interpret_synchronous.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: c5da642067f02ed5ac8a36ac6e822f968d3577af $
 *
 * @file unlang/interpret_synchronous.c
 * @brief Synchronous interpreter
 *
 * @copyright 2021 The FreeRADIUS server project
 */
 
#include "interpret_priv.h"
#include <freeradius-devel/server/module_rlm.h>
 
typedef struct {
        fr_heap_t               *runnable;
        fr_event_list_t         *el;
        int                     yielded;
        unlang_interpret_t      *intp;
} unlang_interpret_synchronous_t;
 
/** Internal request (i.e. one generated by the interpreter) is now complete
 *
 */
static void _request_init_internal(request_t *request, void *uctx)
{
        unlang_interpret_synchronous_t  *intps = uctx;
 
        RDEBUG3("Initialising internal synchronous request");
        unlang_interpret_set(request, intps->intp);
        fr_heap_insert(&intps->runnable, request);
}
 
/** External request is now complete
 *
 */
static void _request_done_external(request_t *request, UNUSED rlm_rcode_t rcode, UNUSED void *uctx)
{
        if (request->master_state != REQUEST_STOP_PROCESSING) {
                /*
                 *      Previously, there was a check to ensure that external requests
                 *      had an indentation level of zero, but this does not apply
                 *      if the request was passed in to the synchronous interpreter
                 *      as its base indentation level may not have been zero to begin
                 *      with.
                 *
                 *      Also check that the request is NOT marked as "yielded", but
                 *      is in fact done.
                 *
                 *      @todo - check that the stack is at frame 0, otherwise
                 *      more things have gone wrong.
                 */
                fr_assert_msg(!unlang_interpret_is_resumable(request),
                              "Request %s is marked as yielded at end of processing", request->name);
        }
 
        RDEBUG3("Done synchronous external request");
}
 
/** Internal request (i.e. one generated by the interpreter) is now complete
 *
 */
static void _request_done_internal(request_t *request, UNUSED rlm_rcode_t rcode, UNUSED void *uctx)
{
        RDEBUG3("Done synchronous internal request");
 
        /* Request will be cleaned up by whatever created it */
}
 
static void _request_done_detached(request_t *request, UNUSED rlm_rcode_t rcode, UNUSED void *uctx)
{
        RDEBUG3("Done synchronous detached request");
 
        /*
         *      Detached requests have to be freed by us
         *      as nothing else can free them.
         *
         *      All other requests must be freed by the
         *      code which allocated them.
         */
        talloc_free(request);
}
 
/** We don't need to do anything for internal -> detached
 *
 */
static void _request_detach(request_t *request, UNUSED void *uctx)
{
        RDEBUG3("Synchronous request detached");
 
        if (request_detach(request) < 0) RPEDEBUG("Failed detaching request");
}
 
/** Request is now runnable
 *
 */
static void _request_runnable(request_t *request, void *uctx)
{
        unlang_interpret_synchronous_t  *intps = uctx;
 
        fr_assert(intps->yielded > 0);
        intps->yielded--;
 
        fr_heap_insert(&intps->runnable, request);
}
 
/** Interpreter yielded request
 *
 */
static void _request_yield(request_t *request, void *uctx)
{
        unlang_interpret_synchronous_t  *intps = uctx;
 
        intps->yielded++;
 
        RDEBUG3("synchronous request yielded");
}
 
/** Interpreter is starting to work on request again
 *
 */
static void _request_resume(request_t *request, UNUSED void *uctx)
{
        RDEBUG3("synchronous request resumed");
}
 
static bool _request_scheduled(request_t const *request, UNUSED void *uctx)
{
        return fr_heap_entry_inserted(request->runnable);
}
 
/** Allocate a new temporary interpreter
 *
 */
static unlang_interpret_synchronous_t *unlang_interpret_synchronous_alloc(TALLOC_CTX *ctx, fr_event_list_t *el)
{
        unlang_interpret_synchronous_t *intps;
 
        MEM(intps = talloc_zero(ctx, unlang_interpret_synchronous_t));
        MEM(intps->runnable = fr_heap_talloc_alloc(intps, fr_pointer_cmp, request_t, runnable, 0));
        if (el) {
                intps->el = el;
        } else {
                MEM(intps->el = fr_event_list_alloc(intps, NULL, NULL));
        }
        MEM(intps->intp = unlang_interpret_init(intps, intps->el,
                                                &(unlang_request_func_t){
                                                        .init_internal = _request_init_internal,
 
                                                        .done_external = _request_done_external,
                                                        .done_internal = _request_done_internal,
                                                        .done_detached = _request_done_detached,
 
                                                        .detach = _request_detach,
                                                        .yield = _request_yield,
                                                        .resume = _request_resume,
                                                        .mark_runnable = _request_runnable,
                                                        .scheduled = _request_scheduled,
                                                },
                                                intps));
 
        return intps;
}
 
/** Execute an unlang section synchronously
 *
 * Create a temporary event loop and swap it out for the one in the request.
 * Execute unlang operations until we receive a non-yield return code then return.
 *
 * @note The use cases for this are very limited.  If you need to use it, chances
 *      are what you're doing could be done better using one of the thread
 *      event loops.
 *
 * @param[in] el        Event list for the temporary interpreter. If NULL a
 *                      temporary list will be allocated.
 * @param[in] request   The current request.
 * @return One of the RLM_MODULE_* macros.
 */
rlm_rcode_t unlang_interpret_synchronous(fr_event_list_t *el, request_t *request)
{
        unlang_interpret_t              *old_intp;
        char const                      *caller;
 
        unlang_interpret_synchronous_t  *intps;
 
        rlm_rcode_t                     rcode;
 
        request_t                       *sub_request = NULL;
        bool                            dont_wait_for_event;
        int                             iterations = 0;
 
        old_intp = unlang_interpret_get(request);
        caller = request->module;
 
        intps = unlang_interpret_synchronous_alloc(request, el);
        unlang_interpret_set(request, intps->intp);
 
        el = intps->el;
 
        rcode = unlang_interpret(request, UNLANG_REQUEST_RESUME);
 
        while ((dont_wait_for_event = (fr_heap_num_elements(intps->runnable) > 0)) ||
               (intps->yielded > 0)) {
                rlm_rcode_t     sub_rcode;
                int             num_events;
 
                /*
                 *      Wait for a timer / IO event.  If there's a
                 *      failure, all kinds of bad things happen.  Oh
                 *      well.
                 */
                DEBUG4("Gathering events - %s", dont_wait_for_event ? "Will not wait" : "will wait");
                num_events = fr_event_corral(el, el->tl->time(), !dont_wait_for_event);
                if (num_events < 0) {
                        RPERROR("fr_event_corral");
                        break;
                }
 
                DEBUG4("%d event(s) pending%s",
                       num_events == -1 ? 0 : num_events, num_events == -1 ? " - event loop exiting" : "");
 
                /*
                 *      This function ends up pushing a
                 *      runnable request into the backlog, OR
                 *      setting new timers.
                 */
                if (num_events > 0) {
                        DEBUG4("Servicing event(s)");
                        fr_event_service(el);
                }
 
                /*
                 *      If there are no runnable requests, then go
                 *      back to check the timers again.  Note that we
                 *      only wait if there are timer events left to
                 *      service.
                 *
                 *      If there WAS a timer event, but servicing that
                 *      timer event did not result in a runnable
                 *      request, THEN we're guaranteed that there is
                 *      still a timer event left.
                 */
                sub_request = fr_heap_pop(&intps->runnable);
                if (!sub_request) {
                        DEBUG4("No pending requests (%d yielded)", intps->yielded);
                        continue;
                }
 
                /*
                 *      Continue interpretation until there's nothing
                 *      in the backlog.  If this request YIELDs, then
                 *      do another loop around.
                 */
                RDEBUG4(">>> interpreter (iteration %i)", ++iterations);
                sub_rcode = unlang_interpret(sub_request, UNLANG_REQUEST_RESUME);
                RDEBUG4("<<< interpreter (iteration %i) - %s", iterations,
                        fr_table_str_by_value(rcode_table, sub_rcode, "<INVALID>"));
 
                /*
                 *      If the request being run was the original request
                 *      then update the rcode we're returning.
                 */
                if (sub_request == request) rcode = sub_rcode;
 
                DEBUG3("%u runnable, %d yielded", fr_heap_num_elements(intps->runnable), intps->yielded);
        }
 
        talloc_free(intps);
        unlang_interpret_set(request, old_intp);
        request->module = caller;
 
        return rcode;
}