1. 28 Jul, 2017 2 commits
  2. 24 Jul, 2017 8 commits
  3. 23 Jul, 2017 2 commits
    • antirez's avatar
      Modules: don't crash when Lua calls a module blocking command. · 31404355
      antirez authored
      Lua scripting does not support calling blocking commands, however all
      the native Redis commands are flagged as "s" (no scripting flag), so
      this is not possible at all. With modules there is no such mechanism in
      order to flag a command as non callable by the Lua scripting engine,
      moreover we cannot trust the modules users from complying all the times:
      it is likely that modules will be released to have blocking commands
      without such commands being flagged correctly, even if we provide a way to
      signal this fact.
      
      This commit attempts to address the problem in a short term way, by
      detecting that a module is trying to block in the context of the Lua
      scripting engine client, and preventing to do this. The module will
      actually believe to block as usually, but what happens is that the Lua
      script receives an error immediately, and the background call is ignored
      by the Redis engine (if not for the cleanup callbacks, once it
      unblocks).
      
      Long term, the more likely solution, is to introduce a new call called
      RedisModule_GetClientFlags(), so that a command can detect if the caller
      is a Lua script, and return an error, or avoid blocking at all.
      
      Being the blocking API experimental right now, more work is needed in
      this regard in order to reach a level well blocking module commands and
      all the other Redis subsystems interact peacefully.
      
      Now the effect is like the following:
      
          127.0.0.1:6379> eval "redis.call('hello.block',1,5000)" 0
          (error) ERR Error running script (call to
          f_b5ba35ff97bc1ef23debc4d6e9fd802da187ed53): @user_script:1: ERR
          Blocking module command called from Lua script
      
      This commit fixes issue #4127 in the short term.
      31404355
    • antirez's avatar
      5bfdfbe1
  4. 20 Jul, 2017 3 commits
    • antirez's avatar
      Make representClusterNodeFlags() more robust. · a3778f3b
      antirez authored
      This function failed when an internal-only flag was set as an only flag
      in a node: the string was trimmed expecting a final comma before
      exiting the function, causing a crash. See issue #4142.
      Moreover generation of flags representation only needed at DEBUG log
      level was always performed: a waste of CPU time. This is fixed as well
      by this commit.
      a3778f3b
    • antirez's avatar
      Fix two bugs in moduleTypeLookupModuleByID(). · b1c2e1a1
      antirez authored
      The function cache was not working at all, and the function returned
      wrong values if there where two or more modules exporting native data
      types.
      
      See issue #4131 for more details.
      b1c2e1a1
    • Leon Chen's avatar
      fix return wrong value of clusterDelNodeSlots · 9e7a8c02
      Leon Chen authored
      9e7a8c02
  5. 18 Jul, 2017 1 commit
  6. 15 Jul, 2017 1 commit
  7. 14 Jul, 2017 6 commits
  8. 12 Jul, 2017 1 commit
    • antirez's avatar
      Fix replication of SLAVEOF inside transaction. · e74f0aa6
      antirez authored
      In Redis 4.0 replication, with the introduction of PSYNC2, masters and
      slaves replicate commands to cascading slaves and to the replication
      backlog itself in a different way compared to the past.
      
      Masters actually replicate the effects of client commands.
      Slaves just propagate what they receive from masters.
      
      This mechanism can cause problems when the configuration of an instance
      is changed from master to slave inside a transaction. For instance
      we could send to a master instance the following sequence:
      
          MULTI
          SLAVEOF 127.0.0.1 0
          EXEC
          SLAVEOF NO ONE
      
      Before the fixes in this commit, the MULTI command used to be propagated
      into the replication backlog, however after the SLAVEOF command the
      instance is a slave, so the EXEC implementation failed to also propagate
      the EXEC command. When the slaves of the above instance reconnected,
      they were incrementally synchronized just sending a "MULTI". This put
      the master client (in the slaves) into MULTI state, breaking the
      replication.
      
      Notably even Redis Sentinel uses the above approach in order to guarantee
      that configuration changes are always performed together with rewrites
      of the configuration and with clients disconnection. Sentiel does:
      
          MULTI
          SLAVEOF ...
          CONFIG REWRITE
          CLIENT KILL TYPE normal
          EXEC
      
      So this was a really problematic issue. However even with the fix in
      this commit, that will add the final EXEC to the replication stream in
      case the instance was switched from master to slave during the
      transaction, the result would be to increment the slave replication
      offset, so a successive reconnection with the new master, will not
      permit a successful partial resynchronization: no way the new master can
      provide us with the backlog needed, we incremented our offset to a value
      that the new master cannot have.
      
      However the EXEC implementation waits to emit the MULTI, so that if the
      commands inside the transaction actually do not need to be replicated,
      no commands propagation happens at all. From multi.c:
      
          if (!must_propagate && !(c->cmd->flags & (CMD_READONLY|CMD_ADMIN))) {
      	execCommandPropagateMulti(c);
      	must_propagate = 1;
          }
      
      The above code is already modified by this commit you are reading.
      Now also ADMIN commands do not trigger the emission of MULTI. It is actually
      not clear why we do not just check for CMD_WRITE... Probably I wrote it this
      way in order to make the code more reliable: better to over-emit MULTI
      than not emitting it in time.
      
      So this commit should indeed fix issue #3836 (verified), however it looks
      like some reconsideration of this code path is needed in the long term.
      
      BONUS POINT: The reverse bug.
      
      Even in a read only slave "B", in a replication setup like:
      
      	A -> B -> C
      
      There are commands without the READONLY nor the ADMIN flag, that are also
      not flagged as WRITE commands. An example is just the PING command.
      
      So if we send B the following sequence:
      
          MULTI
          PING
          SLAVEOF NO ONE
          EXEC
      
      The result will be the reverse bug, where only EXEC is emitted, but not the
      previous MULTI. However this apparently does not create problems in practice
      but it is yet another acknowledge of the fact some work is needed here
      in order to make this code path less surprising.
      
      Note that there are many different approaches we could follow. For instance
      MULTI/EXEC blocks containing administrative commands may be allowed ONLY
      if all the commands are administrative ones, otherwise they could be
      denined. When allowed, the commands could simply never be replicated at all.
      e74f0aa6
  9. 11 Jul, 2017 4 commits
  10. 10 Jul, 2017 5 commits
  11. 06 Jul, 2017 6 commits
  12. 05 Jul, 2017 1 commit