unit: properly update references to units which are merged

When we merge units that some kind of object points to, those pointers
might become invalidated, and needs to be updated. Introduce a UnitRef
struct which links up all the unit references, to ensure corrected
references.

At the same time, drop configured_sockets in the Service object, and
replace it by proper UNIT_TRIGGERS resp. UNIT_TRIGGERED_BY dependencies,
which allow us to simplify a lot of code.

1 files changed, 22 insertions, 0 deletions

diff --git a/src/unit.h b/src/unit.h
index b32c1a702e..4d83309591 100644
--- a/src/unit.h
+++ b/src/unit.h
@@ -32,6 +32,7 @@ typedef enum UnitType UnitType;
 typedef enum UnitLoadState UnitLoadState;
 typedef enum UnitActiveState UnitActiveState;
 typedef enum UnitDependency UnitDependency;
+typedef struct UnitRef UnitRef;
 
 #include "set.h"
 #include "util.h"
@@ -119,6 +120,10 @@ enum UnitDependency {
         /* On Failure */
         UNIT_ON_FAILURE,
 
+        /* Triggers (i.e. a socket triggers a service) */
+        UNIT_TRIGGERS,
+        UNIT_TRIGGERED_BY,
+
         /* Reference information for GC logic */
         UNIT_REFERENCES,              /* Inverse of 'references' is 'referenced_by' */
         UNIT_REFERENCED_BY,
@@ -156,6 +161,9 @@ struct Meta {
 
         usec_t job_timeout;
 
+        /* References to this */
+        LIST_HEAD(UnitRef, refs);
+
         /* Conditions to check */
         LIST_HEAD(Condition, conditions);
 
@@ -237,6 +245,15 @@ struct Meta {
         bool in_audit:1;
 };
 
+struct UnitRef {
+        /* Keeps tracks of references to a unit. This is useful so
+         * that we can merge two units if necessary and correct all
+         * references to them */
+
+        Unit* unit;
+        LIST_FIELDS(UnitRef, refs);
+};
+
 #include "service.h"
 #include "timer.h"
 #include "socket.h"
@@ -536,6 +553,11 @@ bool unit_condition_test(Unit *u);
 
 UnitFileState unit_get_unit_file_state(Unit *u);
 
+Unit* unit_ref_set(UnitRef *ref, Unit *u);
+void unit_ref_unset(UnitRef *ref);
+
+#define UNIT_DEREF(ref) ((ref).unit)
+
 const char *unit_load_state_to_string(UnitLoadState i);
 UnitLoadState unit_load_state_from_string(const char *s);