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 \
  50                 DISPATCH_GLOBAL_OBJECT(dispatch_data_t, _dispatch_data_empty)
  51 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
  52 DISPATCH_EXPORT struct dispatch_data_s _dispatch_data_empty;
  53
  54 #ifdef __BLOCKS__
  55
  56 /*!
  57  * @const DISPATCH_DATA_DESTRUCTOR_DEFAULT
  58  * @discussion The default destructor for dispatch data objects.
  59  * Used at data object creation to indicate that the supplied buffer should
  60  * be copied into internal storage managed by the system.
  61  */
  62 #define DISPATCH_DATA_DESTRUCTOR_DEFAULT NULL
  63
  64 /*!
  65  * @const DISPATCH_DATA_DESTRUCTOR_FREE
  66  * @discussion The destructor for dispatch data objects created from a malloc'd
  67  * buffer. Used at data object creation to indicate that the supplied buffer
  68  * was allocated by the malloc() family and should be destroyed with free(3).
  69  */
  70 #define DISPATCH_DATA_DESTRUCTOR_FREE (_dispatch_data_destructor_free)
  71 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
  72 DISPATCH_EXPORT const dispatch_block_t _dispatch_data_destructor_free;
  73
  74 /*!
  75  * @function dispatch_data_create
  76  * Creates a dispatch data object from the given contiguous buffer of memory. If
  77  * a non-default destructor is provided, ownership of the buffer remains with
  78  * the caller (i.e. the bytes will not be copied). The last release of the data
  79  * object will result in the invocation of the specified destructor on the
  80  * specified queue to free the buffer.
  81  *
  82  * If the DISPATCH_DATA_DESTRUCTOR_FREE destructor is provided the buffer will
  83  * be freed via free(3) and the queue argument ignored.
  84  *
  85  * If the DISPATCH_DATA_DESTRUCTOR_DEFAULT destructor is provided, data object
  86  * creation will copy the buffer into internal memory managed by the system.
  87  *
  88  * @param buffer        A contiguous buffer of data.
  89  * @param size          The size of the contiguous buffer of data.
  90  * @param queue         The queue to which the destructor should be submitted.
  91  * @param destructor    The destructor responsible for freeing the data when it
  92  *                      is no longer needed.
  93  * @result              A newly created dispatch data object.
  94  */
  95 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
  96 DISPATCH_EXPORT DISPATCH_RETURNS_RETAINED DISPATCH_WARN_RESULT DISPATCH_NOTHROW
  97 dispatch_data_t
  98 dispatch_data_create(const void *buffer,
  99         size_t size,
 100         dispatch_queue_t queue,
 101         dispatch_block_t destructor);
 102
 103 /*!
 104  * @function dispatch_data_get_size
 105  * Returns the logical size of the memory region(s) represented by the specified
 106  * dispatch data object.
 107  *
 108  * @param data  The dispatch data object to query.
 109  * @result      The number of bytes represented by the data object.
 110  */
 111 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
 112 DISPATCH_EXPORT DISPATCH_PURE DISPATCH_NONNULL1 DISPATCH_NOTHROW
 113 size_t
 114 dispatch_data_get_size(dispatch_data_t data);
 115
 116 /*!
 117  * @function dispatch_data_create_map
 118  * Maps the memory represented by the specified dispatch data object as a single
 119  * contiguous memory region and returns a new data object representing it.
 120  * If non-NULL references to a pointer and a size variable are provided, they
 121  * are filled with the location and extent of that region. These allow direct
 122  * read access to the represented memory, but are only valid until the returned
 123  * object is released. Under ARC, if that object is held in a variable with
 124  * automatic storage, care needs to be taken to ensure that it is not released
 125  * by the compiler before memory access via the pointer has been completed.
 126  *
 127  * @param data          The dispatch data object to map.
 128  * @param buffer_ptr    A pointer to a pointer variable to be filled with the
 129  *                      location of the mapped contiguous memory region, or
 130  *                      NULL.
 131  * @param size_ptr      A pointer to a size_t variable to be filled with the
 132  *                      size of the mapped contiguous memory region, or NULL.
 133  * @result              A newly created dispatch data object.
 134  */
 135 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
 136 DISPATCH_EXPORT DISPATCH_NONNULL1 DISPATCH_RETURNS_RETAINED
 137 DISPATCH_WARN_RESULT DISPATCH_NOTHROW
 138 dispatch_data_t
 139 dispatch_data_create_map(dispatch_data_t data,
 140         const void **buffer_ptr,
 141         size_t *size_ptr);
 142
 143 /*!
 144  * @function dispatch_data_create_concat
 145  * Returns a new dispatch data object representing the concatenation of the
 146  * specified data objects. Those objects may be released by the application
 147  * after the call returns (however, the system might not deallocate the memory
 148  * region(s) described by them until the newly created object has also been
 149  * released).
 150  *
 151  * @param data1 The data object representing the region(s) of memory to place
 152  *              at the beginning of the newly created object.
 153  * @param data2 The data object representing the region(s) of memory to place
 154  *              at the end of the newly created object.
 155  * @result      A newly created object representing the concatenation of the
 156  *              data1 and data2 objects.
 157  */
 158 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
 159 DISPATCH_EXPORT DISPATCH_NONNULL_ALL DISPATCH_RETURNS_RETAINED
 160 DISPATCH_WARN_RESULT DISPATCH_NOTHROW
 161 dispatch_data_t
 162 dispatch_data_create_concat(dispatch_data_t data1, dispatch_data_t data2);
 163
 164 /*!
 165  * @function dispatch_data_create_subrange
 166  * Returns a new dispatch data object representing a subrange of the specified
 167  * data object, which may be released by the application after the call returns
 168  * (however, the system might not deallocate the memory region(s) described by
 169  * that object until the newly created object has also been released).
 170  *
 171  * @param data          The data object representing the region(s) of memory to
 172  *                      create a subrange of.
 173  * @param offset        The offset into the data object where the subrange
 174  *                      starts.
 175  * @param length        The length of the range.
 176  * @result              A newly created object representing the specified
 177  *                      subrange of the data object.
 178  */
 179 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
 180 DISPATCH_EXPORT DISPATCH_NONNULL1 DISPATCH_RETURNS_RETAINED
 181 DISPATCH_WARN_RESULT DISPATCH_NOTHROW
 182 dispatch_data_t
 183 dispatch_data_create_subrange(dispatch_data_t data,
 184         size_t offset,
 185         size_t length);
 186
 187 /*!
 188  * @typedef dispatch_data_applier_t
 189  * A block to be invoked for every contiguous memory region in a data object.
 190  *
 191  * @param region        A data object representing the current region.
 192  * @param offset        The logical offset of the current region to the start
 193  *                      of the data object.
 194  * @param buffer        The location of the memory for the current region.
 195  * @param size          The size of the memory for the current region.
 196  * @result              A Boolean indicating whether traversal should continue.
 197  */
 198 typedef bool (^dispatch_data_applier_t)(dispatch_data_t region,
 199         size_t offset,
 200         const void *buffer,
 201         size_t size);
 202
 203 /*!
 204  * @function dispatch_data_apply
 205  * Traverse the memory regions represented by the specified dispatch data object
 206  * in logical order and invoke the specified block once for every contiguous
 207  * memory region encountered.
 208  *
 209  * Each invocation of the block is passed a data object representing the current
 210  * region and its logical offset, along with the memory location and extent of
 211  * the region. These allow direct read access to the memory region, but are only
 212  * valid until the passed-in region object is released. Note that the region
 213  * object is released by the system when the block returns, it is the
 214  * responsibility of the application to retain it if the region object or the
 215  * associated memory location are needed after the block returns.
 216  *
 217  * @param data          The data object to traverse.
 218  * @param applier       The block to be invoked for every contiguous memory
 219  *                      region in the data object.
 220  * @result              A Boolean indicating whether traversal completed
 221  *                      successfully.
 222  */
 223 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
 224 DISPATCH_EXPORT DISPATCH_NONNULL_ALL DISPATCH_NOTHROW
 225 bool
 226 dispatch_data_apply(dispatch_data_t data, dispatch_data_applier_t applier);
 227
 228 /*!
 229  * @function dispatch_data_copy_region
 230  * Finds the contiguous memory region containing the specified location among
 231  * the regions represented by the specified object and returns a copy of the
 232  * internal dispatch data object representing that region along with its logical
 233  * offset in the specified object.
 234  *
 235  * @param data          The dispatch data object to query.
 236  * @param location      The logical position in the data object to query.
 237  * @param offset_ptr    A pointer to a size_t variable to be filled with the
 238  *                      logical offset of the returned region object to the
 239  *                      start of the queried data object.
 240  * @result              A newly created dispatch data object.
 241  */
 242 __OSX_AVAILABLE_STARTING(__MAC_10_7,__IPHONE_5_0)
 243 DISPATCH_EXPORT DISPATCH_NONNULL1 DISPATCH_NONNULL3 DISPATCH_RETURNS_RETAINED
 244 DISPATCH_WARN_RESULT DISPATCH_NOTHROW
 245 dispatch_data_t
 246 dispatch_data_copy_region(dispatch_data_t data,
 247         size_t location,
 248         size_t *offset_ptr);
 249
 250 #endif /* __BLOCKS__ */
 251
 252 __END_DECLS
 253
 254 #endif /* __DISPATCH_DATA__ */