#ifndef _DCB_H
#define _DCB_H
/*
 * This file is distributed as part of the SkySQL Gateway.  It 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,
 * version 2.
 *
 * 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., 51
 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Copyright SkySQL Ab 2013
 */
#include <spinlock.h>
#include <buffer.h>

struct session;

/*
 * The function pointer table used by descriptors to call relevant functions
 * within the protocol specific code.
 *
 * Revision History
 *
 * Date		Who			Description
 * 01/06/13	Mark Riddoch		Initial implementation
 * 11/06/13	Mark Riddoch		Updated GWPROTOCOL structure with new
 *					entry points
 *
 */

struct dcb;

typedef struct gw_protocol {
        /*                              
         * The operations that can be performed on the descriptor
	 *
	 *	read		EPOLLIN handler for the socket
	 *	write		Gateway data write entry point
	 *	write_ready	EPOLLOUT handler for the socket, indicates
	 *			that the socket is ready to send more data
	 *	error		EPOLLERR handler for the socket
	 *	hangup		EPOLLHUP handler for the socket
	 *	accept		Accept handler for listener socket only
	 *	close		Gateway close entry point for the socket
         */                             
	int		(*read)(struct dcb *, int);
	int		(*write)(struct dcb *, GWBUF *);
	int		(*write_ready)(struct dcb *, int);
	int		(*error)(struct dcb *, int);
	int		(*hangup)(struct dcb *, int);
	int		(*accept)(struct dcb *, int);
	int		(*close)(struct dcb *, int);
} GWPROTOCOL;

typedef struct dcbstats {
	int		n_reads;	/* Number of reads on this descriptor */
	int		n_writes;	/* Number of writes on this descriptor */
	int		n_accepts;	/* Number of accepts on this descriptor */
	int		n_buffered;	/* Number of buffered writes */
} DCBSTATS;
/*
 * Descriptor Control Block
 */
typedef struct dcb {
	int		fd;		/* The descriptor */
	int 		state;		/* Current descriptor state */
	void		*protocol;	/* The protocol specific state */
	struct session	*session;	/* The owning session */
	GWPROTOCOL	func;		/* The functions for this descrioptor */

	SPINLOCK	writeqlock;	/* Write Queue spinlock */
	GWBUF		*writeq;	/* Write Data Queue */

	DCBSTATS	stats;		/* DCB related statistics */

	struct dcb	*next;		/* Next DCB in the chain of allocated DCB's */
} DCB;

/* DCB states */
#define	DCB_STATE_ALLOC		0	/* Memory allocated but not populated */
#define DCB_STATE_IDLE		1	/* Not yet in the poll mask */
#define DCB_STATE_POLLING	2	/* Waiting in the poll loop */
#define DCB_STATE_PROCESSING	4	/* Processing an event */
#define DCB_STATE_LISTENING	5	/* The DCB is for a listening socket */
#define DCB_STATE_DISCONNECTED	6	/* The socket is now closed */
#define DCB_STATE_FREED		7	/* Memory freed */

/* A few useful macros */
#define	DCB_SESSION(x)			(x)->session
#define DCB_PROTOCOL(x, type)		(type *)((x)->protocol)

extern DCB		*alloc_dcb();			/* Allocate a DCB */
extern void		free_dcb(DCB *);		/* Free a DCB */
extern void		printAllDCBs();			/* Debug to print all DCB in the system */
extern void		printDCB(DCB *);		/* Debug print routine */
extern const char 	*gw_dcb_state2string(int);	/* DCB state to string */

#endif