implement transaction engine

1 files changed, 467 insertions, 89 deletions

diff --git a/manager.c b/manager.c
index d2708aacf3..a870db6cce 100644
--- a/manager.c
+++ b/manager.c
@@ -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;
@@ -37,19 +34,19 @@ 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);
-
-        /* FIXME: This is incomplete */
-
-        hashmap_free(m->jobs_to_add);
-        set_free(m->jobs_to_remove);
+        hashmap_free(m->transaction_jobs);
 
         free(m);
 }
@@ -58,140 +55,521 @@ static void transaction_abort(Manager *m) {
         Job *j;
 
         assert(m);
-        assert(m->n_dependency_depth == 0);
 
-        while ((j = hashmap_steal_first(m->jobs_to_add)))
-                job_free(j);
+        while ((j = hashmap_first(m->transaction_jobs)))
+                if (j->linked)
+                        manager_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);
+
+        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 bool types_match(JobType a, JobType b, JobType c, JobType d) {
+        return
+                (a == c && b == d) ||
+                (a == d && b == c);
+}
+
+static int types_merge(JobType *a, JobType b) {
+        if (*a == b)
+                return 0;
 
-        set_clear(m->jobs_to_remove);
+        if (types_match(*a, b, JOB_START, JOB_VERIFY_STARTED))
+                *a = JOB_START;
+        else if (types_match(*a, b, JOB_START, JOB_RELOAD) ||
+                 types_match(*a, b, JOB_START, JOB_RELOAD_OR_START) ||
+                 types_match(*a, b, JOB_VERIFY_STARTED, JOB_RELOAD_OR_START) ||
+                 types_match(*a, b, JOB_RELOAD, JOB_RELOAD_OR_START))
+                *a = JOB_RELOAD_OR_START;
+        else if (types_match(*a, b, JOB_START, JOB_RESTART) ||
+                 types_match(*a, b, JOB_START, JOB_TRY_RESTART) ||
+                 types_match(*a, b, JOB_VERIFY_STARTED, JOB_RESTART) ||
+                 types_match(*a, b, JOB_RELOAD, JOB_RESTART) ||
+                 types_match(*a, b, JOB_RELOAD_OR_START, JOB_RESTART) ||
+                 types_match(*a, b, JOB_RELOAD_OR_START, JOB_TRY_RESTART) ||
+                 types_match(*a, b, JOB_RESTART, JOB_TRY_RESTART))
+                *a = JOB_RESTART;
+        else if (types_match(*a, b, JOB_VERIFY_STARTED, JOB_RELOAD))
+                *a = JOB_RELOAD;
+        else if (types_match(*a, b, JOB_VERIFY_STARTED, JOB_TRY_RESTART) ||
+                 types_match(*a, b, JOB_RELOAD, JOB_TRY_RESTART))
+                *a = JOB_TRY_RESTART;
+
+        return -EEXIST;
 }
 
-static int transaction_activate(Manager *m) {
+static void manager_merge_and_delete_prospective_job(Manager *m, Job *j, Job *other, JobType t) {
+        JobDependency *l, *last;
+
+        assert(j);
+        assert(other);
+        assert(j->name == other->name);
+        assert(!j->linked);
+
+        j->type = t;
+        j->state = JOB_WAITING;
+
+        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;
+        manager_transaction_delete_job(m, other);
+}
+
+static int transaction_merge_jobs(Manager *m) {
         Job *j;
+        void *state;
+        int r;
+
+        assert(m);
+
+        HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+                JobType t = j->type;
+                Job *k;
+
+                for (k = j->transaction_next; k; k = k->transaction_next)
+                        if ((r = types_merge(&t, k->type)) < 0)
+                                return r;
+
+                while ((k = j->transaction_next)) {
+                        if (j->linked) {
+                                manager_merge_and_delete_prospective_job(m, k, j, t);
+                                j = k;
+                        } else
+                                manager_merge_and_delete_prospective_job(m, j, k, t);
+                }
+
+                assert(!j->transaction_next);
+                assert(!j->transaction_prev);
+        }
+
+        return r;
+}
+
+static int transaction_verify_order_one(Manager *m, Job *j, Job *from, unsigned generation) {
+        void *state;
+        Name *n;
         int r;
+
+        assert(m);
+        assert(j);
+
+        /* Did we find a loop? */
+        if (j->marker && j->generation == generation) {
+                Job *k;
+
+                /* So, we already have been here. We have a
+                 * loop. Let's try to break it. We go backwards in our
+                 * path and try to find a suitable job to remove. */
+
+                for (k = from; k; k = (k->generation == generation ? k->marker : NULL)) {
+                        if (!k->matters_to_anchor) {
+                                manager_transaction_delete_job(m, k);
+                                return -EAGAIN;
+                        }
+
+                        /* Check if this in fact was the beginning of
+                         * the loop */
+                        if (k == j)
+                                break;
+                }
+
+                return -ELOOP;
+        }
+
+        j->marker = from;
+        j->generation = generation;
+
+        /* We assume that the the dependencies are both-ways, and
+         * hence can ignore NAME_AFTER */
+
+        SET_FOREACH(n, j->name->meta.dependencies[NAME_BEFORE], state) {
+                Job *o;
+
+                if (!(o = hashmap_get(m->transaction_jobs, n)))
+                        if (!(o = n->meta.job))
+                                continue;
+
+                if ((r = transaction_verify_order_one(m, o, j, generation)) < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static int transaction_verify_order(Manager *m, unsigned *generation) {
+        bool again;
+        assert(m);
+        assert(generation);
+
+        do {
+                Job *j;
+                int r;
+                void *state;
+
+                again = false;
+
+                HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+
+                        /* Assume merged */
+                        assert(!j->transaction_next);
+                        assert(!j->transaction_prev);
+
+                        if ((r = transaction_verify_order_one(m, j, NULL, (*generation)++)) < 0)  {
+
+                                /* There was a loop, but it was fixed,
+                                 * we need to restart our algorithm */
+                                if (r == -EAGAIN) {
+                                        again = true;
+                                        break;
+                                }
+
+                                return r;
+                        }
+                }
+        } while (again);
+
+        return 0;
+}
+
+static void transaction_collect_garbage(Manager *m) {
+        bool again;
+
+        assert(m);
+
+        do {
+                void *state;
+                Job *j;
+
+                again = false;
+
+                HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+                        if (j->object_list)
+                                continue;
+
+                        manager_transaction_delete_job(m, j);
+                        again = true;
+                        break;
+                }
+
+        } while (again);
+}
+
+static int transaction_is_destructive(Manager *m, JobMode mode) {
         void *state;
+        Job *j;
 
         assert(m);
-        assert(m->n_dependency_depth == 0);
 
-        /* This applies the changes recorded in jobs_to_add and
-         * jobs_to_remove to the actual list of jobs */
+        /* Checks whether applying this transaction means that
+         * existing jobs would be replaced */
 
-        HASHMAP_FOREACH(j, m->jobs_to_add, state) {
-                assert(!j->linked);
+        HASHMAP_FOREACH(j, m->transaction_jobs, state)
+                if (j->name->meta.job && j->name->meta.job != j)
+                        return -EEXIST;
 
-                if ((r = hashmap_put(j->manager->jobs, UINT32_TO_PTR(j->id), j)) < 0)
+        return 0;
+}
+
+static int transaction_apply(Manager *m, JobMode mode) {
+        void *state;
+        Job *j;
+        int r;
+
+        HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+                if (j->linked)
+                        continue;
+
+                if ((r = hashmap_put(m->jobs, UINT32_TO_PTR(j->id), j)) < 0)
                         goto rollback;
         }
 
-        /* all entries are now registered, now make sure the names
-         * know about that. */
+        while ((j = hashmap_steal_first(m->transaction_jobs))) {
+                if (j->linked)
+                        continue;
+
+                if (j->name->meta.job)
+                        job_free(j->name->meta.job);
 
-        while ((j = hashmap_steal_first(m->jobs_to_add))) {
                 j->name->meta.job = j;
                 j->linked = true;
-        }
 
-        while ((j = set_steal_first(m->jobs_to_remove)))
-                job_free(j);
+                /* 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);
+        }
 
         return 0;
 
 rollback:
 
-        HASHMAP_FOREACH(j, m->jobs_to_add, state)
-                hashmap_remove(j->manager->jobs, UINT32_TO_PTR(j->id));
+        HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+                if (j->linked)
+                        continue;
+
+                hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
+        }
+
+        return r;
+}
+
+
+static int transaction_activate(Manager *m, JobMode mode) {
+        int r;
+        unsigned generation = 1;
+
+        assert(m);
+
+        /* This applies the changes recorded in transaction_jobs to
+         * the actual list of jobs, if possible. */
+
+        /* First step: figure out which jobs matter */
+        transaction_find_jobs_that_matter_to_anchor(m, NULL, generation++);
+
+        /* Second step: let's merge entries we can merge */
+        if ((r = transaction_merge_jobs(m)) < 0)
+                goto rollback;
+
+        /* Third step: verify order makes sense */
+        if ((r = transaction_verify_order(m, &generation)) < 0)
+                goto rollback;
+
+        /* Third step: do garbage colletion */
+        transaction_collect_garbage(m);
+
+        /* Fourth step: check whether we can actually apply this */
+        if (mode == JOB_FAIL)
+                if ((r = transaction_is_destructive(m, mode)) < 0)
+                        goto rollback;
+
+        /* Fifth 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;
 }
 
-int manager_add_job(Manager *m, JobType type, Name *name, JobMode mode, Job **_ret) {
-        Job *ret, *other;
-        void *state;
-        Name *dep;
+static Job* transaction_add_job(Manager *m, JobType type, Name *name, bool *is_new) {
+        Job *j, *f;
         int r;
 
         assert(m);
-        assert(type < _JOB_TYPE_MAX);
         assert(name);
-        assert(mode < _JOB_MODE_MAX);
 
-        /* Check for conflicts, first against the jobs we shall
-         * create */
-        if ((other = hashmap_get(m->jobs_to_add, name))) {
+        /* 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 (other->type != type)
-                        return -EEXIST;
+        f = hashmap_get(m->transaction_jobs, name);
 
-        } else if (name->meta.job) {
+        for (j = f; j; j = j->transaction_next) {
+                assert(j->name == name);
 
-                if (name->meta.job->type != type) {
+                if (j->type == type) {
+                        if (is_new)
+                                *is_new = false;
+                        return j;
+                }
+        }
 
-                        if (mode == JOB_FAIL)
-                                return -EEXIST;
+        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 = set_put(m->jobs_to_remove, name->meta.job)) < 0)
-                                return r;
-                }
+        if ((r = hashmap_replace(m->transaction_jobs, name, j)) < 0) {
+                job_free(j);
+                return NULL;
         }
 
-        if (!(ret = job_new(m, type, name)))
-                return -ENOMEM;
+        j->transaction_next = f;
 
-        m->n_dependency_depth ++;
+        if (f)
+                f->transaction_prev = j;
 
-        if ((r = hashmap_put(m->jobs_to_add, name, ret)) < 0)
-                goto fail;
+        j->generation = 0;
+        j->marker = NULL;
+        j->matters_to_anchor = false;
 
-        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;
-        }
+        if (is_new)
+                *is_new = true;
 
-        if (--m->n_dependency_depth <= 0)
-                if ((r = transaction_activate(m)) < 0) {
-                        transaction_abort(m);
-                        return r;
-                }
+        return j;
+}
 
+void manager_transaction_delete_job(Manager *m, Job *j) {
+        assert(m);
+        assert(j);
 
-        if (_ret)
-                *_ret = ret;
+        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);
+
+        if (j->transaction_next)
+                j->transaction_next->transaction_prev = j->transaction_prev;
+
+        j->transaction_prev = j->transaction_next = NULL;
+
+        while (j->subject_list)
+                job_dependency_free(j->subject_list);
+        while (j->object_list)
+                job_dependency_free(j->object_list);
+}
+
+static int real_add_job(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);
+
+        /* First add the job. */
+        if (!(ret = transaction_add_job(m, type, name, &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 = real_add_job(m, JOB_START, dep, ret, true, force, NULL)) < 0)
+                                        goto fail;
+                        SET_FOREACH(dep, ret->name->meta.dependencies[NAME_SOFT_REQUIRES], state)
+                                if ((r = real_add_job(m, JOB_START, dep, ret, !force, force, NULL)) < 0)
+                                        goto fail;
+                        SET_FOREACH(dep, ret->name->meta.dependencies[NAME_WANTS], state)
+                                if ((r = real_add_job(m, JOB_START, dep, ret, false, force, NULL)) < 0)
+                                        goto fail;
+                        SET_FOREACH(dep, ret->name->meta.dependencies[NAME_REQUISITE], state)
+                                if ((r = real_add_job(m, JOB_VERIFY_STARTED, dep, ret, true, force, NULL)) < 0)
+                                        goto fail;
+                        SET_FOREACH(dep, ret->name->meta.dependencies[NAME_SOFT_REQUISITE], state)
+                                if ((r = real_add_job(m, JOB_VERIFY_STARTED, dep, ret, !force, force, NULL)) < 0)
+                                        goto fail;
+                        SET_FOREACH(dep, ret->name->meta.dependencies[NAME_CONFLICTS], state)
+                                if ((r = real_add_job(m, JOB_STOP, dep, ret, true, force, 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 = real_add_job(m, type, dep, ret, true, force, NULL)) < 0)
+                                        goto fail;
+                }
+
+                /* JOB_VERIFY_STARTED, JOB_RELOAD require no dependency handling */
+        }
 
         return 0;
 
 fail:
-        job_free(ret);
+        return r;
+}
+
+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 (--m->n_dependency_depth <= 0)
+        if ((r = real_add_job(m, type, name, NULL, true, force, &ret))) {
                 transaction_abort(m);
+                return r;
+        }
 
-        return r;
-}
+        if ((r = transaction_activate(m, mode)) < 0)
+                return r;
+
+        if (_ret)
+                *_ret = ret;
 
+        return 0;
+}
 
 Job *manager_get_job(Manager *m, uint32_t id) {
         assert(m);
@@ -314,7 +692,7 @@ finish:
         if ((r = name_load_dropin(name)) < 0)
                 return r;
 
-        if ((r = name_link_names(name)) < 0)
+        if ((r = name_link_names(name, true)) < 0)
                 return r;
 
         name->meta.state = NAME_LOADED;