Redis源码研究--redis.h

------------7月3日------------

 /* The redisOp structure defines a Redis Operation, that is an instance of
  * a command with an argument vector, database ID, propagation target
  * (REDIS_PROPAGATE_*), and command pointer.
  *
  * Currently only used to additionally propagate more commands to AOF/Replication
  * after the propagation of the executed command. */
 typedef struct redisOp {
     robj **argv;
     int argc, dbid, target;
     struct redisCommand *cmd;
 } redisOp;

argc 参数个数，argv参数数组，跟main函数里的参数一样

dbid，数据库id，target（propagation传播），暂时不懂。

cmd操作命令。

------------7月4日--------------------

 struct redisCommand {
     char *name;
     redisCommandProc *proc;
     int arity;
     char *sflags; /* Flags as string representation, one char per flag. */
     int flags;    /* The actual flags, obtained from the 'sflags' field. */
     /* Use a function to determine keys arguments in a command line.
      * Used for Redis Cluster redirect. */
     redisGetKeysProc *getkeys_proc;
     /* What keys should be loaded in background when calling this command? */
     int firstkey; /* The first argument that's a key (0 = no keys) */
     int lastkey;  /* The last argument that's a key */
     int keystep;  /* The step between first and last key */
     long long microseconds, calls;
 };

给两三个例子就能懂一点，自己看代码

 void getCommand(redisClient *c);
 void lsetCommand(redisClient *c);
 void saddCommand(redisClient *c);

 {"get",getCommand,,"r",,NULL,,,,,},
 {"lset",lsetCommand,,"wm",,NULL,,,,,},
 {"sadd",saddCommand,-,"wm",,NULL,,,,,}

 /* Our command table.
  *
  * Every entry is composed of the following fields:
  *
  * name: a string representing the command name.
  * function: pointer to the C function implementing the command.
  * arity: number of arguments, it is possible to use -N to say >= N
  * sflags: command flags as string. See below for a table of flags.
  * flags: flags as bitmask. Computed by Redis using the 'sflags' field.
  * get_keys_proc: an optional function to get key arguments from a command.
  *                This is only used when the following three fields are not
  *                enough to specify what arguments are keys.
  * first_key_index: first argument that is a key
  * last_key_index: last argument that is a key
  * key_step: step to get all the keys from first to last argument. For instance
  *           in MSET the step is two since arguments are key,val,key,val,...
  * microseconds: microseconds of total execution time for this command.
  * calls: total number of calls of this command.
  *
  * The flags, microseconds and calls fields are computed by Redis and should
  * always be set to zero.
  *
  * Command flags are expressed using strings where every character represents
  * a flag. Later the populateCommandTable() function will take care of
  * populating the real 'flags' field using this characters.
  *
  * This is the meaning of the flags:
  *
  * w: write command (may modify the key space).
  * r: read command  (will never modify the key space).
  * m: may increase memory usage once called. Don't allow if out of memory.
  * a: admin command, like SAVE or SHUTDOWN.
  * p: Pub/Sub related command.
  * f: force replication of this command, regardless of server.dirty.
  * s: command not allowed in scripts.
  * R: random command. Command is not deterministic, that is, the same command
  *    with the same arguments, with the same key space, may have different
  *    results. For instance SPOP and RANDOMKEY are two random commands.
  * S: Sort command output array if called from script, so that the output
  *    is deterministic.
  * l: Allow command while loading the database.
  * t: Allow command while a slave has stale data but is not allowed to
  *    server this data. Normally no command is accepted in this condition
  *    but just a few.
  * M: Do not automatically propagate the command on MONITOR.
  * k: Perform an implicit ASKING for this command, so the command will be
  *    accepted in cluster mode if the slot is marked as 'importing'.
  */

很明显，redisCommandProc是个函数指针，

typedef void redisCommandProc(redisClient *c);

--------------7月5日----------------------

还是说上面的命令吧

{"get",getCommand,2,"r",0,NULL,1,1,1,0,0},

命令名字叫get，具体实现在getCommand里面，参数有两个（包括get?get name），模式为只读（will never modify the key space）。 

{"lset",lsetCommand,4,"wm",0,NULL,1,1,1,0,0},
命令名字叫lset，具体实现在lsetCommand函数，参数有4个（lset mylist 3 “juan”），模式为写，会使用内存（may increase memory usage once called. Don't allow if out of memory）。

-----------------7月10日----------------------
redisServer里有个aeEventLoop，牵涉到Redis的事件。
Redis事件分两种：

1. 处理文件事件：在多个客户端中实现多路复用，接受它们发来的命令请求，并将命令的执行结果返回给客户端。

2. 时间事件：实现服务器常规操作。

 /* Types and data structures */
 typedef void aeFileProc(struct aeEventLoop *eventLoop, int fd, void *clientData, int mask);
 typedef int aeTimeProc(struct aeEventLoop *eventLoop, long long id, void *clientData);
 typedef void aeEventFinalizerProc(struct aeEventLoop *eventLoop, void *clientData);

 /* File event structure */
 typedef struct aeFileEvent {
     int mask; /* one of AE_(READABLE|WRITABLE) */
     aeFileProc *rfileProc;
     aeFileProc *wfileProc;
     void *clientData;
 } aeFileEvent;

 /* Time event structure */
 typedef struct aeTimeEvent {
     long long id; /* time event identifier. */
     long when_sec; /* seconds */
     long when_ms; /* milliseconds */
     aeTimeProc *timeProc;
     aeEventFinalizerProc *finalizerProc;
     void *clientData;
     struct aeTimeEvent *next;
 } aeTimeEvent;