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. */
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 argv_len; /* Size of argv array (may be more than argc) */
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. */
struct redisCommand *realcmd; /* The original command that was executed by the client,
Used to update error stats in case the c->cmd was modified
during the command invocation (like on GEOADD for example). */
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. */
list *deferred_reply_errors; /* Used for module thread safe contexts. */
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 */
int slot; /* The slot the client is executing against. Set to -1 if no slot is being used */
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_start_cmd_stream_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_applied; /* Applied replication data count in querybuf, if this is a replica. */
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. */
int slave_req; /* Slave requirements: SLAVE_REQ_* */
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) */
dict *pubsubshard_channels; /* shard level channels a client is interested in (SSUBSCRIBE) */
sds peerid; /* Cached peer ID. */
sds sockname; /* Cached connection target address. */
listNode *client_list_node; /* list node in client list */
listNode *postponed_list_node; /* list node within the postponed list */
listNode *pending_read_list_node; /* list node in clients pending read 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 updateClientMemUsage() 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 category the client was, in order to remove it
* before adding it the new value. */
size_t last_memory_usage;
int last_memory_type;
listNode *mem_usage_bucket_node;
clientMemUsageBucket *mem_usage_bucket;
listNode *ref_repl_buf_node; /* Referenced node of replication buffer blocks,
* see the definition of replBufBlock. */
size_t ref_block_pos; /* Access position of referenced buffer block,
* i.e. the next offset to send. */
/* Response buffer */
size_t buf_peak; /* Peak used size of buffer in last 5 sec interval. */
mstime_t buf_peak_last_reset_time; /* keeps the last time the buffer peak value was reset */
int bufpos;
size_t buf_usable_size; /* Usable size of buffer. */
char *buf;
} client;
| 字段 | 描述 |
|---|---|
| fd | 文件描述符 -1表示伪客户端不需要网络通信（lua脚本）>0表示正常网络通信 |
| flags | 客户端标识，以CLIENT_开头 CLIENT_SLAVE表示客户端为slave CLIENT_MASTER表示客户端为master CLIENT_BLOCKED表示客户端正在进行阻塞操作 |
| querybuf | 输入缓冲区用于保存发送的命令 |
##2.数据库
- 数据库存储在redisDb结构中
- struct redisServer记录了redisDb，表示当前正在使用哪个数据库
/* Redis database representation. There are multiple databases identified
* by integers from 0 (the default database) up to the max configured
* database. The database number is the 'id' field in the structure. */
typedef struct redisDb {
dict *dict; /* The keyspace for this DB */
dict *expires; /* Timeout of keys with a timeout set */
dict *blocking_keys; /* Keys with clients waiting for data (BLPOP)*/
dict *ready_keys; /* Blocked keys that received a PUSH */
dict *watched_keys; /* WATCHED keys for MULTI/EXEC CAS */
int id; /* Database ID */
long long avg_ttl; /* Average TTL, just for stats */
unsigned long expires_cursor; /* Cursor of the active expire cycle. */
list *defrag_later; /* List of key names to attempt to defrag one by one, gradually. */
clusterSlotToKeyMapping *slots_to_keys; /* Array of slots to keys. Only used in cluster mode (db 0). */
} redisDb;
selectDb用于切换数据库,实际是改变指针的指向对象
int selectDb(client *c, int id) {
if (id < 0 || id >= server.dbnum)
return C_ERR;
c->db = &server.db[id];
return C_OK;
}
- redis可以有多个数据库，而不同数据库之间是互不影响。数据存储在redisDb中的dict对象
void setKey(client *c, redisDb *db, robj *key, robj *val, int flags) {
int keyfound = 0;
if (flags & SETKEY_ALREADY_EXIST)
keyfound = 1;
else if (!(flags & SETKEY_DOESNT_EXIST))
keyfound = (lookupKeyWrite(db,key) != NULL);
if (!keyfound) {
dbAdd(db,key,val);
} else {
dbOverwrite(db,key,val);
}
incrRefCount(val);
if (!(flags & SETKEY_KEEPTTL)) removeExpire(db,key);
if (!(flags & SETKEY_NO_SIGNAL)) signalModifiedKey(c,db,key);
}
- 在redis中过期键保存在redisDb中expires变量里，expires是dict指针类型。Key保存的是数据库的键对象,Value保存的是数据库键对象的过期时间，长整型Unix时间。
1.设置过期时间
相对方式：expire ,单位秒； pexpire ,单位毫秒
绝对方式：expireat ,单位秒； pexpireat < timestamp >,单位毫秒。其他命令都会转成pexpireat
如expire命令： setExpire(c,c->db,key,when)—->de = dictFind(db->dict,key->ptr)—->dictAddOrFind(db->expires,dictGetKey(de))
2.删除过期时间
persist ，具体函数为removeExpire(c->db,c->argv[1])—->dictDelete(db->expires,key->ptr)
3.查看剩余过期时间
ttl ，秒单位；pttl ，毫秒
lookupKeyReadWithFlags—->getExpire—->ttl = expire-mstime();
- redis中采用的是定期删除和惰性删除的键过期策略，见方法
void activeExpireCycle(int type)