Comments and cleanups in client library.

include/mysql.h

@@ -558,7 +558,7 @@ typedef struct st_mysql_bind
   enum enum_field_types buffer_type;	/* buffer type */
   unsigned long buffer_length;    /* buffer length, must be set for str/binary */  
 
-  /* Following are for internal use. Set by mysql_bind_param */
+  /* Following are for internal use. Set by mysql_stmt_bind_param */
   unsigned char *inter_buffer;    /* for the current data position */
   unsigned long offset;           /* offset position for char/binary fetch */
   unsigned long	internal_length;  /* Used if length is 0 */

libmysql/libmysql.c

@@ -2130,10 +2130,23 @@ mysql_stmt_result_metadata(MYSQL_STMT *stmt)
   DBUG_RETURN(result);
 }
 
+
 /*
   Returns parameter columns meta information in the form of
   result set.
+
+  SYNOPSYS
+    mysql_stmt_param_metadata()
+    stmt    statement handle
+
+  DESCRIPTION
+    This function can be called after you prepared the statement handle
+    with mysql_stmt_prepare().
     XXX: not implemented yet.
+
+  RETURN
+    MYSQL_RES on success, 0 if there is no metadata.
+    Currently this function always returns 0.
 */
 
 MYSQL_RES * STDCALL
@@ -2146,25 +2159,36 @@ mysql_stmt_param_metadata(MYSQL_STMT *stmt)
 
   /*
     TODO: Fix this when server sends the information.
-    Till then keep a dummy prototype 
+    Till then keep a dummy prototype.
   */
   DBUG_RETURN(0); 
 }
 
 
+/* Store type of parameter in network buffer. */
+
+static void store_param_type(char **pos, MYSQL_BIND *param)
+{
+  uint typecode= param->buffer_type | (param->is_unsigned ? 32768 : 0);
+  int2store(*pos, typecode);
+  *pos+= 2;
+}
+
+
 /*
   Functions to store parameter data in network packet.
 
-  All functions have the following characteristics:
-
   SYNOPSIS
     store_param_xxx()
     net			MySQL NET connection
     param		MySQL bind param
 
-  RETURN VALUES
-    0	ok
-    1	Error	(Can't alloc net->buffer)
+  DESCRIPTION
+    These funtions are invoked from mysql_stmt_execute by
+    MYSQL_BIND::store_param_func pointer. This pointer is set once per many
+    executions in mysql_stmt_bind_param. The caller must ensure that network
+    buffer have enough capacity to store parameter (MYSQL_BIND::buffer_length
+    contains needed number of bytes).
 */
 
 static void store_param_tinyint(NET *net, MYSQL_BIND *param)
@@ -2292,7 +2316,8 @@ static void store_param_str(NET *net, MYSQL_BIND *param)
 
   DESCRIPTION
     A data package starts with a string of bits where we set a bit
-    if a parameter is NULL
+    if a parameter is NULL. Unlike bit string in result set row, here
+    we don't have reserved bits for OK/error packet.
 */
 
 static void store_param_null(NET *net, MYSQL_BIND *param)
@@ -2303,8 +2328,9 @@ static void store_param_null(NET *net, MYSQL_BIND *param)
 
 
 /*
-  Set parameter data by reading from input buffers from the
-  client application
+  Store one parameter in network packet: data is read from
+  client buffer and saved in network packet by means of one
+  of store_param_xxxx functions.
 */
 
 static my_bool store_param(MYSQL_STMT *stmt, MYSQL_BIND *param)
@@ -2339,7 +2365,7 @@ static my_bool store_param(MYSQL_STMT *stmt, MYSQL_BIND *param)
   Send the prepared query to server for execution
 */
 
-static my_bool execute(MYSQL_STMT * stmt, char *packet, ulong length)
+static my_bool execute(MYSQL_STMT *stmt, char *packet, ulong length)
 {
   MYSQL *mysql= stmt->mysql;
   NET	*net= &mysql->net;
@@ -2365,14 +2391,6 @@ static my_bool execute(MYSQL_STMT * stmt, char *packet, ulong length)
 }
 
 
-static void store_param_type(char **pos, MYSQL_BIND *param)
-{
-  uint typecode= param->buffer_type | (param->is_unsigned ? 32768 : 0);
-  int2store(*pos, typecode);
-  *pos+= 2;
-}
-
-
 int cli_stmt_execute(MYSQL_STMT *stmt)
 {
   DBUG_ENTER("cli_stmt_execute");
@@ -2413,7 +2431,7 @@ int cli_stmt_execute(MYSQL_STMT *stmt)
 
     for (param= stmt->params; param < param_end; param++)
     {
-      /* check if mysql_long_data() was used */
+      /* check if mysql_stmt_send_long_data() was used */
       if (param->long_data_used)
 	param->long_data_used= 0;	/* Clear for next execute call */
       else if (store_param(stmt, param))
@@ -2587,7 +2605,47 @@ my_bool STDCALL mysql_stmt_attr_get(MYSQL_STMT *stmt,
 
 
 /*
-  Execute the prepared query
+  Send placeholders data to server (if there are placeholders)
+  and execute prepared statement.
+
+  SYNOPSIS
+    mysql_stmt_execute()
+    stmt  statement handle. The handle must be created
+          with mysql_stmt_init() and prepared with
+          mysql_stmt_prepare(). If there are placeholders
+          in the statement they must be bound to local
+          variables with mysql_stmt_bind_param().
+
+  DESCRIPTION
+    This function will automatically flush pending result
+    set (if there is one), send parameters data to the server
+    and read result of statement execution.
+    If previous result set was cached with mysql_stmt_store_result()
+    it will also be freed in the beginning of this call.
+    The server can return 3 types of responses to this command:
+    - error, can be retrieved with mysql_stmt_error()
+    - ok, no result set pending. In this case we just update
+      stmt->insert_id and stmt->affected_rows.
+    - the query returns a result set: there could be 0 .. N
+    rows in it. In this case the server can also send updated
+    result set metadata.
+
+    Next steps you may want to make:
+    - find out if there is result set with mysql_stmt_field_count().
+    If there is one:
+    - optionally, cache entire result set on client to unblock
+    connection with mysql_stmt_store_result()
+    - bind client variables to result set columns and start read rows
+    with mysql_stmt_fetch().
+    - reset statement with mysql_stmt_reset() or close it with
+    mysql_stmt_close()
+    Otherwise:
+    - find out last insert id and number of affected rows with
+    mysql_stmt_insert_id(), mysql_stmt_affected_rows()
+
+  RETURN
+    0   success
+    1   error, message can be retrieved with mysql_stmt_error().
 */
 
 int STDCALL mysql_stmt_execute(MYSQL_STMT *stmt)
@@ -2681,7 +2739,19 @@ unsigned int STDCALL mysql_stmt_field_count(MYSQL_STMT *stmt)
 }
 
 /*
-  Return last inserted id for auto_increment columns
+  Return last inserted id for auto_increment columns.
+
+  SYNOPSIS
+    mysql_stmt_insert_id()
+    stmt    statement handle
+
+  DESCRIPTION
+    Current implementation of this call has a caveat: stmt->insert_id is
+    unconditionally updated from mysql->insert_id in the end of each
+    mysql_stmt_execute(). This works OK if mysql->insert_id contains new
+    value (sent in reply to mysql_stmt_execute()), otherwise stmt->insert_id
+    value gets undefined, as it's updated from some arbitrary value saved in
+    connection structure during some other call.
 */
 
 my_ulonglong STDCALL mysql_stmt_insert_id(MYSQL_STMT *stmt)
@@ -2693,11 +2763,24 @@ my_ulonglong STDCALL mysql_stmt_insert_id(MYSQL_STMT *stmt)
 static my_bool int_is_null_true= 1;		/* Used for MYSQL_TYPE_NULL */
 static my_bool int_is_null_false= 0;
 
+
 /*
-  Setup the parameter data buffers from application
+  Setup the input parameter data buffers from application
+
+  SYNOPSIS
+    mysql_stmt_bind_param()
+    stmt    statement handle
+            The statement must be prepared with mysql_stmt_prepare().
+    bind    Array of mysql_stmt_param_count() bind parameters.
+
+  RETURN
+    0  success
+    1  error, can be retrieved with mysql_stmt_error.
+       Note, that this function doesn't check that size of MYSQL_BIND
+       array is >= mysql_stmt_field_count(),
 */
 
-my_bool STDCALL mysql_stmt_bind_param(MYSQL_STMT *stmt, MYSQL_BIND * bind)
+my_bool STDCALL mysql_stmt_bind_param(MYSQL_STMT *stmt, MYSQL_BIND *bind)
 {
   uint count=0;
   MYSQL_BIND *param, *end;
@@ -3825,6 +3908,49 @@ err:
 }
 
 
+/*
+  Update meta data for statement
+
+  SYNOPSIS
+    stmt_update_metadata()
+    stmt			Statement handler
+    row				Binary data
+
+  NOTES
+    Only updates MYSQL_FIELD->max_length for strings
+*/
+
+static void stmt_update_metadata(MYSQL_STMT *stmt, MYSQL_ROWS *data)
+{
+  MYSQL_BIND  *bind, *end;
+  MYSQL_FIELD *field;
+  uchar *null_ptr, bit;
+  uchar *row= (uchar*) data->data;
+#ifndef DBUG_OFF
+  uchar *row_end= row + data->length;
+#endif
+
+  null_ptr= row;
+  row+= (stmt->field_count+9)/8;		/* skip null bits */
+  bit= 4;					/* first 2 bits are reserved */
+
+  /* Go throw all fields and calculate metadata */
+  for (bind= stmt->bind, end= bind + stmt->field_count, field= stmt->fields ;
+       bind < end ;
+       bind++, field++)
+  {
+    if (!(*null_ptr & bit))
+      (*bind->skip_result)(bind, field, &row);
+    DBUG_ASSERT(row <= row_end);
+    if (!((bit<<=1) & 255))
+    {
+      bit= 1;					/* To next byte */
+      null_ptr++;
+    }
+  }
+}
+
+
 /*
   Store or buffer the binary results to stmt
 */
@@ -4116,50 +4242,6 @@ const char *STDCALL mysql_stmt_error(MYSQL_STMT * stmt)
 }
 
 
-/*
-  Update meta data for statement
-
-  SYNOPSIS
-    stmt_update_metadata()
-    stmt			Statement handler
-    row				Binary data
-
-  NOTES
-    Only updates MYSQL_FIELD->max_length for strings
-
-*/
-
-static void stmt_update_metadata(MYSQL_STMT *stmt, MYSQL_ROWS *data)
-{
-  MYSQL_BIND  *bind, *end;
-  MYSQL_FIELD *field;
-  uchar *null_ptr, bit;
-  uchar *row= (uchar*) data->data;
-#ifndef DBUG_OFF
-  uchar *row_end= row + data->length;
-#endif
-
-  null_ptr= row; 
-  row+= (stmt->field_count+9)/8;		/* skip null bits */
-  bit= 4;					/* first 2 bits are reserved */
-  
-  /* Go throw all fields and calculate metadata */
-  for (bind= stmt->bind, end= bind + stmt->field_count, field= stmt->fields ;
-       bind < end ;
-       bind++, field++)
-  {
-    if (!(*null_ptr & bit))
-      (*bind->skip_result)(bind, field, &row);
-    DBUG_ASSERT(row <= row_end);
-    if (!((bit<<=1) & 255))
-    {
-      bit= 1;					/* To next byte */
-      null_ptr++;
-    }
-  }
-}
-
-
 /********************************************************************
  Transactional APIs
 *********************************************************************/