protocol.cc File Reference

#include "sql_priv.h"
#include "unireg.h"
#include "protocol.h"
#include "sql_class.h"
#include <stdarg.h>

Functions
bool	net_send_error_packet (THD *, uint, const char *, const char *)
bool	net_send_ok (THD *, uint, uint, ulonglong, ulonglong, const char *)
bool	net_send_eof (THD *thd, uint server_status, uint statement_warn_count)
bool	net_send_error (THD *thd, uint sql_errno, const char *err, const char *sqlstate)
uchar *	net_store_data (uchar *to, const uchar *from, size_t length)
uchar *	net_store_data (uchar *to, int32 from)
uchar *	net_store_data (uchar *to, longlong from)

---

Detailed Description

Low level functions for storing data to be send to the MySQL client. The actual communction is handled by the net_xxx functions in net_serv.cc

---

Function Documentation

bool net_send_eof	(	THD *	thd,
		uint	server_status,
		uint	statement_warn_count
	)

Send eof (= end of result set) to the client.

The eof packet has the following structure:

• 254 : Marker (1 byte)
• warning_count : Stored in 2 bytes; New in 4.1 protocol
• status_flag : Stored in 2 bytes; For flags like SERVER_MORE_RESULTS_EXISTS.

Note that the warning count will not be sent if 'no_flush' is set as we don't want to report the warning count until all data is sent to the client.

Parameters:

thd	Thread handler
server_status	The server status
statement_warn_count	Total number of warnings

Returns:

Return values:

FALSE	The message was successfully sent
TRUE	An error occurred and the message wasn't sent properly

bool net_send_error	(	THD *	thd,
		uint	sql_errno,
		const char *	err,
		const char *	sqlstate
	)

Send a error string to client.

Design note:

net_printf_error and net_send_error are low-level functions that shall be used only when a new connection is being established or at server startup.

For SIGNAL/RESIGNAL and GET DIAGNOSTICS functionality it's critical that every error that can be intercepted is issued in one place only, my_message_sql.

Parameters:

thd	Thread handler
sql_errno	The error code to send
err	A pointer to the error message

Returns:

Return values:

FALSE	The message was sent to the client
TRUE	An error occurred and the message wasn't sent properly

bool net_send_error_packet	(	THD *	thd,
		uint	sql_errno,
		const char *	err,
		const char *	sqlstate
	)

Parameters:

thd	Thread handler
sql_errno	The error code to send
err	A pointer to the error message

Returns:

Return values:

FALSE	The message was successfully sent
TRUE	An error occurred and the messages wasn't sent properly

bool net_send_ok	(	THD *	thd,
		uint	server_status,
		uint	statement_warn_count,
		ulonglong	affected_rows,
		ulonglong	id,
		const char *	message
	)

Return ok to the client.

The ok packet has the following structure:

• 0 : Marker (1 byte)
• affected_rows : Stored in 1-9 bytes
• id : Stored in 1-9 bytes
• server_status : Copy of thd->server_status; Can be used by client to check if we are inside an transaction. New in 4.0 protocol
• warning_count : Stored in 2 bytes; New in 4.1 protocol
• message : Stored as packed length (1-9 bytes) + message. Is not stored if no message.

Parameters:

thd	Thread handler
server_status	The server status
statement_warn_count	Total number of warnings
affected_rows	Number of rows changed by statement
id	Auto_increment id for first row (if used)
message	Message to send to the client (Used by mysql_status)

Returns:

Return values:

FALSE	The message was successfully sent
TRUE	An error occurred and the messages wasn't sent properly