summaryrefslogtreecommitdiffstats
path: root/include/apr_queue.h
blob: a3a41704862ae9385d94dfa576ae67c57870df7b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef APR_QUEUE_H
#define APR_QUEUE_H

/**
 * @file apr_queue.h
 * @brief Thread Safe FIFO bounded queue
 * @note Since most implementations of the queue are backed by a condition
 * variable implementation, it isn't available on systems without threads.
 * Although condition variables are sometimes available without threads.
 */

#include "apu.h"
#include "apr_errno.h"
#include "apr_pools.h"

#if APR_HAS_THREADS

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

/**
 * @defgroup APR_Util_FIFO Thread Safe FIFO bounded queue
 * @ingroup APR_Util
 * @{
 */

/**
 * opaque structure
 */
typedef struct apr_queue_t apr_queue_t;

/** 
 * create a FIFO queue
 * @param queue The new queue
 * @param queue_capacity maximum size of the queue
 * @param a pool to allocate queue from
 */
APU_DECLARE(apr_status_t) apr_queue_create(apr_queue_t **queue, 
                                           unsigned int queue_capacity, 
                                           apr_pool_t *a);

/**
 * push/add an object to the queue, blocking if the queue is already full
 *
 * @param queue the queue
 * @param data the data
 * @returns APR_EINTR the blocking was interrupted (try again)
 * @returns APR_EOF the queue has been terminated
 * @returns APR_SUCCESS on a successful push
 */
APU_DECLARE(apr_status_t) apr_queue_push(apr_queue_t *queue, void *data);

/**
 * pop/get an object from the queue, blocking if the queue is already empty
 *
 * @param queue the queue
 * @param data the data
 * @returns APR_EINTR the blocking was interrupted (try again)
 * @returns APR_EOF if the queue has been terminated
 * @returns APR_SUCCESS on a successful pop
 */
APU_DECLARE(apr_status_t) apr_queue_pop(apr_queue_t *queue, void **data);

/**
 * push/add an object to the queue, returning immediately if the queue is full
 *
 * @param queue the queue
 * @param data the data
 * @returns APR_EINTR the blocking operation was interrupted (try again)
 * @returns APR_EAGAIN the queue is full
 * @returns APR_EOF the queue has been terminated
 * @returns APR_SUCCESS on a successful push
 */
APU_DECLARE(apr_status_t) apr_queue_trypush(apr_queue_t *queue, void *data);

/**
 * pop/get an object to the queue, returning immediately if the queue is empty
 *
 * @param queue the queue
 * @param data the data
 * @returns APR_EINTR the blocking operation was interrupted (try again)
 * @returns APR_EAGAIN the queue is empty
 * @returns APR_EOF the queue has been terminated
 * @returns APR_SUCCESS on a successful pop
 */
APU_DECLARE(apr_status_t) apr_queue_trypop(apr_queue_t *queue, void **data);

/**
 * returns the size of the queue.
 *
 * @warning this is not threadsafe, and is intended for reporting/monitoring
 * of the queue.
 * @param queue the queue
 * @returns the size of the queue
 */
APU_DECLARE(unsigned int) apr_queue_size(apr_queue_t *queue);

/**
 * interrupt all the threads blocking on this queue.
 *
 * @param queue the queue
 */
APU_DECLARE(apr_status_t) apr_queue_interrupt_all(apr_queue_t *queue);

/**
 * terminate the queue, sending an interrupt to all the
 * blocking threads
 *
 * @param queue the queue
 */
APU_DECLARE(apr_status_t) apr_queue_term(apr_queue_t *queue);

#ifdef __cplusplus
}
#endif

/** @} */

#endif /* APR_HAS_THREADS */

#endif /* APRQUEUE_H */