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增加ziplist插入节点部分 (#17)

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LingZhaoHui 2022-12-09 23:29:49 +08:00 committed by GitHub
parent 0b8d99cb69
commit 13317a1500
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1 changed files with 10 additions and 4 deletions
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ziplist/readme.md
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@ -305,6 +305,7 @@ int zipPrevLenByteDiff(unsigned char *p, unsigned int len) {
}
```
### 数据复制
内存空间分配使用`memmove`函数实现：
```c
memmove(p+reqlen,p-nextdiff,curlen-offset-1+nextdiff);
@ -318,10 +319,15 @@ if (forcelarge)
else
zipStorePrevEntryLength(p+reqlen,reqlen);
```
### 数据复制
维护 zltail, 将新插入的节点长度算到zltail里面，如果 nextdiff == 4 > 0，说明后个节点的 prevSize 其实变大了的，
也需要把这部分增加落实到 zltail 算在偏移量里，这样才能真的对齐表尾节点
```c
ZIPLIST_TAIL_OFFSET(zl) = intrev32ifbe(intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl))+reqlen);
assert(zipEntrySafe(zl, newlen, p+reqlen, &tail, 1));
if (p[reqlen+tail.headersize+tail.len] != ZIP_END) {
ZIPLIST_TAIL_OFFSET(zl) = intrev32ifbe(intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl))+nextdiff);
}
```
## 删除元素