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1c4dd424 JR |
1 | /* |
2 | * Copyright (c) 2014, 2016 Nicira, Inc. | |
3 | * | |
4 | * Licensed under the Apache License, Version 2.0 (the "License"); | |
5 | * you may not use this file except in compliance with the License. | |
6 | * You may obtain a copy of the License at: | |
7 | * | |
8 | * http://www.apache.org/licenses/LICENSE-2.0 | |
9 | * | |
10 | * Unless required by applicable law or agreed to in writing, software | |
11 | * distributed under the License is distributed on an "AS IS" BASIS, | |
12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
13 | * See the License for the specific language governing permissions and | |
14 | * limitations under the License. | |
15 | */ | |
16 | ||
17 | #ifndef CCMAP_H | |
18 | #define CCMAP_H 1 | |
19 | ||
20 | #include <stdbool.h> | |
21 | #include <stdint.h> | |
22 | #include "ovs-rcu.h" | |
23 | #include "util.h" | |
24 | ||
25 | /* Concurrent hash map for numerical counts of given hash values. | |
26 | * ============================================================== | |
27 | * | |
28 | * A single-writer, multiple-reader count hash table that efficiently supports | |
29 | * duplicates. | |
30 | * | |
31 | * | |
32 | * Thread-safety | |
33 | * ============= | |
34 | * | |
35 | * The general rules are: | |
36 | * | |
37 | * - Only a single thread may safely call into ccmap_inc(), | |
38 | * or ccmap_dec() at any given time. | |
39 | * | |
40 | * - Any number of threads may use functions and macros that search | |
41 | * a given ccmap, even in parallel with other threads | |
42 | * calling ccmap_inc() or ccmap_dec(). | |
43 | */ | |
44 | ||
45 | /* Concurrent hash map. */ | |
46 | struct ccmap { | |
47 | OVSRCU_TYPE(struct ccmap_impl *) impl; | |
48 | }; | |
49 | ||
50 | /* Initialization. */ | |
51 | void ccmap_init(struct ccmap *); | |
52 | void ccmap_destroy(struct ccmap *); | |
53 | ||
54 | /* Count. */ | |
55 | size_t ccmap_count(const struct ccmap *); | |
56 | bool ccmap_is_empty(const struct ccmap *); | |
57 | ||
58 | /* Insertion and deletion. Return the current count after the operation. */ | |
59 | uint32_t ccmap_inc(struct ccmap *, uint32_t hash); | |
60 | uint32_t ccmap_dec(struct ccmap *, uint32_t hash); | |
61 | ||
62 | uint32_t ccmap_find(const struct ccmap *, uint32_t hash); | |
63 | ||
64 | #endif /* ccmap.h */ |