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Redis??Zipmap??????????????????????????????ziplist?????????Zipmap????????????????????????????????????????????????????????????????????????????????

Zipmap????????????????????????????????Zipmap???

   
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   < len>3< free>0< value>"foo"< len>3< free>0< value>"bar"< len>5< free>0< value>"hello"< len>5< free>0< value>"world"

Zipmap??????????

• zmlen?Zipmap???????????????254??????????????254????????Zipmap??????
• len?????????????????????????????
• free?????????????????????

Zipmap??????

Zipmap?????????????????????????????ZipmapSet????????

Zipmap????

Zipmap???????????????????????????????254?????????????????Zipmap?????????

Redis??????

?Redis??Hash???????????????????Zipmap???????Zipmap?????????????????????

????

????????Zipmap?????

unsigned char *zipmapSet(zm, key, klen, val, vlen, update) {    unsigned int zmlen, offset;    unsigned int freelen, reqlen = zipmapRequiredLength(klen, vlen);    unsigned char *p;    freelen = reqlen;    if (update) *update = 0;    p = zipmapLookupRaw(zm, key, klen, &zmlen);    if (p == NULL) {        zm = zipmapResize(zm, zmlen + reqlen);        p = zm + zmlen - 1;        zmlen += reqlen;        if (zm[0] < ZIPMAP_BIGLEN) zm[0]++;    } else {        if (update) *update = 1;        freelen = zipmapRawEntryLength(p);        if (freelen < reqlen) {            offset = p - zm;            zm = zipmapResize(zm, zmlen - freelen + reqlen);            p = zm + offset;            memmove(p + reqlen, p + freelen, zmlen - (offset + freelen + 1));            zmlen = zmlen - freelen + reqlen;            freelen = reqlen;        }    }    empty = freelen - reqlen;    if (empty >= ZIPMAP_VALUE_MAX_FREE) {        offset = p - zm;        memmove(p + reqlen, p + freelen, zmlen - (offset + freelen + 1));        zmlen -= empty;        zm = zipmapResize(zm, zmlen);        p = zm + offset;        vempty = 0;    } else {        vempty = empty;    }    p += zipmapEncodeLength(p, klen);    memcpy(p, key, klen);    p += klen;    p += zipmapEncodeLength(p, vlen);    *p++ = vempty;    memcpy(p, val, vlen);    return zm;}

Zipmap?????

Zipmap?????????????????????????

• ???????????????????????????????????
• ???????????????????????????????????????
• ???????????????????????????

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Zipmap???????????????????????????????????????????Redis??Hash???????????????????????????Zipmap????????????????Redis???????

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