include/apr_queue.h

   1 /* Licensed to the Apache Software Foundation (ASF) under one or more
   2  * contributor license agreements.  See the NOTICE file distributed with
   3  * this work for additional information regarding copyright ownership.
   4  * The ASF licenses this file to You under the Apache License, Version 2.0
   5  * (the "License"); you may not use this file except in compliance with
   6  * the License.  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 APR_QUEUE_H
  18 #define APR_QUEUE_H
  19
  20 /**
  21  * @file apr_queue.h
  22  * @brief Thread Safe FIFO bounded queue
  23  * @note Since most implementations of the queue are backed by a condition
  24  * variable implementation, it isn't available on systems without threads.
  25  * Although condition variables are some times available without threads.
  26  */
  27
  28 #include "apu.h"
  29 #include "apr_errno.h"
  30 #include "apr_pools.h"
  31
  32 #if APR_HAS_THREADS
  33
  34 #ifdef __cplusplus
  35 extern "C" {
  36 #endif /* __cplusplus */
  37
  38 /**
  39  * @defgroup APR_Util_FIFO Thread Safe FIFO bounded queue
  40  * @ingroup APR_Util
  41  * @{
  42  */
  43
  44 /**
  45  * opaque structure
  46  */
  47 typedef struct apr_queue_t apr_queue_t;
  48
  49 /**
  50  * create a FIFO queue
  51  * @param queue The new queue
  52  * @param queue_capacity maximum size of the queue
  53  * @param a pool to allocate queue from
  54  */
  55 APU_DECLARE(apr_status_t) apr_queue_create(apr_queue_t **queue,
  56                                            unsigned int queue_capacity,
  57                                            apr_pool_t *a);
  58
  59 /**
  60  * push/add a object to the queue, blocking if the queue is already full
  61  *
  62  * @param queue the queue
  63  * @param data the data
  64  * @returns APR_EINTR the blocking was interrupted (try again)
  65  * @returns APR_EOF the queue has been terminated
  66  * @returns APR_SUCCESS on a successfull push
  67  */
  68 APU_DECLARE(apr_status_t) apr_queue_push(apr_queue_t *queue, void *data);
  69
  70 /**
  71  * pop/get an object from the queue, blocking if the queue is already empty
  72  *
  73  * @param queue the queue
  74  * @param data the data
  75  * @returns APR_EINTR the blocking was interrupted (try again)
  76  * @returns APR_EOF if the queue has been terminated
  77  * @returns APR_SUCCESS on a successfull pop
  78  */
  79 APU_DECLARE(apr_status_t) apr_queue_pop(apr_queue_t *queue, void **data);
  80
  81 /**
  82  * push/add a object to the queue, returning immediatly if the queue is full
  83  *
  84  * @param queue the queue
  85  * @param data the data
  86  * @returns APR_EINTR the blocking operation was interrupted (try again)
  87  * @returns APR_EAGAIN the queue is full
  88  * @returns APR_EOF the queue has been terminated
  89  * @returns APR_SUCCESS on a successfull push
  90  */
  91 APU_DECLARE(apr_status_t) apr_queue_trypush(apr_queue_t *queue, void *data);
  92
  93 /**
  94  * pop/get an object to the queue, returning immediatly if the queue is empty
  95  *
  96  * @param queue the queue
  97  * @param data the data
  98  * @returns APR_EINTR the blocking operation was interrupted (try again)
  99  * @returns APR_EAGAIN the queue is empty
 100  * @returns APR_EOF the queue has been terminated
 101  * @returns APR_SUCCESS on a successfull push
 102  */
 103 APU_DECLARE(apr_status_t) apr_queue_trypop(apr_queue_t *queue, void **data);
 104
 105 /**
 106  * returns the size of the queue.
 107  *
 108  * @warning this is not threadsafe, and is intended for reporting/monitoring
 109  * of the queue.
 110  * @param queue the queue
 111  * @returns the size of the queue
 112  */
 113 APU_DECLARE(unsigned int) apr_queue_size(apr_queue_t *queue);
 114
 115 /**
 116  * interrupt all the threads blocking on this queue.
 117  *
 118  * @param queue the queue
 119  */
 120 APU_DECLARE(apr_status_t) apr_queue_interrupt_all(apr_queue_t *queue);
 121
 122 /**
 123  * terminate all queue, sendinging a interupt to all the
 124  * blocking threads
 125  *
 126  * @param queue the queue
 127  */
 128 APU_DECLARE(apr_status_t) apr_queue_term(apr_queue_t *queue);
 129
 130 #ifdef __cplusplus
 131 }
 132 #endif
 133
 134 /** @} */
 135
 136 #endif /* APR_HAS_THREADS */
 137
 138 #endif /* APRQUEUE_H */