7ff14e23a5
All prepare commands are executed in every backend server currently connected. All executes are routed to master. If stmt type was recorded in prepare phase in rwsplit router, read-only stmts could be routed to slaves. COM_STMT_PREPARE gets arbitrary number of response packets from backend database. Since statements are prepared in every backend server and only one multi-packet response can be replied to client, redundant multi-packet responses are discarded. This is done in router. Mechanisms from session command handling are utilized with little changes: router must identify when response consists of multiple packets so that it knows to calculate the number of packets in response and that it is able to discard correct number of packets. Information to the reply-handling router is provided by backend protocol, which includes a ordered list of commands of commands sent to protocol-owning backend server. A command is stored to protocol struct in mysql_backend.c:gw_MySQLWrite_backend if the statement buffer's type has GWBUF_TYPE_SINGLE_STMT set in mysql_client.c:route_by_statement. GWBUF_TYPE_SINGLE_STATEMENT indicates that there is single statement in the buffer, as opposite to Read Connection router, which accepts streaming input from client.
287 lines
9.6 KiB
C
287 lines
9.6 KiB
C
#ifndef _RWSPLITROUTER_H
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#define _RWSPLITROUTER_H
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/*
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* This file is distributed as part of the SkySQL Gateway. It is free
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* software: you can redistribute it and/or modify it under the terms of the
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* GNU General Public License as published by the Free Software Foundation,
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* version 2.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 51
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* Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Copyright SkySQL Ab 2013
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*/
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/**
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* @file router.h - The read write split router module heder file
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*
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* @verbatim
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* Revision History
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*
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* See GitHub https://github.com/skysql/MaxScale
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*
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* @endverbatim
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*/
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#include <dcb.h>
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#include <hashtable.h>
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#undef PREP_STMT_CACHING
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#if defined(PREP_STMT_CACHING)
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typedef enum prep_stmt_type {
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PREP_STMT_NAME,
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PREP_STMT_ID
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} prep_stmt_type_t;
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typedef enum prep_stmt_state {
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PREP_STMT_ALLOC,
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PREP_STMT_SENT,
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PREP_STMT_RECV,
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PREP_STMT_DROPPED
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} prep_stmt_state_t;
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#endif /*< PREP_STMT_CACHING */
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typedef enum bref_state {
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BREF_IN_USE = 0x01,
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BREF_WAITING_RESULT = 0x02, /*< for anything that responds */
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BREF_CLOSED = 0x04
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} bref_state_t;
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#define BREF_IS_NOT_USED(s) (s->bref_state & ~BREF_IN_USE)
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#define BREF_IS_IN_USE(s) (s->bref_state & BREF_IN_USE)
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#define BREF_IS_WAITING_RESULT(s) (s->bref_state & BREF_WAITING_RESULT)
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#define BREF_IS_CLOSED(s) (s->bref_state & BREF_CLOSED)
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typedef enum backend_type_t {
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BE_UNDEFINED=-1,
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BE_MASTER,
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BE_JOINED = BE_MASTER,
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BE_SLAVE,
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BE_COUNT
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} backend_type_t;
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typedef struct rses_property_st rses_property_t;
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typedef struct router_client_session ROUTER_CLIENT_SES;
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typedef enum rses_property_type_t {
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RSES_PROP_TYPE_UNDEFINED=-1,
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RSES_PROP_TYPE_SESCMD=0,
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RSES_PROP_TYPE_FIRST = RSES_PROP_TYPE_SESCMD,
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RSES_PROP_TYPE_LAST=RSES_PROP_TYPE_SESCMD,
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RSES_PROP_TYPE_COUNT=RSES_PROP_TYPE_LAST+1
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} rses_property_type_t;
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/**
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* This criteria is used when backends are chosen for a router session's use.
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* Backend servers are sorted to ascending order according to the criteria
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* and top N are chosen.
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*/
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typedef enum select_criteria {
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UNDEFINED_CRITERIA=0,
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LEAST_GLOBAL_CONNECTIONS, /*< all connections established by MaxScale */
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DEFAULT_CRITERIA=LEAST_GLOBAL_CONNECTIONS,
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LEAST_ROUTER_CONNECTIONS, /*< connections established by this router */
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LEAST_BEHIND_MASTER,
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LAST_CRITERIA /*< not used except for an index */
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} select_criteria_t;
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/** default values for rwsplit configuration parameters */
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#define CONFIG_MAX_SLAVE_CONN 1
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#define GET_SELECT_CRITERIA(s) \
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(strncmp(s,"LEAST_GLOBAL_CONNECTIONS", strlen("LEAST_GLOBAL_CONNECTIONS")) == 0 ? \
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LEAST_GLOBAL_CONNECTIONS : ( \
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strncmp(s,"LEAST_BEHIND_MASTER", strlen("LEAST_BEHIND_MASTER")) == 0 ? \
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LEAST_BEHIND_MASTER : ( \
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strncmp(s,"LEAST_ROUTER_CONNECTIONS", strlen("LEAST_ROUTER_CONNECTIONS")) == 0 ? \
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LEAST_ROUTER_CONNECTIONS : UNDEFINED_CRITERIA)))
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/**
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* Session variable command
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*/
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typedef struct mysql_sescmd_st {
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#if defined(SS_DEBUG)
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skygw_chk_t my_sescmd_chk_top;
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#endif
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rses_property_t* my_sescmd_prop; /*< parent property */
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GWBUF* my_sescmd_buf; /*< query buffer */
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unsigned char my_sescmd_packet_type;/*< packet type */
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bool my_sescmd_is_replied; /*< is cmd replied to client */
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#if defined(SS_DEBUG)
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skygw_chk_t my_sescmd_chk_tail;
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#endif
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} mysql_sescmd_t;
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/**
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* Property structure
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*/
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struct rses_property_st {
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#if defined(SS_DEBUG)
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skygw_chk_t rses_prop_chk_top;
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#endif
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ROUTER_CLIENT_SES* rses_prop_rsession; /*< parent router session */
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int rses_prop_refcount;
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rses_property_type_t rses_prop_type;
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union rses_prop_data {
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mysql_sescmd_t sescmd;
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void* placeholder; /*< to be removed due new type */
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} rses_prop_data;
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rses_property_t* rses_prop_next; /*< next property of same type */
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#if defined(SS_DEBUG)
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skygw_chk_t rses_prop_chk_tail;
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#endif
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};
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typedef struct sescmd_cursor_st {
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#if defined(SS_DEBUG)
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skygw_chk_t scmd_cur_chk_top;
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#endif
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ROUTER_CLIENT_SES* scmd_cur_rses; /*< pointer to owning router session */
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rses_property_t** scmd_cur_ptr_property; /*< address of pointer to owner property */
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mysql_sescmd_t* scmd_cur_cmd; /*< pointer to current session command */
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bool scmd_cur_active; /*< true if command is being executed */
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#if defined(SS_DEBUG)
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skygw_chk_t scmd_cur_chk_tail;
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#endif
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} sescmd_cursor_t;
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/**
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* Internal structure used to define the set of backend servers we are routing
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* connections to. This provides the storage for routing module specific data
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* that is required for each of the backend servers.
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*
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* Owned by router_instance, referenced by each routing session.
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*/
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typedef struct backend_st {
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#if defined(SS_DEBUG)
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skygw_chk_t be_chk_top;
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#endif
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SERVER* backend_server; /*< The server itself */
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int backend_conn_count; /*< Number of connections to the server */
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bool be_valid; /*< valid when belongs to the router's configuration */
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#if defined(SS_DEBUG)
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skygw_chk_t be_chk_tail;
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#endif
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} BACKEND;
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/**
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* Reference to BACKEND.
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*
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* Owned by router client session.
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*/
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typedef struct backend_ref_st {
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#if defined(SS_DEBUG)
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skygw_chk_t bref_chk_top;
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#endif
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BACKEND* bref_backend;
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DCB* bref_dcb;
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bref_state_t bref_state;
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sescmd_cursor_t bref_sescmd_cur;
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#if defined(SS_DEBUG)
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skygw_chk_t bref_chk_tail;
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#endif
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} backend_ref_t;
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typedef struct rwsplit_config_st {
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int rw_max_slave_conn_percent;
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int rw_max_slave_conn_count;
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select_criteria_t rw_slave_select_criteria;
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} rwsplit_config_t;
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#if defined(PREP_STMT_CACHING)
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typedef struct prep_stmt_st {
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#if defined(SS_DEBUG)
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skygw_chk_t pstmt_chk_top;
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#endif
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union id {
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int seq;
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char* name;
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} pstmt_id;
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prep_stmt_state_t pstmt_state;
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prep_stmt_type_t pstmt_type;
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#if defined(SS_DEBUG)
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skygw_chk_t pstmt_chk_tail;
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#endif
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} prep_stmt_t;
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#endif /*< PREP_STMT_CACHING */
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/**
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* The client session structure used within this router.
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*/
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struct router_client_session {
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#if defined(SS_DEBUG)
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skygw_chk_t rses_chk_top;
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#endif
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SPINLOCK rses_lock; /*< protects rses_deleted */
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int rses_versno; /*< even = no active update, else odd. not used 4/14 */
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bool rses_closed; /*< true when closeSession is called */
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/** Properties listed by their type */
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rses_property_t* rses_properties[RSES_PROP_TYPE_COUNT];
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backend_ref_t* rses_master_ref;
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backend_ref_t* rses_backend_ref; /*< Pointer to backend reference array */
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rwsplit_config_t rses_config; /*< copied config info from router instance */
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int rses_nbackends;
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int rses_capabilities; /*< input type, for example */
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bool rses_autocommit_enabled;
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bool rses_transaction_active;
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#if defined(PREP_STMT_CACHING)
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HASHTABLE* rses_prep_stmt[2];
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#endif
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struct router_client_session* next;
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#if defined(SS_DEBUG)
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skygw_chk_t rses_chk_tail;
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#endif
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};
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/**
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* The statistics for this router instance
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*/
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typedef struct {
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int n_sessions; /*< Number sessions created */
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int n_queries; /*< Number of queries forwarded */
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int n_master; /*< Number of stmts sent to master */
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int n_slave; /*< Number of stmts sent to slave */
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int n_all; /*< Number of stmts sent to all */
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} ROUTER_STATS;
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/**
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* The per instance data for the router.
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*/
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typedef struct router_instance {
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SERVICE* service; /*< Pointer to service */
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ROUTER_CLIENT_SES* connections; /*< List of client connections */
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SPINLOCK lock; /*< Lock for the instance data */
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BACKEND** servers; /*< Backend servers */
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BACKEND* master; /*< NULL or pointer */
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rwsplit_config_t rwsplit_config; /*< expanded config info from SERVICE */
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int rwsplit_version;/*< version number for router's config */
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unsigned int bitmask; /*< Bitmask to apply to server->status */
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unsigned int bitvalue; /*< Required value of server->status */
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ROUTER_STATS stats; /*< Statistics for this router */
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struct router_instance* next; /*< Next router on the list */
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} ROUTER_INSTANCE;
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#define BACKEND_TYPE(b) (SERVER_IS_MASTER((b)->backend_server) ? BE_MASTER : \
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(SERVER_IS_SLAVE((b)->backend_server) ? BE_SLAVE : BE_UNDEFINED));
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#endif /*< _RWSPLITROUTER_H */
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