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064af421 BP |
1 | /* |
2 | * Copyright (c) 2008, 2009 Nicira Networks. | |
3 | * | |
a14bc59f BP |
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: | |
064af421 | 7 | * |
a14bc59f BP |
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. | |
064af421 BP |
15 | */ |
16 | ||
17 | #include <config.h> | |
18 | #include "queue.h" | |
19 | #include <assert.h> | |
20 | #include "compiler.h" | |
21 | #include "leak-checker.h" | |
22 | #include "ofpbuf.h" | |
23 | ||
24 | static void check_queue(struct ovs_queue *q); | |
25 | ||
26 | /* Initializes 'q' as an empty packet queue. */ | |
27 | void | |
28 | queue_init(struct ovs_queue *q) | |
29 | { | |
30 | q->n = 0; | |
31 | q->head = NULL; | |
32 | q->tail = NULL; | |
33 | } | |
34 | ||
35 | /* Destroys 'q' and all of the packets that it contains. */ | |
36 | void | |
37 | queue_destroy(struct ovs_queue *q) | |
38 | { | |
39 | struct ofpbuf *cur, *next; | |
40 | for (cur = q->head; cur != NULL; cur = next) { | |
41 | next = cur->next; | |
42 | ofpbuf_delete(cur); | |
43 | } | |
44 | } | |
45 | ||
46 | /* Removes and destroys all of the packets in 'q', rendering it empty. */ | |
47 | void | |
48 | queue_clear(struct ovs_queue *q) | |
49 | { | |
50 | queue_destroy(q); | |
51 | queue_init(q); | |
52 | } | |
53 | ||
54 | /* Advances the first packet in 'q' from 'q->head' to 'next', which should be | |
55 | * the second packet in the queue. | |
56 | * | |
57 | * The odd, unsafe interface here allows the first packet in the queue to be | |
58 | * passed to a function for possible consumption (and destruction) and only | |
59 | * dropped from the queue if that function actually accepts it. */ | |
60 | void | |
61 | queue_advance_head(struct ovs_queue *q, struct ofpbuf *next) | |
62 | { | |
63 | assert(q->n); | |
64 | assert(q->head); | |
65 | q->head = next; | |
66 | if (q->head == NULL) { | |
67 | q->tail = NULL; | |
68 | } | |
69 | q->n--; | |
70 | } | |
71 | ||
72 | /* Appends 'b' to the tail of 'q'. */ | |
73 | void | |
74 | queue_push_tail(struct ovs_queue *q, struct ofpbuf *b) | |
75 | { | |
76 | check_queue(q); | |
77 | leak_checker_claim(b); | |
78 | ||
79 | b->next = NULL; | |
80 | if (q->n++) { | |
81 | q->tail->next = b; | |
82 | } else { | |
83 | q->head = b; | |
84 | } | |
85 | q->tail = b; | |
86 | ||
87 | check_queue(q); | |
88 | } | |
89 | ||
90 | /* Removes the first buffer from 'q', which must not be empty, and returns | |
91 | * it. The caller must free the buffer (with ofpbuf_delete()) when it is no | |
92 | * longer needed. */ | |
93 | struct ofpbuf * | |
94 | queue_pop_head(struct ovs_queue *q) | |
95 | { | |
96 | struct ofpbuf *head = q->head; | |
97 | queue_advance_head(q, head->next); | |
98 | return head; | |
99 | } | |
100 | ||
101 | /* Checks the internal integrity of 'q'. For use in debugging. */ | |
102 | static void | |
103 | check_queue(struct ovs_queue *q UNUSED) | |
104 | { | |
105 | #if 0 | |
106 | struct ofpbuf *iter; | |
107 | size_t n; | |
108 | ||
109 | assert(q->n == 0 | |
110 | ? q->head == NULL && q->tail == NULL | |
111 | : q->head != NULL && q->tail != NULL); | |
112 | ||
113 | n = 0; | |
114 | for (iter = q->head; iter != NULL; iter = iter->next) { | |
115 | n++; | |
116 | assert((iter->next != NULL) == (iter != q->tail)); | |
117 | } | |
118 | assert(n == q->n); | |
119 | #endif | |
120 | } |