//节点结构，自带一个指向下一个节点的指针，用来防重
typedef struct dictEntry {
void *key;
union {
void *val;
uint64_t u64;
int64_t s64;
double d;
} v;
struct dictEntry *next;
} dictEntry;
//每个hash表都需要定义hash算法，key复制，值复制，key比较，key销毁，值销毁的方法
typedef struct dictType {
unsigned int (*hashFunction)(const void *key);
void *(*keyDup)(void *privdata, const void *key);
void *(*valDup)(void *privdata, const void *obj);
int (*keyCompare)(void *privdata, const void *key1, const void *key2);
void (*keyDestructor)(void *privdata, void *key);
void (*valDestructor)(void *privdata, void *obj);
} dictType;
//hash表的结构，
typedef struct dictht {
dictEntry **table;//指向第一个节点的指针的指针
unsigned long size;//hash表的容量
unsigned long sizemask;
unsigned long used;//hash表的当前使用量
} dictht;
//字典
typedef struct dict {
dictType *type;
void *privdata;//私有数据，保存着dictType结构中函数的参数。
dictht ht[2];//两张hash表
long rehashidx; /* 扩容标志，-1未扩容，其它则表示正在扩容中 */
int iterators; /* 正在迭代的迭代器数量 */
} dict;
/* 迭代器 */
typedef struct dictIterator {
dict *d;//正在迭代的字典
long index;
int table, safe;
dictEntry *entry, *nextEntry;//当前，下一个键值对
long long fingerprint;
} dictIterator;
//字典是否可重新设置容量标志
static int dict_can_resize = 1;
static unsigned int dict_force_resize_ratio = 5;//强制扩容比率 已用键值对/hash表大小，这个值无用
/* -------------------------- private prototypes ---------------------------- */
static int _dictExpandIfNeeded(dict *ht);
static unsigned long _dictNextPower(unsigned long size);
static int _dictKeyIndex(dict *ht, const void *key);
static int _dictInit(dict *ht, dictType *type, void *privDataPtr);
/* -------------------------- hash functions -------------------------------- */
/* 针对整数的hash算法 */
unsigned int dictIntHashFunction(unsigned int key)
{
key += ~(key << 15);
key ^= (key >> 10);
key += (key << 3);
key ^= (key >> 6);
key += ~(key << 11);
key ^= (key >> 16);
return key;
}
//hash种子
static uint32_t dict_hash_function_seed = 5381;
void dictSetHashFunctionSeed(uint32_t seed) {
dict_hash_function_seed = seed;
}
uint32_t dictGetHashFunctionSeed(void) {
return dict_hash_function_seed;
}
/*
针对字符串的hash算法
*/
unsigned int dictGenHashFunction(const void *key, int len) {
/* 'm' and 'r' are mixing constants generated offline.
They're not really 'magic', they just happen to work well. */
uint32_t seed = dict_hash_function_seed;
const uint32_t m = 0x5bd1e995;
const int r = 24;
/* Initialize the hash to a 'random' value */
uint32_t h = seed ^ len;
/* Mix 4 bytes at a time into the hash */
const unsigned char *data = (const unsigned char *)key;
while(len >= 4) {
uint32_t k = *(uint32_t*)data;
k *= m;
k ^= k >> r;
k *= m;
h *= m;
h ^= k;
data += 4;
len -= 4;
}
/* Handle the last few bytes of the input array */
switch(len) {
case 3: h ^= data[2] << 16;
case 2: h ^= data[1] << 8;
case 1: h ^= data[0]; h *= m;
};
/* Do a few final mixes of the hash to ensure the last few
* bytes are well-incorporated. */
h ^= h >> 13;
h *= m;
h ^= h >> 15;
return (unsigned int)h;
}
/* 不区分大小写的字符串hash算法 */
unsigned int dictGenCaseHashFunction(const unsigned char *buf, int len) {
unsigned int hash = (unsigned int)dict_hash_function_seed;
while (len--)
hash = ((hash << 5) + hash) + (tolower(*buf++)); /* hash * 33 + c */
return hash;
}
/* ----------------------------- API implementation ------------------------- */
/* 字典重置，表为空，各项数据为0 */
static void _dictReset(dictht *ht)
{
ht->table = NULL;
ht->size = 0;
ht->sizemask = 0;
ht->used = 0;
}
/* 创建hash表，并附私有数据 */
dict *dictCreate(dictType *type,
void *privDataPtr)
{
dict *d = zmalloc(sizeof(*d));
_dictInit(d,type,privDataPtr);
return d;
}
/* 一个字典两个hash表 */
int _dictInit(dict *d, dictType *type,
void *privDataPtr)
{
_dictReset(&d->ht[0]);
_dictReset(&d->ht[1]);
d->type = type;
d->privdata = privDataPtr;
d->rehashidx = -1;//扩容进行标志，-1表示没有在扩容
d->iterators = 0;
return DICT_OK;
}
/* 扩容操作 */
int dictResize(dict *d)
{
int minimal;
//如果禁止扩容或者正在扩容，则报错
if (!dict_can_resize || dictIsRehashing(d)) return DICT_ERR;
minimal = d->ht[0].used;
if (minimal < DICT_HT_INITIAL_SIZE)
minimal = DICT_HT_INITIAL_SIZE;
return dictExpand(d, minimal);
}
/* 扩容 */
int dictExpand(dict *d, unsigned long size)
{
dictht n; /* the new hash table */
unsigned long realsize = _dictNextPower(size);//size一定是2的整数倍
/* 如果正在扩容或已用大小超过扩容大小，则报错，出现异常了 */
if (dictIsRehashing(d) || d->ht[0].used > size)
return DICT_ERR;
/* 如果扩容后的大小和当前大小一致，报错 */
if (realsize == d->ht[0].size) return DICT_ERR;
/* 重置表的大小，掩码，重新申请放键值对指针的数组内存，当前使用量重置为0 */
n.size = realsize;
n.sizemask = realsize-1;
n.table = zcalloc(realsize*sizeof(dictEntry*));
n.used = 0;
/* 如果旧表的内存不存在，说明旧表容量是0 */
if (d->ht[0].table == NULL) {
d->ht[0] = n;
return DICT_OK;
}
/* 将n赋值给第2张表，以备扩容用 */
d->ht[1] = n;
d->rehashidx = 0;
return DICT_OK;
}
/* 重新创建hash表,进行n步 */
int dictRehash(dict *d, int n) {
int empty_visits = n*10; /* 最多访问n*10个空值 */
if (!dictIsRehashing(d)) return 0;//如果没有标志在进行rehash则退出
while(n-- && d->ht[0].used != 0) {
dictEntry *de, *nextde;
/* */
assert(d->ht[0].size > (unsigned long)d->rehashidx);
while(d->ht[0].table[d->rehashidx] == NULL) {//如果是空值就继续找
d->rehashidx++;
if (--empty_visits == 0) return 1;
}
de = d->ht[0].table[d->rehashidx];//要重新hash的键值对
/* Move all the keys in this bucket from the old to the new hash HT */
while(de) {
unsigned int h;
nextde = de->next;
/* Get the index in the new hash table */
h = dictHashKey(d, de->key) & d->ht[1].sizemask;//重新hash
de->next = d->ht[1].table[h];
d->ht[1].table[h] = de;
d->ht[0].used--;
d->ht[1].used++;
de = nextde;
}
d->ht[0].table[d->rehashidx] = NULL;
d->rehashidx++;//下一个rehash的key的id
}
/* 检查是否已经全部rehash了 */
if (d->ht[0].used == 0) {
zfree(d->ht[0].table);//释放第一张表
d->ht[0] = d->ht[1];//把第二张表赋值给第一张表
_dictReset(&d->ht[1]);//重置第二张表
d->rehashidx = -1;//重置rehashidx标志
return 0;
}
/* More to rehash... */
return 1;
}
//返回当前时间的毫秒
long long timeInMilliseconds(void) {
struct timeval tv;
gettimeofday(&tv,NULL);
return (((long long)tv.tv_sec)*1000)+(tv.tv_usec/1000);
}
/* rehash一段时间,超过ms毫秒则返回,返回rehash的键值数 */
int dictRehashMilliseconds(dict *d, int ms) {
long long start = timeInMilliseconds();
int rehashes = 0;
while(dictRehash(d,100)) {
rehashes += 100;
if (timeInMilliseconds()-start > ms) break;
}
return rehashes;
}
/* 如果遍历器个数为0,则进行一步rehash */
static void _dictRehashStep(dict *d) {
if (d->iterators == 0) dictRehash(d,1);
}
/* 在字典中添加一个键值对,key=>val */
int dictAdd(dict *d, void *key, void *val)
{
dictEntry *entry = dictAddRaw(d,key);
if (!entry) return DICT_ERR;
dictSetVal(d, entry, val);
return DICT_OK;
}
/* 在字典中添加一个键值对,键是key,并返回这个键值对的指针 */
dictEntry *dictAddRaw(dict *d, void *key)
{
int index;
dictEntry *entry;
dictht *ht;
if (dictIsRehashing(d)) _dictRehashStep(d);//如果rehash标志正在进行,则rehash一步
/* 算出key在本字典中首个稳定的hash表中的索引值 */
if ((index = _dictKeyIndex(d, key)) == -1)
return NULL;
/* 如果rehash正在进行,则用第二个表,否则用第一个表 */
ht = dictIsRehashing(d) ? &d->ht[1] : &d->ht[0];
entry = zmalloc(sizeof(*entry));//申请内存
entry->next = ht->table[index];
ht->table[index] = entry;//给hash表中的槽赋值
ht->used++;//计数
/* Set the hash entry fields. */
dictSetKey(d, entry, key);//设置请申请的内存的键为key
return entry;
}
/* 替换一个键为key的值,替换成val */
int dictReplace(dict *d, void *key, void *val)
{
dictEntry *entry, auxentry;
/* 如果添加成功,说明key并不存在,则替换失败 */
if (dictAdd(d, key, val) == DICT_OK)
return 1;
/* 如果添加不成功,则表示原key已存在 */
entry = dictFind(d, key);
/* 替换值,并回收旧值 */
auxentry = *entry;
dictSetVal(d, entry, val);
dictFreeVal(d, &auxentry);
return 0;
}
/* 返回key在字典中对应的键值对的指针 */
dictEntry *dictReplaceRaw(dict *d, void *key) {
dictEntry *entry = dictFind(d,key);
return entry ? entry : dictAddRaw(d,key);
}
/* 回收一个键值对 */
static int dictGenericDelete(dict *d, const void *key, int nofree)
{
unsigned int h, idx;
dictEntry *he, *prevHe;
int table;
if (d->ht[0].size == 0) return DICT_ERR; /*空表 */
if (dictIsRehashing(d)) _dictRehashStep(d);
h = dictHashKey(d, key);
for (table = 0; table <= 1; table++) {
idx = h & d->ht[table].sizemask;
he = d->ht[table].table[idx];
prevHe = NULL;
while(he) {
if (key==he->key || dictCompareKeys(d, key, he->key)) {
/* Unlink the element from the list */
if (prevHe)
prevHe->next = he->next;
else
d->ht[table].table[idx] = he->next;
if (!nofree) {//是否要销毁,0销毁,1不回收
dictFreeKey(d, he);
dictFreeVal(d, he);
}
zfree(he);
d->ht[table].used--;
return DICT_OK;
}
prevHe = he;
he = he->next;
}
if (!dictIsRehashing(d)) break;//是否要到第二张表中找
}
return DICT_ERR; /* 到此表示没找着 */
}
//删除并回收一个键值对
int dictDelete(dict *ht, const void *key) {
return dictGenericDelete(ht,key,0);
}
//删除不回收一个键值对
int dictDeleteNoFree(dict *ht, const void *key) {
return dictGenericDelete(ht,key,1);
}
/* 销毁一个hash表 */
int _dictClear(dict *d, dictht *ht, void(callback)(void *)) {
unsigned long i;
/* 回收所有的键值对 */
for (i = 0; i < ht->size && ht->used > 0; i++) {
dictEntry *he, *nextHe;
//如果要销毁的是65535以后的数据,则需要调用回调方法+私有数据
if (callback && (i & 65535) == 0) callback(d->privdata);
if ((he = ht->table[i]) == NULL) continue;//找到相应的键值对
while(he) {
nextHe = he->next;
dictFreeKey(d, he);//用专用的方法销毁key
dictFreeVal(d, he);//用专用的方法销毁value
zfree(he);//回收键值对的内存
ht->used--;//已用数减一
he = nextHe;//销毁同一链上的下一个键值对
}
}
/* 回收hash表的槽数组 */
zfree(ht->table);
/* 重置hash表 */
_dictReset(ht);
return DICT_OK; /* 回收是不会失败的,只能成功 */
}
/* 销毁一个字典,一个字典两张表 */
void dictRelease(dict *d)
{
_dictClear(d,&d->ht[0],NULL);
_dictClear(d,&d->ht[1],NULL);
zfree(d);
}
//在字典中查找键为key的键值对
dictEntry *dictFind(dict *d, const void *key)
{
dictEntry *he;
unsigned int h, idx, table;
if (d->ht[0].used + d->ht[1].used == 0) return NULL; /*两个表的使用量为0,表示字典为空*/
if (dictIsRehashing(d)) _dictRehashStep(d);//如果字典正在rehash,则rehash一步
h = dictHashKey(d, key);//算出这个key在字典中对应的索引值
for (table = 0; table <= 1; table++) {
idx = h & d->ht[table].sizemask;//算出在hash表中槽的位置
he = d->ht[table].table[idx];
while(he) {
if (key==he->key || dictCompareKeys(d, key, he->key))//如果key一致,则返回这个键值对的指针,否则查找链上的下一个键值对
return he;
he = he->next;
}
if (!dictIsRehashing(d)) return NULL;//如果字典不在rehash,则说明数据都在第一个表,不用查第二个表,此时还未找到,就说明不存在,否则可以继续到第二个表中找
}
return NULL;
}
//找到key在字典中对应的值
void *dictFetchValue(dict *d, const void *key) {
dictEntry *he;
he = dictFind(d,key);
return he ? dictGetVal(he) : NULL;
}
/* 取一个字典的指纹 */
long long dictFingerprint(dict *d) {
long long integers[6], hash = 0;
int j;
integers[0] = (long) d->ht[0].table;
integers[1] = d->ht[0].size;
integers[2] = d->ht[0].used;
integers[3] = (long) d->ht[1].table;
integers[4] = d->ht[1].size;
integers[5] = d->ht[1].used;
for (j = 0; j < 6; j++) {
hash += integers[j];
/* For the hashing step we use Tomas Wang's 64 bit integer hash. */
hash = (~hash) + (hash << 21); // hash = (hash << 21) - hash - 1;
hash = hash ^ (hash >> 24);
hash = (hash + (hash << 3)) + (hash << 8); // hash * 265
hash = hash ^ (hash >> 14);
hash = (hash + (hash << 2)) + (hash << 4); // hash * 21
hash = hash ^ (hash >> 28);
hash = hash + (hash << 31);
}
return hash;
}
//创建一个字典d的迭代器
dictIterator *dictGetIterator(dict *d)
{
dictIterator *iter = zmalloc(sizeof(*iter));
iter->d = d;
iter->table = 0;
iter->index = -1;
iter->safe = 0;
iter->entry = NULL;
iter->nextEntry = NULL;
return iter;
}
//创建一个安全的字典d的迭代器,对于一个安全的迭代器来说,是不允许字典中途销毁的,除非本迭代器不存在了,则字典才可以销毁
dictIterator *dictGetSafeIterator(dict *d) {
dictIterator *i = dictGetIterator(d);
i->safe = 1;
return i;
}
//根据迭代器iter返回下一个键值对
dictEntry *dictNext(dictIterator *iter)
{
while (1) {
if (iter->entry == NULL) {//当前的键值对为空,表示迭代器还没开始迭代,或者当前值为空
dictht *ht = &iter->d->ht[iter->table];//找到hash表
if (iter->index == -1 && iter->table == 0) {//首次迭代
if (iter->safe)//安全迭代器需要给字典做标记,字典在销毁时会检查
iter->d->iterators++;
else
iter->fingerprint = dictFingerprint(iter->d);//算指纹
}
iter->index++;//更新索引
//如果迭代器的当前索引大于当前被迭代的哈希表的大小,说明当前表已迭代完
if (iter->index >= (long) ht->size) {
if (dictIsRehashing(iter->d) && iter->table == 0) {//如果正在rehash,则进入下一张表继续迭代,索引置0,否则退出迭代
iter->table++;
iter->index = 0;
ht = &iter->d->ht[1];
} else {
break;
}
}
iter->entry = ht->table[iter->index];
} else {
iter->entry = iter->nextEntry;
}
if (iter->entry) {//找到键值对并更新下一个键值对的指针
iter->nextEntry = iter->entry->next;
return iter->entry;//返回找到的不为空的键值对的指针
}
}
return NULL;
}
//回收一个迭代器
void dictReleaseIterator(dictIterator *iter)
{
if (!(iter->index == -1 && iter->table == 0)) {
if (iter->safe)
iter->d->iterators--;
else
assert(iter->fingerprint == dictFingerprint(iter->d));
}
zfree(iter);
}
/* 随机从字典中取出一个key */
dictEntry *dictGetRandomKey(dict *d)
{
dictEntry *he, *orighe;
unsigned int h;
int listlen, listele;
if (dictSize(d) == 0) return NULL;
if (dictIsRehashing(d)) _dictRehashStep(d);
if (dictIsRehashing(d)) {
do {
/* We are sure there are no elements in indexes from 0
* to rehashidx-1 */
h = d->rehashidx + (random() % (d->ht[0].size +
d->ht[1].size -
d->rehashidx));
he = (h >= d->ht[0].size) ? d->ht[1].table[h - d->ht[0].size] :
d->ht[0].table[h];
} while(he == NULL);
} else {
do {
h = random() & d->ht[0].sizemask;
he = d->ht[0].table[h];
} while(he == NULL);
}
/* 随机从一条链上取出一个数据 */
listlen = 0;
orighe = he;
while(he) {
he = he->next;
listlen++;
}
listele = random() % listlen;
he = orighe;
while(listele--) he = he->next;
return he;
}
/* */
unsigned int dictGetSomeKeys(dict *d, dictEntry **des, unsigned int count) {
unsigned long j; /* internal hash table id, 0 or 1. */
unsigned long tables; /* 1 or 2 tables? */
unsigned long stored = 0, maxsizemask;
unsigned long maxsteps;
if (dictSize(d) < count) count = dictSize(d);
maxsteps = count*10;
/* Try to do a rehashing work proportional to 'count'. */
for (j = 0; j < count; j++) {
if (dictIsRehashing(d))
_dictRehashStep(d);
else
break;
}
tables = dictIsRehashing(d) ? 2 : 1;
maxsizemask = d->ht[0].sizemask;
if (tables > 1 && maxsizemask < d->ht[1].sizemask)
maxsizemask = d->ht[1].sizemask;
/* Pick a random point inside the larger table. */
unsigned long i = random() & maxsizemask;
unsigned long emptylen = 0; /* Continuous empty entries so far. */
while(stored < count && maxsteps--) {
for (j = 0; j < tables; j++) {
/* Invariant of the dict.c rehashing: up to the indexes already
* visited in ht[0] during the rehashing, there are no populated
* buckets, so we can skip ht[0] for indexes between 0 and idx-1. */
if (tables == 2 && j == 0 && i < (unsigned long) d->rehashidx) {
/* Moreover, if we are currently out of range in the second
* table, there will be no elements in both tables up to
* the current rehashing index, so we jump if possible.
* (this happens when going from big to small table). */
if (i >= d->ht[1].size) i = d->rehashidx;
continue;
}
if (i >= d->ht[j].size) continue; /* Out of range for this table. */
dictEntry *he = d->ht[j].table[i];
/* Count contiguous empty buckets, and jump to other
* locations if they reach 'count' (with a minimum of 5). */
if (he == NULL) {
emptylen++;
if (emptylen >= 5 && emptylen > count) {
i = random() & maxsizemask;
emptylen = 0;
}
} else {
emptylen = 0;
while (he) {
/* Collect all the elements of the buckets found non
* empty while iterating. */
*des = he;
des++;
he = he->next;
stored++;
if (stored == count) return stored;
}
}
}
i = (i+1) & maxsizemask;
}
return stored;
}
/* 字典遍历相关方法 */
static unsigned long rev(unsigned long v) {
unsigned long s = 8 * sizeof(v); // bit size; must be power of 2
unsigned long mask = ~0;
while ((s >>= 1) > 0) {
mask ^= (mask << s);
v = ((v >> s) & mask) | ((v << s) & ~mask);
}
return v;
}
/* 字典遍历 https:///gqtcgq/article/details/50533336 */
unsigned long dictScan(dict *d,
unsigned long v,//要遍历的索引位置
dictScanFunction *fn,//自定义扫描回调方法
void *privdata)
{
dictht *t0, *t1;
const dictEntry *de;
unsigned long m0, m1;
if (dictSize(d) == 0) return 0;
if (!dictIsRehashing(d)) {//如果没有进行rehash,则只操作第一个表
t0 = &(d->ht[0]);
m0 = t0->sizemask;
/* Emit entries at cursor */
de = t0->table[v & m0];//找到当前这个槽位，然后处理数据
while (de) {
fn(privdata, de);
de = de->next;//只遍历同一链上的
}
} else {//即使在进行rehash,则两个表都要操作
t0 = &d->ht[0];
t1 = &d->ht[1];
/* 保证t0是最大的表 */
if (t0->size > t1->size) {
t0 = &d->ht[1];
t1 = &d->ht[0];
}
m0 = t0->sizemask;
m1 = t1->sizemask;
/* Emit entries at cursor */
de = t0->table[v & m0];
while (de) {
fn(privdata, de);
de = de->next;
}
/* Iterate over indices in larger table that are the expansion
* of the index pointed to by the cursor in the smaller table */
do {
/* 遍历小表 */
de = t1->table[v & m1];
while (de) {
fn(privdata, de);
de = de->next;
}
/* Increment bits not covered by the smaller mask */
v = (((v | m0) + 1) & ~m0) | (v & m0);
/* Continue while bits covered by mask difference is non-zero */
} while (v & (m0 ^ m1));
}
/* Set unmasked bits so incrementing the reversed cursor
* operates on the masked bits of the smaller table */
v |= ~m0;
/* Increment the reverse cursor */
v = rev(v);
v++;
v = rev(v);
return v;
}
/* ------------------------- private functions ------------------------------ */
/* 如果有必要就扩容 */
static int _dictExpandIfNeeded(dict *d)
{
/* 如果正在rehash则不需要扩容 */
if (dictIsRehashing(d)) return DICT_OK;
/* 如果容量为0,则扩容到初始值 */
if (d->ht[0].size == 0) return dictExpand(d, DICT_HT_INITIAL_SIZE);
/* 如果容量已用尽,则扩容至原来的2倍 */
if (d->ht[0].used >= d->ht[0].size &&
(dict_can_resize ||
d->ht[0].used/d->ht[0].size > dict_force_resize_ratio))
{
return dictExpand(d, d->ht[0].used*2);
}
return DICT_OK;
}
/* 比size大的hash表的可用容量值 */
static unsigned long _dictNextPower(unsigned long size)
{
unsigned long i = DICT_HT_INITIAL_SIZE;
if (size >= LONG_MAX) return LONG_MAX;
while(1) {
if (i >= size)
return i;
i *= 2;
}
}
/* 在一个字典中的首个稳定的hash表中找出key的索引 */
static int _dictKeyIndex(dict *d, const void *key)
{
unsigned int h, idx, table;
dictEntry *he;
/* 如果在是否扩容这一块发生错误,表示扩容失败,则下一步无法进行 */
if (_dictExpandIfNeeded(d) == DICT_ERR)
return -1;
/* 用专用方法计算key的hash值 */
h = dictHashKey(d, key);
for (table = 0; table <= 1; table++) {
idx = h & d->ht[table].sizemask;//根据掩码算出槽的位置
he = d->ht[table].table[idx];
while(he) {//如果槽被占用,则he指向链的下一个
if (key==he->key || dictCompareKeys(d, key, he->key))
return -1;
he = he->next;
}
if (!dictIsRehashing(d)) break;//如果此表不在rehash则表示此表稳定,则不再去第二个表中找槽
}
return idx;//返回key在其中一个稳定的hash表中的槽的位置
}
//清空字典,重置各项状态数据
void dictEmpty(dict *d, void(callback)(void*)) {
_dictClear(d,&d->ht[0],callback);
_dictClear(d,&d->ht[1],callback);
d->rehashidx = -1;
d->iterators = 0;
}
//设置字典为可扩容
void dictEnableResize(void) {
dict_can_resize = 1;
}
//设置字典为不可扩容
void dictDisableResize(void) {
dict_can_resize = 0;
}
/* ------------------------------- Debugging ---------------------------------*/
#define DICT_STATS_VECTLEN 50
//用来记录hash表中空槽的数量,链表的不同长度的数量的统计,输出文字描述
size_t _dictGetStatsHt(char *buf, size_t bufsize, dictht *ht, int tableid) {
unsigned long i, slots = 0, chainlen, maxchainlen = 0;
unsigned long totchainlen = 0;
unsigned long clvector[DICT_STATS_VECTLEN];
size_t l = 0;
if (ht->used == 0) {
return snprintf(buf,bufsize,
"No stats available for empty dictionaries\n");
}
/* Compute stats. */
for (i = 0; i < DICT_STATS_VECTLEN; i++) clvector[i] = 0;
for (i = 0; i < ht->size; i++) {
dictEntry *he;
if (ht->table[i] == NULL) {
clvector[0]++;
continue;
}
slots++;
/* For each hash entry on this slot... */
chainlen = 0;
he = ht->table[i];
while(he) {
chainlen++;
he = he->next;
}
clvector[(chainlen < DICT_STATS_VECTLEN) ? chainlen : (DICT_STATS_VECTLEN-1)]++;
if (chainlen > maxchainlen) maxchainlen = chainlen;
totchainlen += chainlen;
}
/* Generate human readable stats. */
l += snprintf(buf+l,bufsize-l,
"Hash table %d stats (%s):\n"
" table size: %ld\n"
" number of elements: %ld\n"
" different slots: %ld\n"
" max chain length: %ld\n"
" avg chain length (counted): %.02f\n"
" avg chain length (computed): %.02f\n"
" Chain length distribution:\n",
tableid, (tableid == 0) ? "main hash table" : "rehashing target",
ht->size, ht->used, slots, maxchainlen,
(float)totchainlen/slots, (float)ht->used/slots);
for (i = 0; i < DICT_STATS_VECTLEN-1; i++) {
if (clvector[i] == 0) continue;
if (l >= bufsize) break;
l += snprintf(buf+l,bufsize-l,
" %s%ld: %ld (%.02f%%)\n",
(i == DICT_STATS_VECTLEN-1)?">= ":"",
i, clvector[i], ((float)clvector[i]/ht->size)*100);
}
/* Unlike snprintf(), teturn the number of characters actually written. */
if (bufsize) buf[bufsize-1] = '\0';
return strlen(buf);
}
//获取字典的状态
void dictGetStats(char *buf, size_t bufsize, dict *d) {
size_t l;
char *orig_buf = buf;
size_t orig_bufsize = bufsize;
l = _dictGetStatsHt(buf,bufsize,&d->ht[0],0);//先输出第一个表的信息
buf += l;
bufsize -= l;
if (dictIsRehashing(d) && bufsize > 0) {//如果正在rehash则输出第二个hash表的信息
_dictGetStatsHt(buf,bufsize,&d->ht[1],1);
}
/* Make sure there is a NULL term at the end. */
if (orig_bufsize) orig_buf[orig_bufsize-1] = '\0';
}