ovsdb/query.c

   1 /* Copyright (c) 2009 Nicira Networks
   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 && ovsdb_condition_evaluate(row, cnd)) {
  38             output_row(row, aux);
  39         }
  40     } else {
  41         /* Linear scan. */
  42         const struct ovsdb_row *row, *next;
  43
  44         HMAP_FOR_EACH_SAFE (row, next, struct ovsdb_row, hmap_node,
  45                             &table->rows) {
  46             if (ovsdb_condition_evaluate(row, cnd) && !output_row(row, aux)) {
  47                 break;
  48             }
  49         }
  50     }
  51 }
  52
  53 static bool
  54 query_row_set_cb(const struct ovsdb_row *row, void *results_)
  55 {
  56     struct ovsdb_row_set *results = results_;
  57     ovsdb_row_set_add_row(results, row);
  58     return true;
  59 }
  60
  61 void
  62 ovsdb_query_row_set(struct ovsdb_table *table,
  63                     const struct ovsdb_condition *condition,
  64                     struct ovsdb_row_set *results)
  65 {
  66     ovsdb_query(table, condition, query_row_set_cb, results);
  67 }
  68
  69 static bool
  70 query_distinct_cb(const struct ovsdb_row *row, void *hash_)
  71 {
  72     struct ovsdb_row_hash *hash = hash_;
  73     ovsdb_row_hash_insert(hash, row);
  74     return true;
  75 }
  76
  77 void
  78 ovsdb_query_distinct(struct ovsdb_table *table,
  79                      const struct ovsdb_condition *condition,
  80                      const struct ovsdb_column_set *columns,
  81                      struct ovsdb_row_set *results)
  82 {
  83     if (!columns || ovsdb_column_set_contains(columns, OVSDB_COL_UUID)) {
  84         /* All the result rows are guaranteed to be distinct anyway. */
  85         return ovsdb_query_row_set(table, condition, results);
  86     } else {
  87         /* Use hash table to drop duplicates. */
  88         struct ovsdb_row_hash_node *node;
  89         struct ovsdb_row_hash hash;
  90
  91         ovsdb_row_hash_init(&hash, columns);
  92         ovsdb_query(table, condition, query_distinct_cb, &hash);
  93         HMAP_FOR_EACH (node, struct ovsdb_row_hash_node, hmap_node,
  94                        &hash.rows) {
  95             ovsdb_row_set_add_row(results, node->row);
  96         }
  97         ovsdb_row_hash_destroy(&hash, false);
  98     }
  99 }