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MaxScale/server/include/dcb.h

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C
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#ifndef _DCB_H
#define _DCB_H
/*
* This file is distributed as part of the MariaDB Corporation MaxScale. 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 MariaDB Corporation Ab 2013-2014
*/
#include <spinlock.h>
#include <buffer.h>
#include <modinfo.h>
#include <gwbitmask.h>
#include <skygw_utils.h>
#include <netinet/in.h>
#include <openssl/crypto.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#define ERRHANDLE
struct session;
struct server;
struct service;
/**
* @file dcb.h The Descriptor Control Block
*
* The function pointer table used by descriptors to call relevant functions
* within the protocol specific code.
*
* @verbatim
* Revision History
*
* Date Who Description
* 01/06/2013 Mark Riddoch Initial implementation
* 11/06/2013 Mark Riddoch Updated GWPROTOCOL structure with new
* entry points
* 18/06/2013 Mark Riddoch Addition of the listener entry point
* 02/07/2013 Massimiliano Pinto Addition of delayqlock, delayq and authlock
* for handling backend asynchronous protocol connection
* and a generic lock for backend authentication
* 12/07/2013 Massimiliano Pinto Added auth entry point
* 15/07/2013 Massimiliano Pinto Added session entry point
* 16/07/2013 Massimiliano Pinto Added command type for dcb
* 07/02/2014 Massimiliano Pinto Added ipv4 data struct into for dcb
* 07/05/2014 Mark Riddoch Addition of callback mechanism
* 08/05/2014 Mark Riddoch Addition of writeq high and low watermarks
* 27/08/2014 Mark Riddoch Addition of write event queuing
* 23/09/2014 Mark Riddoch New poll processing queue
*
* @endverbatim
*/
struct dcb;
/**
* @verbatim
* The operations that can be performed on the descriptor
*
* read EPOLLIN handler for the socket
* write MaxScale 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
* connect Create a connection to the specified server
* for the session pased in
* close MaxScale close entry point for the socket
* listen Create a listener for the protocol
* auth Authentication entry point
* session Session handling entry point
* @endverbatim
*
* This forms the "module object" for protocol modules within the gateway.
*
* @see load_module
*/
typedef struct gw_protocol {
int (*read)(struct dcb *);
int (*write)(struct dcb *, GWBUF *);
int (*write_ready)(struct dcb *);
int (*error)(struct dcb *);
int (*hangup)(struct dcb *);
int (*accept)(struct dcb *);
int (*connect)(struct dcb *, struct server *, struct session *);
int (*close)(struct dcb *);
int (*listen)(struct dcb *, char *);
int (*auth)(struct dcb *, struct server *, struct session *, GWBUF *);
int (*session)(struct dcb *, void *);
} GWPROTOCOL;
/**
* The event queue structure used in the polling loop to maintain a queue
* of events that need to be processed for the DCB.
*
* next The next DCB in the event queue
* prev The previous DCB in the event queue
* pending_events The events that are pending processing
* processing_events The evets currently being processed
* processing Flag to indicate the processing status of the DCB
* eventqlock Spinlock to protect this structure
* inserted Insertion time for logging purposes
* started Time that the processign started
*/
typedef struct {
struct dcb *next;
struct dcb *prev;
uint32_t pending_events;
uint32_t processing_events;
int processing;
SPINLOCK eventqlock;
unsigned long inserted;
unsigned long started;
} DCBEVENTQ;
/**
* The GWPROTOCOL version data. The following should be updated whenever
* the GWPROTOCOL structure is changed. See the rules defined in modinfo.h
* that define how these numbers should change.
*/
#define GWPROTOCOL_VERSION {1, 0, 0}
#define DCBFD_CLOSED -1
/**
* The statitics gathered on a descriptor control block
*/
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 */
int n_high_water; /*< Number of crosses of high water mark */
int n_low_water; /*< Number of crosses of low water mark */
} DCBSTATS;
/**
* The data structure that is embedded witin a DCB and manages the complex memory
* management issues of a DCB.
*
* The DCB structures are used as the user data within the polling loop. This means that
* polling threads may aschronously wake up and access these structures. It is not possible
* to simple remove the DCB from the epoll system and then free the data, as every thread
* that is currently running an epoll call must wake up and re-issue the epoll_wait system
* call, the is the only way we can be sure that no polling thread is pending a wakeup or
* processing an event that will access the DCB.
*
* We solve this issue by making the dcb_free routine merely mark a DCB as a zombie and
* place it on a special zombie list. Before placing the DCB on the zombie list we create
* a bitmask with a bit set in it for each active polling thread. Each thread will call
* a routine to process the zombie list at the end of the polling loop. This routine
* will clear the bit value that corresponds to the calling thread. Once the bitmask
* is completely cleared the DCB can finally be freed and removed from the zombie list.
*/
typedef struct {
GWBITMASK bitmask; /*< The bitmask of threads */
struct dcb *next; /*< Next pointer for the zombie list */
} DCBMM;
/* DCB states */
typedef enum {
DCB_STATE_UNDEFINED, /*< State variable with no state */
DCB_STATE_ALLOC, /*< Memory allocated but not populated */
DCB_STATE_POLLING, /*< Waiting in the poll loop */
DCB_STATE_LISTENING, /*< The DCB is for a listening socket */
DCB_STATE_DISCONNECTED, /*< The socket is now closed */
DCB_STATE_NOPOLLING, /*< Removed from poll mask */
DCB_STATE_ZOMBIE, /*< DCB is no longer active, waiting to free it */
DCB_STATE_FREED /*< Memory freed */
} dcb_state_t;
typedef enum {
DCB_ROLE_SERVICE_LISTENER, /*< Receives initial connect requests from clients */
DCB_ROLE_REQUEST_HANDLER, /*< Serves dedicated client */
DCB_ROLE_INTERNAL /*< Internal DCB not connected to the outside */
} dcb_role_t;
/**
* Callback reasons for the DCB callback mechanism.
*/
typedef enum {
DCB_REASON_CLOSE, /*< The DCB is closing */
DCB_REASON_DRAINED, /*< The write delay queue has drained */
DCB_REASON_HIGH_WATER, /*< Cross high water mark */
DCB_REASON_LOW_WATER, /*< Cross low water mark */
DCB_REASON_ERROR, /*< An error was flagged on the connection */
DCB_REASON_HUP, /*< A hangup was detected */
DCB_REASON_NOT_RESPONDING /*< Server connection was lost */
} DCB_REASON;
/**
* Callback structure - used to track callbacks registered on a DCB
*/
typedef struct dcb_callback {
DCB_REASON reason; /*< The reason for the callback */
int (*cb)(struct dcb *dcb, DCB_REASON reason, void *userdata);
void *userdata; /*< User data to be sent in the callback */
struct dcb_callback
*next; /*< Next callback for this DCB */
} DCB_CALLBACK;
/**
* Descriptor Control Block
*
* A wrapper for a network descriptor within the gateway, it contains all the
* state information necessary to allow for the implementation of the asynchronous
* operation of the potocol and gateway functions. It also provides links to the service
* and session data that is required to route the information within the gateway.
*
* It is important to hold the state information here such that any thread within the
* gateway may be selected to execute the required actions when a network event occurs.
*/
typedef struct dcb {
#if defined(SS_DEBUG)
skygw_chk_t dcb_chk_top;
#endif
bool dcb_errhandle_called; /*< this can be called only once */
dcb_role_t dcb_role;
SPINLOCK dcb_initlock;
DCBEVENTQ evq; /**< The event queue for this DCB */
int fd; /**< The descriptor */
dcb_state_t state; /**< Current descriptor state */
int flags; /**< DCB flags */
char *remote; /**< Address of remote end */
char *user; /**< User name for connection */
struct sockaddr_in ipv4; /**< remote end IPv4 address */
void *protocol; /**< The protocol specific state */
struct session *session; /**< The owning session */
GWPROTOCOL func; /**< The functions for this descriptor */
int writeqlen; /**< Current number of byes in the write queue */
SPINLOCK writeqlock; /**< Write Queue spinlock */
GWBUF *writeq; /**< Write Data Queue */
SPINLOCK delayqlock; /**< Delay Backend Write Queue spinlock */
GWBUF *delayq; /**< Delay Backend Write Data Queue */
GWBUF *dcb_readqueue; /**< read queue for storing incomplete reads */
SPINLOCK authlock; /**< Generic Authorization spinlock */
DCBSTATS stats; /**< DCB related statistics */
unsigned int dcb_server_status; /*< the server role indicator from SERVER */
struct dcb *next; /**< Next DCB in the chain of allocated DCB's */
struct service *service; /**< The related service */
void *data; /**< Specific client data */
DCBMM memdata; /**< The data related to DCB memory management */
SPINLOCK cb_lock; /**< The lock for the callbacks linked list */
DCB_CALLBACK *callbacks; /**< The list of callbacks for the DCB */
SPINLOCK pollinlock;
int pollinbusy;
int readcheck;
SPINLOCK polloutlock;
int polloutbusy;
int writecheck;
unsigned long last_read; /*< Last time the DCB received data */
unsigned int high_water; /**< High water mark */
unsigned int low_water; /**< Low water mark */
struct server *server; /**< The associated backend server */
SSL* ssl; /*< SSL struct for connection */
#if defined(SS_DEBUG)
int dcb_port; /**< port of target server */
skygw_chk_t dcb_chk_tail;
#endif
} DCB;
/**
* The DCB usage filer used for returning DCB's in use for a certain reason
*/
typedef enum {
DCB_USAGE_CLIENT,
DCB_USAGE_LISTENER,
DCB_USAGE_BACKEND,
DCB_USAGE_INTERNAL,
DCB_USAGE_ZOMBIE,
DCB_USAGE_ALL
} DCB_USAGE;
#if defined(FAKE_CODE)
unsigned char dcb_fake_write_errno[10240];
__int32_t dcb_fake_write_ev[10240];
bool fail_next_backend_fd;
bool fail_next_client_fd;
int fail_next_accept;
int fail_accept_errno;
#endif /* FAKE_CODE */
/* A few useful macros */
#define DCB_SESSION(x) (x)->session
#define DCB_PROTOCOL(x, type) (type *)((x)->protocol)
#define DCB_ISZOMBIE(x) ((x)->state == DCB_STATE_ZOMBIE)
#define DCB_WRITEQLEN(x) (x)->writeqlen
#define DCB_SET_LOW_WATER(x, lo) (x)->low_water = (lo);
#define DCB_SET_HIGH_WATER(x, hi) (x)->low_water = (hi);
#define DCB_BELOW_LOW_WATER(x) ((x)->low_water && (x)->writeqlen < (x)->low_water)
#define DCB_ABOVE_HIGH_WATER(x) ((x)->high_water && (x)->writeqlen > (x)->high_water)
#define DCB_POLL_BUSY(x) ((x)->evq.next != NULL)
DCB *dcb_get_zombies(void);
int gw_write(DCB *, const void *, size_t);
int dcb_write(DCB *, GWBUF *);
DCB *dcb_alloc(dcb_role_t);
void dcb_free(DCB *);
DCB *dcb_connect(struct server *, struct session *, const char *);
DCB *dcb_clone(DCB *);
int dcb_read(DCB *, GWBUF **);
int dcb_read_n(DCB*,GWBUF **,int);
int dcb_drain_writeq(DCB *);
void dcb_close(DCB *);
DCB *dcb_process_zombies(int); /* Process Zombies except the one behind the pointer */
void printAllDCBs(); /* Debug to print all DCB in the system */
void printDCB(DCB *); /* Debug print routine */
void dprintAllDCBs(DCB *); /* Debug to print all DCB in the system */
void dprintDCB(DCB *, DCB *); /* Debug to print a DCB in the system */
void dListDCBs(DCB *); /* List all DCBs in the system */
void dListClients(DCB *); /* List al the client DCBs */
const char *gw_dcb_state2string(int); /* DCB state to string */
void dcb_printf(DCB *, const char *, ...); /* DCB version of printf */
int dcb_isclient(DCB *); /* the DCB is the client of the session */
void dcb_hashtable_stats(DCB *, void *); /**< Print statisitics */
void dcb_add_to_zombieslist(DCB* dcb);
int dcb_add_callback(DCB *, DCB_REASON, int (*)(struct dcb *, DCB_REASON, void *),
void *);
int dcb_remove_callback(DCB *, DCB_REASON, int (*)(struct dcb *, DCB_REASON, void *),
void *);
int dcb_isvalid(DCB *); /* Check the DCB is in the linked list */
int dcb_count_by_usage(DCB_USAGE); /* Return counts of DCBs */
bool dcb_set_state(DCB* dcb, dcb_state_t new_state, dcb_state_t* old_state);
void dcb_call_foreach (struct server* server, DCB_REASON reason);
size_t dcb_get_session_id(DCB* dcb);
bool dcb_get_ses_log_info(DCB* dcb, size_t* sesid, int* enabled_logs);
int dcb_create_SSL(DCB* dcb);
int dcb_accept_SSL(DCB* dcb);
int dcb_connect_SSL(DCB* dcb);
int gw_write_SSL(SSL* ssl, const void *buf, size_t nbytes);
int dcb_write_SSL(DCB *dcb,GWBUF *queue);
int dcb_read_SSL(DCB *dcb,GWBUF **head);
int dcb_drain_writeq_SSL(DCB *dcb);
/**
* DCB flags values
*/
#define DCBF_CLONE 0x0001 /*< DCB is a clone */
#define DCBF_HUNG 0x0002 /*< Hangup has been dispatched */
#define DCBF_REPLIED 0x0004 /*< DCB was written to */
#define DCB_IS_CLONE(d) ((d)->flags & DCBF_CLONE)
#define DCB_REPLIED(d) ((d)->flags & DCBF_REPLIED)
#endif /* _DCB_H */
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