redis中客户端结构体
客户端结构体用来存储client端连接的所有信息。
typedef struct client {
uint64_t id; /* Client incremental unique ID. */
connection *conn;
int resp; /* RESP protocol version. Can be 2 or 3. */
redisDb *db; /* Pointer to currently SELECTed DB. */
robj *name; /* As set by CLIENT SETNAME. */
sds querybuf; /* Buffer we use to accumulate client queries. */
size_t qb_pos; /* The position we have read in querybuf. */
sds pending_querybuf; /* If this client is flagged as master, this buffer
represents the yet not applied portion of the
replication stream that we are receiving from
the master. */
size_t querybuf_peak; /* Recent (100ms or more) peak of querybuf size. */
int argc; /* Num of arguments of current command. */
robj **argv; /* Arguments of current command. */
int original_argc; /* Num of arguments of original command if arguments were rewritten. */
robj **original_argv; /* Arguments of original command if arguments were rewritten. */
size_t argv_len_sum; /* Sum of lengths of objects in argv list. */
struct redisCommand *cmd, *lastcmd; /* Last command executed. */
user *user; /* User associated with this connection. If the
user is set to NULL the connection can do
anything (admin). */
int reqtype; /* Request protocol type: PROTO_REQ_* */
int multibulklen; /* Number of multi bulk arguments left to read. */
long bulklen; /* Length of bulk argument in multi bulk request. */
list *reply; /* List of reply objects to send to the client. */
unsigned long long reply_bytes; /* Tot bytes of objects in reply list. */
size_t sentlen; /* Amount of bytes already sent in the current
buffer or object being sent. */
time_t ctime; /* Client creation time. */
long duration; /* Current command duration. Used for measuring latency of blocking/non-blocking cmds */
time_t lastinteraction; /* Time of the last interaction, used for timeout */
time_t obuf_soft_limit_reached_time;
uint64_t flags; /* Client flags: CLIENT_* macros. */
int authenticated; /* Needed when the default user requires auth. */
int replstate; /* Replication state if this is a slave. */
int repl_put_online_on_ack; /* Install slave write handler on first ACK. */
int repldbfd; /* Replication DB file descriptor. */
off_t repldboff; /* Replication DB file offset. */
off_t repldbsize; /* Replication DB file size. */
sds replpreamble; /* Replication DB preamble. */
long long read_reploff; /* Read replication offset if this is a master. */
long long reploff; /* Applied replication offset if this is a master. */
long long repl_ack_off; /* Replication ack offset, if this is a slave. */
long long repl_ack_time;/* Replication ack time, if this is a slave. */
long long repl_last_partial_write; /* The last time the server did a partial write from the RDB child pipe to this replica */
long long psync_initial_offset; /* FULLRESYNC reply offset other slaves
copying this slave output buffer
should use. */
char replid[CONFIG_RUN_ID_SIZE+1]; /* Master replication ID (if master). */
int slave_listening_port; /* As configured with: REPLCONF listening-port */
char *slave_addr; /* Optionally given by REPLCONF ip-address */
int slave_capa; /* Slave capabilities: SLAVE_CAPA_* bitwise OR. */
multiState mstate; /* MULTI/EXEC state */
int btype; /* Type of blocking op if CLIENT_BLOCKED. */
blockingState bpop; /* blocking state */
long long woff; /* Last write global replication offset. */
list *watched_keys; /* Keys WATCHED for MULTI/EXEC CAS */
dict *pubsub_channels; /* channels a client is interested in (SUBSCRIBE) */
list *pubsub_patterns; /* patterns a client is interested in (SUBSCRIBE) */
sds peerid; /* Cached peer ID. */
sds sockname; /* Cached connection target address. */
listNode *client_list_node; /* list node in client list */
listNode *paused_list_node; /* list node within the pause list */
RedisModuleUserChangedFunc auth_callback; /* Module callback to execute
* when the authenticated user
* changes. */
void *auth_callback_privdata; /* Private data that is passed when the auth
* changed callback is executed. Opaque for
* Redis Core. */
void *auth_module; /* The module that owns the callback, which is used
* to disconnect the client if the module is
* unloaded for cleanup. Opaque for Redis Core.*/
/* If this client is in tracking mode and this field is non zero,
* invalidation messages for keys fetched by this client will be send to
* the specified client ID. */
uint64_t client_tracking_redirection;
rax *client_tracking_prefixes; /* A dictionary of prefixes we are already
subscribed to in BCAST mode, in the
context of client side caching. */
/* In clientsCronTrackClientsMemUsage() we track the memory usage of
* each client and add it to the sum of all the clients of a given type,
* however we need to remember what was the old contribution of each
* client, and in which categoty the client was, in order to remove it
* before adding it the new value. */
uint64_t client_cron_last_memory_usage;
int client_cron_last_memory_type;
/* Response buffer */
int bufpos;
char buf[PROTO_REPLY_CHUNK_BYTES];
} client;
整个字段比较多。我挑几个重要的做下记录。
id：客户端的唯一ID。全局变量。
由server.c/initServerConfig中
server.next_client_id = 1; /* Client IDs, start from 1 .*/
定义的。从1开始。
conn下有个fd：客户端socket文件描述符。
db：client所select的数据库对象。我一直感觉这个字段是能删掉的。我工作以来就没用上过db这个概念。甚至这几年，redis官方也一直在淡化这个概念。
name:client的名称，可以用 client setname设置。
lastinteraction：client上次与server交互的时间，用来做client过期处理。
querybuf：输入缓冲区，recv接受的client命令会放在这里。
argc：命令的数量。
argv：具体的命令被存放在robj对象里。
cmd：这是一个redisCommand对象。可以理解成，每一个被解析出来的命令，其实有对应的命令对象。这个就是用来存放命令对象的。
reply：一个list，输出列表。存放待返回client的数据。具体是放在这的：
/* This structure is used in order to represent the output buffer of a client,
* which is actually a linked list of blocks like that, that is: client->reply. */
typedef struct clientReplyBlock {
size_t size, used;
char buf[];
} clientReplyBlock;
size表示的是总大小，used表示的是已使用大小。
reply_bytes：输出链表中空间总和。
sentlen：已返回给客户端的字节数。
buf：输出缓冲区，存储待返回给client的数据。bufpos表示输出缓冲区中数据的最大字节位置。所以，sentlen到bufpos都是需要返回给client的。而reply和buf，看着是一样的东西，其实返回的内容不一样。
