ucx: src/cx/hash_map.h@475335643af4

increase version number to 3.1

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     1 /*

     2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

     3  *

     4  * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.

     5  *

     6  * Redistribution and use in source and binary forms, with or without

     7  * modification, are permitted provided that the following conditions are met:

     8  *

     9  *   1. Redistributions of source code must retain the above copyright

    10  *      notice, this list of conditions and the following disclaimer.

    11  *

    12  *   2. Redistributions in binary form must reproduce the above copyright

    13  *      notice, this list of conditions and the following disclaimer in the

    14  *      documentation and/or other materials provided with the distribution.

    15  *

    16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

    17  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

    18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

    19  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE

    20  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

    21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

    22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

    23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

    24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

    25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

    26  * POSSIBILITY OF SUCH DAMAGE.

    27  */

    28 /**

    29  * \file hash_map.h

    30  * \brief Hash map implementation.

    31  * \author Mike Becker

    32  * \author Olaf Wintermann

    33  * \copyright 2-Clause BSD License

    34  */

    36 #ifndef UCX_HASH_MAP_H

    37 #define UCX_HASH_MAP_H

    39 #include "map.h"

    41 #ifdef __cplusplus

    42 extern "C" {

    43 #endif

    45 /** Internal structure for an element of a hash map. */

    46 struct cx_hash_map_element_s;

    48 /**

    49  * Internal structure for a hash map.

    50  */

    51 struct cx_hash_map_s {

    52     /**

    53      * Base structure for maps.

    54      */

    55     struct cx_map_s base;

    56     /**

    57      * The buckets of this map, each containing a linked list of elements.

    58      */

    59     struct cx_hash_map_element_s **buckets;

    60     /**

    61      * The number of buckets.

    62      */

    63     size_t bucket_count;

    64 };

    67 /**

    68  * Creates a new hash map with the specified number of buckets.

    69  *

    70  * If \p buckets is zero, an implementation defined default will be used.

    71  *

    72  * If \p item_size is CX_STORE_POINTERS, the created map will be created as if

    73  * cxMapStorePointers() was called immediately after creation.

    74  *

    75  * @note Iterators provided by this hash map implementation provide the remove operation.

    76  * The index value of an iterator is incremented when the iterator advanced without removal.

    77  * In other words, when the iterator is finished, \c index==size .

    78  *

    79  * @param allocator the allocator to use

    80  * @param itemsize the size of one element

    81  * @param buckets the initial number of buckets in this hash map

    82  * @return a pointer to the new hash map

    83  */

    84 __attribute__((__nonnull__, __warn_unused_result__))

    85 CxMap *cxHashMapCreate(

    86         CxAllocator const *allocator,

    87         size_t itemsize,

    88         size_t buckets

    89 );

    91 /**

    92  * Creates a new hash map with a default number of buckets.

    93  *

    94  * If \p item_size is CX_STORE_POINTERS, the created map will be created as if

    95  * cxMapStorePointers() was called immediately after creation.

    96  *

    97  * @note Iterators provided by this hash map implementation provide the remove operation.

    98  * The index value of an iterator is incremented when the iterator advanced without removal.

    99  * In other words, when the iterator is finished, \c index==size .

   100  *

   101  * @param itemsize the size of one element

   102  * @return a pointer to the new hash map

   103  */

   104 #define cxHashMapCreateSimple(itemsize) \

   105     cxHashMapCreate(cxDefaultAllocator, itemsize, 0)

   107 /**

   108  * Increases the number of buckets, if necessary.

   109  *

   110  * The load threshold is \c 0.75*buckets. If the element count exceeds the load

   111  * threshold, the map will be rehashed. Otherwise, no action is performed and

   112  * this function simply returns 0.

   113  *

   114  * The rehashing process ensures, that the number of buckets is at least

   115  * 2.5 times the element count. So there is enough room for additional

   116  * elements without the need of another soon rehashing.

   117  *

   118  * You can use this function after filling a map to increase access performance.

   119  *

   120  * @note If the specified map is not a hash map, the behavior is undefined.

   121  *

   122  * @param map the map to rehash

   123  * @return zero on success, non-zero if a memory allocation error occurred

   124  */

   125 __attribute__((__nonnull__))

   126 int cxMapRehash(CxMap *map);

   129 #ifdef __cplusplus

   130 } // extern "C"

   131 #endif

   133 #endif // UCX_HASH_MAP_H

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