1. 28 Apr, 2020 1 commit
  2. 27 Apr, 2020 2 commits
    • Oran Agra's avatar
      Keep track of meaningful replication offset in replicas too · e4d2bb62
      Oran Agra authored
      Now both master and replicas keep track of the last replication offset
      that contains meaningful data (ignoring the tailing pings), and both
      trim that tail from the replication backlog, and the offset with which
      they try to use for psync.
      
      the implication is that if someone missed some pings, or even have
      excessive pings that the promoted replica has, it'll still be able to
      psync (avoid full sync).
      
      the downside (which was already committed) is that replicas running old
      code may fail to psync, since the promoted replica trims pings form it's
      backlog.
      
      This commit adds a test that reproduces several cases of promotions and
      demotions with stale and non-stale pings
      
      Background:
      The mearningful offset on the master was added recently to solve a problem were
      the master is left all alone, injecting PINGs into it's backlog when no one is
      listening and then gets demoted and tries to replicate from a replica that didn't
      have any of the PINGs (or at least not the last ones).
      
      however, consider this case:
      master A has two replicas (B and C) replicating directly from it.
      there's no traffic at all, and also no network issues, just many pings in the
      tail of the backlog. now B gets promoted, A becomes a replica of B, and C
      remains a replica of A. when A gets demoted, it trims the pings from its
      backlog, and successfully replicate from B. however, C is still aware of
      these PINGs, when it'll disconnect and re-connect to A, it'll ask for something
      that's not in the backlog anymore (since A trimmed the tail of it's backlog),
      and be forced to do a full sync (something it didn't have to do before the
      meaningful offset fix).
      
      Besides that, the psync2 test was always failing randomly here and there, it
      turns out the reason were PINGs. Investigating it shows the following scenario:
      
      cycle 1: redis #1 is master, and all the rest are direct replicas of #1
      cycle 2: redis #2 is promoted to master, #1 is a replica of #2 and #3 is replica of #1
      now we see that when #1 is demoted it prints:
      17339:S 21 Apr 2020 11:16:38.523 * Using the meaningful offset 3929963 instead of 3929977 to exclude the final PINGs (14 bytes difference)
      17339:S 21 Apr 2020 11:16:39.391 * Trying a partial resynchronization (request e2b3f8817735fdfe5fa4626766daa938b61419e5:3929964).
      17339:S 21 Apr 2020 11:16:39.392 * Successful partial resynchronization with master.
      and when #3 connects to the demoted #2, #2 says:
      17339:S 21 Apr 2020 11:16:40.084 * Partial resynchronization not accepted: Requested offset for secondary ID was 3929978, but I can reply up to 3929964
      
      so the issue here is that the meaningful offset feature saved the day for the
      demoted master (since it needs to sync from a replica that didn't get the last
      ping), but it didn't help one of the other replicas which did get the last ping.
      e4d2bb62
    • Guy Benoish's avatar
      Add the stream tag to XSETID tests · 43329c9b
      Guy Benoish authored
      43329c9b
  3. 24 Apr, 2020 4 commits
    • antirez's avatar
      LCS -> STRALGO LCS. · 3722f89f
      antirez authored
      STRALGO should be a container for mostly read-only string
      algorithms in Redis. The algorithms should have two main
      characteristics:
      
      1. They should be non trivial to compute, and often not part of
      programming language standard libraries.
      2. They should be fast enough that it is a good idea to have optimized C
      implementations.
      
      Next thing I would love to see? A small strings compression algorithm.
      3722f89f
    • yanhui13's avatar
      add tcl test for cluster slots · f03f1fad
      yanhui13 authored
      f03f1fad
    • antirez's avatar
      Tracking: test expired keys notifications. · 06917e58
      antirez authored
      06917e58
    • antirez's avatar
      Tracking: NOLOOP tests. · e434b2ce
      antirez authored
      e434b2ce
  4. 17 Apr, 2020 2 commits
  5. 07 Apr, 2020 9 commits
  6. 31 Mar, 2020 6 commits
  7. 25 Mar, 2020 7 commits
  8. 12 Mar, 2020 1 commit
    • Oran Agra's avatar
      fix for flaky psync2 test · 61738154
      Oran Agra authored
      *** [err]: PSYNC2: total sum of full synchronizations is exactly 4 in tests/integration/psync2.tcl
      Expected 5 == 4 (context: type eval line 6 cmd {assert {$sum == 4}} proc ::test)
      
      issue was that sometime the test got an unexpected full sync since it
      tried to switch to the replica before it was in sync with it's master.
      61738154
  9. 27 Feb, 2020 8 commits