X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;ds=inline;f=manager.c;h=7941d89a75f52c86dbf8ce729255e3cf1c36a400;hb=83c60c9f0c7581b607dc5c0f84582978894e3d4a;hp=86ed086eb31c3f48f586a9b38831f2dbcc7d5d2d;hpb=a66d02c3290008d50b2b52f84cfbf46a546ba831;p=elogind.git

diff --git a/manager.c b/manager.c
index 86ed086eb..7941d89a7 100644
--- a/manager.c
+++ b/manager.c
@@ -8,7 +8,7 @@
 #include "hashmap.h"
 #include "macro.h"
 #include "strv.h"
-#include "load-fragment.h"
+#include "log.h"
 
 Manager* manager_new(void) {
         Manager *m;
@@ -22,10 +22,7 @@ Manager* manager_new(void) {
         if (!(m->jobs = hashmap_new(trivial_hash_func, trivial_compare_func)))
                 goto fail;
 
-        if (!(m->jobs_to_add = hashmap_new(trivial_hash_func, trivial_compare_func)))
-                goto fail;
-
-        if (!(m->jobs_to_remove = set_new(trivial_hash_func, trivial_compare_func)))
+        if (!(m->transaction_jobs = hashmap_new(trivial_hash_func, trivial_compare_func)))
                 goto fail;
 
         return m;
@@ -37,224 +34,741 @@ fail:
 
 void manager_free(Manager *m) {
         Name *n;
+        Job *j;
 
         assert(m);
 
         while ((n = hashmap_first(m->names)))
                 name_free(n);
 
+        while ((j = hashmap_steal_first(m->transaction_jobs)))
+                job_free(j);
+
         hashmap_free(m->names);
         hashmap_free(m->jobs);
+        hashmap_free(m->transaction_jobs);
 
-        /* FIXME: This is incomplete */
+        free(m);
+}
 
-        hashmap_free(m->jobs_to_add);
-        set_free(m->jobs_to_remove);
+static void transaction_delete_job(Manager *m, Job *j) {
+        assert(m);
+        assert(j);
 
-        free(m);
+        /* Deletes one job from the transaction */
+
+        manager_transaction_unlink_job(m, j);
+
+        if (!j->linked)
+                job_free(j);
+}
+
+static void transaction_delete_name(Manager *m, Name *n) {
+        Job *j;
+
+        /* Deletes all jobs associated with a certain name from the
+         * transaction */
+
+        while ((j = hashmap_get(m->transaction_jobs, n)))
+                transaction_delete_job(m, j);
+}
+
+static void transaction_abort(Manager *m) {
+        Job *j;
+
+        assert(m);
+
+        while ((j = hashmap_first(m->transaction_jobs)))
+                if (j->linked)
+                        transaction_delete_job(m, j);
+                else
+                        job_free(j);
+
+        assert(hashmap_isempty(m->transaction_jobs));
+        assert(!m->transaction_anchor);
+}
+
+static void transaction_find_jobs_that_matter_to_anchor(Manager *m, Job *j, unsigned generation) {
+        JobDependency *l;
+
+        assert(m);
+
+        /* A recursive sweep through the graph that marks all names
+         * that matter to the anchor job, i.e. are directly or
+         * indirectly a dependency of the anchor job via paths that
+         * are fully marked as mattering. */
+
+        for (l = j ? j->subject_list : m->transaction_anchor; l; l = l->subject_next) {
+
+                /* This link does not matter */
+                if (!l->matters)
+                        continue;
+
+                /* This name has already been marked */
+                if (l->object->generation == generation)
+                        continue;
+
+                l->object->matters_to_anchor = true;
+                l->object->generation = generation;
+
+                transaction_find_jobs_that_matter_to_anchor(m, l->object, generation);
+        }
+}
+
+static void transaction_merge_and_delete_job(Manager *m, Job *j, Job *other, JobType t) {
+        JobDependency *l, *last;
+
+        assert(j);
+        assert(other);
+        assert(j->name == other->name);
+        assert(!j->linked);
+
+        /* Merges 'other' into 'j' and then deletes j. */
+
+        j->type = t;
+        j->state = JOB_WAITING;
+        j->forced = j->forced || other->forced;
+
+        j->matters_to_anchor = j->matters_to_anchor || other->matters_to_anchor;
+
+        /* Patch us in as new owner of the JobDependency objects */
+        last = NULL;
+        for (l = other->subject_list; l; l = l->subject_next) {
+                assert(l->subject == other);
+                l->subject = j;
+                last = l;
+        }
+
+        /* Merge both lists */
+        if (last) {
+                last->subject_next = j->subject_list;
+                if (j->subject_list)
+                        j->subject_list->subject_prev = last;
+                j->subject_list = other->subject_list;
+        }
+
+        /* Patch us in as new owner of the JobDependency objects */
+        last = NULL;
+        for (l = other->object_list; l; l = l->object_next) {
+                assert(l->object == other);
+                l->object = j;
+                last = l;
+        }
+
+        /* Merge both lists */
+        if (last) {
+                last->object_next = j->object_list;
+                if (j->object_list)
+                        j->object_list->object_prev = last;
+                j->object_list = other->object_list;
+        }
+
+        /* Kill the other job */
+        other->subject_list = NULL;
+        other->object_list = NULL;
+        transaction_delete_job(m, other);
+}
+
+static int delete_one_unmergeable_job(Manager *m, Job *j) {
+        Job *k;
+
+        assert(j);
+
+        /* Tries to delete one item in the linked list
+         * j->transaction_next->transaction_next->... that conflicts
+         * whith another one, in an attempt to make an inconsistent
+         * transaction work. */
+
+        /* We rely here on the fact that if a merged with b does not
+         * merge with c, either a or b merge with c neither */
+        for (; j; j = j->transaction_next)
+                for (k = j->transaction_next; k; k = k->transaction_next) {
+                        Job *d;
+
+                        /* Is this one mergeable? Then skip it */
+                        if (job_type_is_mergeable(j->type, k->type))
+                                continue;
+
+                        /* Ok, we found two that conflict, let's see if we can
+                         * drop one of them */
+                        if (!j->matters_to_anchor)
+                                d = j;
+                        else if (!k->matters_to_anchor)
+                                d = k;
+                        else
+                                return -ENOEXEC;
+
+                        /* Ok, we can drop one, so let's do so. */
+                        log_debug("Try to fix job merging by deleting job %s/%s", name_id(d->name), job_type_to_string(d->type));
+                        transaction_delete_job(m, d);
+                        return 0;
+                }
+
+        return -EINVAL;
 }
 
-int manager_add_job(Manager *m, JobType type, Name *name, JobMode mode, Job **_ret) {
-        Job *ret, *other;
+static int transaction_merge_jobs(Manager *m) {
+        Job *j;
         void *state;
-        Name *dep;
         int r;
 
         assert(m);
-        assert(type < _JOB_TYPE_MAX);
-        assert(name);
-        assert(mode < _JOB_MODE_MAX);
-        assert(_ret);
 
-        /* Check for conflicts, first against the jobs we shall
-         * create */
-        if ((other = hashmap_get(m->jobs_to_add, name))) {
+        /* First step, check whether any of the jobs for one specific
+         * task conflict. If so, try to drop one of them. */
+        HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+                JobType t;
+                Job *k;
+
+                t = j->type;
+                for (k = j->transaction_next; k; k = k->transaction_next) {
+                        if ((r = job_type_merge(&t, k->type)) >= 0)
+                                continue;
+
+                        /* OK, we could not merge all jobs for this
+                         * action. Let's see if we can get rid of one
+                         * of them */
+
+                        if ((r = delete_one_unmergeable_job(m, j)) >= 0)
+                                /* Ok, we managed to drop one, now
+                                 * let's ask our callers to call us
+                                 * again after garbage collecting */
+                                return -EAGAIN;
+
+                        /* We couldn't merge anything. Failure */
+                        return r;
+                }
+        }
 
-                if (other->type != type)
-                        return -EEXIST;
+        /* Second step, merge the jobs. */
+        HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+                JobType t = j->type;
+                Job *k;
+
+                /* Merge all transactions */
+                for (k = j->transaction_next; k; k = k->transaction_next)
+                        assert_se(job_type_merge(&t, k->type) == 0);
+
+                /* If an active job is mergeable, merge it too */
+                if (j->name->meta.job)
+                        job_type_merge(&t, j->name->meta.job->type); /* Might fail. Which is OK */
+
+                while ((k = j->transaction_next)) {
+                        if (j->linked) {
+                                transaction_merge_and_delete_job(m, k, j, t);
+                                j = k;
+                        } else
+                                transaction_merge_and_delete_job(m, j, k, t);
+                }
 
-        } else if (name->meta.job) {
+                assert(!j->transaction_next);
+                assert(!j->transaction_prev);
+        }
+
+        return 0;
+}
+
+static bool name_matters_to_anchor(Name *n, Job *j) {
+        assert(n);
+        assert(!j->transaction_prev);
+
+        /* Checks whether at least one of the jobs for this name
+         * matters to the anchor. */
+
+        for (; j; j = j->transaction_next)
+                if (j->matters_to_anchor)
+                        return true;
 
-                if (name->meta.job->type != type) {
+        return false;
+}
 
-                        if (mode == JOB_FAIL)
-                                return -EEXIST;
+static int transaction_verify_order_one(Manager *m, Job *j, Job *from, unsigned generation) {
+        void *state;
+        Name *n;
+        int r;
 
-                        if ((r = set_put(m->jobs_to_remove, name->meta.job)) < 0)
-                                return r;
+        assert(m);
+        assert(j);
+        assert(!j->transaction_prev);
+
+        /* Does a recursive sweep through the ordering graph, looking
+         * for a cycle. If we find cycle we try to break it. */
+
+        /* Did we find a cycle? */
+        if (j->marker && j->generation == generation) {
+                Job *k;
+
+                /* So, we already have been here. We have a
+                 * cycle. Let's try to break it. We go backwards in
+                 * our path and try to find a suitable job to
+                 * remove. We use the marker to find our way back,
+                 * since smart how we are we stored our way back in
+                 * there. */
+
+                for (k = from; k; k = (k->generation == generation ? k->marker : NULL)) {
+
+                        if (!k->linked &&
+                            !name_matters_to_anchor(k->name, k)) {
+                                /* Ok, we can drop this one, so let's
+                                 * do so. */
+                                log_debug("Breaking order cycle by deleting job %s/%s", name_id(k->name), job_type_to_string(k->type));
+                                transaction_delete_name(m, k->name);
+                                return -EAGAIN;
+                        }
+
+                        /* Check if this in fact was the beginning of
+                         * the cycle */
+                        if (k == j)
+                                break;
                 }
+
+                return -ENOEXEC;
         }
 
-        if (!(ret = job_new(m, type, name)))
-                return -ENOMEM;
+        /* Make the marker point to where we come from, so that we can
+         * find our way backwards if we want to break a cycle */
+        j->marker = from;
+        j->generation = generation;
 
-        if ((r = hashmap_put(m->jobs_to_add, name, ret)) < 0)
-                goto fail;
+        /* We assume that the the dependencies are bidirectional, and
+         * hence can ignore NAME_AFTER */
+        SET_FOREACH(n, j->name->meta.dependencies[NAME_BEFORE], state) {
+                Job *o;
 
-        if (type == JOB_START || type == JOB_VERIFY_STARTED || type == JOB_RESTART_FINISH) {
-                SET_FOREACH(dep, ret->name->meta.dependencies[NAME_REQUIRES], state)
-                        if ((r = manager_add_job(m, type, dep, mode, NULL)) < 0)
-                                goto fail;
-                SET_FOREACH(dep, ret->name->meta.dependencies[NAME_SOFT_REQUIRES], state)
-                        if ((r = manager_add_job(m, type, dep, JOB_FAIL, NULL)) < 0)
-                                goto fail;
-                SET_FOREACH(dep, ret->name->meta.dependencies[NAME_WANTS], state)
-                        if ((r = manager_add_job(m, type, dep, JOB_FAIL, NULL)) < 0)
-                                goto fail;
-                SET_FOREACH(dep, ret->name->meta.dependencies[NAME_REQUISITE], state)
-                        if ((r = manager_add_job(m, JOB_VERIFY_STARTED, dep, mode, NULL)) < 0)
-                                goto fail;
-                SET_FOREACH(dep, ret->name->meta.dependencies[NAME_SOFT_REQUISITE], state)
-                        if ((r = manager_add_job(m, JOB_VERIFY_STARTED, dep, JOB_FAIL, NULL)) < 0)
-                                goto fail;
-                SET_FOREACH(dep, ret->name->meta.dependencies[NAME_CONFLICTS], state)
-                        if ((r = manager_add_job(m, type, dep, mode, NULL)) < 0)
-                                goto fail;
-
-        } else if (type == JOB_STOP || type == JOB_RESTART || type == JOB_TRY_RESTART) {
-
-                SET_FOREACH(dep, ret->name->meta.dependencies[NAME_REQUIRED_BY], state)
-                        if ((r = manager_add_job(m, type, dep, mode, NULL)) < 0)
-                                goto fail;
+                /* Is there a job for this name? */
+                if (!(o = hashmap_get(m->transaction_jobs, n)))
+
+                        /* Ok, there is no job for this in the
+                         * transaction, but maybe there is already one
+                         * running? */
+                        if (!(o = n->meta.job))
+                                continue;
+
+                if ((r = transaction_verify_order_one(m, o, j, generation)) < 0)
+                        return r;
         }
 
-        if (_ret)
-                *_ret = ret;
+        return 0;
+}
+
+static int transaction_verify_order(Manager *m, unsigned *generation) {
+        Job *j;
+        int r;
+        void *state;
+
+        assert(m);
+        assert(generation);
+
+        /* Check if the ordering graph is cyclic. If it is, try to fix
+         * that up by dropping one of the jobs. */
+
+        HASHMAP_FOREACH(j, m->transaction_jobs, state)
+                if ((r = transaction_verify_order_one(m, j, NULL, (*generation)++)) < 0)
+                        return r;
 
         return 0;
+}
 
-fail:
-        job_free(ret);
+static void transaction_collect_garbage(Manager *m) {
+        bool again;
 
-        return r;
+        assert(m);
+
+        /* Drop jobs that are not required by any other job */
+
+        do {
+                void *state;
+                Job *j;
+
+                again = false;
+
+                HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+                        if (j->object_list)
+                                continue;
+
+                        log_debug("Garbage collecting job %s/%s", name_id(j->name), job_type_to_string(j->type));
+                        transaction_delete_job(m, j);
+                        again = true;
+                        break;
+                }
+
+        } while (again);
 }
 
+static int transaction_is_destructive(Manager *m, JobMode mode) {
+        void *state;
+        Job *j;
 
-Job *manager_get_job(Manager *m, uint32_t id) {
         assert(m);
 
-        return hashmap_get(m->jobs, UINT32_TO_PTR(id));
+        /* Checks whether applying this transaction means that
+         * existing jobs would be replaced */
+
+        HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+
+                /* Assume merged */
+                assert(!j->transaction_prev);
+                assert(!j->transaction_next);
+
+                if (j->name->meta.job &&
+                    j->name->meta.job != j &&
+                    !job_type_is_superset(j->type, j->name->meta.job->type))
+                        return -EEXIST;
+        }
+
+        return 0;
 }
 
-Name *manager_get_name(Manager *m, const char *name) {
+static void transaction_minimize_impact(Manager *m) {
+        bool again;
         assert(m);
-        assert(name);
 
-        return hashmap_get(m->names, name);
+        /* Drops all unnecessary jobs that reverse already active jobs
+         * or that stop a running service. */
+
+        do {
+                Job *j;
+                void *state;
+
+                again = false;
+
+                HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+                        for (; j; j = j->transaction_next) {
+
+                                /* If it matters, we shouldn't drop it */
+                                if (j->matters_to_anchor)
+                                        continue;
+
+                                /* Would this stop a running service?
+                                 * Would this change an existing job?
+                                 * If so, let's drop this entry */
+                                if ((j->type != JOB_STOP || NAME_IS_INACTIVE_OR_DEACTIVATING(name_active_state(j->name))) &&
+                                    (!j->name->meta.job  || job_type_is_conflicting(j->type, j->name->meta.job->state)))
+                                        continue;
+
+                                /* Ok, let's get rid of this */
+                                log_debug("Deleting %s/%s to minimize impact", name_id(j->name), job_type_to_string(j->type));
+                                transaction_delete_job(m, j);
+                                again = true;
+                                break;
+                        }
+
+                        if (again)
+                                break;
+                }
+
+        } while (again);
 }
 
-static int verify_type(Name *name) {
-        char *n;
+static int transaction_apply(Manager *m, JobMode mode) {
         void *state;
+        Job *j;
+        int r;
 
-        assert(name);
+        /* Moves the transaction jobs to the set of active jobs */
 
-        /* Checks that all aliases of this name have the same and valid type */
+        HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+                /* Assume merged */
+                assert(!j->transaction_prev);
+                assert(!j->transaction_next);
 
-        SET_FOREACH(n, name->meta.names, state) {
-                NameType t;
+                if (j->linked)
+                        continue;
 
-                if ((t = name_type_from_string(n)) == _NAME_TYPE_INVALID)
-                        return -EINVAL;
+                if ((r = hashmap_put(m->jobs, UINT32_TO_PTR(j->id), j)) < 0)
+                        goto rollback;
+        }
 
-                if (name->meta.type == _NAME_TYPE_INVALID) {
-                        name->meta.type = t;
+        while ((j = hashmap_steal_first(m->transaction_jobs))) {
+                if (j->linked)
                         continue;
-                }
 
-                if (name->meta.type != t)
-                        return -EINVAL;
+                if (j->name->meta.job)
+                        job_free(j->name->meta.job);
+
+                j->name->meta.job = j;
+                j->linked = true;
+
+                /* We're fully installed. Now let's free data we don't
+                 * need anymore. */
+
+                assert(!j->transaction_next);
+                assert(!j->transaction_prev);
+
+                while (j->subject_list)
+                        job_dependency_free(j->subject_list);
+                while (j->object_list)
+                        job_dependency_free(j->object_list);
         }
 
-        if (name->meta.type == _NAME_TYPE_INVALID)
-                return -EINVAL;
+        m->transaction_anchor = NULL;
 
         return 0;
-}
 
-static int service_load_sysv(Service *s) {
-        assert(s);
+rollback:
 
-        /* Load service data from SysV init scripts, preferably with
-         * LSB headers ... */
+        HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+                if (j->linked)
+                        continue;
 
-        return 0;
+                hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
+        }
+
+        return r;
 }
 
-static int name_load_fstab(Name *n) {
-        assert(n);
-        assert(n->meta.type == NAME_MOUNT || n->meta.type == NAME_AUTOMOUNT);
+static int transaction_activate(Manager *m, JobMode mode) {
+        int r;
+        unsigned generation = 1;
 
-        /* Load mount data from /etc/fstab */
+        assert(m);
 
-        return 0;
-}
+        /* This applies the changes recorded in transaction_jobs to
+         * the actual list of jobs, if possible. */
 
-static int snapshot_load(Snapshot *s) {
-        assert(s);
+        /* First step: figure out which jobs matter */
+        transaction_find_jobs_that_matter_to_anchor(m, NULL, generation++);
 
-        /* Load snapshots from disk */
+        /* Second step: Try not to stop any running services if
+         * we don't have to. Don't try to reverse running
+         * jobs if we don't have to. */
+        transaction_minimize_impact(m);
 
-        return 0;
-}
+        for (;;) {
+                /* Third step: Let's remove unneeded jobs that might
+                 * be lurking. */
+                transaction_collect_garbage(m);
 
-static int name_load_dropin(Name *n) {
-        assert(n);
+                /* Fourth step: verify order makes sense and correct
+                 * cycles if necessary and possible */
+                if ((r = transaction_verify_order(m, &generation)) >= 0)
+                        break;
+
+                if (r != -EAGAIN)
+                        goto rollback;
+
+                /* Let's see if the resulting transaction ordering
+                 * graph is still cyclic... */
+        }
+
+        for (;;) {
+                /* Fifth step: let's drop unmergeable entries if
+                 * necessary and possible, merge entries we can
+                 * merge */
+                if ((r = transaction_merge_jobs(m)) >= 0)
+                        break;
 
-        /* Load dependencies from drop-in directories */
+                if (r != -EAGAIN)
+                        goto rollback;
+
+                /* Sixth step: an entry got dropped, let's garbage
+                 * collect its dependencies. */
+                transaction_collect_garbage(m);
+
+                /* Let's see if the resulting transaction still has
+                 * unmergeable entries ... */
+        }
+
+        /* Seventh step: check whether we can actually apply this */
+        if (mode == JOB_FAIL)
+                if ((r = transaction_is_destructive(m, mode)) < 0)
+                        goto rollback;
+
+        /* Eights step: apply changes */
+        if ((r = transaction_apply(m, mode)) < 0)
+                goto rollback;
+
+        assert(hashmap_isempty(m->transaction_jobs));
+        assert(!m->transaction_anchor);
 
         return 0;
+
+rollback:
+        transaction_abort(m);
+        return r;
 }
 
-static int load(Name *name) {
+static Job* transaction_add_one_job(Manager *m, JobType type, Name *name, bool force, bool *is_new) {
+        Job *j, *f;
         int r;
 
+        assert(m);
         assert(name);
 
-        if (name->meta.state != NAME_STUB)
-                return 0;
+        /* Looks for an axisting prospective job and returns that. If
+         * it doesn't exist it is created and added to the prospective
+         * jobs list. */
 
-        if ((r = verify_type(name)) < 0)
-                return r;
+        f = hashmap_get(m->transaction_jobs, name);
+
+        for (j = f; j; j = j->transaction_next) {
+                assert(j->name == name);
+
+                if (j->type == type) {
+                        if (is_new)
+                                *is_new = false;
+                        return j;
+                }
+        }
+
+        if (name->meta.job && name->meta.job->type == type)
+                j = name->meta.job;
+        else if (!(j = job_new(m, type, name)))
+                return NULL;
+
+        if ((r = hashmap_replace(m->transaction_jobs, name, j)) < 0) {
+                job_free(j);
+                return NULL;
+        }
+
+        j->transaction_next = f;
+
+        if (f)
+                f->transaction_prev = j;
+
+        j->generation = 0;
+        j->marker = NULL;
+        j->matters_to_anchor = false;
+        j->forced = force;
+
+        if (is_new)
+                *is_new = true;
 
-        if (name->meta.type == NAME_SERVICE) {
+        return j;
+}
+
+void manager_transaction_unlink_job(Manager *m, Job *j) {
+        assert(m);
+        assert(j);
 
-                /* Load a .service file */
-                if ((r = name_load_fragment(name)) == 0)
-                        goto finish;
+        if (j->transaction_prev)
+                j->transaction_prev->transaction_next = j->transaction_next;
+        else if (j->transaction_next)
+                hashmap_replace(m->transaction_jobs, j->name, j->transaction_next);
+        else
+                hashmap_remove_value(m->transaction_jobs, j->name, j);
 
-                /* Load a classic init script */
-                if (r == -ENOENT)
-                        if ((r = service_load_sysv(SERVICE(name))) == 0)
-                                goto finish;
+        if (j->transaction_next)
+                j->transaction_next->transaction_prev = j->transaction_prev;
 
-        } else if (name->meta.type == NAME_MOUNT ||
-                   name->meta.type == NAME_AUTOMOUNT) {
+        j->transaction_prev = j->transaction_next = NULL;
 
-                if ((r = name_load_fstab(name)) == 0)
-                        goto finish;
+        while (j->subject_list)
+                job_dependency_free(j->subject_list);
 
-        } else if (name->meta.type == NAME_SNAPSHOT) {
+        while (j->object_list) {
+                Job *other = j->object_list->matters ? j->object_list->subject : NULL;
 
-                if ((r = snapshot_load(SNAPSHOT(name))) == 0)
-                        goto finish;
+                job_dependency_free(j->object_list);
 
-        } else {
-                if ((r = name_load_fragment(name)) == 0)
-                        goto finish;
+                if (other) {
+                        log_debug("Deleting job %s/%s as dependency of job %s/%s",
+                                  name_id(other->name), job_type_to_string(other->type),
+                                  name_id(j->name), job_type_to_string(j->type));
+                        transaction_delete_job(m, other);
+                }
         }
+}
 
-        name->meta.state = NAME_FAILED;
+static int transaction_add_job_and_dependencies(Manager *m, JobType type, Name *name, Job *by, bool matters, bool force, Job **_ret) {
+        Job *ret;
+        void *state;
+        Name *dep;
+        int r;
+        bool is_new;
+
+        assert(m);
+        assert(type < _JOB_TYPE_MAX);
+        assert(name);
+
+        if (name->meta.load_state != NAME_LOADED)
+                return -EINVAL;
+
+        if (!job_type_is_applicable(type, name->meta.type))
+                return -EBADR;
+
+        /* First add the job. */
+        if (!(ret = transaction_add_one_job(m, type, name, force, &is_new)))
+                return -ENOMEM;
+
+        /* Then, add a link to the job. */
+        if (!job_dependency_new(by, ret, matters))
+                return -ENOMEM;
+
+        if (is_new) {
+                /* Finally, recursively add in all dependencies. */
+                if (type == JOB_START || type == JOB_RELOAD_OR_START) {
+                        SET_FOREACH(dep, ret->name->meta.dependencies[NAME_REQUIRES], state)
+                                if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
+                                        goto fail;
+                        SET_FOREACH(dep, ret->name->meta.dependencies[NAME_SOFT_REQUIRES], state)
+                                if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, !force, force, NULL)) < 0 && r != -EBADR)
+                                        goto fail;
+                        SET_FOREACH(dep, ret->name->meta.dependencies[NAME_WANTS], state)
+                                if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, false, force, NULL)) < 0 && r != -EBADR)
+                                        goto fail;
+                        SET_FOREACH(dep, ret->name->meta.dependencies[NAME_REQUISITE], state)
+                                if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
+                                        goto fail;
+                        SET_FOREACH(dep, ret->name->meta.dependencies[NAME_SOFT_REQUISITE], state)
+                                if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, !force, force, NULL)) < 0 && r != -EBADR)
+                                        goto fail;
+                        SET_FOREACH(dep, ret->name->meta.dependencies[NAME_CONFLICTS], state)
+                                if ((r = transaction_add_job_and_dependencies(m, JOB_STOP, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
+                                        goto fail;
+
+                } else if (type == JOB_STOP || type == JOB_RESTART || type == JOB_TRY_RESTART) {
+
+                        SET_FOREACH(dep, ret->name->meta.dependencies[NAME_REQUIRED_BY], state)
+                                if ((r = transaction_add_job_and_dependencies(m, type, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
+                                        goto fail;
+                }
+
+                /* JOB_VERIFY_STARTED, JOB_RELOAD require no dependency handling */
+        }
+
+        return 0;
+
+fail:
         return r;
+}
 
-finish:
-        if ((r = name_load_dropin(name)) < 0)
+int manager_add_job(Manager *m, JobType type, Name *name, JobMode mode, bool force, Job **_ret) {
+        int r;
+        Job *ret;
+
+        assert(m);
+        assert(type < _JOB_TYPE_MAX);
+        assert(name);
+        assert(mode < _JOB_MODE_MAX);
+
+        if ((r = transaction_add_job_and_dependencies(m, type, name, NULL, true, force, &ret))) {
+                transaction_abort(m);
+                return r;
+        }
+
+        if ((r = transaction_activate(m, mode)) < 0)
                 return r;
 
-        name->meta.state = NAME_LOADED;
+        if (_ret)
+                *_ret = ret;
+
         return 0;
 }
 
+Job *manager_get_job(Manager *m, uint32_t id) {
+        assert(m);
+
+        return hashmap_get(m->jobs, UINT32_TO_PTR(id));
+}
+
+Name *manager_get_name(Manager *m, const char *name) {
+        assert(m);
+        assert(name);
+
+        return hashmap_get(m->names, name);
+}
+
 static int dispatch_load_queue(Manager *m) {
         Meta *meta;
 
@@ -270,7 +784,7 @@ static int dispatch_load_queue(Manager *m) {
          * tries to load its data until the queue is empty */
 
         while ((meta = m->load_queue)) {
-                load(NAME(meta));
+                name_load(NAME(meta));
                 LIST_REMOVE(Meta, m->load_queue, meta);
         }
 
@@ -311,10 +825,10 @@ int manager_load_name(Manager *m, const char *name, Name **_ret) {
                 return -ENOMEM;
         }
 
-        if (set_put(ret->meta.names, n) < 0) {
+        if ((r = set_put(ret->meta.names, n)) < 0) {
                 name_free(ret);
                 free(n);
-                return -ENOMEM;
+                return r;
         }
 
         if ((r = name_link(ret)) < 0) {
@@ -334,7 +848,7 @@ finish:
         return 0;
 }
 
-void manager_dump_jobs(Manager *s, FILE *f) {
+void manager_dump_jobs(Manager *s, FILE *f, const char *prefix) {
         void *state;
         Job *j;
 
@@ -342,16 +856,39 @@ void manager_dump_jobs(Manager *s, FILE *f) {
         assert(f);
 
         HASHMAP_FOREACH(j, s->jobs, state)
-                job_dump(j, f);
+                job_dump(j, f, prefix);
 }
 
-void manager_dump_names(Manager *s, FILE *f) {
+void manager_dump_names(Manager *s, FILE *f, const char *prefix) {
         void *state;
         Name *n;
+        const char *t;
 
         assert(s);
         assert(f);
 
-        HASHMAP_FOREACH(n, s->names, state)
-                name_dump(n, f);
+        HASHMAP_FOREACH_KEY(n, t, s->names, state)
+                if (name_id(n) == t)
+                        name_dump(n, f, prefix);
+}
+
+void manager_clear_jobs(Manager *m) {
+        Job *j;
+
+        assert(m);
+
+        transaction_abort(m);
+
+        while ((j = hashmap_first(m->jobs)))
+                job_free(j);
+}
+
+void manager_run_jobs(Manager *m) {
+        Job *j;
+        void *state;
+        int r;
+
+        HASHMAP_FOREACH(j, m->jobs, state) {
+                r = job_run_and_invalidate(j);
+        }
 }