manager: when two pending jobs conflict, keep the one that "conflicts", remove the one that is "conflicted"

This gives the writer of units control which unit is kept and which is
stopped when two units conflict.

1 files changed, 59 insertions, 11 deletions

diff --git a/src/manager.c b/src/manager.c
index 9b6cbc94e0..ddb253ae4e 100644
--- a/src/manager.c
+++ b/src/manager.c
@@ -715,6 +715,20 @@ static void transaction_merge_and_delete_job(Manager *m, Job *j, Job *other, Job
         other->object_list = NULL;
         transaction_delete_job(m, other, true);
 }
+static bool job_is_conflicted_by(Job *j) {
+        JobDependency *l;
+
+        assert(j);
+
+        /* Returns true if this job is pulled in by a least one
+         * ConflictedBy dependency. */
+
+        LIST_FOREACH(object, l, j->object_list)
+                if (l->conflicts)
+                        return true;
+
+        return false;
+}
 
 static int delete_one_unmergeable_job(Manager *m, Job *j) {
         Job *k;
@@ -738,7 +752,36 @@ static int delete_one_unmergeable_job(Manager *m, Job *j) {
 
                         /* Ok, we found two that conflict, let's see if we can
                          * drop one of them */
-                        if (!j->matters_to_anchor)
+                        if (!j->matters_to_anchor && !k->matters_to_anchor) {
+
+                                /* Both jobs don't matter, so let's
+                                 * find the one that is smarter to
+                                 * remove. Let's think positive and
+                                 * rather remove stops then starts --
+                                 * except if something is being
+                                 * stopped because it is conflicted by
+                                 * another unit in which case we
+                                 * rather remove the start. */
+
+                                log_debug("Looking at job %s/%s conflicted_by=%s", j->unit->meta.id, job_type_to_string(j->type), yes_no(j->type == JOB_STOP && job_is_conflicted_by(j)));
+                                log_debug("Looking at job %s/%s conflicted_by=%s", k->unit->meta.id, job_type_to_string(k->type), yes_no(k->type == JOB_STOP && job_is_conflicted_by(k)));
+
+                                if (j->type == JOB_STOP) {
+
+                                        if (job_is_conflicted_by(j))
+                                                d = k;
+                                        else
+                                                d = j;
+
+                                } else if (k->type == JOB_STOP) {
+
+                                        if (job_is_conflicted_by(k))
+                                                d = j;
+                                        else
+                                                d = k;
+                                }
+
+                        } else if (!j->matters_to_anchor)
                                 d = j;
                         else if (!k->matters_to_anchor)
                                 d = k;
@@ -1324,6 +1367,7 @@ static int transaction_add_job_and_dependencies(
                 Job *by,
                 bool matters,
                 bool override,
+                bool conflicts,
                 DBusError *e,
                 Job **_ret) {
         Job *ret;
@@ -1352,46 +1396,50 @@ static int transaction_add_job_and_dependencies(
                 return -ENOMEM;
 
         /* Then, add a link to the job. */
-        if (!job_dependency_new(by, ret, matters))
+        if (!job_dependency_new(by, ret, matters, conflicts))
                 return -ENOMEM;
 
         if (is_new) {
                 /* Finally, recursively add in all dependencies. */
                 if (type == JOB_START || type == JOB_RELOAD_OR_START) {
                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUIRES], i)
-                                if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, true, override, e, NULL)) < 0 && r != -EBADR)
+                                if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, true, override, false, e, NULL)) < 0 && r != -EBADR)
                                         goto fail;
 
                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUIRES_OVERRIDABLE], i)
-                                if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, !override, override, e, NULL)) < 0 && r != -EBADR) {
+                                if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, !override, override, false, e, NULL)) < 0 && r != -EBADR) {
                                         log_warning("Cannot add dependency job for unit %s, ignoring: %s", dep->meta.id, bus_error(e, r));
                                         dbus_error_free(e);
                                 }
 
                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_WANTS], i)
-                                if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, false, false, e, NULL)) < 0) {
+                                if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, false, false, false, e, NULL)) < 0) {
                                         log_warning("Cannot add dependency job for unit %s, ignoring: %s", dep->meta.id, bus_error(e, r));
                                         dbus_error_free(e);
                                 }
 
                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUISITE], i)
-                                if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, true, override, e, NULL)) < 0 && r != -EBADR)
+                                if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, true, override, false, e, NULL)) < 0 && r != -EBADR)
                                         goto fail;
 
                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUISITE_OVERRIDABLE], i)
-                                if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, !override, override, e, NULL)) < 0 && r != -EBADR) {
+                                if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, !override, override, false, e, NULL)) < 0 && r != -EBADR) {
                                         log_warning("Cannot add dependency job for unit %s, ignoring: %s", dep->meta.id, bus_error(e, r));
                                         dbus_error_free(e);
                                 }
 
                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_CONFLICTS], i)
-                                if ((r = transaction_add_job_and_dependencies(m, JOB_STOP, dep, ret, true, override, e, NULL)) < 0 && r != -EBADR)
+                                if ((r = transaction_add_job_and_dependencies(m, JOB_STOP, dep, ret, true, override, true, e, NULL)) < 0 && r != -EBADR)
+                                        goto fail;
+
+                        SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_CONFLICTED_BY], i)
+                                if ((r = transaction_add_job_and_dependencies(m, JOB_STOP, dep, ret, true, override, false, e, NULL)) < 0 && r != -EBADR)
                                         goto fail;
 
                 } else if (type == JOB_STOP || type == JOB_RESTART || type == JOB_TRY_RESTART) {
 
                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUIRED_BY], i)
-                                if ((r = transaction_add_job_and_dependencies(m, type, dep, ret, true, override, e, NULL)) < 0 && r != -EBADR)
+                                if ((r = transaction_add_job_and_dependencies(m, type, dep, ret, true, override, false, e, NULL)) < 0 && r != -EBADR)
                                         goto fail;
                 }
 
@@ -1432,7 +1480,7 @@ static int transaction_add_isolate_jobs(Manager *m) {
                 if (hashmap_get(m->transaction_jobs, u))
                         continue;
 
-                if ((r = transaction_add_job_and_dependencies(m, JOB_STOP, u, NULL, true, false, NULL, NULL)) < 0)
+                if ((r = transaction_add_job_and_dependencies(m, JOB_STOP, u, NULL, true, false, false, NULL, NULL)) < 0)
                         log_warning("Cannot add isolate job for unit %s, ignoring: %s", u->meta.id, strerror(-r));
         }
 
@@ -1455,7 +1503,7 @@ int manager_add_job(Manager *m, JobType type, Unit *unit, JobMode mode, bool ove
 
         log_debug("Trying to enqueue job %s/%s", unit->meta.id, job_type_to_string(type));
 
-        if ((r = transaction_add_job_and_dependencies(m, type, unit, NULL, true, override, e, &ret)) < 0) {
+        if ((r = transaction_add_job_and_dependencies(m, type, unit, NULL, true, override, false, e, &ret)) < 0) {
                 transaction_abort(m);
                 return r;
         }