diff --git a/.redis/.redis.cbp b/.redis/.redis.cbp
new file mode 100644
index 0000000..10d4e3c
--- /dev/null
+++ b/.redis/.redis.cbp
@@ -0,0 +1,1424 @@
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diff --git a/.redis/.redis.layout b/.redis/.redis.layout
new file mode 100644
index 0000000..b70a453
--- /dev/null
+++ b/.redis/.redis.layout
@@ -0,0 +1,20 @@
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diff --git a/src/sds.c b/src/sds.c
index 1189716..a1b6189 100644
--- a/src/sds.c
+++ b/src/sds.c
@@ -89,21 +89,21 @@ static inline char sdsReqType(size_t string_size) {
sds sdsnewlen(const void *init, size_t initlen) {
void *sh;
sds s;
- char type = sdsReqType(initlen);
+ char type = sdsReqType(initlen); // 根据字符串长度选择不同烦人类型。
/* Empty strings are usually created in order to append. Use type 8
* since type 5 is not good at this. */
if (type == SDS_TYPE_5 && initlen == 0) type = SDS_TYPE_8;
- int hdrlen = sdsHdrSize(type);
- unsigned char *fp; /* flags pointer. */
+ int hdrlen = sdsHdrSize(type);// 计算不同头部所需的不同长度
+ unsigned char *fp; /* 指向flags的指针 */
- sh = s_malloc(hdrlen+initlen+1);
+ sh = s_malloc(hdrlen+initlen+1); // "+1" 是为了结束符'\0'
if (sh == NULL) return NULL;
if (init==SDS_NOINIT)
init = NULL;
else if (!init)
memset(sh, 0, hdrlen+initlen+1);
- s = (char*)sh+hdrlen;
- fp = ((unsigned char*)s)-1;
+ s = (char*)sh+hdrlen; // s是指向buf的指针
+ fp = ((unsigned char*)s)-1; // s 是柔性数组buf的指针，-1指向flags
switch(type) {
case SDS_TYPE_5: {
*fp = type | (initlen << SDS_TYPE_BITS);
@@ -140,7 +140,7 @@ sds sdsnewlen(const void *init, size_t initlen) {
}
if (initlen && init)
memcpy(s, init, initlen);
- s[initlen] = '\0';
+ s[initlen] = '\0';// 添加末尾的结束
return s;
}
@@ -164,7 +164,7 @@ sds sdsdup(const sds s) {
/* Free an sds string. No operation is performed if 's' is NULL. */
void sdsfree(sds s) {
if (s == NULL) return;
- s_free((char*)s-sdsHdrSize(s[-1]));
+ s_free((char*)s-sdsHdrSize(s[-1]));// 此处直接释放内存
}
/* Set the sds string length to the length as obtained with strlen(), so
@@ -191,8 +191,8 @@ void sdsupdatelen(sds s) {
* so that next append operations will not require allocations up to the
* number of bytes previously available. */
void sdsclear(sds s) {
- sdssetlen(s, 0);
- s[0] = '\0';
+ sdssetlen(s, 0);// 统计值len归零
+ s[0] = '\0'; // 清空buf
}
/* Enlarge the free space at the end of the sds string so that the caller
@@ -393,15 +393,18 @@ sds sdsgrowzero(sds s, size_t len) {
* end of the specified sds string 's'.
*
* After the call, the passed sds string is no longer valid and all the
- * references must be substituted with the new pointer returned by the call. */
+ * references must be substituted with the new pointer returned by the call.
+ *
+ * 将指针t的内容和指针s的内容拼接在一起，该操作是二进制安全的
+ * */
sds sdscatlen(sds s, const void *t, size_t len) {
size_t curlen = sdslen(s);
s = sdsMakeRoomFor(s,len);
if (s == NULL) return NULL;
- memcpy(s+curlen, t, len);
+ memcpy(s+curlen, t, len);// 直接拼接保证了二进制安全
sdssetlen(s, curlen+len);
- s[curlen+len] = '\0';
+ s[curlen+len] = '\0';// 加上结束符
return s;
}
diff --git a/src/sds.h b/src/sds.h
index adcc12c..8f8a742 100644
--- a/src/sds.h
+++ b/src/sds.h
@@ -45,32 +45,32 @@ typedef char *sds;
/* Note: sdshdr5 is never used, we just access the flags byte directly.
* However is here to document the layout of type 5 SDS strings. */
struct __attribute__ ((__packed__)) sdshdr5 {
- unsigned char flags; /* 3 lsb of type, and 5 msb of string length */
- char buf[];
+ unsigned char flags; /* 低三位存储类型，高5为存储长度 */
+ char buf[]; /* 柔性数组，存放实际内容 */
};
struct __attribute__ ((__packed__)) sdshdr8 {
- uint8_t len; /* used */
- uint8_t alloc; /* excluding the header and null terminator */
- unsigned char flags; /* 3 lsb of type, 5 unused bits */
- char buf[];
+ uint8_t len; /* 已使用长度，用1字节存储 */
+ uint8_t alloc; /* 总长度，用1 字节存储 */
+ unsigned char flags; /* 低三位存储类型，搞5位预留 */
+ char buf[];/* 柔性数组，存放实际内容 */
};
struct __attribute__ ((__packed__)) sdshdr16 {
- uint16_t len; /* used */
- uint16_t alloc; /* excluding the header and null terminator */
- unsigned char flags; /* 3 lsb of type, 5 unused bits */
- char buf[];
+ uint16_t len; /* 已使用长度，用2字节存储 */
+ uint16_t alloc; /* 总长度，用2字节存储 */
+ unsigned char flags; /* 低三位存储类型，高5位预留 */
+ char buf[]; /* 柔性数组，存放实际内容 */
};
struct __attribute__ ((__packed__)) sdshdr32 {
- uint32_t len; /* used */
- uint32_t alloc; /* excluding the header and null terminator */
- unsigned char flags; /* 3 lsb of type, 5 unused bits */
- char buf[];
+ uint32_t len; /* 已使用的长度，用4字节存储 */
+ uint32_t alloc; /* 总长度，用4字节存储 */
+ unsigned char flags; /* 低三位存储类型，高5位预留 */
+ char buf[]; /* 柔性数组，存放实际内容 */
};
struct __attribute__ ((__packed__)) sdshdr64 {
- uint64_t len; /* used */
- uint64_t alloc; /* excluding the header and null terminator */
- unsigned char flags; /* 3 lsb of type, 5 unused bits */
- char buf[];
+ uint64_t len; /* 已使用长度，用8字节存储 */
+ uint64_t alloc; /* 总长度，用8字节存储 */
+ unsigned char flags; /* 低三位存储类型，高5位预留*/
+ char buf[];/* 柔性数组，存放实际内容 */
};
#define SDS_TYPE_5 0