294 lines
9.4 KiB
C
294 lines
9.4 KiB
C
/*
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* Copyright (c) 2018 MariaDB Corporation Ab
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
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*
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* Change Date: 2022-01-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2 or later of the General
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* Public License.
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*/
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#pragma once
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/**
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* @file router.h - The query router public interface definition
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*/
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#include <maxscale/cdefs.h>
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#include <stdint.h>
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#include <maxbase/jansson.h>
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#include <maxscale/buffer.h>
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#include <maxscale/routing.h>
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#include <maxscale/service.hh>
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#include <maxscale/session.h>
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MXS_BEGIN_DECLS
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/**
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* MXS_ROUTER is an opaque type representing a particular router instance.
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*
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* MaxScale itself does not do anything with it, except for receiving it
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* from the @c createInstance function of a router module and subsequently
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* passing it back to the API functions of the router.
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*/
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typedef struct mxs_router
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{
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} MXS_ROUTER;
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/**
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* MXS_ROUTER_SESSION is an opaque type representing the session related
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* data of a particular router instance.
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*
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* MaxScale itself does not do anything with it, except for receiving it
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* from the @c newSession function of a router module and subsequently
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* passing it back to the API functions of the router.
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*/
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typedef struct mxs_router_session
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{
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} MXS_ROUTER_SESSION;
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typedef enum error_action
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{
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ERRACT_NEW_CONNECTION = 0x001,
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ERRACT_REPLY_CLIENT = 0x002
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} mxs_error_action_t;
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/**
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* @verbatim
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* The "module object" structure for a query router module. All entry points
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* marked with `(optional)` are optional entry points which can be set to NULL
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* if no implementation is required.
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*
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* The entry points are:
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* createInstance Called by the service to create a new instance of the query router
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* newSession Called to create a new user session within the query router
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* closeSession Called when a session is closed
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* freeSession Called when a session is freed
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* routeQuery Called on each query that requires routing
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* diagnostics Called to force the router to print diagnostic output
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* clientReply Called to reply to client the data from one or all backends (optional)
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* handleError Called to reply to client errors with optional closeSession
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* or make a request for a new backend connection
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* getCapabilities Called to obtain the capabilities of the router (optional)
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* destroyInstance Called for destroying a router instance (optional)
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*
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* @endverbatim
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*
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* @see load_module
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*/
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typedef struct mxs_router_object
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{
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/**
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* @brief Create a new instance of the router
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*
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* This function is called when a new router instance is created. The return
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* value of this function will be passed as the first parameter to the
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* other API functions.
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*
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* @param service The service where the instance is created
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* @param params Parameters for the router
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*
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* @return New router instance on NULL on error
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*/
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MXS_ROUTER*(*createInstance)(SERVICE * service, MXS_CONFIG_PARAMETER* params);
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/**
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* Called to create a new user session within the router
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*
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* This function is called when a new router session is created for a client.
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* The return value of this function will be passed as the second parameter
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* to the @c routeQuery, @c clientReply, @c closeSession, @c freeSession,
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* and @c handleError functions.
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*
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* @param instance Router instance
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* @param session Client MXS_SESSION object
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*
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* @return New router session or NULL on error
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*/
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MXS_ROUTER_SESSION*(*newSession)(MXS_ROUTER * instance, MXS_SESSION* session);
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/**
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* @brief Called when a session is closed
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*
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* The router should close all objects (including backend DCBs) but not free any memory.
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*
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* @param instance Router instance
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* @param router_session Router session
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*/
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void (* closeSession)(MXS_ROUTER* instance, MXS_ROUTER_SESSION* router_session);
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/**
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* @brief Called when a session is freed
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*
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* The session should free all allocated memory in this function.
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*
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* @param instance Router instance
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* @param router_session Router session
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*/
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void (* freeSession)(MXS_ROUTER* instance, MXS_ROUTER_SESSION* router_session);
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/**
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* @brief Called on each query that requires routing
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*
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* TODO: Document how routeQuery should be used
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*
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* @param instance Router instance
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* @param router_session Router session
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* @param queue Request from the client
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*
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* @return If successful, the function returns 1. If an error occurs
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* and the session should be closed, the function returns 0.
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*/
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int32_t (* routeQuery)(MXS_ROUTER* instance, MXS_ROUTER_SESSION* router_session, GWBUF* queue);
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/**
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* @brief Called for diagnostic output
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*
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* @param instance Router instance
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* @param dcb DCB where the diagnostic information should be written
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*/
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void (* diagnostics)(MXS_ROUTER* instance, DCB* dcb);
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/**
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* @brief Called for diagnostic output
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*
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* @param instance Router instance
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*
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* @return Diagnostic information in JSON format
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*
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* @see jansson.h
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*/
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json_t* (*diagnostics_json)(const MXS_ROUTER * instance);
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/**
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* @brief Called for each reply packet
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*
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* TODO: Document how clientReply should be used
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*
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* @param instance Router instance
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* @param router_session Router session
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* @param queue Response from the server
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* @param backend_dcb The backend DCB which responded to the query
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*/
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void (* clientReply)(MXS_ROUTER* instance,
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MXS_ROUTER_SESSION* router_session,
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GWBUF* queue,
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DCB* backend_dcb);
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/**
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* @brief Called when a backend DCB has failed
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*
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* @param instance Router instance
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* @param router_session Router session
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* @param errmsgbuf Error message buffer
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* @param backend_dcb The backend DCB that has failed
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* @param action The type of the action (TODO: Remove this parameter)
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*
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* @param succp Pointer to a `bool` which should be set to true for success or false for error
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*/
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void (* handleError)(MXS_ROUTER* instance,
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MXS_ROUTER_SESSION* router_session,
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GWBUF* errmsgbuf,
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DCB* backend_dcb,
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mxs_error_action_t action,
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bool* succp);
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/**
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* @brief Called to obtain the capabilities of the router
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*
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* @return Zero or more bitwise-or'd values from the mxs_routing_capability_t enum
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*
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* @see routing.h
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*/
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uint64_t (* getCapabilities)(MXS_ROUTER* instance);
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/**
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* @brief Called for destroying a router instance
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*
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* @param instance Router instance
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*/
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void (* destroyInstance)(MXS_ROUTER* instance);
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/**
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* @brief Configure router instance at runtime
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*
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* This function is guaranteed to be called by only one thread at a time.
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* The router must declare the RCAP_TYPE_RUNTIME_CONFIG in its capabilities
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* in order for this function to be called.
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*
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* Modifications to the router should be made in an atomic manner so that
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* existing sessions do not read a partial configuration. One way to do this
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* is to use shared pointers for storing configurations.
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*
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* @param instance Router instance
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* @param params Updated parameters for the service. The parameters are
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* validated before this function is called.
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*
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* @return True if reconfiguration was successful, false if reconfiguration
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* failed. If reconfiguration failed, the state of the router
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* instance should not be modified.
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*/
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bool (* configureInstance)(MXS_ROUTER* instance, MXS_CONFIG_PARAMETER* params);
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} MXS_ROUTER_OBJECT;
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/**
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* The router module API version. Any change that changes the router API
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* must update these versions numbers in accordance with the rules in
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* modinfo.h.
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*/
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#define MXS_ROUTER_VERSION {4, 0, 0}
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/**
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* Specifies capabilities specific for routers. Common capabilities
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* are defined by @c routing_capability_t.
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*
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* @see enum routing_capability
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*
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* @note The values of the capabilities here *must* be between 0x00010000
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* and 0x00800000, that is, bits 16 to 23.
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*/
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typedef enum router_capability
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{
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RCAP_TYPE_NO_RSESSION = 0x00010000, /**< Router does not use router sessions */
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RCAP_TYPE_NO_USERS_INIT = 0x00020000, /**< Prevent the loading of authenticator
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* users when the service is started */
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RCAP_TYPE_NO_AUTH = 0x00040000, /**< No `user` or `password` parameter required */
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RCAP_TYPE_RUNTIME_CONFIG = 0x00080000, /**< Router supports runtime cofiguration */
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} mxs_router_capability_t;
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typedef enum
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{
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TYPE_UNDEFINED = 0,
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TYPE_MASTER,
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TYPE_ALL
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} mxs_target_t;
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/**
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* @brief Convert mxs_target_t to a string
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*
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* @param target Target to convert
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*
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* @return Target type as string
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*/
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static inline const char* mxs_target_to_str(mxs_target_t target)
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{
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switch (target)
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{
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case TYPE_MASTER:
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return "master";
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case TYPE_ALL:
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return "all";
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default:
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return "UNDEFINED";
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}
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}
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MXS_END_DECLS
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