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1c4dd4246c
cmap implements duplicates as linked lists, which causes removal of rules to become (O^2) with large number of duplicates. This patch fixes the problem by introducing a new 'counting' variant of the cmap (ccmap), which can be efficiently used to keep counts of inserted hash values provided by the caller. This does not require a node in the user data structure, so this makes the user implementation a bit more memory efficient, too. Signed-off-by: Jarno Rajahalme <jarno@ovn.org> Acked-by: Ben Pfaff <blp@ovn.org>
65 lines
1.8 KiB
C
65 lines
1.8 KiB
C
/*
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* Copyright (c) 2014, 2016 Nicira, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef CCMAP_H
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#define CCMAP_H 1
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#include <stdbool.h>
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#include <stdint.h>
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#include "ovs-rcu.h"
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#include "util.h"
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/* Concurrent hash map for numerical counts of given hash values.
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* ==============================================================
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*
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* A single-writer, multiple-reader count hash table that efficiently supports
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* duplicates.
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*
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*
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* Thread-safety
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* =============
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*
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* The general rules are:
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*
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* - Only a single thread may safely call into ccmap_inc(),
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* or ccmap_dec() at any given time.
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*
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* - Any number of threads may use functions and macros that search
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* a given ccmap, even in parallel with other threads
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* calling ccmap_inc() or ccmap_dec().
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*/
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/* Concurrent hash map. */
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struct ccmap {
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OVSRCU_TYPE(struct ccmap_impl *) impl;
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};
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/* Initialization. */
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void ccmap_init(struct ccmap *);
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void ccmap_destroy(struct ccmap *);
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/* Count. */
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size_t ccmap_count(const struct ccmap *);
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bool ccmap_is_empty(const struct ccmap *);
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/* Insertion and deletion. Return the current count after the operation. */
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uint32_t ccmap_inc(struct ccmap *, uint32_t hash);
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uint32_t ccmap_dec(struct ccmap *, uint32_t hash);
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uint32_t ccmap_find(const struct ccmap *, uint32_t hash);
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#endif /* ccmap.h */
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