[ovs-dev] [PATCH] classifier: Refactor table priority updates and tables_priority reordering.

Ben Pfaff blp at nicira.com
Mon Feb 11 18:35:21 UTC 2013


I find this organization clearer.

CC: Jarno Rajahalme <jarno.rajahalme at nsn.com>
Signed-off-by: Ben Pfaff <blp at nicira.com>
---
 lib/classifier.c |  190 ++++++++++++++++++++++++++++++++----------------------
 1 files changed, 114 insertions(+), 76 deletions(-)

diff --git a/lib/classifier.c b/lib/classifier.c
index 5ab8ba9..bcf7a36 100644
--- a/lib/classifier.c
+++ b/lib/classifier.c
@@ -33,11 +33,18 @@ static struct cls_table *insert_table(struct classifier *,
 
 static void destroy_table(struct classifier *, struct cls_table *);
 
+static void update_table_after_insertion(struct classifier *,
+                                         struct cls_table *,
+                                         unsigned int new_priority);
+static void update_table_after_removal(struct classifier *, struct cls_table *,
+                                       unsigned int del_priority);
+
 static struct cls_rule *find_match(const struct cls_table *,
                                    const struct flow *);
 static struct cls_rule *find_equal(struct cls_table *,
                                    const struct miniflow *, uint32_t hash);
-static struct cls_rule *insert_rule(struct cls_table *, struct cls_rule *);
+static struct cls_rule *insert_rule(struct classifier *,
+                                    struct cls_table *, struct cls_rule *);
 
 /* Iterates RULE over HEAD and all of the cls_rules on HEAD->list. */
 #define FOR_EACH_RULE_IN_LIST(RULE, HEAD)                               \
@@ -166,52 +173,6 @@ classifier_count(const struct classifier *cls)
     return cls->n_rules;
 }
 
-static void
-classifier_update_table_max_priority(struct classifier *cls,
-                                     struct cls_table *table,
-                                     unsigned int priority)
-{
-    struct cls_table *iter = table;
-
-    if (priority > table->max_priority) {
-        /* Possibly move 'table' earlier in the priority list.  If we break out
-         * of the loop, then 'table' should be moved just after that 'iter'.
-         * If the loop terminates normally, then 'iter' will be the list head
-         * and we'll move table just after that (e.g. to the front of the
-         * list). */
-        LIST_FOR_EACH_REVERSE_CONTINUE (iter, list_node,
-                                        &cls->tables_priority) {
-            if (iter->max_priority >= priority) {
-                break;
-            }
-        }
-
-        /* Move 'table' just after 'iter' (unless it's already there). */
-        if (iter->list_node.next != &table->list_node) {
-            list_splice(iter->list_node.next,
-                        &table->list_node, table->list_node.next);
-        }
-    } else if (priority < table->max_priority) {
-        /* Possibly move 'table' earlier in the priority list.  If we break out
-         * of the loop, then 'table' should be moved just before that 'iter'.
-         * If the loop terminates normally, then 'iter' will be the list head
-         * and we'll move table just before that (e.g. to the back of the
-         * list). */
-        LIST_FOR_EACH_CONTINUE (iter, list_node, &cls->tables_priority) {
-            if (iter->max_priority <= priority) {
-                break;
-            }
-        }
-
-        /* Move 'table' just before 'iter' (unless it's already there). */
-        if (iter->list_node.prev != &table->list_node) {
-            list_splice(&iter->list_node,
-                        &table->list_node, table->list_node.next);
-        }
-    }
-    table->max_priority = priority;
-}
-
 /* Inserts 'rule' into 'cls'.  Until 'rule' is removed from 'cls', the caller
  * must not modify or free it.
  *
@@ -236,16 +197,7 @@ classifier_replace(struct classifier *cls, struct cls_rule *rule)
         table = insert_table(cls, &rule->match.mask);
     }
 
-    old_rule = insert_rule(table, rule);
-
-    if (rule->priority > table->max_priority) {
-        classifier_update_table_max_priority(cls, table, rule->priority);
-        table->max_count = 1;
-    } else if (!old_rule && rule->priority == table->max_priority) {
-        /* Only if we are not replacing an old entry. */
-        ++table->max_count;
-    }
-
+    old_rule = insert_rule(cls, table, rule);
     if (!old_rule) {
         table->n_table_rules++;
         cls->n_rules++;
@@ -291,20 +243,8 @@ classifier_remove(struct classifier *cls, struct cls_rule *rule)
 
     if (--table->n_table_rules == 0) {
         destroy_table(cls, table);
-    } else if (rule->priority == table->max_priority
-               && --table->max_count == 0) {
-        /* Maintain table's max_priority. */
-        struct cls_rule *head;
-        unsigned int new_max_priority = 0;
-        HMAP_FOR_EACH (head, hmap_node, &table->rules) {
-            if (head->priority > new_max_priority) {
-                new_max_priority = head->priority;
-                table->max_count = 1;
-            } else if (head->priority == new_max_priority) {
-                ++table->max_count;
-            }
-        }
-        classifier_update_table_max_priority(cls, table, new_max_priority);
+    } else {
+        update_table_after_removal(cls, table, rule->priority);
     }
     cls->n_rules--;
 }
@@ -603,6 +543,96 @@ destroy_table(struct classifier *cls, struct cls_table *table)
     free(table);
 }
 
+/* This function performs the following updates for 'table' in 'cls' following
+ * the addition of a new rule with priority 'new_priority' to 'table':
+ *
+ *    - Update 'table->max_priority' and 'table->max_count' if necessary.
+ *
+ *    - Update 'table''s position in 'cls->tables_priority' if necessary.
+ *
+ * This function should only be called after adding a new rule, not after
+ * replacing a rule by an identical one or modifying a rule in-place. */
+static void
+update_table_after_insertion(struct classifier *cls, struct cls_table *table,
+                             unsigned int new_priority)
+{
+    if (new_priority == table->max_priority) {
+        ++table->max_count;
+    } else if (new_priority > table->max_priority) {
+        struct cls_table *iter;
+
+        table->max_priority = new_priority;
+        table->max_count = 1;
+
+        /* Possibly move 'table' earlier in the priority list.  If we break out
+         * of the loop, then 'table' should be moved just after that 'iter'.
+         * If the loop terminates normally, then 'iter' will be the list head
+         * and we'll move table just after that (e.g. to the front of the
+         * list). */
+        iter = table;
+        LIST_FOR_EACH_REVERSE_CONTINUE (iter, list_node,
+                                        &cls->tables_priority) {
+            if (iter->max_priority >= table->max_priority) {
+                break;
+            }
+        }
+
+        /* Move 'table' just after 'iter' (unless it's already there). */
+        if (iter->list_node.next != &table->list_node) {
+            list_splice(iter->list_node.next,
+                        &table->list_node, table->list_node.next);
+        }
+    }
+}
+
+/* This function performs the following updates for 'table' in 'cls' following
+ * the deletion of a rule with priority 'del_priority' from 'table':
+ *
+ *    - Update 'table->max_priority' and 'table->max_count' if necessary.
+ *
+ *    - Update 'table''s position in 'cls->tables_priority' if necessary.
+ *
+ * This function should only be called after removing a rule, not after
+ * replacing a rule by an identical one or modifying a rule in-place. */
+static void
+update_table_after_removal(struct classifier *cls, struct cls_table *table,
+                           unsigned int del_priority)
+{
+    struct cls_table *iter;
+
+    if (del_priority == table->max_priority && --table->max_count == 0) {
+        struct cls_rule *head;
+
+        table->max_priority = 0;
+        HMAP_FOR_EACH (head, hmap_node, &table->rules) {
+            if (head->priority > table->max_priority) {
+                table->max_priority = head->priority;
+                table->max_count = 1;
+            } else if (head->priority == table->max_priority) {
+                ++table->max_count;
+            }
+        }
+
+        /* Possibly move 'table' earlier in the priority list.  If we break out
+         * of the loop, then 'table' should be moved just before that 'iter'.
+         * If the loop terminates normally, then 'iter' will be the list head
+         * and we'll move table just before that (e.g. to the back of the
+         * list). */
+        iter = table;
+        LIST_FOR_EACH_CONTINUE (iter, list_node, &cls->tables_priority) {
+            if (iter->max_priority <= table->max_priority) {
+                break;
+            }
+        }
+
+        /* Move 'table' just before 'iter' (unless it's already there). */
+        if (iter->list_node.prev != &table->list_node) {
+            list_splice(&iter->list_node,
+                        &table->list_node, table->list_node.next);
+        }
+    }
+}
+
 static struct cls_rule *
 find_match(const struct cls_table *table, const struct flow *flow)
 {
@@ -633,9 +663,11 @@ find_equal(struct cls_table *table, const struct miniflow *flow, uint32_t hash)
 }
 
 static struct cls_rule *
-insert_rule(struct cls_table *table, struct cls_rule *new)
+insert_rule(struct classifier *cls,
+            struct cls_table *table, struct cls_rule *new)
 {
     struct cls_rule *head;
+    struct cls_rule *old = NULL;
 
     new->hmap_node.hash = miniflow_hash_in_minimask(&new->match.flow,
                                                     &new->match.mask, 0);
@@ -644,7 +676,7 @@ insert_rule(struct cls_table *table, struct cls_rule *new)
     if (!head) {
         hmap_insert(&table->rules, &new->hmap_node, new->hmap_node.hash);
         list_init(&new->list);
-        return NULL;
+        goto out;
     } else {
         /* Scan the list for the insertion point that will keep the list in
          * order of decreasing priority. */
@@ -659,18 +691,24 @@ insert_rule(struct cls_table *table, struct cls_rule *new)
 
                 if (new->priority == rule->priority) {
                     list_replace(&new->list, &rule->list);
-                    return rule;
+                    old = rule;
+                    goto out;
                 } else {
                     list_insert(&rule->list, &new->list);
-                    return NULL;
+                    goto out;
                 }
             }
         }
 
         /* Insert 'new' at the end of the list. */
         list_push_back(&head->list, &new->list);
-        return NULL;
     }
+
+ out:
+    if (!old) {
+        update_table_after_insertion(cls, table, new->priority);
+    }
+    return old;
 }
 
 static struct cls_rule *
-- 
1.7.2.5




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