apr_poll.h

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00001 /* Licensed to the Apache Software Foundation (ASF) under one or more
00002  * contributor license agreements.  See the NOTICE file distributed with
00003  * this work for additional information regarding copyright ownership.
00004  * The ASF licenses this file to You under the Apache License, Version 2.0
00005  * (the "License"); you may not use this file except in compliance with
00006  * the License.  You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 
00017 #ifndef APR_POLL_H
00018 #define APR_POLL_H
00019 /**
00020  * @file apr_poll.h
00021  * @brief APR Poll interface
00022  */
00023 #include "apr.h"
00024 #include "apr_pools.h"
00025 #include "apr_errno.h"
00026 #include "apr_inherit.h" 
00027 #include "apr_file_io.h" 
00028 #include "apr_network_io.h" 
00029 
00030 #if APR_HAVE_NETINET_IN_H
00031 #include <netinet/in.h>
00032 #endif
00033 
00034 #ifdef __cplusplus
00035 extern "C" {
00036 #endif /* __cplusplus */
00037 
00038 /**
00039  * @defgroup apr_poll Poll Routines
00040  * @ingroup APR 
00041  * @{
00042  */
00043 
00044 /**
00045  * Poll options
00046  */
00047 #define APR_POLLIN    0x001     /**< Can read without blocking */
00048 #define APR_POLLPRI   0x002     /**< Priority data available */
00049 #define APR_POLLOUT   0x004     /**< Can write without blocking */
00050 #define APR_POLLERR   0x010     /**< Pending error */
00051 #define APR_POLLHUP   0x020     /**< Hangup occurred */
00052 #define APR_POLLNVAL  0x040     /**< Descriptior invalid */
00053 
00054 /**
00055  * Pollset Flags
00056  */
00057 #define APR_POLLSET_THREADSAFE 0x001 /**< Adding or Removing a Descriptor is thread safe */
00058 
00059 /** Used in apr_pollfd_t to determine what the apr_descriptor is */
00060 typedef enum { 
00061     APR_NO_DESC,                /**< nothing here */
00062     APR_POLL_SOCKET,            /**< descriptor refers to a socket */
00063     APR_POLL_FILE,              /**< descriptor refers to a file */
00064     APR_POLL_LASTDESC           /**< descriptor is the last one in the list */
00065 } apr_datatype_e ;
00066 
00067 /** Union of either an APR file or socket. */
00068 typedef union {
00069     apr_file_t *f;              /**< file */
00070     apr_socket_t *s;            /**< socket */
00071 } apr_descriptor;
00072 
00073 /** @see apr_pollfd_t */
00074 typedef struct apr_pollfd_t apr_pollfd_t;
00075 
00076 /** Poll descriptor set. */
00077 struct apr_pollfd_t {
00078     apr_pool_t *p;              /**< associated pool */
00079     apr_datatype_e desc_type;   /**< descriptor type */
00080     apr_int16_t reqevents;      /**< requested events */
00081     apr_int16_t rtnevents;      /**< returned events */
00082     apr_descriptor desc;        /**< @see apr_descriptor */
00083     void *client_data;          /**< allows app to associate context */
00084 };
00085 
00086 
00087 /* General-purpose poll API for arbitrarily large numbers of
00088  * file descriptors
00089  */
00090 
00091 /** Opaque structure used for pollset API */
00092 typedef struct apr_pollset_t apr_pollset_t;
00093 
00094 /**
00095  * Setup a pollset object
00096  * @param pollset  The pointer in which to return the newly created object 
00097  * @param size The maximum number of descriptors that this pollset can hold
00098  * @param p The pool from which to allocate the pollset
00099  * @param flags Optional flags to modify the operation of the pollset.
00100  *
00101  * @remark If flags equals APR_POLLSET_THREADSAFE, then a pollset is
00102  * created on which it is safe to make concurrent calls to
00103  * apr_pollset_add(), apr_pollset_remove() and apr_pollset_poll() from
00104  * separate threads.  This feature is only supported on some
00105  * platforms; the apr_pollset_create() call will fail with
00106  * APR_ENOTIMPL on platforms where it is not supported.
00107  */
00108 APR_DECLARE(apr_status_t) apr_pollset_create(apr_pollset_t **pollset,
00109                                              apr_uint32_t size,
00110                                              apr_pool_t *p,
00111                                              apr_uint32_t flags);
00112 
00113 /**
00114  * Destroy a pollset object
00115  * @param pollset The pollset to destroy
00116  */
00117 APR_DECLARE(apr_status_t) apr_pollset_destroy(apr_pollset_t *pollset);
00118 
00119 /**
00120  * Add a socket or file descriptor to a pollset
00121  * @param pollset The pollset to which to add the descriptor
00122  * @param descriptor The descriptor to add
00123  * @remark If you set client_data in the descriptor, that value
00124  *         will be returned in the client_data field whenever this
00125  *         descriptor is signalled in apr_pollset_poll().
00126  * @remark If the pollset has been created with APR_POLLSET_THREADSAFE
00127  *         and thread T1 is blocked in a call to apr_pollset_poll() for
00128  *         this same pollset that is being modified via apr_pollset_add()
00129  *         in thread T2, the currently executing apr_pollset_poll() call in
00130  *         T1 will either: (1) automatically include the newly added descriptor
00131  *         in the set of descriptors it is watching or (2) return immediately
00132  *         with APR_EINTR.  Option (1) is recommended, but option (2) is
00133  *         allowed for implementations where option (1) is impossible
00134  *         or impractical.
00135  */
00136 APR_DECLARE(apr_status_t) apr_pollset_add(apr_pollset_t *pollset,
00137                                           const apr_pollfd_t *descriptor);
00138 
00139 /**
00140  * Remove a descriptor from a pollset
00141  * @param pollset The pollset from which to remove the descriptor
00142  * @param descriptor The descriptor to remove
00143  * @remark If the pollset has been created with APR_POLLSET_THREADSAFE
00144  *         and thread T1 is blocked in a call to apr_pollset_poll() for
00145  *         this same pollset that is being modified via apr_pollset_remove()
00146  *         in thread T2, the currently executing apr_pollset_poll() call in
00147  *         T1 will either: (1) automatically exclude the newly added descriptor
00148  *         in the set of descriptors it is watching or (2) return immediately
00149  *         with APR_EINTR.  Option (1) is recommended, but option (2) is
00150  *         allowed for implementations where option (1) is impossible
00151  *         or impractical.
00152  */
00153 APR_DECLARE(apr_status_t) apr_pollset_remove(apr_pollset_t *pollset,
00154                                              const apr_pollfd_t *descriptor);
00155 
00156 /**
00157  * Block for activity on the descriptor(s) in a pollset
00158  * @param pollset The pollset to use
00159  * @param timeout Timeout in microseconds
00160  * @param num Number of signalled descriptors (output parameter)
00161  * @param descriptors Array of signalled descriptors (output parameter)
00162  */
00163 APR_DECLARE(apr_status_t) apr_pollset_poll(apr_pollset_t *pollset,
00164                                            apr_interval_time_t timeout,
00165                                            apr_int32_t *num,
00166                                            const apr_pollfd_t **descriptors);
00167 
00168 
00169 /**
00170  * Poll the descriptors in the poll structure
00171  * @param aprset The poll structure we will be using. 
00172  * @param numsock The number of descriptors we are polling
00173  * @param nsds The number of descriptors signalled.
00174  * @param timeout The amount of time in microseconds to wait.  This is 
00175  *                a maximum, not a minimum.  If a descriptor is signalled, we 
00176  *                will wake up before this time.  A negative number means 
00177  *                wait until a descriptor is signalled.
00178  * @remark The number of descriptors signalled is returned in the third argument. 
00179  *         This is a blocking call, and it will not return until either a 
00180  *         descriptor has been signalled, or the timeout has expired. 
00181  * @remark The rtnevents field in the apr_pollfd_t array will only be filled-
00182  *         in if the return value is APR_SUCCESS.
00183  */
00184 APR_DECLARE(apr_status_t) apr_poll(apr_pollfd_t *aprset, apr_int32_t numsock,
00185                                    apr_int32_t *nsds, 
00186                                    apr_interval_time_t timeout);
00187 
00188 /** @} */
00189 
00190 
00191 #ifdef __cplusplus
00192 }
00193 #endif
00194 
00195 #endif  /* ! APR_POLL_H */
00196 

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