systemd/src/core/job.h

#pragma once

/***
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd 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
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <stdbool.h>

#include "sd-event.h"

#include "list.h"
#include "unit-name.h"

typedef struct Job Job;
typedef struct JobDependency JobDependency;
typedef enum JobType JobType;
typedef enum JobState JobState;
typedef enum JobMode JobMode;
typedef enum JobResult JobResult;

/* Be careful when changing the job types! Adjust job_merging_table[] accordingly! */
enum JobType {
        JOB_START,                  /* if a unit does not support being started, we'll just wait until it becomes active */
        JOB_VERIFY_ACTIVE,

        JOB_STOP,

        JOB_RELOAD,                 /* if running, reload */

        /* Note that restarts are first treated like JOB_STOP, but
         * then instead of finishing are patched to become
         * JOB_START. */
        JOB_RESTART,                /* If running, stop. Then start unconditionally. */

        _JOB_TYPE_MAX_MERGING,

        /* JOB_NOP can enter into a transaction, but as it won't pull in
         * any dependencies and it uses the special 'nop_job' slot in Unit,
         * it won't have to merge with anything (except possibly into another
         * JOB_NOP, previously installed). JOB_NOP is special-cased in
         * job_type_is_*() functions so that the transaction can be
         * activated. */
        JOB_NOP = _JOB_TYPE_MAX_MERGING, /* do nothing */

        _JOB_TYPE_MAX_IN_TRANSACTION,

        /* JOB_TRY_RESTART can never appear in a transaction, because
         * it always collapses into JOB_RESTART or JOB_NOP before entering.
         * Thus we never need to merge it with anything. */
        JOB_TRY_RESTART = _JOB_TYPE_MAX_IN_TRANSACTION, /* if running, stop and then start */

        /* Similar to JOB_TRY_RESTART but collapses to JOB_RELOAD or JOB_NOP */
        JOB_TRY_RELOAD,

        /* JOB_RELOAD_OR_START won't enter into a transaction and cannot result
         * from transaction merging (there's no way for JOB_RELOAD and
         * JOB_START to meet in one transaction). It can result from a merge
         * during job installation, but then it will immediately collapse into
         * one of the two simpler types. */
        JOB_RELOAD_OR_START,        /* if running, reload, otherwise start */

        _JOB_TYPE_MAX,
        _JOB_TYPE_INVALID = -1
};

enum JobState {
        JOB_WAITING,
        JOB_RUNNING,
        _JOB_STATE_MAX,
        _JOB_STATE_INVALID = -1
};

enum JobMode {
        JOB_FAIL,                /* Fail if a conflicting job is already queued */
        JOB_REPLACE,             /* Replace an existing conflicting job */
        JOB_REPLACE_IRREVERSIBLY,/* Like JOB_REPLACE + produce irreversible jobs */
        JOB_ISOLATE,             /* Start a unit, and stop all others */
        JOB_FLUSH,               /* Flush out all other queued jobs when queing this one */
        JOB_IGNORE_DEPENDENCIES, /* Ignore both requirement and ordering dependencies */
        JOB_IGNORE_REQUIREMENTS, /* Ignore requirement dependencies */
        _JOB_MODE_MAX,
        _JOB_MODE_INVALID = -1
};

enum JobResult {
        JOB_DONE,                /* Job completed successfully */
        JOB_CANCELED,            /* Job canceled by a conflicting job installation or by explicit cancel request */
        JOB_TIMEOUT,             /* Job timeout elapsed */
        JOB_FAILED,              /* Job failed */
        JOB_DEPENDENCY,          /* A required dependency job did not result in JOB_DONE */
        JOB_SKIPPED,             /* Negative result of JOB_VERIFY_ACTIVE */
        JOB_INVALID,             /* JOB_RELOAD of inactive unit */
        JOB_ASSERT,              /* Couldn't start a unit, because an assert didn't hold */
        JOB_UNSUPPORTED,         /* Couldn't start a unit, because the unit type is not supported on the system */
        _JOB_RESULT_MAX,
        _JOB_RESULT_INVALID = -1
};

#include "unit.h"

struct JobDependency {
        /* Encodes that the 'subject' job needs the 'object' job in
         * some way. This structure is used only while building a transaction. */
        Job *subject;
        Job *object;

        LIST_FIELDS(JobDependency, subject);
        LIST_FIELDS(JobDependency, object);

        bool matters;
        bool conflicts;
};

struct Job {
        Manager *manager;
        Unit *unit;

        LIST_FIELDS(Job, transaction);
        LIST_FIELDS(Job, run_queue);
        LIST_FIELDS(Job, dbus_queue);

        LIST_HEAD(JobDependency, subject_list);
        LIST_HEAD(JobDependency, object_list);

        /* Used for graph algs as a "I have been here" marker */
        Job* marker;
        unsigned generation;

        uint32_t id;

        JobType type;
        JobState state;

        sd_event_source *timer_event_source;
        usec_t begin_usec;

        /*
         * This tracks where to send signals, and also which clients
         * are allowed to call DBus methods on the job (other than
         * root).
         *
         * There can be more than one client, because of job merging.
         */
        sd_bus_track *clients;
        char **deserialized_clients;

        JobResult result;

        bool installed:1;
        bool in_run_queue:1;
        bool matters_to_anchor:1;
        bool in_dbus_queue:1;
        bool sent_dbus_new_signal:1;
        bool ignore_order:1;
        bool irreversible:1;
};

Job* job_new(Unit *unit, JobType type);
Job* job_new_raw(Unit *unit);
void job_free(Job *job);
Job* job_install(Job *j);
int job_install_deserialized(Job *j);
void job_uninstall(Job *j);
void job_dump(Job *j, FILE*f, const char *prefix);
int job_serialize(Job *j, FILE *f, FDSet *fds);
int job_deserialize(Job *j, FILE *f, FDSet *fds);
int job_coldplug(Job *j);

JobDependency* job_dependency_new(Job *subject, Job *object, bool matters, bool conflicts);
void job_dependency_free(JobDependency *l);

int job_merge(Job *j, Job *other);

JobType job_type_lookup_merge(JobType a, JobType b) _pure_;

_pure_ static inline bool job_type_is_mergeable(JobType a, JobType b) {
        return job_type_lookup_merge(a, b) >= 0;
}

_pure_ static inline bool job_type_is_conflicting(JobType a, JobType b) {
        return a != JOB_NOP && b != JOB_NOP && !job_type_is_mergeable(a, b);
}

_pure_ static inline bool job_type_is_superset(JobType a, JobType b) {
        /* Checks whether operation a is a "superset" of b in its actions */
        if (b == JOB_NOP)
                return true;
        if (a == JOB_NOP)
                return false;
        return a == job_type_lookup_merge(a, b);
}

bool job_type_is_redundant(JobType a, UnitActiveState b) _pure_;

/* Collapses a state-dependent job type into a simpler type by observing
 * the state of the unit which it is going to be applied to. */
JobType job_type_collapse(JobType t, Unit *u);

int job_type_merge_and_collapse(JobType *a, JobType b, Unit *u);

void job_add_to_run_queue(Job *j);
void job_add_to_dbus_queue(Job *j);

int job_start_timer(Job *j);

int job_run_and_invalidate(Job *j);
int job_finish_and_invalidate(Job *j, JobResult result, bool recursive, bool already);

char *job_dbus_path(Job *j);

void job_shutdown_magic(Job *j);

int job_get_timeout(Job *j, usec_t *timeout) _pure_;

const char* job_type_to_string(JobType t) _const_;
JobType job_type_from_string(const char *s) _pure_;

const char* job_state_to_string(JobState t) _const_;
JobState job_state_from_string(const char *s) _pure_;

const char* job_mode_to_string(JobMode t) _const_;
JobMode job_mode_from_string(const char *s) _pure_;

const char* job_result_to_string(JobResult t) _const_;
JobResult job_result_from_string(const char *s) _pure_;

const char* job_type_to_access_method(JobType t);