src/cx/hash_key.h

Mon, 08 Aug 2022 17:12:00 +0200

author
Mike Becker <universe@uap-core.de>
date
Mon, 08 Aug 2022 17:12:00 +0200
changeset 572
f0f99dd06d9f
parent 563
69a83fad8a35
child 603
c49104015a6b
permissions
-rw-r--r--

#201 - remove dangerous allocator config

There is no plausible use case, except using the testing
allocator in the test case, and having the possibility to
specify any allocator (including another mempool) causes
more harm than good.

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
/**
 * \file hash_key.h
 * \brief Interface for map implementations.
 * \author Mike Becker
 * \author Olaf Wintermann
 * \version 3.0
 * \copyright 2-Clause BSD License
 */


#ifndef UCX_HASH_KEY_H
#define UCX_HASH_KEY_H

#include "stddef.h"

#ifdef __cplusplus
extern "C" {
#endif

/** Internal structure for a key within a hash map. */
struct cx_hash_key_s {
    /** The key data. */
    union {
        unsigned char *bytes;
        unsigned char const *cbytes;
        char const *cstr;
        char *str;
        void *obj;
    } data;
    /**
     * The key data length.
     */
    size_t len;
    /** The hash value of the key data. */
    unsigned hash;
};

/**
 * Type for a hash key.
 */
typedef struct cx_hash_key_s CxHashKey;

/**
 * Computes a murmur hash-2.
 *
 * You need to initialize data and len in the key struct.
 * The hash is then directly written to that struct.
 *
 * @param key the key, the hash shall be computed for
 */
void cx_hash_murmur(CxHashKey *key);

/**
 * Computes a hash key from a string.
 *
 * The string needs to be zero-terminated.
 *
 * @param str the string
 * @return the hash key
 */
__attribute__((__warn_unused_result__))
CxHashKey cx_hash_key_str(char const *str);

/**
 * Computes a hash key from a byte array.
 *
 * @param bytes the array
 * @param len the length
 * @return the hash key
 */
__attribute__((__warn_unused_result__))
CxHashKey cx_hash_key_bytes(
        unsigned char const *bytes,
        size_t len
);

/**
 * Computes a hash key for an arbitrary object.
 *
 * The computation uses the in-memory representation that might not be
 * the same on different platforms. Therefore, this hash should not be
 * used for data exchange with different machines.
 *
 * @param obj a pointer to an arbitrary object
 * @param len the length of object in memory
 * @return the hash key
 */
__attribute__((__warn_unused_result__))
CxHashKey cx_hash_key(
        void *obj,
        size_t len
);

#ifdef __cplusplus
} // extern "C"
#endif

#endif /* UCX_HASH_KEY_H */

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