- 24 Nov, 2016 1 commit
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antirez authored
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- 23 Nov, 2016 1 commit
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antirez authored
1. Master replication offset was cleared after switching configuration to some other slave, since it was assumed you can't PSYNC after a switch. Note the case anymore and when we successfully PSYNC we need to have our offset untouched. 2. Secondary replication ID was not reset to "000..." pattern at startup. 3. Master in error state replying -LOADING or other transient errors forced the slave to discard the cached master and full resync. This is now fixed. 4. Better logging of what's happening on failed PSYNCs.
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- 16 Nov, 2016 1 commit
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deep011 authored
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- 10 Nov, 2016 1 commit
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antirez authored
This means that stopping a slave and restarting it will still make it able to PSYNC with the master. Moreover the master itself will retain its ID/offset, in case it gets turned into a slave, or if a slave will try to PSYNC with it with an exactly updated offset (otherwise there is no backlog). This change was possible thanks to PSYNC v2 that makes saving the current replication state much simpler.
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- 09 Nov, 2016 2 commits
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antirez authored
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antirez authored
The gist of the changes is that now, partial resynchronizations between slaves and masters (without the need of a full resync with RDB transfer and so forth), work in a number of cases when it was impossible in the past. For instance: 1. When a slave is promoted to mastrer, the slaves of the old master can partially resynchronize with the new master. 2. Chained slalves (slaves of slaves) can be moved to replicate to other slaves or the master itsef, without requiring a full resync. 3. The master itself, after being turned into a slave, is able to partially resynchronize with the new master, when it joins replication again. In order to obtain this, the following main changes were operated: * Slaves also take a replication backlog, not just masters. * Same stream replication for all the slaves and sub slaves. The replication stream is identical from the top level master to its slaves and is also the same from the slaves to their sub-slaves and so forth. This means that if a slave is later promoted to master, it has the same replication backlong, and can partially resynchronize with its slaves (that were previously slaves of the old master). * A given replication history is no longer identified by the `runid` of a Redis node. There is instead a `replication ID` which changes every time the instance has a new history no longer coherent with the past one. So, for example, slaves publish the same replication history of their master, however when they are turned into masters, they publish a new replication ID, but still remember the old ID, so that they are able to partially resynchronize with slaves of the old master (up to a given offset). * The replication protocol was slightly modified so that a new extended +CONTINUE reply from the master is able to inform the slave of a replication ID change. * REPLCONF CAPA is used in order to notify masters that a slave is able to understand the new +CONTINUE reply. * The RDB file was extended with an auxiliary field that is able to select a given DB after loading in the slave, so that the slave can continue receiving the replication stream from the point it was disconnected without requiring the master to insert "SELECT" statements. This is useful in order to guarantee the "same stream" property, because the slave must be able to accumulate an identical backlog. * Slave pings to sub-slaves are now sent in a special form, when the top-level master is disconnected, in order to don't interfer with the replication stream. We just use out of band "\n" bytes as in other parts of the Redis protocol. An old design document is available here: https://gist.github.com/antirez/ae068f95c0d084891305 However the implementation is not identical to the description because during the work to implement it, different changes were needed in order to make things working well.
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- 24 Sep, 2016 1 commit
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charsyam authored
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- 02 Aug, 2016 1 commit
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Qu Chen authored
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- 27 Jul, 2016 1 commit
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antirez authored
This feature is useful, especially in deployments using Sentinel in order to setup Redis HA, where the slave is executed with NAT or port forwarding, so that the auto-detected port/ip addresses, as listed in the "INFO replication" output of the master, or as provided by the "ROLE" command, don't match the real addresses at which the slave is reachable for connections.
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- 22 Jul, 2016 1 commit
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antirez authored
In a previous commit the replication code was changed in order to centralize the BGSAVE for replication trigger in replicationCron(), however after further testings, the 1 second delay imposed by this change is not acceptable. So now the BGSAVE is only delayed if the AOF rewriting process is active. However past comments made sure that replicationCron() is always able to trigger the BGSAVE when needed, making the code generally more robust. The new code is more similar to the initial @oranagra patch where the BGSAVE was delayed only if an AOF rewrite was in progress. Trivia: delaying the BGSAVE uncovered a minor Sentinel issue that is now fixed.
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- 21 Jul, 2016 1 commit
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antirez authored
This makes the replication code conceptually simpler by removing the synchronous BGSAVE trigger in syncCommand(). This also means that socket and disk BGSAVE targets are handled by the same code.
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- 03 Dec, 2015 1 commit
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antirez authored
Now we have a single function to call in any state of the slave handshake, instead of using different functions for different states which is error prone. Change performed in the context of issue #2479 but does not fix it, since should be functionally identical to the past. Just an attempt to make replication.c simpler to follow.
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- 15 Oct, 2015 1 commit
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antirez authored
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- 02 Oct, 2015 1 commit
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antirez authored
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- 01 Oct, 2015 1 commit
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antirez authored
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- 30 Sep, 2015 3 commits
- 21 Aug, 2015 1 commit
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antirez authored
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- 20 Aug, 2015 1 commit
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antirez authored
Before this commit, after triggering a BGSAVE it was up to the caller of startBgsavForReplication() to handle slaves in WAIT_BGSAVE_START in order to update them accordingly. However when the replication target is the socket, this is not possible since the process of updating the slaves and sending the FULLRESYNC reply must be coupled with the process of starting an RDB save (the reason is, we need to send the FULLSYNC command and spawn a child that will start to send RDB data to the slaves ASAP). This commit moves the responsibility of handling slaves in WAIT_BGSAVE_START to startBgsavForReplication() so that for both diskless and disk-based replication we have the same chain of responsiblity. In order accomodate such change, the syncCommand() also needs to put the client in the slave list ASAP (just after the initial checks) and not at the end, so that startBgsavForReplication() can find the new slave alrady in the list. Another related change is what happens if the BGSAVE fails because of fork() or other errors: we now remove the slave from the list of slaves and send an error, scheduling the slave connection to be terminated. As a side effect of this change the following errors found by Oran Agra are fixed (thanks!): 1. rdbSaveToSlavesSockets() on failed fork will get the slaves cleaned up, otherwise they remain in a wrong state forever since we setup them for full resync before actually trying to fork. 2. updateSlavesWaitingBgsave() with replication target set as "socket" was broken since the function changed the slaves state from WAIT_BGSAVE_START to WAIT_BGSAVE_END via replicationSetupSlaveForFullResync(), so later rdbSaveToSlavesSockets() will not find any slave in the right state (WAIT_BGSAVE_START) to feed.
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- 07 Aug, 2015 1 commit
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antirez authored
It is simpler if removing the read event handler from the FD is up to slaveTryPartialResynchronization, after all it is only called in the context of syncWithMaster. This commit also makes sure that on error all the event handlers are removed from the socket before closing it.
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- 06 Aug, 2015 3 commits
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antirez authored
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antirez authored
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antirez authored
Add the concept of slaves capabilities to Redis, the slave now presents to the Redis master with a set of capabilities in the form: REPLCONF capa SOMECAPA capa OTHERCAPA ... This has the effect of setting slave->slave_capa with the corresponding SLAVE_CAPA macros that the master can test later to understand if it the slave will understand certain formats and protocols of the replication process. This makes it much simpler to introduce new replication capabilities in the future in a way that don't break old slaves or masters. This patch was designed and implemented together with Oran Agra (@oranagra).
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- 05 Aug, 2015 4 commits
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antirez authored
For PINGs we use the period configured by the user, but for the newlines of slaves waiting for an RDB to be created (including slaves waiting for the FULLRESYNC reply) we need to ping with frequency of 1 second, since the timeout is fixed and needs to be refreshed.
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antirez authored
In previous commits we moved the FULLRESYNC to the moment we start the BGSAVE, so that the offset we provide is the right one. However this also means that we need to re-emit the SELECT statement every time a new slave starts to accumulate the changes. To obtian this effect in a more clean way, the function that sends the FULLRESYNC reply was overloaded with a more important role of also doing this and chanigng the slave state. So it was renamed to replicationSetupSlaveForFullResync() to better reflect what it does now.
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antirez authored
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antirez authored
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- 04 Aug, 2015 1 commit
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antirez authored
This commit attempts to fix a bug involving PSYNC and diskless replication (currently experimental) found by Yuval Inbar from Redis Labs and that was later found to have even more far reaching effects (the bug also exists when diskstore is off). The gist of the bug is that, a Redis master replies with +FULLRESYNC to a PSYNC attempt that fails and requires a full resynchronization. However, the baseline offset sent along with FULLRESYNC was always the current master replication offset. This is not ok, because there are many reasosn that may delay the RDB file creation. And... guess what, the master offset we communicate must be the one of the time the RDB was created. So for example: 1) When the BGSAVE for replication is delayed since there is one already but is not good for replication. 2) When the BGSAVE is not needed as we attach one currently ongoing. 3) When because of diskless replication the BGSAVE is delayed. In all the above cases the PSYNC reply is wrong and the slave may reconnect later claiming to need a wrong offset: this may cause data curruption later.
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- 28 Jul, 2015 2 commits
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antirez authored
Using chained replication where C is slave of B which is in turn slave of A, if B reconnects the replication link with A but discovers it is no longer possible to PSYNC, slaves of B must be disconnected and PSYNC not allowed, since the new B dataset may be completely different after the synchronization with the master. Note that there are varius semantical differences in the way this is handled now compared to the past. In the past the semantics was: 1. When a slave lost connection with its master, disconnected the chained slaves ASAP. Which is not needed since after a successful PSYNC with the master, the slaves can continue and don't need to resync in turn. 2. However after a failed PSYNC the replication backlog was not reset, so a slave was able to PSYNC successfully even if the instance did a full sync with its master, containing now an entirely different data set. Now instead chained slaves are not disconnected when the slave lose the connection with its master, but only when it is forced to full SYNC with its master. This means that if the slave having chained slaves does a successful PSYNC all its slaves can continue without troubles. See issue #2694 for more details.
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antirez authored
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- 27 Jul, 2015 1 commit
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antirez authored
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- 26 Jul, 2015 6 commits
- 11 Jun, 2015 1 commit
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antirez authored
We usually want to reach the master using the address of the interface Redis is bound to (via the "bind" config option). That's useful since the master will get (and publish) the slave address getting the peer name of the incoming socket connection from the slave. However, when this is not possible, for example because the slave is bound to the loopback interface but repliaces from a master accessed via an external interface, we want to still connect with the master even from a different interface: in this case it is not really important that the master will provide any other address, while it is vital to be able to replicate correctly. Related to issues #2609 and #2612.
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- 01 Apr, 2015 1 commit
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antirez authored
When we fail to setup the write handler it does not make sense to take the client around, it is missing writes: whatever is a client or a slave anyway the connection should terminated ASAP. Moreover what the function does exactly with its return value, and in which case the write handler is installed on the socket, was not clear, so the functions comment are improved to make the goals of the function more obvious. Also related to #2485.
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