dispatch/data.h

   1 /*
   2  * Copyright (c) 2009-2011 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_APACHE_LICENSE_HEADER_START@
   5  *
   6  * Licensed under the Apache License, Version 2.0 (the "License");
   7  * you may not use this file except in compliance with the License.
   8  * You may obtain a copy of the License at
   9  *
  10  *     http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  * Unless required by applicable law or agreed to in writing, software
  13  * distributed under the License is distributed on an "AS IS" BASIS,
  14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15  * See the License for the specific language governing permissions and
  16  * limitations under the License.
  17  *
  18  * @APPLE_APACHE_LICENSE_HEADER_END@
  19  */
  20
  21 #ifndef __DISPATCH_DATA__
  22 #define __DISPATCH_DATA__
  23
  24 #ifndef __DISPATCH_INDIRECT__
  25 #error "Please #include <dispatch/dispatch.h> instead of this file directly."
  26 #include <dispatch/base.h> // for HeaderDoc
  27 #endif
  28
  29 __BEGIN_DECLS
  30
  31 /*! @header
  32  * Dispatch data objects describe contiguous or sparse regions of memory that
  33  * may be managed by the system or by the application.
  34  * Dispatch data objects are immutable, any direct access to memory regions
  35  * represented by dispatch objects must not modify that memory.
  36  */
  37
  38 /*!
  39  * @typedef dispatch_data_t
  40  * A dispatch object representing memory regions.
  41  */
  42 DISPATCH_DECL(dispatch_data);
  43
  44 /*!
  45  * @var dispatch_data_empty
  46  * @discussion The singleton dispatch data object representing a zero-length
  47  * memory region.
  48  */
  49 #define dispatch_data_empty (&_dispatch_data_empty)
  50 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
  51 DISPATCH_EXPORT struct dispatch_data_s _dispatch_data_empty;
  52
  53 #ifdef __BLOCKS__
  54
  55 /*!
  56  * @const DISPATCH_DATA_DESTRUCTOR_DEFAULT
  57  * @discussion The default destructor for dispatch data objects.
  58  * Used at data object creation to indicate that the supplied buffer should
  59  * be copied into internal storage managed by the system.
  60  */
  61 #define DISPATCH_DATA_DESTRUCTOR_DEFAULT NULL
  62
  63 /*!
  64  * @const DISPATCH_DATA_DESTRUCTOR_FREE
  65  * @discussion The destructor for dispatch data objects created from a malloc'd
  66  * buffer. Used at data object creation to indicate that the supplied buffer
  67  * was allocated by the malloc() family and should be destroyed with free(3).
  68  */
  69 #define DISPATCH_DATA_DESTRUCTOR_FREE (_dispatch_data_destructor_free)
  70 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
  71 DISPATCH_EXPORT const dispatch_block_t _dispatch_data_destructor_free;
  72
  73 /*!
  74  * @function dispatch_data_create
  75  * Creates a dispatch data object from the given contiguous buffer of memory. If
  76  * a non-default destructor is provided, ownership of the buffer remains with
  77  * the caller (i.e. the bytes will not be copied). The last release of the data
  78  * object will result in the invocation of the specified destructor on the
  79  * specified queue to free the buffer.
  80  *
  81  * If the DISPATCH_DATA_DESTRUCTOR_FREE destructor is provided the buffer will
  82  * be freed via free(3) and the queue argument ignored.
  83  *
  84  * If the DISPATCH_DATA_DESTRUCTOR_DEFAULT destructor is provided, data object
  85  * creation will copy the buffer into internal memory managed by the system.
  86  *
  87  * @param buffer        A contiguous buffer of data.
  88  * @param size          The size of the contiguous buffer of data.
  89  * @param queue         The queue to which the destructor should be submitted.
  90  * @param destructor    The destructor responsible for freeing the data when it
  91  *                      is no longer needed.
  92  * @result              A newly created dispatch data object.
  93  */
  94 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
  95 DISPATCH_EXPORT DISPATCH_MALLOC DISPATCH_WARN_RESULT DISPATCH_NOTHROW
  96 dispatch_data_t
  97 dispatch_data_create(const void *buffer,
  98         size_t size,
  99         dispatch_queue_t queue,
 100         dispatch_block_t destructor);
 101
 102 /*!
 103  * @function dispatch_data_get_size
 104  * Returns the logical size of the memory region(s) represented by the specified
 105  * dispatch data object.
 106  *
 107  * @param data  The dispatch data object to query.
 108  * @result      The number of bytes represented by the data object.
 109  */
 110 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
 111 DISPATCH_EXPORT DISPATCH_PURE DISPATCH_NONNULL1 DISPATCH_NOTHROW
 112 size_t
 113 dispatch_data_get_size(dispatch_data_t data);
 114
 115 /*!
 116  * @function dispatch_data_create_map
 117  * Maps the memory represented by the specified dispatch data object as a single
 118  * contiguous memory region and returns a new data object representing it.
 119  * If non-NULL references to a pointer and a size variable are provided, they
 120  * are filled with the location and extent of that region. These allow direct
 121  * read access to the represented memory, but are only valid until the copy
 122  * object is released.
 123  *
 124  * @param data          The dispatch data object to map.
 125  * @param buffer_ptr    A pointer to a pointer variable to be filled with the
 126  *                      location of the mapped contiguous memory region, or
 127  *                      NULL.
 128  * @param size_ptr      A pointer to a size_t variable to be filled with the
 129  *                      size of the mapped contiguous memory region, or NULL.
 130  * @result              A newly created dispatch data object.
 131  */
 132 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
 133 DISPATCH_EXPORT DISPATCH_NONNULL1 DISPATCH_WARN_RESULT DISPATCH_NOTHROW
 134 dispatch_data_t
 135 dispatch_data_create_map(dispatch_data_t data,
 136         const void **buffer_ptr,
 137         size_t *size_ptr);
 138
 139 /*!
 140  * @function dispatch_data_create_concat
 141  * Returns a new dispatch data object representing the concatenation of the
 142  * specified data objects. Those objects may be released by the application
 143  * after the call returns (however, the system might not deallocate the memory
 144  * region(s) described by them until the newly created object has also been
 145  * released).
 146  *
 147  * @param data1 The data object representing the region(s) of memory to place
 148  *              at the beginning of the newly created object.
 149  * @param data2 The data object representing the region(s) of memory to place
 150  *              at the end of the newly created object.
 151  * @result      A newly created object representing the concatenation of the
 152  *              data1 and data2 objects.
 153  */
 154 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
 155 DISPATCH_EXPORT DISPATCH_NONNULL_ALL DISPATCH_WARN_RESULT DISPATCH_NOTHROW
 156 dispatch_data_t
 157 dispatch_data_create_concat(dispatch_data_t data1, dispatch_data_t data2);
 158
 159 /*!
 160  * @function dispatch_data_create_subrange
 161  * Returns a new dispatch data object representing a subrange of the specified
 162  * data object, which may be released by the application after the call returns
 163  * (however, the system might not deallocate the memory region(s) described by
 164  * that object until the newly created object has also been released).
 165  *
 166  * @param data          The data object representing the region(s) of memory to
 167  *                      create a subrange of.
 168  * @param offset        The offset into the data object where the subrange
 169  *                      starts.
 170  * @param length        The length of the range.
 171  * @result              A newly created object representing the specified
 172  *                      subrange of the data object.
 173  */
 174 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
 175 DISPATCH_EXPORT DISPATCH_NONNULL1 DISPATCH_WARN_RESULT DISPATCH_NOTHROW
 176 dispatch_data_t
 177 dispatch_data_create_subrange(dispatch_data_t data,
 178         size_t offset,
 179         size_t length);
 180
 181 /*!
 182  * @typedef dispatch_data_applier_t
 183  * A block to be invoked for every contiguous memory region in a data object.
 184  *
 185  * @param region        A data object representing the current region.
 186  * @param offset        The logical offset of the current region to the start
 187  *                      of the data object.
 188  * @param buffer        The location of the memory for the current region.
 189  * @param size          The size of the memory for the current region.
 190  * @result              A Boolean indicating whether traversal should continue.
 191  */
 192 typedef bool (^dispatch_data_applier_t)(dispatch_data_t region,
 193         size_t offset,
 194         const void *buffer,
 195         size_t size);
 196
 197 /*!
 198  * @function dispatch_data_apply
 199  * Traverse the memory regions represented by the specified dispatch data object
 200  * in logical order and invoke the specified block once for every contiguous
 201  * memory region encountered.
 202  *
 203  * Each invocation of the block is passed a data object representing the current
 204  * region and its logical offset, along with the memory location and extent of
 205  * the region. These allow direct read access to the memory region, but are only
 206  * valid until the passed-in region object is released. Note that the region
 207  * object is released by the system when the block returns, it is the
 208  * responsibility of the application to retain it if the region object or the
 209  * associated memory location are needed after the block returns.
 210  *
 211  * @param data          The data object to traverse.
 212  * @param applier       The block to be invoked for every contiguous memory
 213  *                      region in the data object.
 214  * @result              A Boolean indicating whether traversal completed
 215  *                      successfully.
 216  */
 217 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
 218 DISPATCH_EXPORT DISPATCH_NONNULL_ALL DISPATCH_NOTHROW
 219 bool
 220 dispatch_data_apply(dispatch_data_t data, dispatch_data_applier_t applier);
 221
 222 /*!
 223  * @function dispatch_data_copy_region
 224  * Finds the contiguous memory region containing the specified location among
 225  * the regions represented by the specified object and returns a copy of the
 226  * internal dispatch data object representing that region along with its logical
 227  * offset in the specified object.
 228  *
 229  * @param data          The dispatch data object to query.
 230  * @param location      The logical position in the data object to query.
 231  * @param offset_ptr    A pointer to a size_t variable to be filled with the
 232  *                      logical offset of the returned region object to the
 233  *                      start of the queried data object.
 234  * @result              A newly created dispatch data object.
 235  */
 236 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
 237 DISPATCH_EXPORT DISPATCH_NONNULL1 DISPATCH_NONNULL3 DISPATCH_WARN_RESULT
 238 DISPATCH_NOTHROW
 239 dispatch_data_t
 240 dispatch_data_copy_region(dispatch_data_t data,
 241         size_t location,
 242         size_t *offset_ptr);
 243
 244 #endif /* __BLOCKS__ */
 245
 246 __END_DECLS
 247
 248 #endif /* __DISPATCH_DATA__ */