svc/startd/transition.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */


/*
 * transition.c - Graph State Machine
 *
 * The graph state machine is implemented here, with a typical approach
 * of a function per state.  Separating the implementation allows more
 * clarity into the actions taken on notification of state change, as well
 * as a place for future expansion including hooks for configurable actions.
 * All functions are called with dgraph_lock held.
 *
 * The start action for this state machine is not explicit.  The states
 * (ONLINE and DEGRADED) which need to know when they're entering the state
 * due to a daemon restart implement this understanding by checking for
 * transition from uninitialized.  In the future, this would likely be better
 * as an explicit start action instead of relying on an overloaded transition.
 *
 * All gt_enter functions use the same set of return codes.
 *    0              success
 *    ECONNABORTED   repository connection aborted
 */

#include "startd.h"

static int
gt_running(restarter_instance_state_t state)
{
    if (state == RESTARTER_STATE_ONLINE ||
        state == RESTARTER_STATE_DEGRADED)
        return (1);

    return (0);
}

static int
gt_enter_uninit(scf_handle_t *h, graph_vertex_t *v,
    restarter_instance_state_t old_state, restarter_error_t rerr)
{
    int err;
    scf_instance_t *inst;

    /* Initialize instance by refreshing it. */

    err = libscf_fmri_get_instance(h, v->gv_name, &inst);
    switch (err) {
    case 0:
        break;

    case ECONNABORTED:
        return (ECONNABORTED);

    case ENOENT:
        return (0);

    case EINVAL:
    case ENOTSUP:
    default:
        bad_error("libscf_fmri_get_instance", err);
    }

    err = refresh_vertex(v, inst);
    if (err == 0)
        graph_enable_by_vertex(v, v->gv_flags & GV_ENABLED, 0);

    scf_instance_destroy(inst);

    /* If the service was running, propagate a stop event. */
    if (gt_running(old_state)) {
        log_framework(LOG_DEBUG, "Propagating stop of %s.\n",
            v->gv_name);

        graph_transition_propagate(v, PROPAGATE_STOP, rerr);
    }

    graph_transition_sulogin(RESTARTER_STATE_UNINIT, old_state);
    return (0);
}

/* ARGSUSED */
static int
gt_enter_maint(scf_handle_t *h, graph_vertex_t *v,
    restarter_instance_state_t old_state, restarter_error_t rerr)
{
    int to_offline = v->gv_flags & GV_TOOFFLINE;

    /*
     * If the service was running, propagate a stop event.  If the
     * service was not running the maintenance transition may satisfy
     * optional dependencies and should be propagated to determine
     * whether new dependents are satisfiable.
     * Instances that transition to maintenance and have the GV_TOOFFLINE
     * flag are special because they can expose new subtree leaves so
     * propagate the offline to the instance dependencies.
     */

    /* instance transitioning to maintenance is considered disabled */
    v->gv_flags &= ~GV_TODISABLE;
    v->gv_flags &= ~GV_TOOFFLINE;

    if (gt_running(old_state)) {
        /*
         * Handle state change during instance disabling.
         * Propagate offline to the new exposed leaves.
         */
        if (to_offline) {
            log_framework(LOG_DEBUG, "%s removed from subtree\n",
                v->gv_name);

            graph_offline_subtree_leaves(v, (void *)h);
        }

        log_framework(LOG_DEBUG, "Propagating maintenance (stop) of "
            "%s.\n", v->gv_name);

        graph_transition_propagate(v, PROPAGATE_STOP, rerr);
    } else {
        log_framework(LOG_DEBUG, "Propagating maintenance of %s.\n",
            v->gv_name);

        graph_transition_propagate(v, PROPAGATE_SAT, rerr);
    }

    graph_transition_sulogin(RESTARTER_STATE_MAINT, old_state);
    return (0);
}

/* ARGSUSED */
static int
gt_enter_offline(scf_handle_t *h, graph_vertex_t *v,
    restarter_instance_state_t old_state, restarter_error_t rerr)
{
    int to_offline = v->gv_flags & GV_TOOFFLINE;

    v->gv_flags &= ~GV_TOOFFLINE;

    /*
     * If the instance should be enabled, see if we can start it.
     * Otherwise send a disable command.
     * If a instance has the GV_TOOFFLINE flag set then it must
     * remains offline until the disable process completes.
     */
    if (v->gv_flags & GV_ENABLED) {
        if (to_offline == 0)
            graph_start_if_satisfied(v);
    } else {
        if (gt_running(old_state) && v->gv_post_disable_f)
            v->gv_post_disable_f();

        vertex_send_event(v, RESTARTER_EVENT_TYPE_DISABLE);
    }

    /*
     * If the service was running, propagate a stop event.  If the
     * service was not running the offline transition may satisfy
     * optional dependencies and should be propagated to determine
     * whether new dependents are satisfiable.
     * Instances that transition to offline and have the GV_TOOFFLINE flag
     * are special because they can expose new subtree leaves so propagate
     * the offline to the instance dependencies.
     */
    if (gt_running(old_state)) {
        /*
         * Handle state change during instance disabling.
         * Propagate offline to the new exposed leaves.
         */
        if (to_offline) {
            log_framework(LOG_DEBUG, "%s removed from subtree\n",
                v->gv_name);

            graph_offline_subtree_leaves(v, (void *)h);
        }

        log_framework(LOG_DEBUG, "Propagating stop of %s.\n",
            v->gv_name);

        graph_transition_propagate(v, PROPAGATE_STOP, rerr);

        /*
         * The offline transition may satisfy require_any/restart
         * dependencies and should be propagated to determine
         * whether new dependents are satisfiable.
         */
        graph_transition_propagate(v, PROPAGATE_SAT, rerr);
    } else {
        log_framework(LOG_DEBUG, "Propagating offline of %s.\n",
            v->gv_name);

        graph_transition_propagate(v, PROPAGATE_SAT, rerr);
    }

    graph_transition_sulogin(RESTARTER_STATE_OFFLINE, old_state);
    return (0);
}

/* ARGSUSED */
static int
gt_enter_disabled(scf_handle_t *h, graph_vertex_t *v,
    restarter_instance_state_t old_state, restarter_error_t rerr)
{
    int to_offline = v->gv_flags & GV_TOOFFLINE;

    v->gv_flags &= ~GV_TODISABLE;
    v->gv_flags &= ~GV_TOOFFLINE;

    /*
     * If the instance should be disabled, no problem.  Otherwise,
     * send an enable command, which should result in the instance
     * moving to OFFLINE unless the instance is part of a subtree
     * (non root) and in this case the result is unpredictable.
     */
    if (v->gv_flags & GV_ENABLED) {
        vertex_send_event(v, RESTARTER_EVENT_TYPE_ENABLE);
    } else if (gt_running(old_state) && v->gv_post_disable_f) {
        v->gv_post_disable_f();
    }

    /*
     * If the service was running, propagate this as a stop.  If the
     * service was not running the disabled transition may satisfy
     * optional dependencies and should be propagated to determine
     * whether new dependents are satisfiable.
     */
    if (gt_running(old_state)) {
        /*
         * We need to propagate the offline to new exposed leaves in
         * case we've just disabled an instance that was part of a
         * subtree.
         */
        if (to_offline) {
            log_framework(LOG_DEBUG, "%s removed from subtree\n",
                v->gv_name);

            /*
             * Handle state change during instance disabling.
             * Propagate offline to the new exposed leaves.
             */
            graph_offline_subtree_leaves(v, (void *)h);
        }


        log_framework(LOG_DEBUG, "Propagating stop of %s.\n",
            v->gv_name);

        graph_transition_propagate(v, PROPAGATE_STOP, rerr);

    } else {
        log_framework(LOG_DEBUG, "Propagating disable of %s.\n",
            v->gv_name);

        graph_transition_propagate(v, PROPAGATE_SAT, rerr);
    }

    graph_transition_sulogin(RESTARTER_STATE_DISABLED, old_state);
    return (0);
}

static int
gt_internal_online_or_degraded(scf_handle_t *h, graph_vertex_t *v,
    restarter_instance_state_t old_state, restarter_error_t rerr)
{
    int r;

    /*
     * If the instance has just come up, update the start
     * snapshot.
     */
    if (gt_running(old_state) == 0) {
        /*
         * Don't fire if we're just recovering state
         * after a restart.
         */
        if (old_state != RESTARTER_STATE_UNINIT &&
            v->gv_post_online_f)
            v->gv_post_online_f();

        r = libscf_snapshots_poststart(h, v->gv_name, B_TRUE);
        switch (r) {
        case 0:
        case ENOENT:
            /*
             * If ENOENT, the instance must have been
             * deleted.  Pretend we were successful since
             * we should get a delete event later.
             */
            break;

        case ECONNABORTED:
            return (ECONNABORTED);

        case EACCES:
        case ENOTSUP:
        default:
            bad_error("libscf_snapshots_poststart", r);
        }
    }

    if (!(v->gv_flags & GV_ENABLED)) {
        vertex_send_event(v, RESTARTER_EVENT_TYPE_DISABLE);
    } else if (v->gv_flags & GV_TOOFFLINE) {
        /*
         * If the vertex has the GV_TOOFFLINE flag set then that's
         * because the instance was transitioning from offline to
         * online and the reverse disable algorithm doesn't offline
         * those instances because it was already appearing offline.
         * So do it now.
         */
        offline_vertex(v);
    }

    if (gt_running(old_state) == 0) {
        log_framework(LOG_DEBUG, "Propagating start of %s.\n",
            v->gv_name);

        graph_transition_propagate(v, PROPAGATE_START, rerr);
    } else if (rerr == RERR_REFRESH) {
        /* For refresh we'll get a message sans state change */

        log_framework(LOG_DEBUG, "Propagating refresh of %s.\n",
            v->gv_name);

        graph_transition_propagate(v, PROPAGATE_STOP, rerr);
    }

    return (0);
}

static int
gt_enter_online(scf_handle_t *h, graph_vertex_t *v,
    restarter_instance_state_t old_state, restarter_error_t rerr)
{
    int r;

    r = gt_internal_online_or_degraded(h, v, old_state, rerr);
    if (r != 0)
        return (r);

    graph_transition_sulogin(RESTARTER_STATE_ONLINE, old_state);
    return (0);
}

static int
gt_enter_degraded(scf_handle_t *h, graph_vertex_t *v,
    restarter_instance_state_t old_state, restarter_error_t rerr)
{
    int r;

    r = gt_internal_online_or_degraded(h, v, old_state, rerr);
    if (r != 0)
        return (r);

    graph_transition_sulogin(RESTARTER_STATE_DEGRADED, old_state);
    return (0);
}

/*
 * gt_transition() implements the state transition for the graph
 * state machine.  It can return:
 *    0              success
 *    ECONNABORTED   repository connection aborted
 *
 * v->gv_state should be set to the state we're transitioning to before
 * calling this function.
 */
int
gt_transition(scf_handle_t *h, graph_vertex_t *v, restarter_error_t rerr,
    restarter_instance_state_t old_state)
{
    int err;
    int lost_repository = 0;

    /*
     * If there's a common set of work to be done on exit from the
     * old_state, include it as a separate set of functions here.  For
     * now there's no such work, so there are no gt_exit functions.
     */

    err = vertex_subgraph_dependencies_shutdown(h, v, old_state);
    switch (err) {
    case 0:
        break;

    case ECONNABORTED:
        lost_repository = 1;
        break;

    default:
        bad_error("vertex_subgraph_dependencies_shutdown", err);
    }

    /*
     * Now call the appropriate gt_enter function for the new state.
     */
    switch (v->gv_state) {
    case RESTARTER_STATE_UNINIT:
        err = gt_enter_uninit(h, v, old_state, rerr);
        break;

    case RESTARTER_STATE_DISABLED:
        err = gt_enter_disabled(h, v, old_state, rerr);
        break;

    case RESTARTER_STATE_OFFLINE:
        err = gt_enter_offline(h, v, old_state, rerr);
        break;

    case RESTARTER_STATE_ONLINE:
        err = gt_enter_online(h, v, old_state, rerr);
        break;

    case RESTARTER_STATE_DEGRADED:
        err = gt_enter_degraded(h, v, old_state, rerr);
        break;

    case RESTARTER_STATE_MAINT:
        err = gt_enter_maint(h, v, old_state, rerr);
        break;

    default:
        /* Shouldn't be in an invalid state. */
#ifndef NDEBUG
        uu_warn("%s:%d: Invalid state %d.\n", __FILE__, __LINE__,
            v->gv_state);
#endif
        abort();
    }

    switch (err) {
    case 0:
        break;

    case ECONNABORTED:
        lost_repository = 1;
        break;

    default:
#ifndef NDEBUG
        uu_warn("%s:%d: "
            "gt_enter_%s() failed with unexpected error %d.\n",
            __FILE__, __LINE__, instance_state_str[v->gv_state], err);
#endif
        abort();
    }

    return (lost_repository ? ECONNABORTED : 0);
}