/*-*- Mode: C; c-basic-offset: 8 -*-*/
#include <assert.h>
+#include <errno.h>
#include "macro.h"
#include "job.h"
job_dependency_free(l);
}
-void job_dump(Job *j, FILE*f, const char *prefix) {
+const char* job_type_to_string(JobType t) {
static const char* const job_type_table[_JOB_TYPE_MAX] = {
[JOB_START] = "start",
[JOB_TRY_RESTART] = "try-restart",
};
+
+ if (t < 0 || t >= _JOB_TYPE_MAX)
+ return "n/a";
+
+ return job_type_table[t];
+}
+
+void job_dump(Job *j, FILE*f, const char *prefix) {
+
static const char* const job_state_table[_JOB_STATE_MAX] = {
[JOB_WAITING] = "waiting",
[JOB_RUNNING] = "running",
"%s\tAction: %s → %s\n"
"%s\tState: %s\n",
prefix, j->id,
- prefix, name_id(j->name), job_type_table[j->type],
+ prefix, name_id(j->name), job_type_to_string(j->type),
prefix, job_state_table[j->state]);
}
return false;
}
+
+static bool types_match(JobType a, JobType b, JobType c, JobType d) {
+ return
+ (a == c && b == d) ||
+ (a == d && b == c);
+}
+
+int job_type_merge(JobType *a, JobType b) {
+ if (*a == b)
+ return 0;
+
+ /* Merging is associative! a merged with b merged with c is
+ * the same as a merged with c merged with b. */
+
+ /* Mergeability is transitive! if a can be merged with b and b
+ * with c then a also with c */
+
+ /* Also, if a merged with b cannot be merged with c, then
+ * either a or b cannot be merged with c either */
+
+ 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;
+ else
+ return -EEXIST;
+
+ return 0;
+}
+
+bool job_type_mergeable(JobType a, JobType b) {
+ return job_type_merge(&a, b) >= 0;
+}
+
+bool job_type_is_superset(JobType a, JobType b) {
+
+ /* Checks whether operation a is a "superset" of b */
+
+ if (a == b)
+ return true;
+
+ switch (a) {
+ case JOB_START:
+ return b == JOB_VERIFY_STARTED;
+
+ case JOB_RELOAD:
+ return b == JOB_VERIFY_STARTED;
+
+ case JOB_RELOAD_OR_START:
+ return
+ b == JOB_RELOAD ||
+ b == JOB_START;
+
+ case JOB_RESTART:
+ return
+ b == JOB_START ||
+ b == JOB_VERIFY_STARTED ||
+ b == JOB_RELOAD ||
+ b == JOB_RELOAD_OR_START ||
+ b == JOB_TRY_RESTART;
+
+ case JOB_TRY_RESTART:
+ return
+ b == JOB_VERIFY_STARTED ||
+ b == JOB_RELOAD;
+ default:
+ return false;
+
+ }
+}
assert(m);
assert(j);
+ /* 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);
+ /* 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 */
}
}
-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;
-
- 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 void transaction_merge_and_delete_job(Manager *m, Job *j, Job *other, JobType t) {
JobDependency *l, *last;
assert(j->name == other->name);
assert(!j->linked);
+ /* Merges 'other' into 'j' and then deletes j. */
+
j->type = t;
j->state = JOB_WAITING;
transaction_delete_job(m, other);
}
+static int delete_one_unmergable_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_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", name_id(d->name));
+ transaction_delete_job(m, d);
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
static int transaction_merge_jobs(Manager *m) {
Job *j;
void *state;
assert(m);
+ /* 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_unmergable_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;
+ }
+ }
+
+ /* Second step, merge the jobs. */
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;
+ assert_se(job_type_merge(&t, k->type) == 0);
while ((k = j->transaction_next)) {
if (j->linked) {
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;
+
+ return false;
+}
+
static int transaction_verify_order_one(Manager *m, Job *j, Job *from, unsigned generation) {
void *state;
Name *n;
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. */
+ * 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->matters_to_anchor) {
+
+ 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", name_id(k->name));
- transaction_delete_job(m, k);
+ transaction_delete_name(m, k->name);
return -EAGAIN;
}
break;
}
- return -ELOOP;
+ return -ENOEXEC;
}
+ /* 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;
- /* We assume that the the dependencies are both-ways, and
+ /* 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;
+ /* 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;
}
static int transaction_verify_order(Manager *m, unsigned *generation) {
- bool again;
+ Job *j;
+ int r;
+ void *state;
+
assert(m);
assert(generation);
- do {
- Job *j;
- int r;
- void *state;
-
- again = false;
-
- HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+ /* Check if the ordering graph is cyclic. If it is, try to fix
+ * that up by dropping one of the jobs. */
- /* Assume merged */
- assert(!j->transaction_next);
- assert(!j->transaction_prev);
-
- if ((r = transaction_verify_order_one(m, j, NULL, (*generation)++)) < 0) {
-
- /* There was a cycleq, but it was fixed,
- * we need to restart our algorithm */
- if (r == -EAGAIN) {
- again = true;
- break;
- }
-
- return r;
- }
- }
- } while (again);
+ HASHMAP_FOREACH(j, m->transaction_jobs, state)
+ if ((r = transaction_verify_order_one(m, j, NULL, (*generation)++)) < 0)
+ return r;
return 0;
}
assert(m);
+ /* Drop jobs that are not required by any other job */
+
do {
void *state;
Job *j;
* existing jobs would be replaced */
HASHMAP_FOREACH(j, m->transaction_jobs, state)
- if (j->name->meta.job && j->name->meta.job != j)
+ 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;
Job *j;
int r;
+ /* Moves the transaction jobs to the set of active jobs */
+
HASHMAP_FOREACH(j, m->transaction_jobs, state) {
if (j->linked)
continue;
job_dependency_free(j->object_list);
}
+ m->transaction_anchor = NULL;
+
return 0;
rollback:
/* 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;
+ for (;;) {
+ /* Second step: Let's remove unneeded jobs that might
+ * be lurking. */
+ transaction_collect_garbage(m);
- /* Third step: verify order makes sense */
- if ((r = transaction_verify_order(m, &generation)) < 0)
- goto rollback;
+ /* Third step: verify order makes sense and correct
+ * cycles if necessary and possible */
+ if ((r = transaction_verify_order(m, &generation)) >= 0)
+ break;
- /* Third step: do garbage colletion */
- transaction_collect_garbage(m);
+ if (r != -EAGAIN)
+ goto rollback;
- /* Fourth step: check whether we can actually apply this */
+ /* Let's see if the resulting transaction ordering
+ * graph is still cyclic... */
+ }
+
+ for (;;) {
+ /* Fourth step: let's drop unmergable entries if
+ * necessary and possible, merge entries we can
+ * merge */
+ if ((r = transaction_merge_jobs(m)) >= 0)
+ break;
+
+ if (r != -EAGAIN)
+ goto rollback;
+
+ /* Fifth step: an entry got dropped, let's garbage
+ * collect its dependencies. */
+ transaction_collect_garbage(m);
+
+ /* Let's see if the resulting transaction still has
+ * unmergable entries ... */
+ }
+
+ /* Sith 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 */
+ /* Seventh step: apply changes */
if ((r = transaction_apply(m, mode)) < 0)
goto rollback;
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) {
int main(int argc, char *argv[]) {
Manager *m = NULL;
- Name *a = NULL, *b = NULL, *c = NULL, *d = NULL, *e;
+ Name *a = NULL, *b = NULL, *c = NULL, *d = NULL, *e = NULL, *g = NULL;
Job *j;
assert_se(chdir("test2") == 0);
manager_dump_names(m, stdout, "\t");
printf("Test2: (Cyclic Order, Unfixable)\n");
- assert_se(manager_add_job(m, JOB_START, d, JOB_REPLACE, false, &j) == -ELOOP);
+ assert_se(manager_add_job(m, JOB_START, d, JOB_REPLACE, false, &j) == -ENOEXEC);
manager_dump_jobs(m, stdout, "\t");
- printf("Test3: (Cyclic Order, Fixable)\n");
+ printf("Test3: (Cyclic Order, Fixable, Garbage Collector)\n");
assert_se(manager_add_job(m, JOB_START, e, JOB_REPLACE, false, &j) == 0);
manager_dump_jobs(m, stdout, "\t");
+ printf("Test4: (Identical transaction)\n");
+ assert_se(manager_add_job(m, JOB_START, e, JOB_FAIL, false, &j) == 0);
+ manager_dump_jobs(m, stdout, "\t");
+
+ printf("Loaded3:\n");
+ assert_se(manager_load_name(m, "g.service", &g) == 0);
+ manager_dump_names(m, stdout, "\t");
+
+ printf("Test5: (Colliding transaction, fail)\n");
+ assert_se(manager_add_job(m, JOB_START, g, JOB_FAIL, false, &j) == -EEXIST);
+
+ printf("Test6: (Colliding transaction, replace)\n");
+ assert_se(manager_add_job(m, JOB_START, g, JOB_REPLACE, false, &j) == 0);
+ manager_dump_jobs(m, stdout, "\t");
+
manager_free(m);
return 0;
~ianmdlvl / elogind.git / commitdiff