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Commit 231ec666 authored by konstantin@mysql.com's avatar konstantin@mysql.com
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More comments in prepared statements code.

parent 21783e85
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Showing with 160 additions and 79 deletions
libmysql/libmysql.c
View file @ 231ec666
......@@ -1640,70 +1640,46 @@ myodbc_remove_escape(MYSQL *mysql,char *name)
}
/********************************************************************
Implementation of new client API for 4.1 version.
Implementation of new client-server prototypes for 4.1 version
starts from here ..
mysql_* are real prototypes used by applications
mysql_stmt_* are real prototypes used by applications.
To make API work in embedded library all functions performing
real I/O are prefixed with 'cli_' (abbreviated from 'Call Level
Interface'). This functions are invoked via pointers set in
MYSQL::methods structure. Embedded counterparts, prefixed with
'emb_' reside in libmysqld/lib_sql.cc.
*********************************************************************/
/********************************************************************
Misc Utility functions
********************************************************************/
/*
Set the internal stmt error messages
*/
static void set_stmt_error(MYSQL_STMT * stmt, int errcode,
const char *sqlstate)
{
DBUG_ENTER("set_stmt_error");
DBUG_PRINT("enter", ("error: %d '%s'", errcode, ER(errcode)));
DBUG_ASSERT(stmt != 0);
stmt->last_errno= errcode;
strmov(stmt->last_error, ER(errcode));
strmov(stmt->sqlstate, sqlstate);
DBUG_VOID_RETURN;
}
/******************* Declarations ***********************************/
/*
Copy error message to statement handler
These functions are called by function pointer MYSQL_STMT::read_row_func.
Each function corresponds to one of the read methods:
- mysql_stmt_fetch without prior mysql_stmt_store_result,
- mysql_stmt_fetch when result is stored,
- mysql_stmt_fetch when there are no rows (always returns MYSQL_NO_DATA)
*/
void set_stmt_errmsg(MYSQL_STMT * stmt, const char *err, int errcode,
const char *sqlstate)
{
DBUG_ENTER("set_stmt_error_msg");
DBUG_PRINT("enter", ("error: %d/%s '%s'", errcode, sqlstate, err));
DBUG_ASSERT(stmt != 0);
stmt->last_errno= errcode;
if (err && err[0])
strmov(stmt->last_error, err);
strmov(stmt->sqlstate, sqlstate);
DBUG_VOID_RETURN;
}
static int stmt_read_row_unbuffered(MYSQL_STMT *stmt, unsigned char **row);
static int stmt_read_row_buffered(MYSQL_STMT *stmt, unsigned char **row);
static int stmt_read_row_no_data(MYSQL_STMT *stmt, unsigned char **row);
/**************** Misc utility functions ****************************/
/*
Reallocate the NET package to be at least of 'length' bytes
SYNPOSIS
my_realloc_str()
net The NET structure to modify
int length Ensure that net->buff is at least this big
net The NET structure to modify
length Ensure that net->buff is at least this big
RETURN VALUES
0 ok
1 Error
*/
static my_bool my_realloc_str(NET *net, ulong length)
......@@ -1719,20 +1695,54 @@ static my_bool my_realloc_str(NET *net, ulong length)
DBUG_RETURN(res);
}
/********************************************************************
Prepare related implementations
********************************************************************/
static int stmt_read_row_unbuffered(MYSQL_STMT *stmt, unsigned char **row);
static int stmt_read_row_buffered(MYSQL_STMT *stmt, unsigned char **row);
static int stmt_read_row_no_data(MYSQL_STMT *stmt, unsigned char **row);
/*
Set statement error code, sqlstate, and error message
from given errcode and sqlstate.
*/
static void set_stmt_error(MYSQL_STMT * stmt, int errcode,
const char *sqlstate)
{
DBUG_ENTER("set_stmt_error");
DBUG_PRINT("enter", ("error: %d '%s'", errcode, ER(errcode)));
DBUG_ASSERT(stmt != 0);
stmt->last_errno= errcode;
strmov(stmt->last_error, ER(errcode));
strmov(stmt->sqlstate, sqlstate);
DBUG_VOID_RETURN;
}
/*
Set statement error code, sqlstate, and error message.
*/
void set_stmt_errmsg(MYSQL_STMT * stmt, const char *err, int errcode,
const char *sqlstate)
{
DBUG_ENTER("set_stmt_errmsg");
DBUG_PRINT("enter", ("error: %d/%s '%s'", errcode, sqlstate, err));
DBUG_ASSERT(stmt != 0);
stmt->last_errno= errcode;
if (err && err[0])
strmov(stmt->last_error, err);
strmov(stmt->sqlstate, sqlstate);
DBUG_VOID_RETURN;
}
/*
Read the prepared statement results ..
Read and unpack server reply to COM_PREPARE command (sent from
mysql_stmt_prepare).
NOTE
This is only called for connection to servers that supports
prepared statements (and thus the 4.1 protocol)
SYNOPSIS
cli_read_prepare_result()
mysql connection handle
stmt statement handle
RETURN VALUES
0 ok
......@@ -1752,7 +1762,9 @@ my_bool cli_read_prepare_result(MYSQL *mysql, MYSQL_STMT *stmt)
pos= (uchar*) mysql->net.read_pos;
stmt->stmt_id= uint4korr(pos+1); pos+= 5;
/* Number of columns in result set */
field_count= uint2korr(pos); pos+= 2;
/* Number of placeholders in the statement */
param_count= uint2korr(pos); pos+= 2;
if (param_count != 0)
......@@ -1802,10 +1814,30 @@ MYSQL_STMT * STDCALL mysql_prepare(MYSQL *mysql, const char *query,
#endif
/*
Allocate memory and init prepared statement structure
Allocate memory and init prepared statement structure.
SYNOPSIS
mysql_stmt_init()
mysql connection handle
mysql connection handle
DESCRIPTION
This is an entry point of the new API. Returned handle stands for
a server-side prepared statement. Memory for this structure (~700
bytes) is allocated using 'malloc'. Once created, the handle can be
reused many times. Created statement handle is bound to connection
handle provided to this call: it's lifetime is limited by lifetime
of connection.
'mysql_stmt_init()' is a pure local call, server side structure is
created only in mysql_stmt_prepare.
Next steps you may want to make:
- set a statement attribute (mysql_stmt_attr_set()),
- prepare statement handle with a query (mysql_stmt_prepare()),
- close statement handle and free it's memory (mysql_stmt_close()),
- reset statement with mysql_stmt_reset() (a no-op which will
just return).
Behaviour of the rest of API calls on this statement is not defined yet
(though we're working on making each wrong call sequence return
error).
RETURN VALUE
statement structure upon success and NULL if out of
......@@ -1838,27 +1870,41 @@ mysql_stmt_init(MYSQL *mysql)
DBUG_RETURN(stmt);
}
/*
Prepare server side statement with query:
Prepare server side statement with query.
SYNOPSIS
mysql_stmt_prepare()
query statement to prepare
length statement length
stmt statement handle
query statement to prepare
length statement length
DESCRIPTION
- if this is a re-prepare of the statement, first close previous data
Associate statement with statement handle. This is done both on
client and server sides. At this point the server parses given query
and creates an internal structure to represent it.
Next steps you may want to make:
- find out if this statement returns a result set by
calling mysql_stmt_field_count(), and get result set metadata
with mysql_stmt_result_metadata(),
- if query contains placeholders, bind input parameters to placeholders
using mysql_stmt_bind_param(),
- otherwise proceed directly to mysql_stmt_execute().
IMPLEMENTATION NOTES
- if this is a re-prepare of the statement, first close previous data
structure on the server and free old statement data
- send the query to server and get back number of placeholders,
- then send the query to server and get back number of placeholders,
number of columns in result set (if any), and result set metadata.
At the same time allocate memory for input and output parameters
At the same time allocate memory for input and output parameters
to have less checks in mysql_stmt_bind_{param, result}.
RETURN VALUES
0 success
!0 error
!0 error
*/
int STDCALL
mysql_stmt_prepare(MYSQL_STMT *stmt, const char *query, ulong length)
{
......@@ -1938,8 +1984,10 @@ mysql_stmt_prepare(MYSQL_STMT *stmt, const char *query, ulong length)
}
/*
Get the execute query meta information for non-select
statements.
Get result set metadata from reply to mysql_stmt_execute.
This is used mainly for SHOW commands, as metadata for these
commands is sent only with result set.
To be removed when all commands will fully support prepared mode.
*/
static unsigned int alloc_stmt_fields(MYSQL_STMT *stmt)
......@@ -1983,8 +2031,31 @@ static unsigned int alloc_stmt_fields(MYSQL_STMT *stmt)
}
/*
Returns prepared meta information in the form of resultset
to client.
Returns prepared statement metadata in the form of a result set.
SYNOPSIS
mysql_stmt_result_metadata()
stmt statement handle
RETURN
NULL statement contains no result set or out of memory.
In the latter case you can retreive error message
with mysql_stmt_error.
MYSQL_RES a result set with no rows
DESCRIPTION
This function should be used after mysql_stmt_execute().
You can safely check that prepared statement has a result set by calling
mysql_stmt_num_fields(): if number of fields is not zero, you can call
this function to get fields metadata.
Next steps you may want to make:
- find out number of columns in result set by calling
mysql_num_fields(res) (the same value is returned by
mysql_stmt_num_fields)
- fetch metadata for any column with mysql_fetch_field,
mysql_fetch_field_direct, mysql_fetch_fields, mysql_field_seek.
- free returned MYSQL_RES structure with mysql_free_result.
- proceed to binding of output parameters.
*/
MYSQL_RES * STDCALL
......@@ -2016,8 +2087,9 @@ mysql_stmt_result_metadata(MYSQL_STMT *stmt)
}
/*
Returns parameter columns meta information in the form of
resultset.
Returns parameter columns meta information in the form of
result set.
XXX: not implemented yet.
*/
MYSQL_RES * STDCALL
......@@ -2036,12 +2108,8 @@ mysql_stmt_param_metadata(MYSQL_STMT *stmt)
}
/********************************************************************
Prepare-execute, and param handling
*********************************************************************/
/****************************************************************************
Functions to store parameter data from a prepared statement.
/*
Functions to store parameter data in network packet.
All functions have the following characteristics:
......@@ -2053,7 +2121,7 @@ mysql_stmt_param_metadata(MYSQL_STMT *stmt)
RETURN VALUES
0 ok
1 Error (Can't alloc net->buffer)
****************************************************************************/
*/
static void store_param_tinyint(NET *net, MYSQL_BIND *param)
{
......@@ -2162,7 +2230,8 @@ static void store_param_datetime(NET *net, MYSQL_BIND *param)
static void store_param_str(NET *net, MYSQL_BIND *param)
{
ulong length= param->length ? *param->length : param->buffer_length;
/* param->length is always set in mysql_stmt_bind_param */
ulong length= *param->length;
char *to= (char *) net_store_length((char *) net->write_pos, length);
memcpy(to, param->buffer, length);
net->write_pos= (uchar*) to+length;
......@@ -2538,6 +2607,7 @@ my_ulonglong STDCALL mysql_stmt_insert_id(MYSQL_STMT *stmt)
return stmt->insert_id;
}
static my_bool int_is_null_true= 1; /* Used for MYSQL_TYPE_NULL */
static my_bool int_is_null_false= 0;
......@@ -2630,6 +2700,11 @@ my_bool STDCALL mysql_stmt_bind_param(MYSQL_STMT *stmt, MYSQL_BIND * bind)
case MYSQL_TYPE_VAR_STRING:
case MYSQL_TYPE_STRING:
param->store_param_func= store_param_str;
/*
For variable length types we expect user to set
length or buffer_length. Otherwise mysql_stmt_execute
will just fail.
*/
break;
default:
strmov(stmt->sqlstate, unknown_sqlstate);
......@@ -2671,7 +2746,6 @@ my_bool STDCALL mysql_stmt_bind_param(MYSQL_STMT *stmt, MYSQL_BIND * bind)
1 error
*/
my_bool STDCALL
mysql_stmt_send_long_data(MYSQL_STMT *stmt, uint param_number,
const char *data, ulong length)
......@@ -2769,6 +2843,7 @@ static uint read_binary_time(MYSQL_TIME *tm, uchar **pos)
uchar *to;
uint length;
/* net_field_length will set pos to the first byte of data */
if (!(length= net_field_length(pos)))
{
set_zero_time(tm);
......
sql/sql_prepare.cc
View file @ 231ec666
......@@ -210,7 +210,13 @@ static ulong get_param_length(uchar **packet, ulong len)
if (len < 5)
return 0;
(*packet)+=9; // Must be 254 when here
/* TODO: why uint4korr here? (should be uint8korr) */
/*
In our client-server protocol all numbers bigger than 2^24
stored as 8 bytes with uint8korr. Here we always know that
parameter length is less than 2^4 so don't look at the second
4 bytes. But still we need to obey the protocol hence 9 in the
assignment above.
*/
return (ulong) uint4korr(pos+1);
}
#else
......
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