ovsdb/query.c

   1 /* Copyright (c) 2009, 2010 Nicira, Inc.
   2  *
   3  * Licensed under the Apache License, Version 2.0 (the "License");
   4  * you may not use this file except in compliance with the License.
   5  * You may obtain a copy of the License at:
   6  *
   7  *     http://www.apache.org/licenses/LICENSE-2.0
   8  *
   9  * Unless required by applicable law or agreed to in writing, software
  10  * distributed under the License is distributed on an "AS IS" BASIS,
  11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12  * See the License for the specific language governing permissions and
  13  * limitations under the License.
  14  */
  15
  16 #include <config.h>
  17
  18 #include "query.h"
  19
  20 #include "column.h"
  21 #include "condition.h"
  22 #include "row.h"
  23 #include "table.h"
  24
  25 void
  26 ovsdb_query(struct ovsdb_table *table, const struct ovsdb_condition *cnd,
  27             bool (*output_row)(const struct ovsdb_row *, void *aux), void *aux)
  28 {
  29     if (cnd->n_clauses > 0
  30         && cnd->clauses[0].column->index == OVSDB_COL_UUID
  31         && cnd->clauses[0].function == OVSDB_F_EQ) {
  32         /* Optimize the case where the query has a clause of the form "uuid ==
  33          * <some-uuid>", since we have an index on UUID. */
  34         const struct ovsdb_row *row;
  35
  36         row = ovsdb_table_get_row(table, &cnd->clauses[0].arg.keys[0].uuid);
  37         if (row && row->table == table &&
  38             ovsdb_condition_match_every_clause(row, cnd)) {
  39             output_row(row, aux);
  40         }
  41     } else {
  42         /* Linear scan. */
  43         const struct ovsdb_row *row, *next;
  44
  45         HMAP_FOR_EACH_SAFE (row, next, hmap_node, &table->rows) {
  46             if (ovsdb_condition_match_every_clause(row, cnd) &&
  47                 !output_row(row, aux)) {
  48                 break;
  49             }
  50         }
  51     }
  52 }
  53
  54 static bool
  55 query_row_set_cb(const struct ovsdb_row *row, void *results_)
  56 {
  57     struct ovsdb_row_set *results = results_;
  58     ovsdb_row_set_add_row(results, row);
  59     return true;
  60 }
  61
  62 void
  63 ovsdb_query_row_set(struct ovsdb_table *table,
  64                     const struct ovsdb_condition *condition,
  65                     struct ovsdb_row_set *results)
  66 {
  67     ovsdb_query(table, condition, query_row_set_cb, results);
  68 }
  69
  70 static bool
  71 query_distinct_cb(const struct ovsdb_row *row, void *hash_)
  72 {
  73     struct ovsdb_row_hash *hash = hash_;
  74     ovsdb_row_hash_insert(hash, row);
  75     return true;
  76 }
  77
  78 void
  79 ovsdb_query_distinct(struct ovsdb_table *table,
  80                      const struct ovsdb_condition *condition,
  81                      const struct ovsdb_column_set *columns,
  82                      struct ovsdb_row_set *results)
  83 {
  84     if (!columns || ovsdb_column_set_contains(columns, OVSDB_COL_UUID)) {
  85         /* All the result rows are guaranteed to be distinct anyway. */
  86         ovsdb_query_row_set(table, condition, results);
  87         return;
  88     } else {
  89         /* Use hash table to drop duplicates. */
  90         struct ovsdb_row_hash_node *node;
  91         struct ovsdb_row_hash hash;
  92
  93         ovsdb_row_hash_init(&hash, columns);
  94         ovsdb_query(table, condition, query_distinct_cb, &hash);
  95         HMAP_FOR_EACH (node, hmap_node, &hash.rows) {
  96             ovsdb_row_set_add_row(results, node->row);
  97         }
  98         ovsdb_row_hash_destroy(&hash, false);
  99     }
 100 }