增加 redis-check-aof 部分注释(#90)

Co-authored-by: Binbin <[email protected]>

Author: yancz2000

README.md

@@ -49,6 +49,7 @@ redis 仓库链接：https://github.com/redis/redis<br>
 | [ae.c](https://github.com/CN-annotation-team/redis7.0-chinese-annotated/blob/7.0-cn-annotated/src/ae.c) | redis 事件循环器功能 | 完成 |
 | [multi.c](https://github.com/CN-annotation-team/redis7.0-chinese-annotated/blob/7.0-cn-annotated/src/multi.c) | redis 事务实现  | 完成 |
 | [redis-check-rdb.c](https://github.com/CN-annotation-team/redis7.0-chinese-annotated/blob/7.0-cn-annotated/src/redis-check-rdb.c) | Redis RDB 检查工具 | 完成 |
+| [redis-check-aof.c](https://github.com/CN-annotation-team/redis7.0-chinese-annotated/blob/7.0-cn-annotated/src/redis-check-aof.c) | Redis AOF 检查工具 | 低于一半 |
 | [evict.c](https://github.com/CN-annotation-team/redis7.0-chinese-annotated/blob/7.0-cn-annotated/src/evict.c) | 四种 redis 内存淘汰算法  | 完成 |
 | [aof.c](https://github.com/CN-annotation-team/redis7.0-chinese-annotated/blob/7.0-cn-annotated/src/aof.c) | redis AOF 功能  | 过半 |
 | [replication.c](https://github.com/CN-annotation-team/redis7.0-chinese-annotated/blob/7.0-cn-annotated/src/replication.c) | Redis 主从复制 | 低于一半 |
@@ -57,7 +58,7 @@ redis 仓库链接：https://github.com/redis/redis<br>
 | [networking.c](https://github.com/CN-annotation-team/redis7.0-chinese-annotated/blob/7.0-cn-annotated/src/networking.c) | Redis 客户端、主、副本 I/O 相关 | 低于一半 |
 </p>
 尚未有中文注释的文件不会出现在表格中。<br>
-更新日期：2022/11/5
+更新日期：2022/11/7
 
 
 ## 关于提交 PR 的方法：

src/redis-check-aof.c

@@ -354,6 +354,7 @@ int checkSingleAof(char *aof_filename, char *aof_filepath, int last_file, int fi
  * 1. The file is an old style RDB-preamble AOF
  * 2. The file is a BASE AOF in Multi Part AOF
  * */
+/* 判断是否是混合持久化 AOF 类型或者是 MP-AOF 的 base 文件，根据前 5 个字符是否为 REDIS */
 int fileIsRDB(char *filepath) {
     FILE *fp = fopen(filepath, "r");
     if (fp == NULL) {
@@ -389,6 +390,7 @@ int fileIsRDB(char *filepath) {
 
 /* Used to determine whether the file is a manifest file. */
 #define MANIFEST_MAX_LINE 1024
+/* 判断文件是否是清单文件 */
 int fileIsManifest(char *filepath) {
     int is_manifest = 0;
     FILE *fp = fopen(filepath, "r");
@@ -440,6 +442,7 @@ int fileIsManifest(char *filepath) {
  * redis-check-aof tool will automatically perform different 
  * verification logic according to different file formats.
  * */
+/* 获取 AOF 文件的类型，在三种中选择一种返回 */ 
 input_file_type getInputFileType(char *filepath) {
     if (fileIsManifest(filepath)) {
         return AOF_MULTI_PART;
@@ -461,16 +464,23 @@ input_file_type getInputFileType(char *filepath) {
  * 
  * Note that in Multi Part AOF, we only allow truncation for the last AOF file.
  * */
+/* MP-AOF 检查，检查成功后：
+ * 1. 清单文件格式有效
+ * 2. BASE AOF 和 INCR AOFs 格式都有效
+ * 3. 没有 BASE 或 INCR AOFs 文件丢失
+ * 4. 在截取 AOF 文件时，此场景只允许截断最后一个 INCR AOF 文件 */
 void checkMultiPartAof(char *dirpath, char *manifest_filepath, int fix) {
     int total_num = 0, aof_num = 0, last_file;
     int ret;
 
     printf("Start checking Multi Part AOF\n");
+    /* 加载 AOF 清单文件 */    
     aofManifest *am = aofLoadManifestFromFile(manifest_filepath);
 
     if (am->base_aof_info) total_num++;
     if (am->incr_aof_list) total_num += listLength(am->incr_aof_list);
 
+    /* 检查 BASE AOF */    
     if (am->base_aof_info) {
         sds aof_filename = am->base_aof_info->file_name;
         sds aof_filepath = makePath(dirpath, aof_filename);
@@ -492,6 +502,7 @@ void checkMultiPartAof(char *dirpath, char *manifest_filepath, int fix) {
         sdsfree(aof_filepath);
     }
 
+    /* 检查 INCR AOFs */    
     if (listLength(am->incr_aof_list)) {
         listNode *ln;
         listIter li;
@@ -525,6 +536,7 @@ void checkMultiPartAof(char *dirpath, char *manifest_filepath, int fix) {
 /* Check if old style AOF is valid. Internally, it will identify whether 
  * the AOF is in RDB-preamble format, and will eventually call `checkSingleAof`
  * to do the check. */
+/* 在旧的 AOF 模式（RESP 和混合持久化）下调用此处理函数 */
 void checkOldStyleAof(char *filepath, int fix, int preamble) {
     printf("Start checking Old-Style AOF\n");
     int ret = checkSingleAof(filepath, filepath, 1, fix, preamble);
@@ -540,12 +552,17 @@ void checkOldStyleAof(char *filepath, int fix, int preamble) {
     }
 }
 
+/* redis-check-aof 工具的主入口函数，用来检查 AOF 文件的正确性，并能对错误文件进行一定程度的修复
+ * 此工具的使用场景：
+ * 1）独立的可执行文件来检查某个 AOF 文件 
+ * 2）被 server 调用去检查已经打开的文件 */
 int redis_check_aof_main(int argc, char **argv) {
     char *filepath;
     char temp_filepath[PATH_MAX + 1];
     char *dirpath;
     int fix = 0;
 
+    /* 根据入参数量，做相应分支处理 */
     if (argc < 2) {
         goto invalid_args;
     } else if (argc == 2) {
@@ -579,6 +596,8 @@ int redis_check_aof_main(int argc, char **argv) {
     dirpath = dirname(temp_filepath);
 
     /* Select the corresponding verification method according to the input file type. */
+    /* 获取 AOF 的类型，然后根据类型进入不同的分支处理函数
+     * 类型有 增量 AOF、RESP 和混合持久化 */    
     input_file_type type = getInputFileType(filepath);
     switch (type) {
     case AOF_MULTI_PART:
@@ -594,6 +613,7 @@ int redis_check_aof_main(int argc, char **argv) {
 
     exit(0);
 
+/* 在参数输入错误时，打印帮助信息 */
 invalid_args:
     printf("Usage: %s [--fix|--truncate-to-timestamp $timestamp] <file.manifest|file.aof>\n",
         argv[0]);

src/redis-check-rdb.c

@@ -210,7 +210,7 @@ int redis_check_rdb(char *rdbfilename, FILE *fp) {
     int selected_dbid = -1;
     int type, rdbver;
     char buf[1024];
-     /* now 毫秒时间戳 */
+    /* now 毫秒时间戳 */
     long long expiretime, now = mstime();
     static rio rdb; /* Pointed by global struct riostate. */
     struct stat sb;
@@ -230,9 +230,9 @@ int redis_check_rdb(char *rdbfilename, FILE *fp) {
     rdbstate.rio = &rdb;
     rdb.update_cksum = rdbLoadProgressCallback;
 
-	/* 对 RDB 文件前 9 个字符做判断：
-	 * 1）前 5 个字符必须为 REDIS
-	 * 2）第 6-9 个字符为版本号，版本号必须大于等于 1，并且小于 RDB_VERSION */    
+    /* 对 RDB 文件前 9 个字符做判断：
+     * 1）前 5 个字符必须为 REDIS
+     * 2）第 6-9 个字符为版本号，版本号必须大于等于 1，并且小于 RDB_VERSION */    
     if (rioRead(&rdb,buf,9) == 0) goto eoferr;
     buf[9] = '\0';
     if (memcmp(buf,"REDIS",5) != 0) {
@@ -452,7 +452,7 @@ static sds checkRdbVersion(void) {
 int redis_check_rdb_main(int argc, char **argv, FILE *fp) {
     struct timeval tv;
 
-    /* 判断入参数量是否等于2，并且 fp 指针不为空，否则打印使用帮助并退出程序 */
+    /* 判断入参数量是否等于 2，并且 fp 指针不为空，否则打印使用帮助并退出程序 */
     if (argc != 2 && fp == NULL) {
         fprintf(stderr, "Usage: %s <rdb-file-name>\n", argv[0]);
         exit(1);