core: split dependency types into atoms

1 files changed, 196 insertions, 0 deletions

diff --git a/src/core/unit-dependency-atom.c b/src/core/unit-dependency-atom.c
new file mode 100644
index 0000000000..4b012ed265
--- /dev/null
+++ b/src/core/unit-dependency-atom.c
@@ -0,0 +1,196 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "unit-dependency-atom.h"
+
+static const UnitDependencyAtom atom_map[_UNIT_DEPENDENCY_MAX] = {
+        /* A table that maps high-level dependency types to low-level dependency "atoms". The latter actually
+         * describe specific facets of dependency behaviour. The former combine them into one user-facing
+         * concept. Atoms are a bit mask, though a bunch of dependency types have only a single bit set.
+         *
+         * Typically when the user configures a dependency they go via dependency type, but when we act on
+         * them we go by atom.
+         *
+         * NB: when you add a new dependency type here, make sure to also add one to the (best-effort)
+         * reverse table in unit_dependency_from_unique_atom() further down. */
+
+        [UNIT_REQUIRES]               = UNIT_ATOM_PULL_IN_START |
+                                        UNIT_ATOM_RETROACTIVE_START_REPLACE |
+                                        UNIT_ATOM_ADD_STOP_WHEN_UNNEEDED_QUEUE |
+                                        UNIT_ATOM_ADD_DEFAULT_TARGET_DEPENDENCY_QUEUE,
+
+        [UNIT_REQUISITE]              = UNIT_ATOM_PULL_IN_VERIFY |
+                                        UNIT_ATOM_ADD_STOP_WHEN_UNNEEDED_QUEUE |
+                                        UNIT_ATOM_ADD_DEFAULT_TARGET_DEPENDENCY_QUEUE,
+
+        [UNIT_WANTS]                  = UNIT_ATOM_PULL_IN_START_IGNORED |
+                                        UNIT_ATOM_RETROACTIVE_START_FAIL |
+                                        UNIT_ATOM_ADD_STOP_WHEN_UNNEEDED_QUEUE |
+                                        UNIT_ATOM_ADD_DEFAULT_TARGET_DEPENDENCY_QUEUE,
+
+        [UNIT_BINDS_TO]               = UNIT_ATOM_PULL_IN_START |
+                                        UNIT_ATOM_RETROACTIVE_START_REPLACE |
+                                        UNIT_ATOM_CANNOT_BE_ACTIVE_WITHOUT |
+                                        UNIT_ATOM_ADD_STOP_WHEN_UNNEEDED_QUEUE |
+                                        UNIT_ATOM_ADD_DEFAULT_TARGET_DEPENDENCY_QUEUE,
+
+        [UNIT_PART_OF]                = UNIT_ATOM_ADD_DEFAULT_TARGET_DEPENDENCY_QUEUE,
+
+        [UNIT_REQUIRED_BY]            = UNIT_ATOM_PROPAGATE_STOP |
+                                        UNIT_ATOM_PROPAGATE_RESTART |
+                                        UNIT_ATOM_PROPAGATE_START_FAILURE |
+                                        UNIT_ATOM_PINS_STOP_WHEN_UNNEEDED |
+                                        UNIT_ATOM_DEFAULT_TARGET_DEPENDENCIES,
+
+        [UNIT_REQUISITE_OF]           = UNIT_ATOM_PROPAGATE_STOP |
+                                        UNIT_ATOM_PROPAGATE_RESTART |
+                                        UNIT_ATOM_PROPAGATE_START_FAILURE |
+                                        UNIT_ATOM_PROPAGATE_INACTIVE_START_AS_FAILURE |
+                                        UNIT_ATOM_PINS_STOP_WHEN_UNNEEDED |
+                                        UNIT_ATOM_DEFAULT_TARGET_DEPENDENCIES,
+
+        [UNIT_WANTED_BY]              = UNIT_ATOM_DEFAULT_TARGET_DEPENDENCIES |
+                                        UNIT_ATOM_PINS_STOP_WHEN_UNNEEDED,
+
+        [UNIT_BOUND_BY]               = UNIT_ATOM_RETROACTIVE_STOP_ON_STOP |
+                                        UNIT_ATOM_PROPAGATE_STOP |
+                                        UNIT_ATOM_PROPAGATE_RESTART |
+                                        UNIT_ATOM_PROPAGATE_START_FAILURE |
+                                        UNIT_ATOM_PINS_STOP_WHEN_UNNEEDED |
+                                        UNIT_ATOM_DEFAULT_TARGET_DEPENDENCIES,
+
+        [UNIT_CONSISTS_OF]            = UNIT_ATOM_PROPAGATE_STOP |
+                                        UNIT_ATOM_PROPAGATE_RESTART,
+
+        [UNIT_CONFLICTS]              = UNIT_ATOM_PULL_IN_STOP |
+                                        UNIT_ATOM_RETROACTIVE_STOP_ON_START,
+
+        [UNIT_CONFLICTED_BY]          = UNIT_ATOM_PULL_IN_STOP_IGNORED |
+                                        UNIT_ATOM_RETROACTIVE_STOP_ON_START |
+                                        UNIT_ATOM_PROPAGATE_STOP_FAILURE,
+
+        /* These are simple dependency types: they consist of a single atom only */
+        [UNIT_BEFORE]                 = UNIT_ATOM_BEFORE,
+        [UNIT_AFTER]                  = UNIT_ATOM_AFTER,
+        [UNIT_ON_FAILURE]             = UNIT_ATOM_ON_FAILURE,
+        [UNIT_TRIGGERS]               = UNIT_ATOM_TRIGGERS,
+        [UNIT_TRIGGERED_BY]           = UNIT_ATOM_TRIGGERED_BY,
+        [UNIT_PROPAGATES_RELOAD_TO]   = UNIT_ATOM_PROPAGATES_RELOAD_TO,
+        [UNIT_JOINS_NAMESPACE_OF]     = UNIT_ATOM_JOINS_NAMESPACE_OF,
+        [UNIT_REFERENCES]             = UNIT_ATOM_REFERENCES,
+        [UNIT_REFERENCED_BY]          = UNIT_ATOM_REFERENCED_BY,
+
+        /* These are dependency types without effect on our state engine. We maintain them only to make
+         * things discoverable/debuggable as they are the inverse dependencies to some of the above. As they
+         * have no effect of their own, they all map to no atoms at all, i.e. the value 0. */
+        [UNIT_RELOAD_PROPAGATED_FROM] = 0,
+};
+
+UnitDependencyAtom unit_dependency_to_atom(UnitDependency d) {
+        if (d < 0)
+                return _UNIT_DEPENDENCY_ATOM_INVALID;
+
+        assert(d < _UNIT_DEPENDENCY_MAX);
+
+        return atom_map[d];
+}
+
+UnitDependency unit_dependency_from_unique_atom(UnitDependencyAtom atom) {
+
+        /* This is a "best-effort" function that maps the specified 'atom' mask to a dependency type that is
+         * is equal to or has a superset of bits set if that's uniquely possible. The idea is that this
+         * function is used when iterating through deps that have a specific atom: if there's exactly one
+         * dependency type of the specific atom we don't need iterate through all deps a unit has, but can
+         * pinpoint things directly.
+         *
+         * This function will return _UNIT_DEPENDENCY_INVALID in case the specified value is not known or not
+         * uniquely defined, i.e. there are multiple dependencies with the atom or the combination set. */
+
+        switch ((int64_t) atom) {
+
+                /* Note that we can't list UNIT_REQUIRES here since it's a true subset of UNIT_BINDS_TO, and
+                 * hence its atom bits not uniquely mappable. */
+
+        case UNIT_ATOM_PULL_IN_VERIFY |
+                UNIT_ATOM_ADD_STOP_WHEN_UNNEEDED_QUEUE |
+                UNIT_ATOM_ADD_DEFAULT_TARGET_DEPENDENCY_QUEUE:
+        case UNIT_ATOM_PULL_IN_VERIFY: /* a single dep type uses this atom */
+                return UNIT_REQUISITE;
+
+        case UNIT_ATOM_PULL_IN_START_IGNORED |
+                UNIT_ATOM_RETROACTIVE_START_FAIL |
+                UNIT_ATOM_ADD_STOP_WHEN_UNNEEDED_QUEUE |
+                UNIT_ATOM_ADD_DEFAULT_TARGET_DEPENDENCY_QUEUE:
+        case UNIT_ATOM_RETROACTIVE_START_FAIL:
+                return UNIT_WANTS;
+
+        case UNIT_ATOM_PULL_IN_START |
+                UNIT_ATOM_RETROACTIVE_START_REPLACE |
+                UNIT_ATOM_CANNOT_BE_ACTIVE_WITHOUT |
+                UNIT_ATOM_ADD_STOP_WHEN_UNNEEDED_QUEUE |
+                UNIT_ATOM_ADD_DEFAULT_TARGET_DEPENDENCY_QUEUE:
+        case UNIT_ATOM_CANNOT_BE_ACTIVE_WITHOUT:
+                return UNIT_BINDS_TO;
+
+        case UNIT_ATOM_PROPAGATE_STOP |
+                UNIT_ATOM_PROPAGATE_RESTART |
+                UNIT_ATOM_PROPAGATE_START_FAILURE |
+                UNIT_ATOM_PROPAGATE_INACTIVE_START_AS_FAILURE |
+                UNIT_ATOM_PINS_STOP_WHEN_UNNEEDED |
+                UNIT_ATOM_DEFAULT_TARGET_DEPENDENCIES:
+        case UNIT_ATOM_PROPAGATE_INACTIVE_START_AS_FAILURE:
+                return UNIT_REQUISITE_OF;
+
+        case UNIT_ATOM_RETROACTIVE_STOP_ON_STOP |
+                UNIT_ATOM_PROPAGATE_STOP |
+                UNIT_ATOM_PROPAGATE_RESTART |
+                UNIT_ATOM_PROPAGATE_START_FAILURE |
+                UNIT_ATOM_PINS_STOP_WHEN_UNNEEDED |
+                UNIT_ATOM_DEFAULT_TARGET_DEPENDENCIES:
+        case UNIT_ATOM_RETROACTIVE_STOP_ON_STOP:
+                return UNIT_BOUND_BY;
+
+        case UNIT_ATOM_PULL_IN_STOP |
+                UNIT_ATOM_RETROACTIVE_STOP_ON_START:
+        case UNIT_ATOM_PULL_IN_STOP:
+                return UNIT_CONFLICTS;
+
+        case UNIT_ATOM_PULL_IN_STOP_IGNORED |
+                UNIT_ATOM_RETROACTIVE_STOP_ON_START |
+                UNIT_ATOM_PROPAGATE_STOP_FAILURE:
+        case UNIT_ATOM_PULL_IN_STOP_IGNORED:
+        case UNIT_ATOM_PROPAGATE_STOP_FAILURE:
+                return UNIT_CONFLICTED_BY;
+
+        /* And now, the simple ones */
+
+        case UNIT_ATOM_BEFORE:
+                return UNIT_BEFORE;
+
+        case UNIT_ATOM_AFTER:
+                return UNIT_AFTER;
+
+        case UNIT_ATOM_ON_FAILURE:
+                return UNIT_ON_FAILURE;
+
+        case UNIT_ATOM_TRIGGERS:
+                return UNIT_TRIGGERS;
+
+        case UNIT_ATOM_TRIGGERED_BY:
+                return UNIT_TRIGGERED_BY;
+
+        case UNIT_ATOM_PROPAGATES_RELOAD_TO:
+                return UNIT_PROPAGATES_RELOAD_TO;
+
+        case UNIT_ATOM_JOINS_NAMESPACE_OF:
+                return UNIT_JOINS_NAMESPACE_OF;
+
+        case UNIT_ATOM_REFERENCES:
+                return UNIT_REFERENCES;
+
+        case UNIT_ATOM_REFERENCED_BY:
+                return UNIT_REFERENCED_BY;
+
+        default:
+                return _UNIT_DEPENDENCY_INVALID;
+        }
+}