core: add internal API to remove dependencies again, based on dependency mask

poettering · poettering · commit c999cf385aee · 2017-11-10T19:45:29.000+01:00
let's make use of the dependency mask, and add internal API to remove
dependencies ago, based on bits in the dependency mask.
diff --git a/src/core/unit.c b/src/core/unit.c
@@ -4831,3 +4831,72 @@ int unit_fork_helper_process(Unit *u, pid_t *ret) {
         *ret = pid;
         return 1;
 }
+
+static void unit_update_dependency_mask(Unit *u, UnitDependency d, Unit *other, UnitDependencyInfo di) {
+        assert(u);
+        assert(d >= 0);
+        assert(d < _UNIT_DEPENDENCY_MAX);
+        assert(other);
+
+        if (di.origin_mask == 0 && di.destination_mask == 0) {
+                /* No bit set anymore, let's drop the whole entry */
+                assert_se(hashmap_remove(u->dependencies[d], other));
+                log_unit_debug(u, "%s lost dependency %s=%s", u->id, unit_dependency_to_string(d), other->id);
+        } else
+                /* Mask was reduced, let's update the entry */
+                assert_se(hashmap_update(u->dependencies[d], other, di.data) == 0);
+}
+
+void unit_remove_dependencies(Unit *u, UnitDependencyMask mask) {
+        UnitDependency d;
+
+        assert(u);
+
+        /* Removes all dependencies u has on other units marked for ownership by 'mask'. */
+
+        if (mask == 0)
+                return;
+
+        for (d = 0; d < _UNIT_DEPENDENCY_MAX; d++) {
+                bool done;
+
+                do {
+                        UnitDependencyInfo di;
+                        Unit *other;
+                        Iterator i;
+
+                        done = true;
+
+                        HASHMAP_FOREACH_KEY(di.data, other, u->dependencies[d], i) {
+                                UnitDependency q;
+
+                                if ((di.origin_mask & ~mask) == di.origin_mask)
+                                        continue;
+                                di.origin_mask &= ~mask;
+                                unit_update_dependency_mask(u, d, other, di);
+
+                                /* We updated the dependency from our unit to the other unit now. But most dependencies
+                                 * imply a reverse dependency. Hence, let's delete that one too. For that we go through
+                                 * all dependency types on the other unit and delete all those which point to us and
+                                 * have the right mask set. */
+
+                                for (q = 0; q < _UNIT_DEPENDENCY_MAX; q++) {
+                                        UnitDependencyInfo dj;
+
+                                        dj.data = hashmap_get(other->dependencies[q], u);
+                                        if ((dj.destination_mask & ~mask) == dj.destination_mask)
+                                                continue;
+                                        dj.destination_mask &= ~mask;
+
+                                        unit_update_dependency_mask(other, q, u, dj);
+                                }
+
+                                unit_add_to_gc_queue(other);
+
+                                done = false;
+                                break;
+                        }
+
+                } while (!done);
+        }
+}
diff --git a/src/core/unit.h b/src/core/unit.h
@@ -740,6 +740,8 @@ void unit_set_exec_params(Unit *s, ExecParameters *p);
 
 int unit_fork_helper_process(Unit *u, pid_t *ret);
 
+void unit_remove_dependencies(Unit *u, UnitDependencyMask mask);
+
 /* Macros which append UNIT= or USER_UNIT= to the message */
 
 #define log_unit_full(unit, level, error, ...)                          \
diff --git a/src/test/test-engine.c b/src/test/test-engine.c
@@ -115,6 +115,33 @@ int main(int argc, char *argv[]) {
         assert_se(manager_add_job(m, JOB_START, h, JOB_FAIL, NULL, &j) == 0);
         manager_dump_jobs(m, stdout, "\t");
 
+        assert_se(!hashmap_get(a->dependencies[UNIT_PROPAGATES_RELOAD_TO], b));
+        assert_se(!hashmap_get(b->dependencies[UNIT_RELOAD_PROPAGATED_FROM], a));
+        assert_se(!hashmap_get(a->dependencies[UNIT_PROPAGATES_RELOAD_TO], c));
+        assert_se(!hashmap_get(c->dependencies[UNIT_RELOAD_PROPAGATED_FROM], a));
+
+        assert_se(unit_add_dependency(a, UNIT_PROPAGATES_RELOAD_TO, b, true, UNIT_DEPENDENCY_UDEV) == 0);
+        assert_se(unit_add_dependency(a, UNIT_PROPAGATES_RELOAD_TO, c, true, UNIT_DEPENDENCY_PROC_SWAP) == 0);
+
+        assert_se(hashmap_get(a->dependencies[UNIT_PROPAGATES_RELOAD_TO], b));
+        assert_se(hashmap_get(b->dependencies[UNIT_RELOAD_PROPAGATED_FROM], a));
+        assert_se(hashmap_get(a->dependencies[UNIT_PROPAGATES_RELOAD_TO], c));
+        assert_se(hashmap_get(c->dependencies[UNIT_RELOAD_PROPAGATED_FROM], a));
+
+        unit_remove_dependencies(a, UNIT_DEPENDENCY_UDEV);
+
+        assert_se(!hashmap_get(a->dependencies[UNIT_PROPAGATES_RELOAD_TO], b));
+        assert_se(!hashmap_get(b->dependencies[UNIT_RELOAD_PROPAGATED_FROM], a));
+        assert_se(hashmap_get(a->dependencies[UNIT_PROPAGATES_RELOAD_TO], c));
+        assert_se(hashmap_get(c->dependencies[UNIT_RELOAD_PROPAGATED_FROM], a));
+
+        unit_remove_dependencies(a, UNIT_DEPENDENCY_PROC_SWAP);
+
+        assert_se(!hashmap_get(a->dependencies[UNIT_PROPAGATES_RELOAD_TO], b));
+        assert_se(!hashmap_get(b->dependencies[UNIT_RELOAD_PROPAGATED_FROM], a));
+        assert_se(!hashmap_get(a->dependencies[UNIT_PROPAGATES_RELOAD_TO], c));
+        assert_se(!hashmap_get(c->dependencies[UNIT_RELOAD_PROPAGATED_FROM], a));
+
         manager_free(m);
 
         return 0;
