coord.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: 836b13654accd2a0cfb926e1e81523b26bed6b75 $
 *
 * @brief Coordination thread management
 * @file io/coord.c
 *
 * @copyright 2026 Network RADIUS SAS (legal@networkradius.com)
 */
RCSID("$Id: 836b13654accd2a0cfb926e1e81523b26bed6b75 $")
 
#include <freeradius-devel/io/listen.h>
#include <freeradius-devel/io/schedule.h>
#include <freeradius-devel/io/thread.h>
#include <freeradius-devel/io/coord_priv.h>
#include <freeradius-devel/unlang/base.h>
#include <freeradius-devel/util/syserror.h>
 
#include <stdalign.h>
 
#define FR_CONTROL_ID_COORD_WORKER_ATTACH       (1)     //!< Message sent from worker to attach to a coordinator
#define FR_CONTROL_ID_COORD_WORKER_DETACH       (2)     //!< Message sent from worker to detach from a coordinator
#define FR_CONTROL_ID_COORD_WORKER_ACK          (3)     //!< Message sent to worker to acknowledge attach / detach
#define FR_CONTROL_ID_COORD_DATA                (4)     //!< Worker <-> coordinator message to pass data to a callback
 
#define MIN_WORKER_ID -1        //!< The minimum value we expect as worker id.  -1 is the main thread.
 
static fr_dlist_head_t  *coord_regs = NULL;
static fr_dlist_head_t  *coord_threads = NULL;
static fr_rb_tree_t     coords = (fr_rb_tree_t){ .num_elements = 0 };
 
/** A coordinator which receives messages from workers
 */
struct fr_coord_s {
        fr_coord_reg_t                  *coord_reg;     //!< Coordinator registration details.
        fr_event_list_t                 *el;            //!< Coordinator event list.
        fr_rb_node_t                    node;           //!< Entry in the tree of coordinators.
        fr_coord_cb_reg_t               *callbacks;     //!< Array of callbacks for worker -> coordinator messages.
        uint32_t                        num_callbacks;  //!< Number of callbacks defined.
        fr_coord_cb_inst_t              **cb_inst;      //!< Array of callback instance specific data.
 
        uint32_t                        max_workers;    //!< Maximum number of workers we expect.
        uint32_t                        num_workers;    //!< How many workers are attached.
 
        fr_control_t                    *coord_recv_control;    //!< Control plane for worker -> coordinator messages.
        fr_atomic_queue_t               *coord_recv_aq;         //!< Atomic queue for worker -> coordinator
        fr_ring_buffer_t                **coord_send_rb;        //!< Ring buffers for coordinator -> worker control messages.
        fr_control_t                    **coord_send_control;   //!< Control planes for coordinator -> worker messages.
        fr_message_set_t                **coord_send_ms;        //!< Message sets for coordinator -> worker data.
        fr_atomic_queue_t               **coord_send_aq;        //!< Atomic queues for coordinator -> worker data.
 
        bool                            exiting;        //!< Is this coordinator shutting down.
        bool                            single_thread;  //!< Are we in single thread mode.
};
 
/** The worker end of worker <-> coordinator communication.
 */
struct fr_coord_worker_s {
        fr_coord_t                      *coord;                 //!< Coordinator this worker is related to
        fr_ring_buffer_t                *worker_send_rb;        //!< Ring buffer for worker -> coordinator control plane
        fr_message_set_t                *worker_send_ms;        //!< Message set for worker -> coordinator messages
        fr_control_t                    *worker_recv_control;   //!< Coordinator -> worker control plane
        fr_atomic_queue_t               *worker_recv_aq;        //!< Atomic queue for coordinator -> worker messages
        fr_coord_worker_cb_reg_t        *callbacks;             //!< Callbacks for coordinator -> worker messages
        uint32_t                        num_callbacks;          //!< Number of callbacks registered.
};
 
/** A coordinator registration
 */
struct fr_coord_reg_s {
        char const                      *name;                  //!< Name for debugging.
        fr_dlist_t                      entry;                  //!< Entry in list of registrations.
        fr_coord_cb_reg_t               *coord_cb;              //!< Callbacks for worker -> coordinator messages.
        fr_coord_worker_cb_reg_t        *worker_cb;             //!< Callbacks for coordinator -> worker messages.
        size_t                          worker_send_size;       //!< Initial size for worker -> coordinator ring buffer.
        size_t                          coord_send_size;        //!< Initial size for coordinator -> worker ring buffer.
        module_instance_t const         *mi;                    //!< Module instance which registered this coordinator.
};
 
/** Scheduler specific information for coordinator threads
 */
typedef struct {
        fr_thread_t                     thread;                 //!< common thread information - must be first!
 
        uint32_t                        max_workers;            //!< Maximum number of workers which will connect to this coordinator.
        fr_coord_reg_t                  *coord_reg;             //!< Coordinator registration details.
        fr_coord_t                      *coord;                 //!< The coordinator data structure.
        fr_sem_t                        *sem;                   //!< For inter-thread signaling.
} fr_schedule_coord_t;
 
/** Control plane message used for workers attaching / detaching to coordinators
 */
typedef struct {
        int32_t                         worker;                 //!< Worker ID
        fr_control_t                    *worker_recv_control;   //!< Control plane to send messages to this worker
        fr_atomic_queue_t               *worker_recv_aq;        //!< Atomic queue to send data to this worker
} fr_coord_worker_attach_msg_t;
 
typedef struct {
        int32_t                         worker;                 //!< Worker ID
        bool                            exiting;                //!< Is the server exiting
} fr_coord_worker_detach_msg_t;
 
/** Compare coordinators by registration
 */
static fr_cmp_ret_t coord_cmp(void const *one, void const *two)
{
        fr_coord_t const *a = one, *b = two;
 
        return CMP(a->coord_reg, b->coord_reg);
}
 
/** Register a coordinator
 *
 * To be called from mod_instantiate of a module which uses a coordinator
 *
 * @param reg_ctx       Registration data
 * @return
 *      - coordination registration on success
 *      - NULL on failure
 */
fr_coord_reg_t *fr_coord_register(fr_coord_reg_ctx_t *reg_ctx)
{
        fr_coord_reg_t          *coord_reg;
 
        fr_assert(reg_ctx->coord_cb);
        fr_assert(reg_ctx->worker_cb);
        fr_assert(reg_ctx->mi);
 
        /* Allocate the list of registered coordinators if not already done */
        if (!coord_regs) {
                MEM(coord_regs = talloc_zero(NULL, fr_dlist_head_t));
                fr_dlist_talloc_init(coord_regs, fr_coord_reg_t, entry);
        }
 
        MEM(coord_reg = talloc(coord_regs, fr_coord_reg_t));
        *coord_reg = (fr_coord_reg_t) {
                .name = reg_ctx->name,
                .coord_cb = reg_ctx->coord_cb,
                .worker_cb = reg_ctx->worker_cb,
                .worker_send_size = reg_ctx->worker_send_size ? reg_ctx->worker_send_size : 4096,
                .coord_send_size = reg_ctx->coord_send_size ? reg_ctx->coord_send_size : 4096,
                .mi = reg_ctx->mi,
        };
 
        fr_dlist_insert_tail(coord_regs, coord_reg);
 
        return coord_reg;
}
 
/** De-register a coordinator
 *
 * To be called from mod_detach of a module which uses a coordinator
 *
 * @param coord_reg     to de-register
 */
void fr_coord_deregister(fr_coord_reg_t *coord_reg)
{
        fr_dlist_remove(coord_regs, coord_reg);
 
        talloc_free(coord_reg);
 
        if (fr_dlist_num_elements(coord_regs) == 0) TALLOC_FREE(coord_regs);
}
 
/** Wait for all the coordinator threads to exit
 *
 * To be called during the scheduler shutdown in multi-threaded mode.
 */
void fr_coord_thread_join(void)
{
        int     ret;
 
        if (!coord_threads) return;
 
        fr_dlist_foreach(coord_threads, fr_schedule_coord_t, sc) {
                if ((ret = pthread_join(sc->thread.pthread_id, NULL)) != 0) {
                        ERROR("Failed joining coordinator %s: %s", sc->coord_reg->name, fr_syserror(ret));
                } else {
                        DEBUG2("Coordinator %s joined (cleaned up)", sc->coord_reg->name);
                }
 
                fr_dlist_remove(coord_threads, sc);
                talloc_free(sc);
        }
}
 
/** Callback for a coordinator receiving data from a worker
 */
static void coord_data_recv(void const *data, size_t data_size, fr_time_t now, void *uctx)
{
        fr_coord_t              *coord = talloc_get_type_abort(uctx, fr_coord_t);
        fr_coord_msg_t          cm;
        fr_coord_data_t         *cd;
        fr_dbuff_t              dbuff;
 
        fr_assert(data_size == sizeof(cm));
        memcpy(&cm, data, data_size);
        fr_assert((cm.worker >= MIN_WORKER_ID) && (cm.worker < (int32_t)coord->max_workers));
 
        if (unlikely(!fr_atomic_queue_pop(coord->coord_recv_aq, (void **)&cd))) return;
 
        DEBUG3("Coordinator %s got data from worker %d for callback %d",
               coord->coord_reg->name, cm.worker, cd->coord_cb_id);
 
        if (cd->coord_cb_id >= coord->num_callbacks) {
                ERROR("Received data for callback %d which is not defined", cd->coord_cb_id);
                fr_message_done(&cd->m);
                return;
        }
 
        fr_dbuff_init(&dbuff, (uint8_t const *)cd->m.data, cd->m.data_size);
        coord->callbacks[cd->coord_cb_id].callback(coord, cm.worker, &dbuff, now,
                                                   MODULE_CTX(coord->coord_reg->mi,
                                                              module_thread(coord->coord_reg->mi)->data, NULL, NULL),
                                                   coord->cb_inst[cd->coord_cb_id] ?
                                                   coord->cb_inst[cd->coord_cb_id]->inst_data : NULL,
                                                   coord->callbacks[cd->coord_cb_id].uctx);
        fr_message_done(&cd->m);
}
 
/** Callback for a worker receiving data from a coordinator
 */
static void coord_worker_data_recv(void const *data, size_t data_size, fr_time_t now, void *uctx)
{
        fr_coord_worker_t       *cw = talloc_get_type_abort(uctx, fr_coord_worker_t);
        fr_coord_msg_t          cm;
        fr_coord_data_t         *cd;
        fr_dbuff_t              dbuff;
 
        fr_assert(data_size == sizeof(cm));
        memcpy(&cm, data, data_size);
 
        if (unlikely(!fr_atomic_queue_pop(cw->worker_recv_aq, (void **)&cd))) return;
 
        DEBUG3("Coordinator %s sent message for callback %d", cw->coord->coord_reg->name, cd->coord_cb_id);
 
        if (cd->coord_cb_id >= cw->num_callbacks) {
                ERROR("Received message for callback %d which is not defined", cd->coord_cb_id);
                fr_message_done(&cd->m);
                return;
        }
 
        fr_dbuff_init(&dbuff, (uint8_t const *)cd->m.data, cd->m.data_size);
        cw->callbacks[cd->coord_cb_id].callback(cw, &dbuff, now,
                                                MODULE_CTX(cw->coord->coord_reg->mi,
                                                           module_thread(cw->coord->coord_reg->mi)->data, NULL, NULL),
                                                cw->callbacks[cd->coord_cb_id].uctx);
        fr_message_done(&cd->m);
}
 
/** Callback run by a coordinator when a worker attaches
 */
static void coord_worker_attach(void const *data, NDEBUG_UNUSED size_t data_size, UNUSED fr_time_t now, void *uctx)
{
        fr_coord_t                              *coord = talloc_get_type_abort(uctx, fr_coord_t);
        fr_coord_worker_attach_msg_t const      *msg = data;
        fr_coord_msg_t                          ack;
        uint32_t                                thread_id;
 
        fr_assert(data_size == sizeof(fr_coord_worker_attach_msg_t));
        fr_assert((msg->worker >= MIN_WORKER_ID) && (msg->worker < (int32_t)coord->max_workers));
 
        DEBUG2("Worker %d attached to %s", msg->worker, coord->coord_reg->name);
        coord->num_workers++;
        thread_id = msg->worker - MIN_WORKER_ID;
        coord->coord_send_control[thread_id] = msg->worker_recv_control;
        coord->coord_send_aq[thread_id] = msg->worker_recv_aq;
 
        ack.worker = msg->worker;
        fr_control_message_send(coord->coord_send_control[thread_id], coord->coord_send_rb[thread_id],
                                FR_CONTROL_ID_COORD_WORKER_ACK, &ack, sizeof(ack));
}
 
/** Callback run by a coordinator when a worker detaches
 */
static void coord_worker_detach(void const *data, NDEBUG_UNUSED size_t data_size, UNUSED fr_time_t now, void *uctx)
{
        fr_coord_t                              *coord = talloc_get_type_abort(uctx, fr_coord_t);
        fr_coord_worker_detach_msg_t const      *msg = data;
        fr_coord_msg_t                          ack;
        uint32_t                                thread_id, i;
 
        fr_assert(data_size == sizeof(fr_coord_worker_detach_msg_t));
        fr_assert((msg->worker >= MIN_WORKER_ID) && (msg->worker < (int32_t)coord->max_workers));
        thread_id = msg->worker - MIN_WORKER_ID;
 
        DEBUG2("Worker %d detached from %s", msg->worker, coord->coord_reg->name);
        coord->num_workers--;
        if (msg->exiting) coord->exiting = true;
 
        /*
         *      If all workers have detached, and we're exiting, run any exit callbacks.
         */
        if (coord->exiting && (coord->num_workers == 0)) {
                fr_coord_cb_inst_t *cb_inst;
                for (i = 0; i < coord->num_callbacks; i++) {
                        cb_inst = coord->cb_inst[i];
                        if (!cb_inst || !cb_inst->exit_cb) continue;
                        cb_inst->exit_cb(coord, coord->el, cb_inst->inst_data);
                }
        }
 
        ack.worker = msg->worker;
        fr_control_message_send(coord->coord_send_control[thread_id], coord->coord_send_rb[thread_id],
                                FR_CONTROL_ID_COORD_WORKER_ACK, &ack, sizeof(fr_coord_msg_t));
 
        coord->coord_send_control[thread_id] = NULL;
        coord->coord_send_aq[thread_id] = NULL;
}
 
/** Create a coordinator from its registration
 *
 * @param ctx           to allocate the coordinator in
 * @param el            Event list to run this coordinator
 * @param coord_reg     Registration to configure this coordinator
 * @param single_thread Is the server in single thread mode
 * @param max_workers   The maximum number of workers which will attach
 * @return
 *      - the coordinator on success
 *      - NULL on failure
 */
static fr_coord_t *fr_coord_create(TALLOC_CTX *ctx, fr_event_list_t *el, fr_coord_reg_t *coord_reg,
                                   bool single_thread, uint32_t max_workers)
{
        fr_coord_t              *coord;
        uint32_t                i, num_threads = max_workers - MIN_WORKER_ID;
        fr_coord_cb_reg_t       *cb = coord_reg->coord_cb;
        fr_atomic_queue_t       *aq;
 
        MEM(coord = talloc(ctx, fr_coord_t));
        *coord = (fr_coord_t) {
                .el = el,
                .coord_reg = coord_reg,
                .single_thread = single_thread,
                .max_workers = max_workers
        };
 
        /* Allocate atomic queue / control for receiving messages from workers */
        aq = fr_atomic_queue_talloc(coord, FR_CONTROL_MAX_MESSAGES);
        if (!aq) {
                fr_strerror_const("Failed creating worker -> coordinator atomic queue");
        fail:
                talloc_free(coord);
                return NULL;
        }
        coord->coord_recv_control = fr_control_create(coord, el, aq, 5);
        if (!coord->coord_recv_control) {
                fr_strerror_const("Failed creating worker -> coordinator control plane");
                goto fail;
        }
 
        /* Allocate atomic queue for workers sending data to coordinators */
        coord->coord_recv_aq = fr_atomic_queue_talloc(coord, FR_CONTROL_MAX_MESSAGES);
        if (!coord->coord_recv_aq) {
                fr_strerror_const("Failed creating worker -> coordinator data atomic queue");
                goto fail;
        }
 
        if (fr_control_callback_add(&coord->coord_recv_control, FR_CONTROL_ID_COORD_WORKER_ATTACH,
                                    coord_worker_attach, coord) < 0) goto fail;
        if (fr_control_callback_add(&coord->coord_recv_control, FR_CONTROL_ID_COORD_WORKER_DETACH,
                                    coord_worker_detach, coord) < 0) goto fail;
        if (fr_control_callback_add(&coord->coord_recv_control, FR_CONTROL_ID_COORD_DATA,
                                    coord_data_recv, coord) < 0) goto fail;
 
        /* Count the number of callbacks defined, for sanity checking messages */
        while (cb->callback) {
                coord->num_callbacks++;
                cb++;
        }
        coord->callbacks = coord_reg->coord_cb;
 
        if (fr_control_open(coord->coord_recv_control) < 0) {
                fr_strerror_const("Failed opening control plane");
                goto fail;
        }
 
        /*
         *      Coordinator side arrays for holding pointers to worker
         *      specific communication structures.  The array sizes are the
         *      number of threads expected to attach which is the number of
         *      workers plus any additional threads, currently just the main
         *      thread (worker id -1)
         */
        MEM(coord->coord_send_rb = talloc_array(coord, fr_ring_buffer_t *, num_threads));
        MEM(coord->coord_send_ms = talloc_array(coord, fr_message_set_t *, num_threads));
        for (i = 0; i < num_threads; i++) {
                coord->coord_send_rb[i] = fr_ring_buffer_create(coord, FR_CONTROL_MAX_MESSAGES * FR_CONTROL_MAX_SIZE);
                if (!coord->coord_send_rb[i]) goto fail;
 
                coord->coord_send_ms[i] = fr_message_set_create(coord, FR_CONTROL_MAX_MESSAGES, sizeof(fr_coord_data_t),
                                                                coord_reg->coord_send_size, true);
                if (!coord->coord_send_ms[i]) goto fail;
        }
        MEM(coord->coord_send_control = talloc_zero_array(coord, fr_control_t *, num_threads));
        MEM(coord->coord_send_aq = talloc_zero_array(coord, fr_atomic_queue_t *, num_threads));
 
        MEM(coord->cb_inst = talloc_zero_array(coord, fr_coord_cb_inst_t *, coord->num_callbacks));
 
        for (i = 0; i < coord->num_callbacks; i++) {
                if (!coord->callbacks[i].inst_create) continue;
                coord->cb_inst[i] = coord->callbacks[i].inst_create(coord, coord, coord->el, coord->single_thread,
                                                                    coord->callbacks[i].uctx);
                if (!coord->cb_inst[i]) goto fail;
        }
 
        return coord;
}
 
static void fr_coord_destroy(fr_coord_t *coord){
        uint32_t i;
 
        for (i = 0; i < coord->num_callbacks; i++) {
                if (!coord->callbacks[i].inst_destroy) continue;
                coord->callbacks[i].inst_destroy(coord, coord->cb_inst[i], coord->single_thread,
                                                 coord->callbacks[i].uctx);
        }
}
 
/** Run the event loop for a coordinator thread when in multi-threaded mode
 */
static void fr_coordinate(fr_coord_t *coord)
{
        uint32_t                i;
        fr_coord_cb_inst_t      *cb_inst;
 
        /*
         *      Run until we're told to exit AND the number of
         *      workers has dropped to zero.
         *
         *      Whenever a worker detaches, coord->num_workers
         *      is decremented, so when coord->num_workers == 0,
         *      all workers have detached and are no longer using
         *      the channel.
         */
        while (true) {
                bool wait_for_events = true;
                int num_events;
                fr_time_t now = fr_time();
 
                /*
                 *      Check if any coordinator instances report that they have
                 *      events to process.
                 */
                for (i = 0; i < coord->num_callbacks; i++) {
                        cb_inst = coord->cb_inst[i];
                        if (!cb_inst || !cb_inst->event_pre_cb) continue;
                        wait_for_events = (cb_inst->event_pre_cb(now, fr_time_delta_wrap(0), cb_inst->inst_data) == 0);
                        if (!wait_for_events) break;
                }
 
                if (wait_for_events) {
                        if (unlikely(coord->exiting) && (coord->num_workers == 0)) break;
                }
 
                /*
                 *      Check the event list.  If there's an error
                 *      (e.g. exit), we stop looping and clean up.
                 */
                DEBUG4("Gathering events");
                num_events = fr_event_corral(coord->el, fr_time(), true);
                DEBUG4("%u event(s) pending%s",
                       num_events == -1 ? 0 : num_events, num_events == -1 ? " - event loop exiting" : "");
                if (num_events < 0) break;
 
                /*
                 *      Service outstanding events.
                 */
                if (num_events > 0) {
                        DEBUG4("Servicing event(s)");
                        fr_event_service(coord->el);
                }
 
                /*
                 *      Run any registered instance specific event callbacks
                 */
                for (i = 0; i < coord->num_callbacks; i++) {
                        cb_inst = coord->cb_inst[i];
                        if (cb_inst && cb_inst->event_post_cb) cb_inst->event_post_cb(coord->el, now, cb_inst->inst_data);
                }
        }
 
        fr_coord_destroy(coord);
 
        return;
}
 
/** Entry point for a coordinator thread
 */
static void *fr_coordinate_thread(void *arg)
{
        fr_schedule_coord_t     *sc = talloc_get_type_abort(arg, fr_schedule_coord_t);
        fr_coord_reg_t          *coord_reg = sc->coord_reg;
        fr_thread_status_t      status = FR_THREAD_FAIL;
        char                    coordinate_name[64];
 
        snprintf(coordinate_name, sizeof(coordinate_name), "Coordinate %s", coord_reg->name);
 
        if (fr_thread_setup(&sc->thread, coordinate_name) < 0) goto fail;
 
        sc->coord = fr_coord_create(sc->thread.ctx, sc->thread.el, coord_reg, false, sc->max_workers);
        if (!sc->coord) {
                PERROR("%s - Failed creating coordinator thread", coordinate_name);
                goto fail;
        }
 
        /*
         *      Create all the thread specific data for the coordinator thread
         */
        if (fr_thread_instantiate(sc->thread.ctx, sc->thread.el) < 0) goto fail;
 
        /*
         *      Tell the originator that the thread has started.
         */
        fr_thread_start(&sc->thread, sc->sem);
 
        fr_coordinate(sc->coord);
 
        status = FR_THREAD_EXITED;
 
fail:
        fr_thread_detach();
 
        fr_thread_exit(&sc->thread, status, sc->sem);
 
        return NULL;
}
 
/** Start all registered coordinator threads in multi-threaded mode
 *
 * @param num_workers   The number of workers which will be attaching
 * @param sem           Semaphore to use signalling the threads are ready
 * @return
 *      - 0 on success
 *      - -1 on failure
 */
int fr_coord_start(uint32_t num_workers, fr_sem_t *sem)
{
        int num = 0;
 
        if (!coord_regs) return 0;
 
        MEM(coord_threads = talloc(NULL, fr_dlist_head_t));
        fr_dlist_init(coord_threads, fr_schedule_coord_t, thread.entry);
        fr_rb_inline_talloc_init(&coords, fr_coord_t, node, coord_cmp, NULL);
 
        fr_dlist_foreach(coord_regs, fr_coord_reg_t, coord_reg) {
                fr_schedule_coord_t *sc;
 
                MEM(sc = talloc_zero(coord_threads, fr_schedule_coord_t));
 
                sc->thread.id = num++;
                sc->coord_reg = coord_reg;
                sc->max_workers = num_workers;
                sc->sem = sem;
 
                if (fr_thread_create(&sc->thread.pthread_id, fr_coordinate_thread, sc) < 0) {
                        talloc_free(sc);
                        PERROR("Failed creating coordinator %s", coord_reg->name);
                        return -1;
                };
 
                fr_dlist_insert_tail(coord_threads, sc);
        }
 
        /*
         *      Wait for all the coordinators to start.
         */
        if (fr_thread_wait_list(sem, coord_threads) < 0) {
                ERROR("Failed creating coordinator threads");
                return -1;
        }
 
        /*
         *      Insert the coordinators in the tree
         */
        fr_dlist_foreach(coord_threads, fr_schedule_coord_t, sc) {
                fr_assert(sc->coord);
                fr_rb_insert(&coords, sc->coord);
        }
 
        return 0;
}
 
/** Clean up coordinators in single threaded mode
 */
void fr_coords_destroy(void)
{
        fr_coord_t              *coord;
        fr_rb_iter_inorder_t    iter;
 
        if (fr_rb_num_elements(&coords) == 0) return;
 
        for (coord = fr_rb_iter_init_inorder(&coords, &iter);
             coord;
             coord = fr_rb_iter_next_inorder(&coords, &iter)) {
                fr_rb_iter_delete_inorder(&coords, &iter);
                fr_coord_destroy(coord);
                talloc_free(coord);
        }
}
 
/** Start coordinators in single threaded mode
 */
int fr_coords_create(TALLOC_CTX *ctx, fr_event_list_t *el)
{
        if (!coord_regs) return 0;
 
        fr_rb_inline_talloc_init(&coords, fr_coord_t, node, coord_cmp, NULL);
 
        fr_dlist_foreach(coord_regs, fr_coord_reg_t, coord_reg) {
                char            coordinate_name[64];
                fr_coord_t      *coord;
 
                snprintf(coordinate_name, sizeof(coordinate_name), "Coordinator %s", coord_reg->name);
 
                INFO("%s - Starting", coordinate_name);
 
                coord = fr_coord_create(ctx, el, coord_reg, true, 1);
                if (!coord) {
                        PERROR("%s - Failed creating coordinator thread", coordinate_name);
                        return -1;
                }
 
                fr_rb_insert(&coords, coord);
        }
 
        return 0;
}
 
/** Signal a coordinator that a worker wants to detach
 *
 * @param cw            Worker which is detaching.
 * @param exiting       Is the server exiting.
 */
int fr_coord_detach(fr_coord_worker_t *cw, bool exiting)
{
        fr_coord_worker_detach_msg_t    *msg;
 
        msg = talloc(cw, fr_coord_worker_detach_msg_t);
        msg->worker = fr_schedule_worker_id();
        msg->exiting = exiting;
 
        if (fr_control_message_send(cw->coord->coord_recv_control, cw->worker_send_rb,
                                    FR_CONTROL_ID_COORD_WORKER_DETACH,
                                    msg, sizeof(fr_coord_worker_detach_msg_t)) < 0) return -1;
 
        if (!cw->coord->single_thread) fr_control_wait(cw->worker_recv_control);
 
        return 0;
}
 
/** A worker got an ack from a coordinator in response to attach / detach
 */
static void coordinate_worker_ack(NDEBUG_UNUSED void const *data, NDEBUG_UNUSED size_t data_size,
                                  UNUSED fr_time_t now, UNUSED void *uctx)
{
#ifndef NDEBUG
        fr_coord_msg_t const            *cm = data;
 
        fr_assert(data_size == sizeof(fr_coord_msg_t));
        fr_assert(cm->worker == fr_schedule_worker_id());
#endif
}
 
/** Attach a worker to a coordinator
 *
 * @param ctx           To allocate worker structure in
 * @param el            Event list for control messages
 * @param coord_reg     Coordinator registration to attach to.
 * @return
 *      - Worker structure for coordinator use on success
 *      - NULL on failure
 */
fr_coord_worker_t *fr_coord_attach(TALLOC_CTX *ctx, fr_event_list_t *el, fr_coord_reg_t *coord_reg)
{
        fr_coord_worker_t               *cw;
        fr_coord_worker_cb_reg_t        *cb_reg = coord_reg->worker_cb;
        fr_coord_worker_attach_msg_t    msg;
        fr_coord_t                      find;
        fr_atomic_queue_t               *aq;
 
        cw = talloc_zero(ctx, fr_coord_worker_t);
 
        find = (fr_coord_t) {
                .coord_reg = coord_reg
        };
        fr_rb_find((void **)&cw->coord, &coords, &find);
        if (!cw->coord) {
        fail:
                talloc_free(cw);
                return NULL;
        }
 
        aq = fr_atomic_queue_talloc(cw, 1024);
        cw->worker_recv_aq = fr_atomic_queue_talloc(cw, FR_CONTROL_MAX_MESSAGES);
        cw->worker_recv_control = fr_control_create(cw, el, aq, 0);
        cw->worker_send_rb = fr_ring_buffer_create(cw, FR_CONTROL_MAX_MESSAGES * FR_CONTROL_MAX_SIZE);
        cw->worker_send_ms = fr_message_set_create(cw, FR_CONTROL_MAX_MESSAGES, sizeof(fr_coord_data_t),
                                                   coord_reg->worker_send_size, true);
 
        while (cb_reg->callback) {
                cw->num_callbacks++;
                cb_reg++;
        }
        cw->callbacks = coord_reg->worker_cb;
 
        if (fr_control_callback_add(&cw->worker_recv_control, FR_CONTROL_ID_COORD_WORKER_ACK,
                                    coordinate_worker_ack, cw) < 0) goto fail;
        if (fr_control_callback_add(&cw->worker_recv_control, FR_CONTROL_ID_COORD_DATA,
                                    coord_worker_data_recv, cw) < 0) goto fail;
 
        if (fr_control_open(cw->worker_recv_control) < 0) goto fail;
 
        msg.worker_recv_control = cw->worker_recv_control;
        msg.worker_recv_aq = cw->worker_recv_aq;
        msg.worker = fr_schedule_worker_id();
 
        if (fr_control_message_send(cw->coord->coord_recv_control, cw->worker_send_rb,
                                    FR_CONTROL_ID_COORD_WORKER_ATTACH,
                                    &msg, sizeof(fr_coord_worker_attach_msg_t)) < 0) goto fail;
 
        if (!cw->coord->single_thread) fr_control_wait(cw->worker_recv_control);
 
        return cw;
}
 
/** Send generic data from a coordinator to a worker
 *
 * @param coord         Coordinator which is sending the data.
 * @param worker_id     Worker to send data to.
 * @param cb_id         Callback ID for the worker to run.
 * @param dbuff         Buffer containing data to send.
 * @return
 *      - 0 on success
 *      - <0 on failure
 */
int fr_coord_to_worker_send(fr_coord_t *coord, int32_t worker_id, uint32_t cb_id, fr_dbuff_t *dbuff)
{
        fr_coord_msg_t          cm;
        fr_coord_data_t         *cd = NULL;
        uint32_t                thread_id = worker_id - MIN_WORKER_ID;
 
        fr_assert((worker_id >= MIN_WORKER_ID) && (worker_id < (int32_t)coord->max_workers));
 
        cm = (fr_coord_msg_t) {
                .worker = worker_id
        };
 
        cd = (fr_coord_data_t *)fr_message_and_data_alloc(coord->coord_send_ms[thread_id], fr_dbuff_used(dbuff));
        if (!cd) return -1;
 
        memcpy(cd->m.data, fr_dbuff_buff(dbuff), fr_dbuff_used(dbuff));
        cd->coord_cb_id = cb_id;
        if (!fr_atomic_queue_push(coord->coord_send_aq[thread_id], cd)) {
                fr_message_done((fr_message_t *)cd);
                return -1;
        }
        return fr_control_message_send(coord->coord_send_control[thread_id], coord->coord_send_rb[thread_id],
                                       FR_CONTROL_ID_COORD_DATA,
                                       &cm, sizeof(fr_coord_msg_t));
}
 
/** Broadcast data from a coordinator to all workers
 *
 * @param coord         Coordinator which is sending the data.
 * @param cb_id         Callback ID for the workers to run.
 * @param dbuff         Buffer containing data to send.
 * @return
 *      - 0 on success
 *      - <0 on failure - indicating the number of sends which failed.
 */
int fr_coord_to_worker_broadcast(fr_coord_t *coord, uint32_t cb_id, fr_dbuff_t *dbuff)
{
        int32_t         i;
        int             failed = 0;
 
        for (i = 0; i < (int32_t)coord->max_workers; i++) {
                if (!coord->coord_send_control[i - MIN_WORKER_ID]) continue;
                if (fr_coord_to_worker_send(coord, i, cb_id, dbuff) < 0) failed++;
        }
 
        return 0 - failed;
}
 
/** Send data from a worker to a coordinator
 *
 * @param cw            Worker side of coordinator sending the data.
 * @param cb_id         Callback ID for the coordinator to run.
 * @param dbuff         Buffer containing data to send.
 * @return
 *      - 0 on success
 *      - < 0 on failure
 */
int fr_worker_to_coord_send(fr_coord_worker_t *cw, uint32_t cb_id, fr_dbuff_t *dbuff)
{
        fr_coord_msg_t          cm;
        fr_coord_data_t         *cd = NULL;
 
        cm = (fr_coord_msg_t) {
                .worker = fr_schedule_worker_id()
        };
 
        cd = (fr_coord_data_t *) fr_message_and_data_commit(cw->worker_send_ms, (fr_message_t *)cd, fr_dbuff_used(dbuff));
        if (!cd) return -1;
 
        memcpy(cd->m.data, fr_dbuff_buff(dbuff), fr_dbuff_used(dbuff));
        cd->coord_cb_id = cb_id;
        if (!fr_atomic_queue_push(cw->coord->coord_recv_aq, cd)) {
                fr_message_done((fr_message_t *)cd);
                return -1;
        }
 
        return fr_control_message_send(cw->coord->coord_recv_control, cw->worker_send_rb,
                                       FR_CONTROL_ID_COORD_DATA, &cm, sizeof(fr_coord_msg_t));
}
 
/** Insert instance specific pre-event callbacks
 */
int fr_coord_pre_event_insert(fr_event_list_t *el)
{
        fr_coord_t              *coord;
        fr_rb_iter_inorder_t    iter;
        fr_coord_cb_inst_t      *cb_inst;
        uint32_t                i;
 
        if (!coord_regs) return 0;
 
        for (coord = fr_rb_iter_init_inorder(&coords, &iter);
             coord != NULL;
             coord = fr_rb_iter_next_inorder(&coords, &iter)) {
                for (i = 0; i < coord->num_callbacks; i++) {
                        cb_inst = coord->cb_inst[i];
                        if (cb_inst && cb_inst->event_pre_cb &&
                            fr_event_pre_insert(el, cb_inst->event_pre_cb, cb_inst->inst_data) < 0) {
                                return -1;
                        }
                }
        }
        return 0;
}
 
/** Insert instance specific post-event callbacks
 */
int fr_coord_post_event_insert(fr_event_list_t *el)
{
        fr_coord_t              *coord;
        fr_rb_iter_inorder_t    iter;
        fr_coord_cb_inst_t      *cb_inst;
        uint32_t                i;
 
        if (!coord_regs) return 0;
 
        for (coord = fr_rb_iter_init_inorder(&coords, &iter);
             coord != NULL;
             coord = fr_rb_iter_next_inorder(&coords, &iter)) {
                for (i = 0; i < coord->num_callbacks; i++) {
                        cb_inst = coord->cb_inst[i];
                        if (cb_inst && cb_inst->event_post_cb &&
                            fr_event_post_insert(el, cb_inst->event_post_cb, cb_inst->inst_data) < 0) {
                                return -1;
                        }
                }
        }
        return 0;
}
 
/** Event loop callback to exit the loop when all workers have detached from all coordinators
 *
 * Used during single threaded shut down to allow the event loop to run any
 * tidy up needed by coordinators.
 */
static void fr_coord_close_post_event(fr_event_list_t *el, UNUSED fr_time_t now, UNUSED void *uctx)
{
        fr_coord_t              *coord;
        fr_rb_iter_inorder_t    iter;
 
        if (fr_rb_num_elements(&coords) == 0) return;
 
        for (coord = fr_rb_iter_init_inorder(&coords, &iter);
             coord;
             coord = fr_rb_iter_next_inorder(&coords, &iter)) {
                if (coord->num_workers > 0) return;
        }
 
        fr_event_loop_exit(el, SIGINT);
}
 
int fr_coord_close_event_insert(fr_event_list_t *el)
{
        return fr_event_post_insert(el, fr_coord_close_post_event, NULL);
}
 
/** Return the coordinator name
 */
char const *fr_coord_name(fr_coord_t const *coord)
{
        return coord->coord_reg->name;
}