coord_pair.c

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/*
 *   This program 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: 9ac95b4853edf81826658f951fa8760d03ca8e53 $
 *
 * @brief Sending pair lists to and from coordination threads
 * @file io/coord_pair.c
 *
 * @copyright 2026 Network RADIUS SAS (legal@networkradius.com)
 */
RCSID("$Id: 9ac95b4853edf81826658f951fa8760d03ca8e53 $")
 
#include <freeradius-devel/internal/internal.h>
#include <freeradius-devel/io/listen.h>
#include <freeradius-devel/io/coord_pair.h>
#include <freeradius-devel/io/coord_priv.h>
#include <freeradius-devel/server/main_config.h>
#include <freeradius-devel/unlang/base.h>
 
static _Atomic(uint64_t) request_number = 0;
 
FR_SLAB_TYPES(request, request_t)
FR_SLAB_FUNCS(request, request_t)
 
static fr_dlist_head_t  *coord_pair_regs = NULL;
static module_list_t    *coord_pair_modules;
static fr_dict_attr_t const     *attr_worker_id = NULL;
 
/** Registration of pair list callbacks
 *
 */
struct fr_coord_pair_reg_s {
        char const                      *name;                  //!< Name for log / request name.
        fr_dlist_t                      entry;                  //!< Entry in list of pair list registrations
        fr_dict_attr_t const            *attr_packet_type;      //!< Attribute containing packet type
        fr_dict_attr_t const            *root;                  //!< Pair list decoding root attribute
        fr_coord_worker_pair_cb_reg_t   **callbacks;            //!< Array of pointers to callbacks
        uint32_t                        max_packet_type;        //!< Largest valid value for packet type
        uint32_t                        cb_id;                  //!< The coordinator callback ID used for pair list handling
        fr_time_delta_t                 max_request_time;       //!< Maximum time for coordinator request processing.
        fr_slab_config_t                reuse;                  //!< Request slab allocation config.
        virtual_server_t const          *vs;                    //!< Virtual server containing coordinator process sections.
};
 
struct fr_coord_pair_s {
        fr_coord_t                      *coord;                 //!< Coordinator which this coord pair is attached to.
        fr_coord_pair_reg_t             *coord_pair_reg;        //!< Registration details for this coord pair
        fr_event_list_t                 *el;                    //!< Event list for interpreter.
        unlang_interpret_t              *intp;                  //!< Interpreter for running requests.
        fr_heap_t                       *runnable;              //!< Current runnable requests.
 
        fr_timer_list_t                 *timeout;               //!< Track when requests timeout using a dlist.
        fr_time_delta_t                 predicted;              //!< How long we predict a request will take to execute.
        fr_time_tracking_t              tracking;               //!< How much time the coordinator has spent doing things.
        uint64_t                        num_active;             //!< Number of active requests.
        request_slab_list_t             *slab;                  //!< slab allocator for request_t
};
 
/** Packet context used when coordinator messages are processed through an interpreter
 *
 * Allows access to the coordinator structure and arbitrary data
 * throughout the state machine.
 */
typedef struct {
        fr_coord_pair_t                 *coord_pair;            //!< Coordinator pair this packet is for.
        void                            *uctx;                  //!< Source specific ctx.
} fr_coord_packet_ctx_t;
 
/** Conf parser to read slab settings from module config
 */
static const conf_parser_t request_reuse_config[] = {
        FR_SLAB_CONFIG_CONF_PARSER
        CONF_PARSER_TERMINATOR
};
 
/** Remove a coord pair registration from the list when it is freed
 */
static int _coord_pair_reg_free(fr_coord_pair_reg_t *to_free)
{
        fr_assert(coord_pair_regs);
 
        fr_dlist_remove(coord_pair_regs, to_free);
 
        /* If all the registrations are gone, free the list */
        if (fr_dlist_num_elements(coord_pair_regs) == 0) {
                TALLOC_FREE(coord_pair_regs);
                TALLOC_FREE(coord_pair_modules);
        }
        return 0;
}
 
/** Register a set of callbacks for pair list based coordinator messages
 *
 * Returns a structure to pass as uctx to fr_coord_cb_t using the
 * macro FR_COORD_PAIR_CB_CTX_SET.
 *
 * @param reg_ctx       Callback details to register.
 */
fr_coord_pair_reg_t *fr_coord_pair_register(fr_coord_pair_reg_ctx_t *reg_ctx)
{
        fr_coord_pair_reg_t             *coord_pair_reg;
        fr_coord_worker_pair_cb_reg_t   *cb_reg = reg_ctx->worker_cb;
        CONF_SECTION                    *cs;
        CONF_PAIR                       *cp;
 
        fr_assert(reg_ctx->root);
 
        /* Resolve the Worker-Id attribute if not already done */
        if (!attr_worker_id) {
                attr_worker_id = fr_dict_attr_by_name(NULL, fr_dict_root(fr_dict_internal()), "Worker-Id");
                if (!attr_worker_id) {
                        ERROR("Failed to resolve Worker-Id attribute");
                        return NULL;
                }
        }
 
        if (!coord_pair_regs) {
                MEM(coord_pair_regs = talloc_zero(NULL, fr_dlist_head_t));
                fr_dlist_init(coord_pair_regs, fr_coord_pair_reg_t, entry);
                MEM(coord_pair_modules = module_list_alloc(NULL, &module_list_type_global, "coord", true));
        }
 
        MEM(coord_pair_reg = talloc(coord_pair_regs, fr_coord_pair_reg_t));
        *coord_pair_reg = (fr_coord_pair_reg_t) {
                .name = reg_ctx->name,
                .root = reg_ctx->root,
                .cb_id = reg_ctx->cb_id,
                .max_request_time = fr_time_delta_eq(reg_ctx->max_request_time, fr_time_delta_from_msec(0)) ?
                        main_config->worker.max_request_time : reg_ctx->max_request_time,
        };
 
        while (cb_reg->callback) {
                if (cb_reg->packet_type > coord_pair_reg->max_packet_type) {
                        coord_pair_reg->max_packet_type = cb_reg->packet_type;
                }
                cb_reg++;
        }
 
        /*
         *      A sane limit on packet type values to avoid a huge array.
         *      If larger values are needed in the future we can use a folded array.
         */
        fr_assert(coord_pair_reg->max_packet_type <= 256);
 
        MEM(coord_pair_reg->callbacks = talloc_zero_array(coord_pair_reg, fr_coord_worker_pair_cb_reg_t *,
                                                          coord_pair_reg->max_packet_type + 1));
 
        cb_reg = reg_ctx->worker_cb;
        while (cb_reg->callback) {
                coord_pair_reg->callbacks[cb_reg->packet_type] = cb_reg;
                cb_reg++;
        }
 
        cs = cf_section_find(reg_ctx->cs, "reuse", NULL);
 
        /*
         *      Create an empty "reuse" section if one is not found, so defaults are applied
         */
        if (!cs) {
                cs = cf_section_alloc(reg_ctx->cs, reg_ctx->cs, "reuse", NULL);
        }
 
        if (cf_section_rules_push(cs, request_reuse_config) < 0) {
        fail:
                talloc_free(coord_pair_reg);
                return NULL;
        }
        if (cf_section_parse(coord_pair_reg, &coord_pair_reg->reuse, cs) < 0) goto fail;
 
        /*
         *      Set defaults for request slab allocation, if not set by conf parsing
         */
        if (!coord_pair_reg->reuse.child_pool_size) coord_pair_reg->reuse.child_pool_size = REQUEST_POOL_SIZE;
        if (!coord_pair_reg->reuse.num_children) coord_pair_reg->reuse.num_children = REQUEST_POOL_NUM_OBJECTS;
 
        cp = cf_pair_find(reg_ctx->cs, "virtual_server");
        if (!cp) {
                cf_log_err(reg_ctx->cs, "Missing virtual_server option");
                goto fail;
        }
 
        coord_pair_reg->vs = virtual_server_find(cf_pair_value(cp));
        if (!coord_pair_reg->vs) {
                cf_log_err(cp, "Virtual server not found");
                goto fail;
        }
 
        /*
         *      Validate that the virtual server uses the correct namespace.
         */
        if (reg_ctx->root->dict != virtual_server_dict_by_cs(virtual_server_cs(coord_pair_reg->vs))) {
                cf_log_err(cp, "Virtual server has namespace %s, should be %s",
                           fr_dict_root(virtual_server_dict_by_cs(virtual_server_cs(coord_pair_reg->vs)))->name,
                           fr_dict_root(coord_pair_reg->root->dict)->name);
                goto fail;
        }
        coord_pair_reg->attr_packet_type = virtual_server_packet_type_by_cs(virtual_server_cs(coord_pair_reg->vs));
 
        fr_dlist_insert_tail(coord_pair_regs, coord_pair_reg);
        talloc_set_destructor(coord_pair_reg, _coord_pair_reg_free);
 
        return coord_pair_reg;
}
 
/** Return the coordinator callback ID associated with a coord_pair_reg_t
 */
uint32_t fr_coord_pair_reg_cb_id(fr_coord_pair_reg_t *coord_pair_reg)
{
        fr_assert(coord_pair_reg);
        return coord_pair_reg->cb_id;
}
 
/*
 *      The following set of callbacks for request handling are mirrors of
 *      their equivalent in worker.c
 */
 
/** Signal the unlang interpreter that it needs to stop running the request
 *
 * @param[in] request   request to cancel.  The request may still run to completion.
 */
static void coord_pair_stop_request(request_t *request)
{
        unlang_interpret_signal(request, FR_SIGNAL_CANCEL);
}
 
/** Enforce max_request_time
 *
 * @param[in] tl        the coordinators's timer list.
 * @param[in] when      the current time
 * @param[in] uctx      the request_t timing out.
 */
static void _coord_pair_request_timeout(UNUSED fr_timer_list_t *tl, UNUSED fr_time_t when, void *uctx)
{
        request_t       *request = talloc_get_type_abort(uctx, request_t);
 
        REDEBUG("Request has reached max_request_time - signalling it to stop");
        coord_pair_stop_request(request);
 
        request->rcode = RLM_MODULE_TIMEOUT;
}
 
/** Set, or re-set the request timer
 *
 * @param[in] coord_pair        the coord_pair_t containing the timeout lists.
 * @param[in] request           that we're timing out.
 * @param[in] timeout           the timeout to set.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
static int fr_coord_pair_request_timeout_set(fr_coord_pair_t *coord_pair, request_t *request, fr_time_delta_t timeout)
{
        if (unlikely(fr_timer_in(request, coord_pair->timeout, &request->timeout, timeout,
                                 true, _coord_pair_request_timeout, request) < 0)) {
                RERROR("Failed to create request timeout timer");
                return -1;
        }
 
        return 0;
}
 
/** Start time tracking for a request, and mark it as runnable.
 */
static int coord_pair_request_time_tracking_start(fr_coord_pair_t *coord_pair, request_t *request, fr_time_t now)
{
        fr_assert(!fr_timer_armed(request->timeout));
 
        if (unlikely(fr_coord_pair_request_timeout_set(coord_pair, request,
                                                       coord_pair->coord_pair_reg->max_request_time) < 0)) {
                RERROR("Failed to set request timeout");
                return -1;
        }
 
        RDEBUG3("Time tracking started in yielded state");
        fr_time_tracking_start(&coord_pair->tracking, &request->async->tracking, now);
        fr_time_tracking_yield(&request->async->tracking, now);
        coord_pair->num_active++;
 
        fr_assert(!fr_heap_entry_inserted(request->runnable));
        (void) fr_heap_insert(&coord_pair->runnable, request);
 
        return 0;
}
 
/** End time tracking for a request
 */
static void coord_pair_request_time_tracking_end(fr_coord_pair_t *coord_pair, request_t *request, fr_time_t now)
{
        RDEBUG3("Time tracking ended");
        fr_time_tracking_end(&coord_pair->predicted, &request->async->tracking, now);
        fr_assert(coord_pair->num_active > 0);
        coord_pair->num_active--;
 
        TALLOC_FREE(request->timeout);  /* Disarm the request timer */
}
 
 
static inline CC_HINT(always_inline)
void coord_pair_request_init(fr_event_list_t *el, request_t *request, fr_time_t now, void *packet_ctx)
{
        if (!request->packet) MEM(request->packet = fr_packet_alloc(request, false));
        if (!request->reply) MEM(request->reply = fr_packet_alloc(request, false));
 
        request->packet->timestamp = now;
        request->async = talloc_zero(request, fr_async_t);
        request->async->recv_time = now;
        request->async->el = el;
        request->async->packet_ctx = packet_ctx;
        fr_dlist_entry_init(&request->async->entry);
}
 
static inline CC_HINT(always_inline)
void coord_pair_request_name_number(request_t *request, char const *name)
{
        request->number = atomic_fetch_add_explicit(&request_number, 1, memory_order_seq_cst);
        if (request->name) talloc_const_free(request->name);
        request->name = talloc_asprintf(request, "Coord-%s-%"PRIu64, name, request->number);
}
 
static int _coord_pair_request_deinit( request_t *request, UNUSED void *uctx)
{
        return request_slab_deinit(request);
}
 
static request_t *coord_pair_request_bootstrap(fr_coord_pair_t *coord_pair, fr_time_t now, void *uctx)
{
        request_t               *request;
        fr_coord_packet_ctx_t   *packet_ctx;
 
        request = request_slab_reserve(coord_pair->slab);
        if (!request) {
                ERROR("Coordinator failed allocating new request");
                return NULL;
        }
 
        request_slab_element_set_destructor(request, _coord_pair_request_deinit, coord_pair);
 
        if (request_init(request, REQUEST_TYPE_INTERNAL,
                         (&(request_init_args_t){
                                .namespace = virtual_server_dict_by_cs(virtual_server_cs(coord_pair->coord_pair_reg->vs))
                         }))) {
                ERROR("Coordinator failed initializing new request");
                request_slab_release(request);
                return NULL;
        }
 
        MEM(packet_ctx = talloc(request, fr_coord_packet_ctx_t));
        *packet_ctx = (fr_coord_packet_ctx_t) {
                .coord_pair = coord_pair,
                .uctx = uctx
        };
        coord_pair_request_init(coord_pair->el, request, now, packet_ctx);
        coord_pair_request_name_number(request, coord_pair->coord_pair_reg->name);
 
        unlang_interpret_set(request, coord_pair->intp);
 
        return request;
}
 
static void coord_pair_request_start(fr_coord_pair_t *coord_pair, request_t *request, fr_time_t now)
{
        fr_pair_t       *vp;
 
        vp = fr_pair_find_by_da(&request->request_pairs, NULL, coord_pair->coord_pair_reg->attr_packet_type);
        if (!vp) {
                RERROR("Missing %s attribute", coord_pair->coord_pair_reg->attr_packet_type->name);
        error:
                request_slab_release(request);
                return;
        }
 
        request->packet->code = vp->vp_uint32;
 
        if (virtual_server_push(NULL, request, coord_pair->coord_pair_reg->vs, UNLANG_TOP_FRAME) < 0) {
                RERROR("Protocol failed to set 'process' function");
                goto error;
        }
 
        coord_pair_request_time_tracking_start(coord_pair, request, now);
}
 
static void _coord_pair_request_internal_init(request_t *request, void *uctx)
{
        fr_coord_pair_t *coord_pair = talloc_get_type_abort(uctx, fr_coord_pair_t);
        fr_time_t       now = fr_time();
 
        fr_assert(request->packet);
        fr_assert(request->reply);
 
        request->packet->timestamp = now;
        request->async = talloc_zero(request, fr_async_t);
        request->async->recv_time = now;
        request->async->el = coord_pair->el;
        fr_dlist_entry_init(&request->async->entry);
 
        /*
         *      Requests generated by the interpreter
         *      are always marked up as internal.
         */
        fr_assert(request_is_internal(request));
        coord_pair_request_time_tracking_start(coord_pair, request, now);
}
 
/** External request is now complete - will never happen with coordinators
 *
 */
static void _coord_pair_request_done_external(UNUSED request_t *request, UNUSED rlm_rcode_t rcode, UNUSED void *uctx)
{
        fr_assert(0);
}
 
/** Internal request (i.e. one generated by the interpreter) is now complete
 *
 * Whatever generated the request is now responsible for freeing it.
 */
static void _coord_pair_request_done_internal(request_t *request, UNUSED rlm_rcode_t rcode, void *uctx)
{
        fr_coord_pair_t *coord_pair = talloc_get_type_abort(uctx, fr_coord_pair_t);
 
        coord_pair_request_time_tracking_end(coord_pair, request, fr_time());
 
        fr_assert(!fr_heap_entry_inserted(request->runnable));
        fr_assert(!fr_timer_armed(request->timeout));
        fr_assert(!fr_dlist_entry_in_list(&request->async->entry));
}
 
/** Detached request (i.e. one generated by the interpreter with no parent) is now complete
 *
 * As the request has no parent, then there's nothing to free it
 * so we have to.
 */
static void _coord_pair_request_done_detached(request_t *request, UNUSED rlm_rcode_t rcode, UNUSED void *uctx)
{
        fr_assert(!fr_heap_entry_inserted(request->runnable));
 
        TALLOC_FREE(request->timeout);
 
        fr_assert(!fr_dlist_entry_in_list(&request->async->entry));
 
        talloc_free(request);
}
 
/** Make us responsible for running the request
 *
 */
static void _coord_pair_request_detach(request_t *request, void *uctx)
{
        fr_coord_pair_t *coord_pair = talloc_get_type_abort(uctx, fr_coord_pair_t);
 
        RDEBUG4("%s - Request detaching", __FUNCTION__);
 
        if (request_is_detachable(request)) {
                /*
                *       End the time tracking...  We don't track detached requests,
                *       because they don't contribute for the time consumed by an
                *       external request.
                */
                if (request->async->tracking.state == FR_TIME_TRACKING_YIELDED) {
                        RDEBUG3("Forcing time tracking to running state, from yielded, for request detach");
                        fr_time_tracking_resume(&request->async->tracking, fr_time());
                }
                coord_pair_request_time_tracking_end(coord_pair, request, fr_time());
 
                if (request_detach(request) < 0) RPEDEBUG("Failed detaching request");
 
                RDEBUG3("Request is detached");
        } else {
                fr_assert_msg(0, "Request is not detachable");
        }
}
 
/** Request is now runnable
 *
 */
static void _coord_pair_request_runnable(request_t *request, void *uctx)
{
        fr_coord_pair_t *coord_pair = uctx;
 
        RDEBUG4("%s - Request marked as runnable", __FUNCTION__);
        fr_heap_insert(&coord_pair->runnable, request);
}
 
/** Interpreter yielded request
 *
 */
static void _coord_pair_request_yield(request_t *request, UNUSED void *uctx)
{
        RDEBUG4("%s - Request yielded", __FUNCTION__);
        if (likely(!request_is_detached(request))) fr_time_tracking_yield(&request->async->tracking, fr_time());
}
 
/** Interpreter is starting to work on request again
 *
 */
static void _coord_pair_request_resume(request_t *request, UNUSED void *uctx)
{
        RDEBUG4("%s - Request resuming", __FUNCTION__);
        if (likely(!request_is_detached(request))) fr_time_tracking_resume(&request->async->tracking, fr_time());
}
 
/** Check if a request is scheduled
 *
 */
static bool _coord_pair_request_scheduled(request_t const *request, UNUSED void *uctx)
{
        return fr_heap_entry_inserted(request->runnable);
}
 
/** Update a request's priority
 *
 */
static void _coord_pair_request_prioritise(request_t *request, void *uctx)
{
        fr_coord_pair_t *coord_pair = talloc_get_type_abort(uctx, fr_coord_pair_t);
 
        RDEBUG4("%s - Request priority changed", __FUNCTION__);
 
        /* Extract the request from the runnable queue _if_ it's in the runnable queue */
        if (fr_heap_extract(&coord_pair->runnable, request) < 0) return;
 
        /* Reinsert it to re-evaluate its new priority */
        fr_heap_insert(&coord_pair->runnable, request);
}
 
/** Compare two requests by priority and sequence
 */
static int8_t coord_pair_runnable_cmp(void const *one, void const *two)
{
        request_t const *a = one, *b = two;
        int ret;
 
        ret = CMP(b->priority, a->priority);
        if (ret != 0) return ret;
 
        return CMP(a->sequence, b->sequence);
}
 
void fr_coord_pair_inst_destroy(UNUSED fr_coord_t *coord, fr_coord_cb_inst_t *inst, bool single_thread, UNUSED void *uctx) {
        fr_coord_pair_t *coord_pair = talloc_get_type_abort(inst->inst_data, fr_coord_pair_t);
        int             ret, count = 0;
 
        if (!single_thread) unlang_interpret_set_thread_default(NULL);
 
        ret = fr_timer_list_force_run(coord_pair->timeout);
        if (unlikely(ret < 0)) {
                fr_assert_msg(0, "Failed to force run the timeout list");
        } else {
                count += ret;
        }
 
        DEBUG("Coordinator is exiting - stopped %u requests", count);
}
 
/** Create the coord_pair coord instance data
 */
static fr_coord_pair_t *fr_coord_pair_create(TALLOC_CTX *ctx, fr_coord_t *coord, fr_event_list_t *el,
                                             bool single_thread, void *uctx)
{
        fr_coord_pair_t         *coord_pair;
        fr_coord_pair_reg_t     *coord_pair_reg = talloc_get_type_abort(uctx, fr_coord_pair_reg_t);
 
        MEM(coord_pair = talloc(ctx, fr_coord_pair_t));
        *coord_pair = (fr_coord_pair_t) {
                .coord = coord,
                .coord_pair_reg = coord_pair_reg,
                .el = el
        };
 
        coord_pair->runnable = fr_heap_talloc_alloc(coord_pair, coord_pair_runnable_cmp, request_t, runnable, 0);
        if (!coord_pair->runnable) {
                fr_strerror_const("Failed creating runnable heap");
        fail:
                talloc_free(coord_pair);
                return NULL;
        }
 
        coord_pair->timeout = fr_timer_list_ordered_alloc(coord_pair, el->tl);
        if (!coord_pair->timeout) {
                fr_strerror_const("Failed creating timeouts list");
                goto fail;
        }
 
        coord_pair->intp = unlang_interpret_init(coord_pair, el,
                                        &(unlang_request_func_t){
                                                .init_internal = _coord_pair_request_internal_init,
 
                                                .done_external = _coord_pair_request_done_external,
                                                .done_internal = _coord_pair_request_done_internal,
                                                .done_detached = _coord_pair_request_done_detached,
 
                                                .detach = _coord_pair_request_detach,
                                                .yield = _coord_pair_request_yield,
                                                .resume = _coord_pair_request_resume,
                                                .mark_runnable = _coord_pair_request_runnable,
 
                                                .scheduled = _coord_pair_request_scheduled,
                                                .prioritise = _coord_pair_request_prioritise
                                        }, coord_pair);
 
        if (!coord_pair->intp) goto fail;
 
        if (!(coord_pair->slab = request_slab_list_alloc(coord_pair, el, &coord_pair_reg->reuse, NULL, NULL,
                                                         coord_pair, true, false))) {
                goto fail;
        }
 
        if (!single_thread) unlang_interpret_set_thread_default(coord_pair->intp);
 
        return coord_pair;
}
 
static inline CC_HINT(always_inline) void coord_run_request(fr_coord_pair_t *coord_pair, fr_time_t start)
{
        request_t       *request;
        fr_time_t       now;
 
        now = start;
 
        while (fr_time_delta_lt(fr_time_sub(now, start), fr_time_delta_from_msec(1)) &&
        ((request = fr_heap_pop(&coord_pair->runnable)) != NULL)) {
                REQUEST_VERIFY(request);
                fr_assert(!fr_heap_entry_inserted(request->runnable));
 
                (void)unlang_interpret(request, UNLANG_REQUEST_RESUME);
 
                now = fr_time();
        }
}
 
/*
 *      Pre and post events used in single threaded mode
 */
 
static int fr_coord_pair_pre_event(UNUSED fr_time_t now, UNUSED fr_time_delta_t wake, void *uctx)
{
        fr_coord_pair_t *coord_pair = talloc_get_type_abort(uctx, fr_coord_pair_t);
        request_t *request;
 
        request = fr_heap_peek(coord_pair->runnable);
        return request ? 1 : 0;
}
 
static void fr_coord_pair_post_event(UNUSED fr_event_list_t *el, UNUSED fr_time_t now, void *uctx)
{
        fr_coord_pair_t *coord_pair = talloc_get_type_abort(uctx, fr_coord_pair_t);
 
        coord_run_request(coord_pair, fr_time());
}
 
/** Event callback in multi threaded mode
 */
static void fr_coord_pair_event(UNUSED fr_event_list_t *el, void *uctx)
{
        fr_coord_pair_t *coord_pair = talloc_get_type_abort(uctx, fr_coord_pair_t);
 
        coord_run_request(coord_pair, fr_time());
}
 
/** Callback run when a coordinator receives pair list data
 *
 * Converts the data into a request.
 */
void fr_coord_pair_data_recv(UNUSED fr_coord_t *coord, uint32_t worker_id, fr_dbuff_t *dbuff, fr_time_t now, void *inst, void *uctx)
{
        fr_coord_pair_reg_t     *coord_pair_reg = talloc_get_type_abort(uctx, fr_coord_pair_reg_t);
        fr_coord_pair_t         *coord_pair = talloc_get_type_abort(inst, fr_coord_pair_t);
        request_t               *request;
        fr_pair_t               *vp;
 
        request = coord_pair_request_bootstrap(coord_pair, now, coord_pair_reg);
        if (!request) return;
 
        if (fr_pair_append_by_da(request->request_ctx, &vp, &request->request_pairs, attr_worker_id) < 0) {
        error:
                request_slab_release(request);
                return;
        };
        vp->vp_int32 = worker_id;
 
        if (fr_internal_decode_list_dbuff(request->pair_list.request, &request->request_pairs,
                                          fr_dict_root(request->proto_dict), dbuff, NULL) < 0) {
                RERROR("Failed decoding packet");
                goto error;
        }
 
        coord_pair_request_start(coord_pair, request, now);
}
 
/** Callback run when a worker receives pair list data
 *
 * Finds the packet type attribute in the data and calls the callback
 * registered against the value of that attribute.
 *
 * @param cw    Worker which received the message.
 * @param dbuff Data received.
 * @param now   Time the data is received.
 * @param uctx  The coord_pair registration.
 */
void fr_coord_worker_pair_data_recv(fr_coord_worker_t *cw, fr_dbuff_t *dbuff, fr_time_t now, module_ctx_t *mctx, void *uctx)
{
        fr_coord_pair_reg_t             *coord_pair_reg = talloc_get_type_abort(uctx, fr_coord_pair_reg_t);
        fr_pair_list_t                  list;
        fr_pair_t                       *vp;
 
        fr_pair_list_init(&list);
        if (fr_internal_decode_list_dbuff(NULL, &list, coord_pair_reg->root, dbuff, NULL) < 0) {
                PERROR("Failed to decode data as pair list");
                goto free;
        }
 
        vp = fr_pair_find_by_da_nested(&list, NULL, coord_pair_reg->attr_packet_type);
 
        if (!vp) {
                ERROR("Message received without %s", coord_pair_reg->attr_packet_type->name);
                goto free;
        }
 
        if (vp->vp_uint32 > coord_pair_reg->max_packet_type || !coord_pair_reg->callbacks[vp->vp_uint32]) {
                ERROR("Message received with invalid value %pP", vp);
                goto free;
        }
 
        coord_pair_reg->callbacks[vp->vp_uint32]->callback(cw, coord_pair_reg, &list, now, mctx,
                                                           coord_pair_reg->callbacks[vp->vp_uint32]->uctx);
 
free:
        fr_pair_list_free(&list);
}
 
/** Send a reply list from a coordinator to a worker
 *
 * @param request       containing the reply to send.
 * @param worker_id     to send the reply to.
 * @return
 *      - 0 on success
 *      - -1 on failure
 */
int fr_coord_to_worker_reply_send(request_t *request, uint32_t worker_id)
{
        fr_dbuff_t              dbuff;
        fr_dbuff_uctx_talloc_t  tctx;
        fr_coord_packet_ctx_t   *packet_ctx = talloc_get_type_abort(request->async->packet_ctx, fr_coord_packet_ctx_t);
        fr_coord_pair_reg_t     *coord_pair_reg = talloc_get_type_abort(packet_ctx->uctx, fr_coord_pair_reg_t);
        int                     ret;
 
        if (fr_dbuff_init_talloc(NULL, &dbuff, &tctx, 1024, SIZE_MAX) == NULL) return -1;
        if (fr_internal_encode_list(&dbuff, &request->reply_pairs, NULL) < 0) {
                fr_dbuff_free_talloc(&dbuff);
                return -1;
        }
 
        ret = fr_coord_to_worker_send(packet_ctx->coord_pair->coord, worker_id, coord_pair_reg->cb_id, &dbuff);
 
        fr_dbuff_free_talloc(&dbuff);
 
        return ret;
}
 
/** Send a reply list from a coordinator to all workers
 *
 * @param request       containing the reply to send.
 * @return
 *      - 0 on success
 *      - < 0 on failure
 */
int fr_coord_to_worker_reply_broadcast(request_t *request)
{
        fr_dbuff_t              dbuff;
        fr_dbuff_uctx_talloc_t  tctx;
        fr_coord_packet_ctx_t   *packet_ctx = talloc_get_type_abort(request->async->packet_ctx, fr_coord_packet_ctx_t);
        fr_coord_pair_reg_t     *coord_pair_reg = talloc_get_type_abort(packet_ctx->uctx, fr_coord_pair_reg_t);
        int                     ret;
 
        if (fr_dbuff_init_talloc(NULL, &dbuff, &tctx, 1024, SIZE_MAX) == NULL) return -1;
        if (fr_internal_encode_list(&dbuff, &request->reply_pairs, NULL) < 0) {
                fr_dbuff_free_talloc(&dbuff);
                return -1;
        }
 
        ret = fr_coord_to_worker_broadcast(packet_ctx->coord_pair->coord, coord_pair_reg->cb_id, &dbuff);
 
        fr_dbuff_free_talloc(&dbuff);
 
        return ret;
}
 
/** Send a pair list from a worker to a coordinator
 *
 * The pair list must include an attribute indicating the packet type
 *
 * @param cw    The coord worker sending the data.
 * @param list  of pairs to send.
 * @return
 *      - 0 on success
 *      - -1 on failure
 */
int fr_worker_to_coord_pair_send(fr_coord_worker_t *cw, fr_coord_pair_reg_t *coord_pair_reg, fr_pair_list_t *list)
{
        fr_dbuff_t              dbuff;
        fr_dbuff_uctx_talloc_t  tctx;
        int                     ret;
 
        if (fr_dbuff_init_talloc(NULL, &dbuff, &tctx, 1024, SIZE_MAX) == NULL) return -1;
        if (fr_internal_encode_list(&dbuff, list, NULL) < 0) {
                fr_dbuff_free_talloc(&dbuff);
                return -1;
        }
 
        ret = fr_worker_to_coord_send(cw, coord_pair_reg->cb_id, &dbuff);
 
        fr_dbuff_free_talloc(&dbuff);
        return ret;
}
 
/** Instance creation called during coordinator creation.
 *
 * @param ctx           to allocate the instance in.
 * @param el            Event list for instance to use.
 * @param single_thread is the server in single thread mode.
 * @param uctx          configured for the callback this instance relates to.
 * @return
 *      - fr_coord_cb_inst_t on success
 *      - NULL on failure
 */
fr_coord_cb_inst_t *fr_coord_pair_inst_create(TALLOC_CTX *ctx, fr_coord_t *coord, fr_event_list_t *el,
                                               bool single_thread, void *uctx)
{
        fr_coord_cb_inst_t      *cb_inst;
        fr_coord_pair_t         *coord_pair;
 
        MEM(cb_inst = talloc(ctx, fr_coord_cb_inst_t));
 
        *cb_inst = (fr_coord_cb_inst_t) {
                .event_pre_cb = fr_coord_pair_pre_event,
                .event_post_cb = fr_coord_pair_post_event,
                .event_cb = fr_coord_pair_event
        };
 
        coord_pair = fr_coord_pair_create(ctx, coord, el, single_thread, uctx);
        if (!coord_pair) {
                talloc_free(cb_inst);
                return NULL;
        }
 
        cb_inst->inst_data = coord_pair;
 
        return cb_inst;
}
 
/** Return the coord_pair associated with a coord_pair internal request
 *
 * @param request       to fetch associated coordinator for.
 * @return fr_coord_t
 */
fr_coord_pair_t *fr_coord_pair_request_coord_pair(request_t *request)
{
        fr_coord_packet_ctx_t   *packet_ctx = talloc_get_type_abort(request->async->packet_ctx, fr_coord_packet_ctx_t);
        return packet_ctx->coord_pair;
}
 
/** Start a coordinator request to run through a coord_pair process module
 *
 * @param coord_pair    with the process module to run the request.
 * @param list          Pairs to populate the request.
 * @param now           Request time.
 * @return
 *      0 on success
 *      -1 on failure
 */
int fr_coord_pair_coord_request_start(fr_coord_pair_t *coord_pair, fr_pair_list_t *list, fr_time_t now)
{
        request_t       *request;
 
        request = coord_pair_request_bootstrap(coord_pair, now, coord_pair->coord_pair_reg);
        if (!request) return -1;
 
        fr_pair_list_steal(request->request_ctx, list);
        fr_pair_list_append(&request->request_pairs, list);
 
        coord_pair_request_start(coord_pair, request, now);
        return 0;
}