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MaxScale/server/include/dcb.h
Markus Makela e6607dca40 tee.c: 
Added clientReply and setUpstream entry points
    Tee filter now waits for the branch session to be replied to and if the reply isn't received in five seconds it closes the branch session.
dcb.h:
    Added the DCBF_REPLIED flag that is currently only set in dcb_null_write
dcb.c:
    The DCBF_REPLIED flag is now set in dcb_null_write
2014-12-30 17:40:47 +02:00

339 lines
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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>
#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 int high_water; /**< High water mark */
unsigned int low_water; /**< Low water mark */
#if defined(SS_DEBUG)
int dcb_port; /**< port of target server */
skygw_chk_t dcb_chk_tail;
#endif
} DCB;
#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_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 */
bool dcb_set_state(DCB* dcb, dcb_state_t new_state, dcb_state_t* old_state);
void dcb_call_foreach (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);
/**
* 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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