ovsdb: Provide a way for for_each_txn_row() callback to delete any row.

[sliver-openvswitch.git] / ovsdb / transaction.c

diff --git a/ovsdb/transaction.c b/ovsdb/transaction.c
index b7c57e5..f67018b 100644 (file)
--- a/ovsdb/transaction.c
+++ b/ovsdb/transaction.c
@@ -57,9 +57,11 @@ struct ovsdb_txn_table {
  *
  *      - A row modified by a transaction will have non-null 'old' and 'new'.
  *
- *      - 'old' and 'new' both null is invalid.  It would indicate that a row
- *        was added then deleted within a single transaction, but we instead
- *        handle that case by deleting the txn_row entirely.
+ *      - 'old' and 'new' both null indicates that a row was added then deleted
+ *        within a single transaction.  Most of the time we instead delete the
+ *        ovsdb_txn_row entirely, but inside a for_each_txn_row() callback
+ *        there are restrictions that sometimes mean we have to leave the
+ *        ovsdb_txn_row in place.
  */
 struct ovsdb_txn_row {
     struct hmap_node hmap_node; /* In ovsdb_txn_table's txn_rows hmap. */
@@ -67,6 +69,12 @@ struct ovsdb_txn_row {
     struct ovsdb_row *new;      /* The new row. */
     size_t n_refs;              /* Number of remaining references. */
 
+    /* These members are the same as the corresponding members of 'old' or
+     * 'new'.  They are present here for convenience and because occasionally
+     * there can be an ovsdb_txn_row where both 'old' and 'new' are NULL. */
+    struct uuid uuid;
+    struct ovsdb_table *table;
+
     /* Used by for_each_txn_row(). */
     unsigned int serial;        /* Serial number of in-progress commit. */
 
@@ -110,7 +118,9 @@ ovsdb_txn_row_abort(struct ovsdb_txn *txn OVS_UNUSED,
 
     ovsdb_txn_row_prefree(txn_row);
     if (!old) {
-        hmap_remove(&new->table->rows, &new->hmap_node);
+        if (new) {
+            hmap_remove(&new->table->rows, &new->hmap_node);
+        }
     } else if (!new) {
         hmap_insert(&old->table->rows, &old->hmap_node, ovsdb_row_hash(old));
     } else {
@@ -140,10 +150,7 @@ find_txn_row(const struct ovsdb_table *table, const struct uuid *uuid)
 
     HMAP_FOR_EACH_WITH_HASH (txn_row, hmap_node,
                              uuid_hash(uuid), &table->txn_table->txn_rows) {
-        const struct ovsdb_row *row;
-
-        row = txn_row->old ? txn_row->old : txn_row->new;
-        if (uuid_equals(uuid, ovsdb_row_get_uuid(row))) {
+        if (uuid_equals(uuid, &txn_row->uuid)) {
             return txn_row;
         }
     }
@@ -208,7 +215,7 @@ ovsdb_txn_adjust_row_refs(struct ovsdb_txn *txn, const struct ovsdb_row *r,
 static struct ovsdb_error * WARN_UNUSED_RESULT
 update_row_ref_count(struct ovsdb_txn *txn, struct ovsdb_txn_row *r)
 {
-    struct ovsdb_table *table = r->old ? r->old->table : r->new->table;
+    struct ovsdb_table *table = r->table;
     struct shash_node *node;
 
     SHASH_FOR_EACH (node, &table->schema->columns) {
@@ -241,8 +248,7 @@ check_ref_count(struct ovsdb_txn *txn OVS_UNUSED, struct ovsdb_txn_row *r)
         return ovsdb_error("referential integrity violation",
                            "cannot delete %s row "UUID_FMT" because "
                            "of %zu remaining reference(s)",
-                           r->old->table->schema->name,
-                           UUID_ARGS(ovsdb_row_get_uuid(r->old)),
+                           r->table->schema->name, UUID_ARGS(&r->uuid),
                            r->n_refs);
     }
 }
@@ -328,7 +334,7 @@ assess_weak_refs(struct ovsdb_txn *txn, struct ovsdb_txn_row *txn_row)
         return NULL;
     }
 
-    table = txn_row->new->table;
+    table = txn_row->table;
     SHASH_FOR_EACH (node, &table->schema->columns) {
         const struct ovsdb_column *column = node->data;
         struct ovsdb_datum *datum = &txn_row->new->fields[column->index];
@@ -412,9 +418,8 @@ assess_weak_refs(struct ovsdb_txn *txn, struct ovsdb_txn_row *txn_row)
 static struct ovsdb_error * WARN_UNUSED_RESULT
 determine_changes(struct ovsdb_txn *txn, struct ovsdb_txn_row *txn_row)
 {
-    struct ovsdb_table *table;
+    struct ovsdb_table *table = txn_row->table;
 
-    table = (txn_row->old ? txn_row->old : txn_row->new)->table;
     if (txn_row->old && txn_row->new) {
         struct shash_node *node;
         bool changed = false;
@@ -534,7 +539,7 @@ ovsdb_txn_for_each_change(const struct ovsdb_txn *txn,
 
     LIST_FOR_EACH (t, node, &txn->txn_tables) {
         HMAP_FOR_EACH (r, hmap_node, &t->txn_rows) {
-            if (!cb(r->old, r->new, r->changed, aux)) {
+            if ((r->old || r->new) && !cb(r->old, r->new, r->changed, aux)) {
                 break;
             }
         }
@@ -560,6 +565,7 @@ static struct ovsdb_txn_row *
 ovsdb_txn_row_create(struct ovsdb_txn *txn, struct ovsdb_table *table,
                      const struct ovsdb_row *old_, struct ovsdb_row *new)
 {
+    const struct ovsdb_row *row = old_ ? old_ : new;
     struct ovsdb_row *old = (struct ovsdb_row *) old_;
     size_t n_columns = shash_count(&table->schema->columns);
     struct ovsdb_txn_table *txn_table;
@@ -567,7 +573,9 @@ ovsdb_txn_row_create(struct ovsdb_txn *txn, struct ovsdb_table *table,
 
     txn_row = xzalloc(offsetof(struct ovsdb_txn_row, changed)
                       + bitmap_n_bytes(n_columns));
-    txn_row->old = (struct ovsdb_row *) old;
+    txn_row->uuid = *ovsdb_row_get_uuid(row);
+    txn_row->table = row->table;
+    txn_row->old = old;
     txn_row->new = new;
     txn_row->n_refs = old ? old->n_refs : 0;
     txn_row->serial = serial - 1;
@@ -663,8 +671,7 @@ ovsdb_txn_get_comment(const struct ovsdb_txn *txn)
 static void
 ovsdb_txn_row_prefree(struct ovsdb_txn_row *txn_row)
 {
-    struct ovsdb_row *row = txn_row->old ? txn_row->old : txn_row->new;
-    struct ovsdb_txn_table *txn_table = row->table->txn_table;
+    struct ovsdb_txn_table *txn_table = txn_row->table->txn_table;
 
     txn_table->n_processed--;
     hmap_remove(&txn_table->txn_rows, &txn_row->hmap_node);
@@ -697,6 +704,9 @@ ovsdb_txn_table_destroy(struct ovsdb_txn_table *txn_table)
  * in within the same txn_table.  It may *not* delete any txn_tables.  As long
  * as these rules are followed, 'cb' will be called exactly once for each
  * txn_row in 'txn', even those added by 'cb'.
+ *
+ * (Even though 'cb' is not allowed to delete some txn_rows, it can still
+ * delete any actual row by clearing a txn_row's 'new' member.)
  */
 static struct ovsdb_error * WARN_UNUSED_RESULT
 for_each_txn_row(struct ovsdb_txn *txn,