            Lex->sql_command= SQLCOM_SHOW_FUNC_CODE;
+	    Lex->spname= $3;
+#endif
+          }
+        ;
 
 show_engine_param:
 	STATUS_SYM
@@ -7534,6 +7557,7 @@ keyword_sp:
 	| CHANGED		{}
 	| CIPHER_SYM		{}
 	| CLIENT_SYM		{}
+        | CODE_SYM              {}
 	| COLLATION_SYM		{}
         | COLUMNS               {}
 	| COMMITTED_SYM		{}