io.h

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#pragma once
 
/*
 *   This program is 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; either version 2 of the License, or (at
 *   your option) any later version.
 *
 *   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 St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: 4ca4698a31886d7684a78504386801f903c58098 $
 * @file lib/redis/io.h
 * @brief Redis asynchronous I/O connection allocation
 *
 * @copyright 2019 The FreeRADIUS server project
 * @copyright 2019 Network RADIUS SAS (legal@networkradius.com)
 *
 * @author Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
RCSIDH(redis_io_h, "$Id: 4ca4698a31886d7684a78504386801f903c58098 $")
 
#include <freeradius-devel/redis/base.h>
#include <freeradius-devel/util/event.h>
#include <freeradius-devel/server/connection.h>
 
#include <hiredis/async.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
typedef struct {
        char                    *hostname;
        uint16_t                port;
        uint32_t                database;       //!< number on Redis server.
 
        char const              *password;      //!< to authenticate to Redis.
        fr_time_delta_t         connection_timeout;
        fr_time_delta_t         reconnection_delay;
        char const              *log_prefix;
} fr_redis_io_conf_t;
 
typedef uint64_t fr_redis_sqn_t;
 
typedef struct {
        fr_dlist_t      entry;
        fr_redis_sqn_t  sqn;
} fr_redis_sqn_ignore_t;
 
/** Store I/O state
 *
 * There are three layers of wrapping structures
 *
 * fr_connection_t -> fr_redis_handle_t -> redisAsyncContext
 *
 */
typedef struct {
        bool                    read_set;               //!< We're listening for reads.
        bool                    write_set;              //!< We're listening for writes.
        bool                    ignore_disconnect_cb;   //!< Ensure that redisAsyncFree doesn't cause
                                                        ///< a callback loop.
        fr_event_timer_t const  *timer;                 //!< Connection timer.
 
 
        redisAsyncContext       *ac;                    //!< Async handle for hiredis.
 
        fr_dlist_head_t         ignore;                 //!< Contains SQNs for responses that should be ignored.
 
        fr_redis_sqn_t          req_sqn;                //!< Current redis request number.
                                                        ///< Note: It would take 5.8 million years running
                                                        ///< at 100,000 requests/s to overflow, but my OCD
                                                        ///< requires that the max uses for trunk connections
                                                        ///< is set to UINT64_MAX if not specified by
                                                        ///< the user. It's one branch, and it makes me
                                                        ///< happy, deal with it.
        fr_redis_sqn_t          rsp_sqn;                //!< Current redis response number.
} fr_redis_handle_t;
 
/** Tell the handle we sent a command, and get the SQN that command was assigned
 *
 * *MUST* be called for every command sent using the handle. Relies on the fact
 * that responses from REDIS are FIFO with requests.
 *
 * @param[in] h the request was sent on.
 * @return the handle specific SQN.
 */
static inline fr_redis_sqn_t fr_redis_connection_sent_request(fr_redis_handle_t *h)
{
        return h->req_sqn++;
}
 
/** Ignore a response with a specific sequence number
 *
 * @param[in] h         to ignore the response on.
 * @param[in] sqn       the command to ignore.
 */
static inline void fr_redis_connection_ignore_response(fr_redis_handle_t *h, fr_redis_sqn_t sqn)
{
        fr_redis_sqn_ignore_t *ignore;
 
        fr_assert(sqn <= h->rsp_sqn);
 
        MEM(ignore = talloc_zero(h, fr_redis_sqn_ignore_t));
        ignore->sqn = sqn;
        fr_dlist_insert_tail(&h->ignore, ignore);
}
 
/** Update the response sequence number and check if we should ignore the response
 *
 * *MUST* be called for every reply received using the handle. Relies on the fact
 * that responses from REDIS are FIFO with requests.
 *
 * @param[in] h         to check for ignored responses.
 */
static inline bool fr_redis_connection_process_response(fr_redis_handle_t *h)
{
        fr_redis_sqn_t          check = h->rsp_sqn++;
        fr_redis_sqn_ignore_t   *head;
 
        fr_assert(h->rsp_sqn <= h->req_sqn);            /* Can't have more responses than requests */
 
        head = fr_dlist_head(&h->ignore);
        if (!head || (head->sqn > check)) return true;  /* First response to ignore is some time after this one */
        fr_assert(head->sqn == check);
 
        fr_dlist_remove(&h->ignore, head);
        talloc_free(head);
 
        return false;
}
 
fr_connection_t         *fr_redis_connection_alloc(TALLOC_CTX *ctx, fr_event_list_t *el,
                                                   fr_connection_conf_t const *conn_conf,
                                                   fr_redis_io_conf_t const *io_conf,
                                                   char const *log_prefix);
 
redisAsyncContext       *fr_redis_connection_get_async_ctx(fr_connection_t *conn);
 
#ifdef __cplusplus
}
#endif