【Redisソースプロファイル】-Reids内蔵データ構造の整数集合intset

オリジナル作品、転載は明記してください:http://blog.csdn.net/Xiejingfa/article/details/51124203
今日はRedisの比較的簡単な組み込みデータ構造である整数集合intsetについて説明します.
1、intsetストレージ構造
整数集合とは、その名の通り、一連の整数を格納する集合である.Redisではintset構造体の定義は次のとおりです.

/*         */
typedef struct intset {
    //     
    uint32_t encoding;
    //        
    uint32_t length;
    //          
    int8_t contents[];
} intset;

ここで、encodingはintsetストレージのフルタイプを表し、3つの異なる符号化:INTSET_ENC_INT16、INTSET_ENC_INT32、INTSET_ENC_INT 64はint 16_をそれぞれ表すt、int32_t、int64_t 3つの異なるタイプの整数.1つのintsetに格納されている整数は同じタイプです.lengthはintsetに格納されている要素の数を示します.contents配列こそ本当に整数を格納する場所であり、各整数が占有するバイト数はencodingによって指摘され、2バイト、4バイト、8バイトである可能性がある.
intsetのストレージ構造は下図の通りです.

2、元素ストレージの特徴
集合として、集合に要素があるかどうかを判断するのは一般的な操作です.intsetでcontents配列を順番に検索することによって実現すると、必ず低効率をもたらす.このためintsetは、保存した要素を順番(インクリメンタル順)に並べ、二分法により検索プロセスを高速化します.
searchメソッドの実装を見ることができます.

/*     ：     intset        ，      ，          pos   1，     0，  pos              */
static uint8_t intsetSearch(intset *is, int64_t value, uint32_t *pos) {
    int min = 0, max = intrev32ifbe(is->length)-1, mid = -1;
    int64_t cur = -1;

    /* The value can never be found when the set is empty */
    //   intset  ，  0
    if (intrev32ifbe(is->length) == 0) {
        if (pos) *pos = 0;
        return 0;
    } else {
        /* Check for the case where we know we cannot find the value, * but do know the insert position. */
        // intset         ，                       value    
        //   intset        ，                 
        if (value > _intsetGet(is,intrev32ifbe(is->length)-1)) {
            if (pos) *pos = intrev32ifbe(is->length);
            return 0;
        } else if (value < _intsetGet(is,0)) {
            if (pos) *pos = 0;
            return 0;
        }
    }

    //              
    while(max >= min) {
        mid = ((unsigned int)min + (unsigned int)max) >> 1;
        cur = _intsetGet(is,mid);
        if (value > cur) {
            min = mid+1;
        } else if (value < cur) {
            max = mid-1;
        } else {
            break;
        }
    }

    if (value == cur) {
        //       
        if (pos) *pos = mid;
        return 1;
    } else {
        //       ，      
        if (pos) *pos = min;
        return 0;
    }
}

3、intsetUpgradeAndAdd操作
intsetにはint 16しか保存できない以上t、int32_t、int64_tのタイプの整数であれば、現在のintsetがint 16_を格納する場合がある.tの整数数ですが、int 32を挿入したいです.tの新しい値.この場合、古いコレクションのすべての要素をint 32_に調整する必要があります.t符号化し、新しい値を挿入します.intsetUpgradeAndAdd関数は、このような状況を処理するために使用されます.

static intset *intsetUpgradeAndAdd(intset *is, int64_t value) {
    //       
    uint8_t curenc = intrev32ifbe(is->encoding);
    //       
    uint8_t newenc = _intsetValueEncoding(value);
    int length = intrev32ifbe(is->length);
    //        intset->contents        ，prepend               
    int prepend = value < 0 ? 1 : 0;

    /* First set new encoding and resize */
    //           intset     
    is->encoding = intrev32ifbe(newenc);
    is = intsetResize(is,intrev32ifbe(is->length)+1);

    /* Upgrade back-to-front so we don't overwrite values. * Note that the "prepend" variable is used to make sure we have an empty * space at either the beginning or the end of the intset. */
    //         ，           
    while(length--)
        _intsetSet(is,length+prepend,_intsetGetEncoded(is,length,curenc));

    /* Set the value at the beginning or the end. */
    //     ，      0，    contents    ，     contents    
    if (prepend)
        _intsetSet(is,0,value);
    else
        _intsetSet(is,intrev32ifbe(is->length),value);
    //       
    is->length = intrev32ifbe(intrev32ifbe(is->length)+1);
    return is;
}

intsetは比較的簡単なデータ構造で、以下は注釈後のソースコードで、参考にしてください.

/* * Copyright (c) 2009-2012, Pieter Noordhuis <pcnoordhuis at gmail dot com> * Copyright (c) 2009-2012, Salvatore Sanfilippo <antirez at gmail dot com> * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * * Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * 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. * * Neither the name of Redis nor the names of its contributors may be used * to endorse or promote products derived from this software without * specific prior written permission. * * 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 OWNER 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. */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "intset.h"
#include "zmalloc.h"
#include "endianconv.h"

/*     intset             ，         */

/* Note that these encodings are ordered, so: * INTSET_ENC_INT16 < INTSET_ENC_INT32 < INTSET_ENC_INT64. */
/*            */
#define INTSET_ENC_INT16 (sizeof(int16_t)) // int16_t  
#define INTSET_ENC_INT32 (sizeof(int32_t)) // int32_t  
#define INTSET_ENC_INT64 (sizeof(int64_t)) // int64_t  

/* Return the required encoding for the provided value. */
/*                */
static uint8_t _intsetValueEncoding(int64_t v) {
    if (v < INT32_MIN || v > INT32_MAX)
        return INTSET_ENC_INT64;
    else if (v < INT16_MIN || v > INT16_MAX)
        return INTSET_ENC_INT32;
    else
        return INTSET_ENC_INT16;
}

/* Return the value at pos, given an encoding. */
/*  intset.contents                       */
static int64_t _intsetGetEncoded(intset *is, int pos, uint8_t enc) {
    int64_t v64;
    int32_t v32;
    int16_t v16;

    if (enc == INTSET_ENC_INT64) {
        //  pos     8      int64_t  
        memcpy(&v64,((int64_t*)is->contents)+pos,sizeof(v64));
        //          
        memrev64ifbe(&v64);
        return v64;
    } else if (enc == INTSET_ENC_INT32) {
        //  pos     4      int32_t  
        memcpy(&v32,((int32_t*)is->contents)+pos,sizeof(v32));
        //          
        memrev32ifbe(&v32);
        return v32;
    } else {
        //  pos     2      int16_t  
        memcpy(&v16,((int16_t*)is->contents)+pos,sizeof(v16));
        //          
        memrev16ifbe(&v16);
        return v16;
    }
}

/* Return the value at pos, using the configured encoding. */
/*   intset.contents         ，     intset.encoding  。 */
static int64_t _intsetGet(intset *is, int pos) {
    return _intsetGetEncoded(is,pos,intrev32ifbe(is->encoding));
}

/* Set the value at pos, using the configured encoding. */
/*  intset.contents           ，     intset.encoding  。 */
static void _intsetSet(intset *is, int pos, int64_t value) {
    //       
    uint32_t encoding = intrev32ifbe(is->encoding);

    //             
    if (encoding == INTSET_ENC_INT64) {
        ((int64_t*)is->contents)[pos] = value;
        memrev64ifbe(((int64_t*)is->contents)+pos);
    } else if (encoding == INTSET_ENC_INT32) {
        ((int32_t*)is->contents)[pos] = value;
        memrev32ifbe(((int32_t*)is->contents)+pos);
    } else {
        ((int16_t*)is->contents)[pos] = value;
        memrev16ifbe(((int16_t*)is->contents)+pos);
    }
}

/* Create an empty intset. */
/*            */
intset *intsetNew(void) {
    intset *is = zmalloc(sizeof(intset));
    //     int16_t  
    is->encoding = intrev32ifbe(INTSET_ENC_INT16);
    is->length = 0;
    return is;
}

/* Resize the intset */
/*   intset      */
static intset *intsetResize(intset *is, uint32_t len) {
    //         
    uint32_t size = len*intrev32ifbe(is->encoding);
    //         ，realloc     
    is = zrealloc(is,sizeof(intset)+size);
    return is;
}

/* Search for the position of "value". Return 1 when the value was found and * sets "pos" to the position of the value within the intset. Return 0 when * the value is not present in the intset and sets "pos" to the position * where "value" can be inserted. */
/*     ：     intset        ，      ，          pos   1，     0，  pos              */
static uint8_t intsetSearch(intset *is, int64_t value, uint32_t *pos) {
    int min = 0, max = intrev32ifbe(is->length)-1, mid = -1;
    int64_t cur = -1;

    /* The value can never be found when the set is empty */
    //   intset  ，  0
    if (intrev32ifbe(is->length) == 0) {
        if (pos) *pos = 0;
        return 0;
    } else {
        /* Check for the case where we know we cannot find the value, * but do know the insert position. */
        // intset         ，                       value    
        //   intset ，                 
        if (value > _intsetGet(is,intrev32ifbe(is->length)-1)) {
            if (pos) *pos = intrev32ifbe(is->length);
            return 0;
        } else if (value < _intsetGet(is,0)) {
            if (pos) *pos = 0;
            return 0;
        }
    }

    //              
    while(max >= min) {
        mid = ((unsigned int)min + (unsigned int)max) >> 1;
        cur = _intsetGet(is,mid);
        if (value > cur) {
            min = mid+1;
        } else if (value < cur) {
            max = mid-1;
        } else {
            break;
        }
    }

    if (value == cur) {
        //       
        if (pos) *pos = mid;
        return 1;
    } else {
        //       ，      
        if (pos) *pos = min;
        return 0;
    }
}

/* Upgrades the intset to a larger encoding and inserts the given integer. */
/*              intset       。      intset  int16_t    ，       int32_t   ，                   int32_t  ，       。               。 */
static intset *intsetUpgradeAndAdd(intset *is, int64_t value) {
    //       
    uint8_t curenc = intrev32ifbe(is->encoding);
    //       
    uint8_t newenc = _intsetValueEncoding(value);
    int length = intrev32ifbe(is->length);
    //        intset->contents        ，prepend               
    int prepend = value < 0 ? 1 : 0;

    /* First set new encoding and resize */
    //           intset     
    is->encoding = intrev32ifbe(newenc);
    is = intsetResize(is,intrev32ifbe(is->length)+1);

    /* Upgrade back-to-front so we don't overwrite values. * Note that the "prepend" variable is used to make sure we have an empty * space at either the beginning or the end of the intset. */
    //         ，           
    while(length--)
        _intsetSet(is,length+prepend,_intsetGetEncoded(is,length,curenc));

    /* Set the value at the beginning or the end. */
    //     ，      0，    contents    ，     contents    
    if (prepend)
        _intsetSet(is,0,value);
    else
        _intsetSet(is,intrev32ifbe(is->length),value);
    //       
    is->length = intrev32ifbe(intrev32ifbe(is->length)+1);
    return is;
}

/*  from          to        ，      。       ，contents            。 */
static void intsetMoveTail(intset *is, uint32_t from, uint32_t to) {
    void *src, *dst;
    //   from           
    uint32_t bytes = intrev32ifbe(is->length)-from;
    uint32_t encoding = intrev32ifbe(is->encoding);

    //                 、           
    if (encoding == INTSET_ENC_INT64) {
        src = (int64_t*)is->contents+from;
        dst = (int64_t*)is->contents+to;
        bytes *= sizeof(int64_t);
    } else if (encoding == INTSET_ENC_INT32) {
        src = (int32_t*)is->contents+from;
        dst = (int32_t*)is->contents+to;
        bytes *= sizeof(int32_t);
    } else {
        src = (int16_t*)is->contents+from;
        dst = (int16_t*)is->contents+to;
        bytes *= sizeof(int16_t);
    }
    //     
    memmove(dst,src,bytes);
}

/* Insert an integer in the intset */
/*  intset        */
intset *intsetAdd(intset *is, int64_t value, uint8_t *success) {
    //                 ，     
    uint8_t valenc = _intsetValueEncoding(value);
    uint32_t pos;
    if (success) *success = 1;

    /* Upgrade encoding if necessary. If we need to upgrade, we know that * this value should be either appended (if > 0) or prepended (if < 0), * because it lies outside the range of existing values. */
    //              intset     ，        
    if (valenc > intrev32ifbe(is->encoding)) {
        /* This always succeeds, so we don't need to curry *success. */
        return intsetUpgradeAndAdd(is,value);
    } else {
        /* Abort if the value is already present in the set. * This call will populate "pos" with the right position to insert * the value when it cannot be found. */
        //              
        if (intsetSearch(is,value,&pos)) {
            if (success) *success = 0;
            return is;
        }

        //   intsetSearch   ，pos          
        is = intsetResize(is,intrev32ifbe(is->length)+1);
        //         pos              
        if (pos < intrev32ifbe(is->length)) intsetMoveTail(is,pos,pos+1);
    }

    //         
    _intsetSet(is,pos,value);
    is->length = intrev32ifbe(intrev32ifbe(is->length)+1);
    //       
    return is;
}

/* Delete integer from intset */
/*  intset          ，  success              */
intset *intsetRemove(intset *is, int64_t value, int *success) {
    uint8_t valenc = _intsetValueEncoding(value);
    uint32_t pos;
    if (success) *success = 0;

    //   intset      value，          
    if (valenc <= intrev32ifbe(is->encoding) && intsetSearch(is,value,&pos)) {
        uint32_t len = intrev32ifbe(is->length);

        /* We know we can delete */
        if (success) *success = 1;

        /* Overwrite value with tail and update length */
        //                         
        if (pos < (len-1)) intsetMoveTail(is,pos+1,pos);
        //   intset       
        is = intsetResize(is,len-1);
        //       
        is->length = intrev32ifbe(len-1);
    }
    return is;
}

/* Determine whether a value belongs to this set */
/*   intset          */
uint8_t intsetFind(intset *is, int64_t value) {
    uint8_t valenc = _intsetValueEncoding(value);
    return valenc <= intrev32ifbe(is->encoding) && intsetSearch(is,value,NULL);
}

/* Return random member */
/*     intset       */
int64_t intsetRandom(intset *is) {
    return _intsetGet(is,rand()%intrev32ifbe(is->length));
}

/* Sets the value to the value at the given position. When this position is * out of range the function returns 0, when in range it returns 1. */
/*   intset        ，         contents      0，    1。 */
uint8_t intsetGet(intset *is, uint32_t pos, int64_t *value) {
    //   pos    
    if (pos < intrev32ifbe(is->length)) {
        //   _intsetGet        
        *value = _intsetGet(is,pos);
        return 1;
    }
    return 0;
}

/* Return intset length */
/*   intset         */
uint32_t intsetLen(intset *is) {
    return intrev32ifbe(is->length);
}

/* Return intset blob size in bytes. */
/*   intset        */
size_t intsetBlobLen(intset *is) {
    return sizeof(intset)+intrev32ifbe(is->length)*intrev32ifbe(is->encoding);
}

/*           */
#ifdef INTSET_TEST_MAIN
#include <sys/time.h>

void intsetRepr(intset *is) {
    int i;
    for (i = 0; i < intrev32ifbe(is->length); i++) {
        printf("%lld
", (uint64_t)_intsetGet(is,i));
    }
    printf("
");
}

void error(char *err) {
    printf("%s
", err);
    exit(1);
}

void ok(void) {
    printf("OK
");
}

long long usec(void) {
    struct timeval tv;
    gettimeofday(&tv,NULL);
    return (((long long)tv.tv_sec)*1000000)+tv.tv_usec;
}

#define assert(_e) ((_e)?(void)0:(_assert(#_e,__FILE__,__LINE__),exit(1)))
void _assert(char *estr, char *file, int line) {
    printf("

=== ASSERTION FAILED ===
");
    printf("==> %s:%d '%s' is not true
",file,line,estr);
}

intset *createSet(int bits, int size) {
    uint64_t mask = (1<<bits)-1;
    uint64_t i, value;
    intset *is = intsetNew();

    for (i = 0; i < size; i++) {
        if (bits > 32) {
            value = (rand()*rand()) & mask;
        } else {
            value = rand() & mask;
        }
        is = intsetAdd(is,value,NULL);
    }
    return is;
}

void checkConsistency(intset *is) {
    int i;

    for (i = 0; i < (intrev32ifbe(is->length)-1); i++) {
        uint32_t encoding = intrev32ifbe(is->encoding);

        if (encoding == INTSET_ENC_INT16) {
            int16_t *i16 = (int16_t*)is->contents;
            assert(i16[i] < i16[i+1]);
        } else if (encoding == INTSET_ENC_INT32) {
            int32_t *i32 = (int32_t*)is->contents;
            assert(i32[i] < i32[i+1]);
        } else {
            int64_t *i64 = (int64_t*)is->contents;
            assert(i64[i] < i64[i+1]);
        }
    }
}

int main(int argc, char **argv) {
    uint8_t success;
    int i;
    intset *is;
    sranddev();

    printf("Value encodings: "); {
        assert(_intsetValueEncoding(-32768) == INTSET_ENC_INT16);
        assert(_intsetValueEncoding(+32767) == INTSET_ENC_INT16);
        assert(_intsetValueEncoding(-32769) == INTSET_ENC_INT32);
        assert(_intsetValueEncoding(+32768) == INTSET_ENC_INT32);
        assert(_intsetValueEncoding(-2147483648) == INTSET_ENC_INT32);
        assert(_intsetValueEncoding(+2147483647) == INTSET_ENC_INT32);
        assert(_intsetValueEncoding(-2147483649) == INTSET_ENC_INT64);
        assert(_intsetValueEncoding(+2147483648) == INTSET_ENC_INT64);
        assert(_intsetValueEncoding(-9223372036854775808ull) == INTSET_ENC_INT64);
        assert(_intsetValueEncoding(+9223372036854775807ull) == INTSET_ENC_INT64);
        ok();
    }

    printf("Basic adding: "); {
        is = intsetNew();
        is = intsetAdd(is,5,&success); assert(success);
        is = intsetAdd(is,6,&success); assert(success);
        is = intsetAdd(is,4,&success); assert(success);
        is = intsetAdd(is,4,&success); assert(!success);
        ok();
    }

    printf("Large number of random adds: "); {
        int inserts = 0;
        is = intsetNew();
        for (i = 0; i < 1024; i++) {
            is = intsetAdd(is,rand()%0x800,&success);
            if (success) inserts++;
        }
        assert(intrev32ifbe(is->length) == inserts);
        checkConsistency(is);
        ok();
    }

    printf("Upgrade from int16 to int32: "); {
        is = intsetNew();
        is = intsetAdd(is,32,NULL);
        assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT16);
        is = intsetAdd(is,65535,NULL);
        assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT32);
        assert(intsetFind(is,32));
        assert(intsetFind(is,65535));
        checkConsistency(is);

        is = intsetNew();
        is = intsetAdd(is,32,NULL);
        assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT16);
        is = intsetAdd(is,-65535,NULL);
        assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT32);
        assert(intsetFind(is,32));
        assert(intsetFind(is,-65535));
        checkConsistency(is);
        ok();
    }

    printf("Upgrade from int16 to int64: "); {
        is = intsetNew();
        is = intsetAdd(is,32,NULL);
        assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT16);
        is = intsetAdd(is,4294967295,NULL);
        assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT64);
        assert(intsetFind(is,32));
        assert(intsetFind(is,4294967295));
        checkConsistency(is);

        is = intsetNew();
        is = intsetAdd(is,32,NULL);
        assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT16);
        is = intsetAdd(is,-4294967295,NULL);
        assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT64);
        assert(intsetFind(is,32));
        assert(intsetFind(is,-4294967295));
        checkConsistency(is);
        ok();
    }

    printf("Upgrade from int32 to int64: "); {
        is = intsetNew();
        is = intsetAdd(is,65535,NULL);
        assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT32);
        is = intsetAdd(is,4294967295,NULL);
        assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT64);
        assert(intsetFind(is,65535));
        assert(intsetFind(is,4294967295));
        checkConsistency(is);

        is = intsetNew();
        is = intsetAdd(is,65535,NULL);
        assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT32);
        is = intsetAdd(is,-4294967295,NULL);
        assert(intrev32ifbe(is->encoding) == INTSET_ENC_INT64);
        assert(intsetFind(is,65535));
        assert(intsetFind(is,-4294967295));
        checkConsistency(is);
        ok();
    }

    printf("Stress lookups: "); {
        long num = 100000, size = 10000;
        int i, bits = 20;
        long long start;
        is = createSet(bits,size);
        checkConsistency(is);

        start = usec();
        for (i = 0; i < num; i++) intsetSearch(is,rand() % ((1<<bits)-1),NULL);
        printf("%ld lookups, %ld element set, %lldusec
",num,size,usec()-start);
    }

    printf("Stress add+delete: "); {
        int i, v1, v2;
        is = intsetNew();
        for (i = 0; i < 0xffff; i++) {
            v1 = rand() % 0xfff;
            is = intsetAdd(is,v1,NULL);
            assert(intsetFind(is,v1));

            v2 = rand() % 0xfff;
            is = intsetRemove(is,v2,NULL);
            assert(!intsetFind(is,v2));
        }
        checkConsistency(is);
        ok();
    }
}
#endif