ovsdb-data: Consolidate ovsdb atom and json strings.

ovsdb_atom_string and json_string are basically the same data structure
and ovsdb-server frequently needs to convert one to another.  We can
avoid that by using json_string from the beginning for all ovsdb
strings.  So, the conversion turns into simple json_clone(), i.e.
increment of a reference counter.  This change gives a moderate
performance boost in some scenarios, improves the code clarity and
may be useful for future development.

Acked-by: Mike Pattrick <mkp@redhat.com>
Acked-by: Dumitru Ceara <dceara@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

2 files changed, 19 insertions, 33 deletions

diff --git a/lib/ovsdb-data.c b/lib/ovsdb-data.c
index 6654ed6de..2832e94ea 100644
--- a/lib/ovsdb-data.c
+++ b/lib/ovsdb-data.c
@@ -136,7 +136,7 @@ ovsdb_atom_is_default(const union ovsdb_atom *atom,
         return atom->boolean == false;
 
     case OVSDB_TYPE_STRING:
-        return atom->s->string[0] == '\0';
+        return json_string(atom->s)[0] == '\0';
 
     case OVSDB_TYPE_UUID:
         return uuid_is_zero(&atom->uuid);
@@ -172,8 +172,7 @@ ovsdb_atom_clone(union ovsdb_atom *new, const union ovsdb_atom *old,
         break;
 
     case OVSDB_TYPE_STRING:
-        new->s = old->s;
-        new->s->n_refs++;
+        new->s = json_clone(old->s);
         break;
 
     case OVSDB_TYPE_UUID:
@@ -215,7 +214,7 @@ ovsdb_atom_hash(const union ovsdb_atom *atom, enum ovsdb_atomic_type type,
         return hash_boolean(atom->boolean, basis);
 
     case OVSDB_TYPE_STRING:
-        return hash_string(atom->s->string, basis);
+        return json_hash(atom->s, basis);
 
     case OVSDB_TYPE_UUID:
         return hash_int(uuid_hash(&atom->uuid), basis);
@@ -247,7 +246,7 @@ ovsdb_atom_compare_3way(const union ovsdb_atom *a,
         return a->boolean - b->boolean;
 
     case OVSDB_TYPE_STRING:
-        return a->s == b->s ? 0 : strcmp(a->s->string, b->s->string);
+        return a->s == b->s ? 0 : strcmp(json_string(a->s), json_string(b->s));
 
     case OVSDB_TYPE_UUID:
         return uuid_compare_3way(&a->uuid, &b->uuid);
@@ -405,7 +404,7 @@ ovsdb_atom_from_json__(union ovsdb_atom *atom,
 
     case OVSDB_TYPE_STRING:
         if (json->type == JSON_STRING) {
-            atom->s = ovsdb_atom_string_create(json->string);
+            atom->s = json_clone(json);
             return NULL;
         }
         break;
@@ -474,7 +473,7 @@ ovsdb_atom_to_json(const union ovsdb_atom *atom, enum ovsdb_atomic_type type)
         return json_boolean_create(atom->boolean);
 
     case OVSDB_TYPE_STRING:
-        return json_string_create(atom->s->string);
+        return json_clone(atom->s);
 
     case OVSDB_TYPE_UUID:
         return wrap_json("uuid", json_string_create_nocopy(
@@ -726,14 +725,10 @@ ovsdb_atom_to_string(const union ovsdb_atom *atom, enum ovsdb_atomic_type type,
         break;
 
     case OVSDB_TYPE_STRING:
-        if (string_needs_quotes(atom->s->string)) {
-            struct json json;
-
-            json.type = JSON_STRING;
-            json.string = atom->s->string;
-            json_to_ds(&json, 0, out);
+        if (string_needs_quotes(json_string(atom->s))) {
+            json_to_ds(atom->s, 0, out);
         } else {
-            ds_put_cstr(out, atom->s->string);
+            ds_put_cstr(out, json_string(atom->s));
         }
         break;
 
@@ -755,7 +750,7 @@ ovsdb_atom_to_bare(const union ovsdb_atom *atom, enum ovsdb_atomic_type type,
                    struct ds *out)
 {
     if (type == OVSDB_TYPE_STRING) {
-        ds_put_cstr(out, atom->s->string);
+        ds_put_cstr(out, json_string(atom->s));
     } else {
         ovsdb_atom_to_string(atom, type, out);
     }
@@ -882,7 +877,7 @@ ovsdb_atom_check_constraints(const union ovsdb_atom *atom,
         return NULL;
 
     case OVSDB_TYPE_STRING:
-        return check_string_constraints(atom->s->string, &base->string);
+        return check_string_constraints(json_string(atom->s), &base->string);
 
     case OVSDB_TYPE_UUID:
         return NULL;
diff --git a/lib/ovsdb-data.h b/lib/ovsdb-data.h
index f66ed3472..47115a7b8 100644
--- a/lib/ovsdb-data.h
+++ b/lib/ovsdb-data.h
@@ -19,6 +19,7 @@
 #include <stdlib.h>
 #include "compiler.h"
 #include "ovsdb-types.h"
+#include "openvswitch/json.h"
 #include "openvswitch/shash.h"
 #include "util.h"
 
@@ -32,25 +33,16 @@ struct ds;
 struct ovsdb_symbol_table;
 struct smap;
 
-struct ovsdb_atom_string {
-    char *string;
-    size_t n_refs;
-};
-
-static inline struct ovsdb_atom_string *
+static inline struct json *
 ovsdb_atom_string_create_nocopy(char *str)
 {
-    struct ovsdb_atom_string *s = xzalloc(sizeof *s);
-
-    s->string = str;
-    s->n_refs = 1;
-    return s;
+    return json_string_create_nocopy(str);
 }
 
-static inline struct ovsdb_atom_string *
+static inline struct json *
 ovsdb_atom_string_create(const char *str)
 {
-    return ovsdb_atom_string_create_nocopy(xstrdup(str));
+    return json_string_create(str);
 }
 
 /* One value of an atomic type (given by enum ovs_atomic_type). */
@@ -58,7 +50,7 @@ union ovsdb_atom {
     int64_t integer;
     double real;
     bool boolean;
-    struct ovsdb_atom_string *s;
+    struct json *s;
     struct uuid uuid;
 };
 
@@ -88,9 +80,8 @@ ovsdb_atom_needs_destruction(enum ovsdb_atomic_type type)
 static inline void
 ovsdb_atom_destroy(union ovsdb_atom *atom, enum ovsdb_atomic_type type)
 {
-    if (type == OVSDB_TYPE_STRING && !--atom->s->n_refs) {
-        free(atom->s->string);
-        free(atom->s);
+    if (type == OVSDB_TYPE_STRING) {
+        json_destroy(atom->s);
     }
 }