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由 antirez 提交于
The REPLCONF command is an internal command (not designed to be directly used by normal clients) that allows a slave to set some replication related state in the master before issuing SYNC to start the replication. The initial motivation for this command, and the only reason currently it is used by the implementation, is to let the slave instance communicate its listening port to the slave, so that the master can show all the slaves with their listening ports in the "replication" section of the INFO output. This allows clients to auto discover and query all the slaves attached into a master. Currently only a single option of the REPLCONF command is supported, and it is called "listening-port", so the slave now starts the replication process with something like the following chat: REPLCONF listening-prot 6380 SYNC Note that this works even if the master is an older version of Redis and does not understand REPLCONF, because the slave ignores the REPLCONF error. In the future REPLCONF can be used for partial replication and other replication related features where there is the need to exchange information between master and slave. NOTE: This commit also fixes a bug: the INFO outout already carried information about slaves, but the port was broken, and was obtained with getpeername(2), so it was actually just the ephemeral port used by the slave to connect to the master as a client.
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