redis源码阅读-intset(整数集合)

¶redis源码阅读-intset(整数集合)

¶intset

intset是redis实现的整数集合，是redis集合键底层实现之一。主要用在数据量比较小，并且是整数的地方。
intset能保存int16_t,int32_t,int64_t类型的整数，并且可以保存其中不会出现重复数据，而且其数据的大小是从小到大有序排列(这个有序排列我还没想明白是怎么实现的)。
intset的结构如下：

typedef struct intset {
    uint32_t encoding; // intset集合真正的类型,有uint16_t,uint32_t,uint64_t三种类型。
    uint32_t length; // 长度
    int8_t contents[]; // 内容数组,存储整数集合，其声明类型没有意义
} intset;

其中的encoding是用来判断intset是什么类型的，而contents是用来存储intset集合元素的，默认声明是int8_t，但是没有意义。
intset有个特性就是升级,当加入intset的值的编码比当前Intset的编码大时，intset会自动升级为加入的值一样的编码。例如：当前intset是int8_t类型，有4个元素，总共占8*3=24位的内存空间，现在加入一个int32_t类型的65535,intset这个集合升级为占32*4=128位的内存空间，而升级后不能降级。

¶intset.h

/*
 * 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.
 */

#ifndef __INTSET_H
#define __INTSET_H
#include <stdint.h>
// 定义整数集合结构
typedef struct intset {
    uint32_t encoding; // intset集合真正的类型,有uint16_t,uint32_t,uint64_t三种类型。
    uint32_t length; // 长度
    int8_t contents[]; // 内容数组,存储整数集合，其声明类型没有意义
} intset;

// 创建一个整数集合
intset *intsetNew(void);
// 将整数值存入整数集合
intset *intsetAdd(intset *is, int64_t value, uint8_t *success);
// 将整数值从整数集合移除
intset *intsetRemove(intset *is, int64_t value, int *success);
// 通过指定的整数从整数集合中查找
uint8_t intsetFind(intset *is, int64_t value);
int64_t intsetRandom(intset *is);
uint8_t intsetGet(intset *is, uint32_t pos, int64_t *value);
// 获取整数集合的长度
uint32_t intsetLen(const intset *is);
// 获取整数集合占用内存空间的长度
size_t intsetBlobLen(intset *is);

// 用于测试
#ifdef REDIS_TEST
int intsetTest(int argc, char *argv[]);
#endif

#endif // __INTSET_H

¶intset.c

/*
 * 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"

/* Note that these encodings are ordered, so:
 * INTSET_ENC_INT16 < INTSET_ENC_INT32 < INTSET_ENC_INT64. */
 
/*
 * 大小端字节序：https://www.cnblogs.com/gremount/p/8830707.html
 * 在计算机中，一般是从低位字节开始读取，而人总是习惯从高位字节开始读取
 * 为了适应计算机需求，需要将字节转换为小端字节序，也就是把字节的低位转到高位
 */

// 各种整数类型占位大小
#define INTSET_ENC_INT16 (sizeof(int16_t))
#define INTSET_ENC_INT32 (sizeof(int32_t))
#define INTSET_ENC_INT64 (sizeof(int64_t))

/* Return the required encoding for the provided value. */
// 返回提供的整数类型的占位大小,虽然输入的是int64_t类型，但是如果输入的值范围在更小的类型中，那就返回适合的类型占位大小
static uint8_t _intsetValueEncoding(int64_t v) {
    if (v < INT32_MIN || v > INT32_MAX) // 如果输入的数值小于整型所占最小范围或者大于整型所占最大范围，那确定它是64位整型
        re1turn 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. */
/* 从is中获取pos位置的整数,它是通过enc编码来获取地址的
 * 因为在intset集合中,contents一般声明为int8_t类型，取地址一般是8位8位的取。但是intset集合的类型是encoding来决定的
 * 如果intset是int16_t类型，却8位8位的取地址，取出的内容都是不对的。我们需要将contents的类型转换为enc指定的类型。
 * 取地址的时候通过enc指定的位数来取，这样就能取得正确的地址，获取正确地址中的正确内容
 * intset *is : 整数集合
 * int pos : 整数集合中一个整数所在位置
 * uint8_t enc : 类型值 uint8_t类型值是1 , uint16_t类型值是2 , uint32_t类型值是4 , uint64_t类型值是8
 * 一般enc都是is->encoding
 */
static int64_t _intsetGetEncoded(intset *is, int pos, uint8_t enc) {
    int64_t v64;
    int32_t v32;
    int16_t v16;

	// 如果enc=8 , 表示is是一个uint64_t类型的整数集合
    if (enc == INTSET_ENC_INT64) {
		// 不管怎样，先将is的contents类型转换为int64_t,将int64_t类型区域复制给v64
        memcpy(&v64,((int64_t*)is->contents)+pos,sizeof(v64));
        memrev64ifbe(&v64); // 将v64地址转换为小端字节序,方便计算机读取
        return v64; // 然后返回v64的内容
    } else if (enc == INTSET_ENC_INT32) {
        memcpy(&v32,((int32_t*)is->contents)+pos,sizeof(v32));
        memrev32ifbe(&v32);
        return v32;
    } else {
        memcpy(&v16,((int16_t*)is->contents)+pos,sizeof(v16));
        memrev16ifbe(&v16);
        return v16;
    }
}

/* Return the value at pos, using the configured encoding. */
// 获取pos位置的整型变量，整型集合的类型直接从encoding中获取
static int64_t _intsetGet(intset *is, int pos) {
    return _intsetGetEncoded(is,pos,intrev32ifbe(is->encoding));
}

/* Set the value at pos, using the configured encoding. */
// 在pos位置设置一个整数值
static void _intsetSet(intset *is, int pos, int64_t value) {
    uint32_t encoding = intrev32ifbe(is->encoding); //先获取is是哪种类型的整数集合

    if (encoding == INTSET_ENC_INT64) { // 如果is是uint64_t类型的整数集合,先将is中的contents强制转换为int64_t类型，将value放置在64位的区域内
        ((int64_t*)is->contents)[pos] = value;
        memrev64ifbe(((int64_t*)is->contents)+pos); // 将地址转换为小端地址序存储
    } 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. */
// 创建一个空的整数集合
intset *intsetNew(void) {
    intset *is = zmalloc(sizeof(intset));
    is->encoding = intrev32ifbe(INTSET_ENC_INT16);
    is->length = 0;
    return is;
}

/* Resize the intset */
// 改变整数集合大小
static intset *intsetResize(intset *is, uint32_t len) {
    uint32_t size = len*intrev32ifbe(is->encoding);
    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. */
/* 搜索pos位置的value,如果value被找到，则返回1,并且pos位置在集合中
 * 如果value没有被找到，则返回0,并且pos位置不在集合中,就为pos置0或者最大值
 */
static uint8_t intsetSearch(intset *is, int64_t value, uint32_t *pos) {
	// 使用二分查找法
    int min = 0, max = intrev32ifbe(is->length)-1, mid = -1; // min:最小值，max:最大值，mid:初始中间值
    int64_t cur = -1; // 当前游标

    /* The value can never be found when the set is empty */
    if (intrev32ifbe(is->length) == 0) { // 当集合长度为0,表示为空
        if (pos) *pos = 0; // 如果输入的pos地址不畏NULL,就给它置0
        return 0;
    } else {
        /* Check for the case where we know we cannot find the value,
         * but do know the insert position. */
         // 在intset集合中,最大值会被放在最后，最小值会被放在最前
         // 因为，数据编码最大的会放在最后面，而最大值的数据编码是最大的
        if (value > _intsetGet(is,max)) { 
            if (pos) *pos = intrev32ifbe(is->length);
            return 0;
        } else if (value < _intsetGet(is,0)) {
            if (pos) *pos = 0;
            return 0;
        }
    }

	// 当索引最大值大于索引最小值
    while(max >= min) {
        mid = ((unsigned int)min + (unsigned int)max) >> 1; // (相当于min+max)/2
        cur = _intsetGet(is,mid); // 获取中间值
        // 判断value值在哪边,如果在中间就表示已经被找到,索引值就不要改变，直接执行下一步
        if (value > cur) {
            min = mid+1;
        } else if (value < cur) {
            max = mid-1;
        } else {
            break;
        }
    }
	
	// 表示已经被找到
    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. */
// 新增value,并根据新增value的编码来升级intset的编码
static intset *intsetUpgradeAndAdd(intset *is, int64_t value) {
    uint8_t curenc = intrev32ifbe(is->encoding); // 将encoding转换为32为的小端字节序，并返回其内容
    uint8_t newenc = _intsetValueEncoding(value); // 获取value值的编码类型
    int length = intrev32ifbe(is->length); // 获取is的长度
    int prepend = value < 0 ? 1 : 0; 

    /* First set new encoding and resize */
    is->encoding = intrev32ifbe(newenc); // is小端字节序存储新编码
    is = intsetResize(is,intrev32ifbe(is->length)+1); // 扩容

    /* 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. */
     /* 如果prepend=1,表示需要在最前面增加值，就将intset集合中的元素一个一个的向后摞一位，使得索引为0时是空的
      * 如果prepend=0,表示需要在最后面增加值，就将intset集合重新增加一遍，不改变索引
      */
    while(length--)
        _intsetSet(is,length+prepend,_intsetGetEncoded(is,length,curenc));

    /* Set the value at the beginning or the end. */
    // 如果输入的整数是小于0的，就将其安放在最开始
    if (prepend)
        _intsetSet(is,0,value);
    else // 否则就放在结束
        _intsetSet(is,intrev32ifbe(is->length),value);
    is->length = intrev32ifbe(intrev32ifbe(is->length)+1);
    return is;
}

// 向后移动元素,主要是用来为新元素预留空间
static void intsetMoveTail(intset *is, uint32_t from, uint32_t to) {
    void *src, *dst;
    uint32_t bytes = intrev32ifbe(is->length)-from; // 获取索引from后的元素数
    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 */
// 添加一个整数到intset,添加成功，success=1,否则success=0
intset *intsetAdd(intset *is, int64_t value, uint8_t *success) {
    uint8_t valenc = _intsetValueEncoding(value); // 为value值设置一个合适的编码
    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. */
    if (valenc > intrev32ifbe(is->encoding)) { // 如果需要增加值的编码比is的编码大，就需要升级is为value一样的编码,并将value增加到最后
        /* This always succeeds, so we don't need to curry *success. */
        return intsetUpgradeAndAdd(is,value);
    } else { // 如果编码一样或者更小，就找到value的插入点
        /* 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)) { // 表示查找到intset有相同的值
            if (success) *success = 0;
            return is;
        }

        is = intsetResize(is,intrev32ifbe(is->length)+1);
        // 如果pos=0,就直接将整体向后移一位，空出第一位
        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 */
// 从intset中删除
intset *intsetRemove(intset *is, int64_t value, int *success) {
    uint8_t valenc = _intsetValueEncoding(value);
    uint32_t pos;
    if (success) *success = 0;

    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);
        is = intsetResize(is,len-1);
        is->length = intrev32ifbe(len-1);
    }
    return is;
}

/* Determine whether a value belongs to this set */
// 查询value,调用intsetSearch函数,查询成功返回1,失败返回0
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 */
// 返回一个随机索引中的值
int64_t intsetRandom(intset *is) {
    return _intsetGet(is,rand()%intrev32ifbe(is->length));
}

/* Get the value at the given position. When this position is
 * out of range the function returns 0, when in range it returns 1. */
 // 获取pos位置的整型变量，如果成功获取，返回1,并且value存储获取到的值;否则返回0,value=NULL
uint8_t intsetGet(intset *is, uint32_t pos, int64_t *value) {
    if (pos < intrev32ifbe(is->length)) {
        *value = _intsetGet(is,pos);
        return 1;
    }
    return 0;
}

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

/* Return intset blob size in bytes. */
// len*encoding+sizeof(intset);返回的是内存空间的长度
size_t intsetBlobLen(intset *is) {
    return sizeof(intset)+intrev32ifbe(is->length)*intrev32ifbe(is->encoding);
}

#ifdef REDIS_TEST
#include <sys/time.h>
#include <time.h>

#if 0
static void intsetRepr(intset *is) {
    for (uint32_t i = 0; i < intrev32ifbe(is->length); i++) {
        printf("%lld\n", (uint64_t)_intsetGet(is,i));
    }
    printf("\n");
}

static void error(char *err) {
    printf("%s\n", err);
    exit(1);
}
#endif

static void ok(void) {
    printf("OK\n");
}

static 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)))
static void _assert(char *estr, char *file, int line) {
    printf("\n\n=== ASSERTION FAILED ===\n");
    printf("==> %s:%d '%s' is not true\n",file,line,estr);
}

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

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

static void checkConsistency(intset *is) {
    for (uint32_t 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]);
        }
    }
}

#define UNUSED(x) (void)(x)
int intsetTest(int argc, char **argv) {
    uint8_t success;
    int i;
    intset *is;
    srand(time(NULL));

    UNUSED(argc);
    UNUSED(argv);

    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: "); {
        uint32_t 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\n",
               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();
    }

    return 0;
}
#endif

¶文献整理

1. Redis内部数据结构详解(7)——intset
2. Redis之整数集合intset
3. redis中整数聚合的add操作