1. 04 Dec, 2017 1 commit
  2. 28 Oct, 2016 1 commit
  3. 27 Jun, 2016 1 commit
    • antirez's avatar
      Fix quicklistReplaceAtIndex() by updating the quicklist ziplist size. · 5e176e1a
      antirez authored
      The quicklist takes a cached version of the ziplist representation size
      in bytes. The implementation must update this length every time the
      underlying ziplist changes. However quicklistReplaceAtIndex() failed to
      fix the length.
      
      During LSET calls, the size of the ziplist blob and the cached size
      inside the quicklist diverged. Later, when this size is used in an
      authoritative way, for example during nodes splitting in order to copy
      the nodes, we end with a duplicated node that may contain random
      garbage.
      
      This commit should fix issue #3343, however several problems were found
      reviewing the quicklist.c code in search of this bug that should be
      addressed soon or later.
      
      For example:
      
      1. To take a cached ziplist length is fragile since failing to update it
      leads to this kind of issues.
      
      2. The node splitting code needs auditing. For example it works just for
      a side effect of ziplistDeleteRange() to be able to cope with a wrong
      count of elements to remove. The code inside quicklist.c assumes that
      -1 means "delete till the end" while actually it's just a count of how
      many elements to delete, and is an unsigned count. So -1 gets converted
      into the maximum integer, and just by chance the ziplist code stops
      deleting elements after there are no more to delete.
      
      3. Node splitting is extremely inefficient, it copies the node and
      removes elements from both nodes even when actually there is to move a
      single entry from one node to the other, or when the new resulting node
      is empty at all so there is nothing to copy but just to create a new
      node.
      
      However at least for Redis 3.2 to introduce fresh code inside
      quicklist.c may be even more risky, so instead I'm writing a better
      fuzzy tester to stress the internals a bit more in order to anticipate
      other possible bugs.
      
      This bug was found using a fuzzy tester written after having some clue
      about where the bug could be. The tester eventually created a ~2000
      commands sequence able to always crash Redis. I wrote a better version
      of the tester that searched for the smallest sequence that could crash
      Redis automatically. Later this smaller sequence was minimized by
      removing random commands till it still crashed the server. This resulted
      into a sequence of 7 commands. With this small sequence it was just a
      matter of filling the code with enough printf() to understand enough
      state to fix the bug.
      5e176e1a
  4. 20 Jun, 2016 1 commit
  5. 17 Feb, 2015 2 commits
  6. 02 Jan, 2015 8 commits
    • Matt Stancliff's avatar
      Set optional 'static' for Quicklist+Redis · 25e12d10
      Matt Stancliff authored
      This also defines REDIS_STATIC='' for building everything
      inside src/ and everything inside deps/lua/.
      25e12d10
    • Matt Stancliff's avatar
      Add branch prediction hints to quicklist · bbbbfb14
      Matt Stancliff authored
      Actually makes a noticeable difference.
      
      Branch hints were selected based on profiler hotspots.
      bbbbfb14
    • Matt Stancliff's avatar
      Cleanup quicklist style · 5f506b6d
      Matt Stancliff authored
      Small fixes due to a new version of clang-format (it's less
      crazy than the older version).
      5f506b6d
    • Matt Stancliff's avatar
      Allow compression of interior quicklist nodes · abdd1414
      Matt Stancliff authored
      Let user set how many nodes to *not* compress.
      
      We can specify a compression "depth" of how many nodes
      to leave uncompressed on each end of the quicklist.
      
      Depth 0 = disable compression.
      Depth 1 = only leave head/tail uncompressed.
        - (read as: "skip 1 node on each end of the list before compressing")
      Depth 2 = leave head, head->next, tail->prev, tail uncompressed.
        - ("skip 2 nodes on each end of the list before compressing")
      Depth 3 = Depth 2 + head->next->next + tail->prev->prev
        - ("skip 3 nodes...")
      etc.
      
      This also:
        - updates RDB storage to use native quicklist compression (if node is
          already compressed) instead of uncompressing, generating the RDB string,
          then re-compressing the quicklist node.
        - internalizes the "fill" parameter for the quicklist so we don't
          need to pass it to _every_ function.  Now it's just a property of
          the list.
        - allows a runtime-configurable compression option, so we can
          expose a compresion parameter in the configuration file if people
          want to trade slight request-per-second performance for up to 90%+
          memory savings in some situations.
        - updates the quicklist tests to do multiple passes: 200k+ tests now.
      abdd1414
    • Matt Stancliff's avatar
      Remove malloc failure checks · 8d702189
      Matt Stancliff authored
      We trust zmalloc to kill the whole process on memory failure
      8d702189
    • Matt Stancliff's avatar
      Add adaptive quicklist fill factor · c6bf20c2
      Matt Stancliff authored
      Fill factor now has two options:
        - negative (1-5) for size-based ziplist filling
        - positive for length-based ziplist filling with implicit size cap.
      
      Negative offsets define ziplist size limits of:
        -1: 4k
        -2: 8k
        -3: 16k
        -4: 32k
        -5: 64k
      
      Positive offsets now automatically limit their max size to 8k.  Any
      elements larger than 8k will be in individual nodes.
      
      Positive ziplist fill factors will keep adding elements
      to a ziplist until one of:
        - ziplist has FILL number of elements
          - or -
        - ziplist grows above our ziplist max size (currently 8k)
      
      When using positive fill factors, if you insert a large
      element (over 8k), that element will automatically allocate
      an individual quicklist node with one element and no other elements will be
      in the same ziplist inside that quicklist node.
      
      When using negative fill factors, elements up to the size
      limit can be added to one quicklist node.  If an element
      is added larger than the max ziplist size, that element
      will be allocated an individual ziplist in a new quicklist node.
      
      Tests also updated to start testing at fill factor -5.
      c6bf20c2
    • Matt Stancliff's avatar
      Add ziplistMerge() · 9d2dc024
      Matt Stancliff authored
      This started out as #2158 by sunheehnus, but I kept rewriting it
      until I could understand things more easily and get a few more
      correctness guarantees out of the readability flow.
      
      The original commit created and returned a new ziplist with the contents of
      both input ziplists, but I prefer to grow one of the input ziplists
      and destroy the other one.
      
      So, instead of malloc+copy as in #2158, the merge now reallocs one of
      the existing ziplists and copies the other ziplist into the new space.
      
      Also added merge test cases to ziplistTest()
      9d2dc024
    • Matt Stancliff's avatar
      Add quicklist implementation · 5e362b84
      Matt Stancliff authored
      This replaces individual ziplist vs. linkedlist representations
      for Redis list operations.
      
      Big thanks for all the reviews and feedback from everybody in
      https://github.com/antirez/redis/pull/2143
      5e362b84