Redis源码剖析 - Reids内置数据结构之整数集合intset

Posted 2023-02-15 Fred^_^

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Redis源码剖析系列文章汇总：传送门

今天我们来介绍Redis中一个比较简单的内置数据结构 – 整数集合intset。

---

1、intset存储结构

整数集合，顾名思义，就是存储一系列整数的集合。在Redis中，intset结构体的定义如下：

/* 整数集合结构体 */
typedef struct intset 
    // 编码方式
    uint32_t encoding;
    // 保存的元素数量
    uint32_t length;
    // 真正存放数据的地方
    int8_t contents[];
 intset;

其中：encoding表示intset存储的整型类型，共有3中不同编码：INTSET_ENC_INT16、INTSET_ENC_INT32、INTSET_ENC_INT64分别表示int16_t、int32_t、int64_t三种不同类型的整数。一个intset中存储的整数都是相同类型的。length指明了intset中存放的元素个数。contents数组才是真正存放整数的地方，每个整数占用的字节数由encoding指出，可能是2字节、4字节、8字节。

intset的存储结构如下图：

2、元素存储特点

作为一个集合，判断集合中是否存在某个元素是一个常用的操作。在intset中如果通过顺序查找contents数组来实现必定带来低效率。为此，intset将其保存的元素按序（递增顺序）排列，通过二分法加快查找过程。

我们可以看看search方法的实现：

/* 查找函数：在整数集合intset中查找给定的整数，如果查找成功，则将其索引位置赋值给pos并返回1，
    否则返回0，此时pos指向一个可插入新节点的位置 */
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 */
    // 如果intset为空，返回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中的元素是排好序的，判断第一个和最后一个元素的数值就可以确定给定数value有无可能
        // 落在intset包含的整数区间中，如果给定值不在该区间则无需继续查找
        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;
        
    

    // 利用二分法查找一个插入位置
    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) 
        // 查找到指定值
        if (pos) *pos = mid;
        return 1;
     else 
        // 未找到给定值，返回插入位置
        if (pos) *pos = min;
        return 0;
    

3、intsetUpgradeAndAdd操作

既然intset中只能保存int16_t、int32_t、int64_t中一种类型的整数，那就可能存在这么一种情况：当前的intset存放int16_t的整型数，但想往其中插入一个int32_t的新值。此时需要对旧集合中的所有元素全部调整为int32_t编码，然后再插入新值。intsetUpgradeAndAdd函数就是用来处理这种情况的。

static intset *intsetUpgradeAndAdd(intset *is, int64_t value) 
    // 旧的编码方式
    uint8_t curenc = intrev32ifbe(is->encoding);
    // 新的编码方式
    uint8_t newenc = _intsetValueEncoding(value);
    int length = intrev32ifbe(is->length);
    // 插入的新值放在intset->contents数组的前面或后面，prepend用来保证留出一个空间来存放新值
    int prepend = value < 0 ? 1 : 0;

    /* First set new encoding and resize */
    // 设置新的编码然后调整intset的容量大小
    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. */
    // 从后往前开始复制，这样就不会发生覆盖现象
    while(length--)
        _intsetSet(is,length+prepend,_intsetGetEncoded(is,length,curenc));

    /* Set the value at the beginning or the end. */
    // 插入新值，如果新值大于0，则追加到contents数组后面，否则插入到contents数组前边
    if (prepend)
        _intsetSet(is,0,value);
    else
        _intsetSet(is,intrev32ifbe(is->length),value);
    // 更新长度信息
    is->length = intrev32ifbe(intrev32ifbe(is->length)+1);
    return is;

---

intset是一种比较简单的数据结构，下面是注释后的源码，供大家参考：

/*
 * 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"

/* 整数集合intset中是以递增的形式存放整数的，可以加快查找速度 */

/* Note that these encodings are ordered, so:
 * INTSET_ENC_INT16 < INTSET_ENC_INT32 < INTSET_ENC_INT64. */
/* 三种不同整数类型编码 */
#define INTSET_ENC_INT16 (sizeof(int16_t))  // int16_t整型
#define INTSET_ENC_INT32 (sizeof(int32_t))  // int32_t整型
#define INTSET_ENC_INT64 (sizeof(int64_t))  // int64_t整型

/* Return the required encoding for the provided value. */
/* 返回存储给定整数值的编码方式 */
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. */
/* 将intset.contents数组指定位置的数据按指定的编码方式解析并返回 */
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) 
        // 将pos位置开始的8个字节解析为int64_t整数
        memcpy(&v64,((int64_t*)is->contents)+pos,sizeof(v64));
        // 统一转换为小端模式
        memrev64ifbe(&v64);
        return v64;
     else if (enc == INTSET_ENC_INT32) 
        // 将pos位置开始的4个字节解析为int32_t整数
        memcpy(&v32,((int32_t*)is->contents)+pos,sizeof(v32));
        // 统一转换为小端模式
        memrev32ifbe(&v32);
        return v32;
     else 
        // 将pos位置开始的2个字节解析为int16_t整数
        memcpy(&v16,((int16_t*)is->contents)+pos,sizeof(v16));
        // 统一转换为小端模式
        memrev16ifbe(&v16);
        return v16;
    


/* Return the value at pos, using the configured encoding. */
/* 获取intset.contents数组指定位置的数据，编码方式由intset.encoding指定。 */
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intset.contents数组指定位置上设置数值，编码方式由intset.encoding指定。 */
static void _intsetSet(intset *is, int pos, int64_t value) 
    // 获取编码方式
    uint32_t encoding = intrev32ifbe(is->encoding);

    // 依据编码方式设置相应的值
    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. */
/* 创建一个空的整数结合 */
intset *intsetNew(void) 
    intset *is = zmalloc(sizeof(intset));
    // 默认存放int16_t整数
    is->encoding = intrev32ifbe(INTSET_ENC_INT16);
    is->length = 0;
    return is;


/* Resize the intset */
/* 调整intset的容量大小 */
static intset *intsetResize(intset *is, uint32_t len) 
    // 计算新增的字节数
    uint32_t size = len*intrev32ifbe(is->encoding);
    // 重新分配内存空间，realloc在原地分配
    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. */
/* 查找函数：在整数集合intset中查找给定的整数，如果查找成功，则将其索引位置赋值给pos并返回1，
    否则返回0，此时pos指向一个可插入新节点的位置 */
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 */
    // 如果intset为空，返回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中的元素是排好序的，判断第一个和最后一个元素的数值就可以确定给定数value有无可能
        // 落在intset中，如果给定值不在该区间则无需继续查找
        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;
        
    

    // 利用二分法查找一个插入位置
    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) 
        // 查找到指定值
        if (pos) *pos = mid;
        return 1;
     else 
        // 未找到给定值，返回插入位置
        if (pos) *pos = min;
        return 0;
    


/* Upgrades the intset to a larger encoding and inserts the given integer. */
/* 使用更大的编码方式更新整个intset并插入一个数字。
    如果当前的intset存放int16_t的整型数，如果要插入一个int32_t的新值，则需要对旧集合中的所有元素全部
    调整为int32_t编码，然后再插入新值。这个函数就是用来处理这种情况的。
*/
static intset *intsetUpgradeAndAdd(intset *is, int64_t value) 
    // 旧的编码方式
    uint8_t curenc = intrev32ifbe(is->encoding);
    // 新的编码方式
    uint8_t newenc = _intsetValueEncoding(value);
    int length = intrev32ifbe(is->length);
    // 插入的新值放在intset->contents数组的前面或后面，prepend用来保证留出一个空间来存放新值
    int prepend = value < 0 ? 1 : 0;

    /* First set new encoding and resize */
    // 设置新的编码然后调整intset的容量大小
    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. */
    // 从后往前开始复制，这样就不会发生覆盖现象
    while(length--)
        _intsetSet(is,length+prepend,_intsetGetEncoded(is,length,curenc));

    /* Set the value at the beginning or the end. */
    // 插入新值，如果新值大于0，则追加到contents数组后面，否则插入到contents数组前边
    if (prepend)
        _intsetSet(is,0,value);
    else
        _intsetSet(is,intrev32ifbe(is->length),value);
    // 更新长度信息
    is->length = intrev32ifbe(intrev32ifbe(is->length)+1);
    return is;


/* 将from位置开始的数据移动到to位置开始后的空间，用户删除操作。
    该操作结束后，contents数组尾端可能存在无效数据。 */
static void intsetMoveTail(intset *is, uint32_t from, uint32_t to) 
    void *src, *dst;
    // 计算from位置开始共有多少个元素
    uint32_t bytes = intrev32ifbe(is->length)-from;
    uint32_t encoding = intrev32ifbe(is->encoding);

    // 根据编码方式计算需要移动的字节数、目标位置和移动开始位置
    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);
    
    // 内存移动
    memmove(dst,src,bytes);


/* Insert an integer in the intset */
/* 往intset中添加一个元素 */
intset *intsetAdd(intset *is, int64_t value, uint8_t *success) 
    // 获取存储待插入新值所需要的字节数，即编码方式
    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. */
    // 如果新值的编码方式大于当前intset的编码方式，需要扩展后再插入
    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. */
        // 判断待插入值是不是已经存在
        if (intsetSearch(is,value,&pos)) 
            if (success) *success = 0;
            return is;
        

        // 经过intsetSearch操作后，pos指向了一个可插入位置
        is = intsetResize(is,intrev32ifbe(is->length)+1);
        // 移动元素以保住在pos位置留出足够空间用来容纳新值
        if (pos < intrev32ifbe(is->length)) intsetMoveTail(is,pos,pos+1);
    

    // 写入待插入整数值
    _intsetSet(is,pos,value);
    is->length = intrev32ifbe(intrev32ifbe(is->length)+1);
    // 更新长度信息
    return is;


/* Delete integer from intset */
/* 从intset中删除一个给定的整数，参数success用来标识是否执行了删除操作 */
intset *intsetRemove(intset *is, int64_t value, int *success) 
    uint8_t valenc = _intsetValueEncoding(value);
    uint32_t pos;
    if (success) *success = 0;

    // 先在intset中查找给定值value，只有该值存在才能删除
    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 */
        // 将待删除元素后面的元素移动到待删除元素当前的位置
        if (pos < (len-1)) intsetMoveTail(is,pos+1,pos);
        // 调整intset的内存空间大小
        is = intsetResize(is,len-1);
        // 更新长度信息
        is->length = intrev32ifbe(len-1);
    
    return is;


/* Determine whether a value belongs to this set */
/* 判断intset中是否包含指定的值 */
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 */
/* 随机返回intset中的一个元素 */
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. */
/* 返回intset中指定位置的元素，如果指定的位置超出contents的长度则返回0，否则返回1。 */
uint8_t intsetGet(intset *is, uint32_t pos, int64_t *value) 
    // 判断pos是否合法
    if (pos < intrev32ifbe(is->length)) 
        // 调用_intsetGet函数返回相应的值
        *value = _intsetGet(is,pos);
        return 1;
    
    return 0;


/* Return intset length */
/* 返回intset中保存的元素个数 */
uint32_t intsetLen(intset *is) 
    return intrev32ifbe(is->length);


/* Return intset blob size in bytes. */
/* 返回intset所占用的字节数 */
size_t intsetBlobLen(intset *is) 
    return sizeof(intset)+intrev32ifbe(is->length)*intrev32ifbe(is->encoding);


/* 下面是一些测试代码 */
#ifdef INTSET_TEST_MAIN
#include <sys/time.h>

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


void error(char *err) 
    printf("%s\\n", err);
    exit(1);


void ok(void) 
    printf("OK\\n");


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("\\n\\n=== ASSERTION FAILED ===\\n");
    printf("==> %s:%d '%s' is not true\\n",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([phone]) == INTSET_ENC_INT32);
        assert(_intsetValueEncoding(-2147483649) == INTSET_ENC_INT64);
        assert(_intsetValueEncoding([phone]) == 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\\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();
    

#endif