1. 21 Jul, 2020 1 commit
    • Ondřej Surý's avatar
      Fix the rbt hashtable and grow it when setting max-cache-size · e24bc324
      Ondřej Surý authored
      There were several problems with rbt hashtable implementation:
      
      1. Our internal hashing function returns uint64_t value, but it was
         silently truncated to unsigned int in dns_name_hash() and
         dns_name_fullhash() functions.  As the SipHash 2-4 higher bits are
         more random, we need to use the upper half of the return value.
      
      2. The hashtable implementation in rbt.c was using modulo to pick the
         slot number for the hash table.  This has several problems because
         modulo is: a) slow, b) oblivious to patterns in the input data.  This
         could lead to very uneven distribution of the hashed data in the
         hashtable.  Combined with the single-linked lists we use, it could
         really hog-down the lookup and removal of the nodes from the rbt
         tree[a].  The Fibonacci Hashing is much better fit for the hashtable
         function here.  For longer description, read "Fibonacci Hashing: The
         Optimization that the World Forgot"[b] or just look at the Linux
         kernel.  Also this will make Diego very happy :).
      
      3. The hashtable would rehash every time the number of nodes in the rbt
         tree would exceed 3 * (hashtable size).  The overcommit will make the
         uneven distribution in the hashtable even worse, but the main problem
         lies in the rehashing - every time the database grows beyond the
         limit, each subsequent rehashing will be much slower.  The mitigation
         here is letting the rbt know how big the cache can grown and
         pre-allocate the hashtable to be big enough to actually never need to
         rehash.  This will consume more memory at the start, but since the
         size of the hashtable is capped to `1 << 32` (e.g. 4 mio entries), it
         will only consume maximum of 32GB of memory for hashtable in the
         worst case (and max-cache-size would need to be set to more than
         4TB).  Calling the dns_db_adjusthashsize() will also cap the maximum
         size of the hashtable to the pre-computed number of bits, so it won't
         try to consume more gigabytes of memory than available for the
         database.
      
         FIXME: What is the average size of the rbt node that gets hashed?  I
         chose the pagesize (4k) as initial value to precompute the size of
         the hashtable, but the value is based on feeling and not any real
         data.
      
      For future work, there are more places where we use result of the hash
      value modulo some small number and that would benefit from Fibonacci
      Hashing to get better distribution.
      
      Notes:
      a. A doubly linked list should be used here to speedup the removal of
         the entries from the hashtable.
      b. https://probablydance.com/2018/06/16/fibonacci-hashing-the-optimization-that-the-world-forgot-or-a-better-alternative-to-integer-modulo/
      e24bc324
  2. 25 May, 2020 1 commit
  3. 14 Feb, 2020 1 commit
  4. 13 Feb, 2020 3 commits
    • Evan Hunt's avatar
      apply the modified style · e851ed0b
      Evan Hunt authored
      e851ed0b
    • Ondřej Surý's avatar
      Use clang-tidy to add curly braces around one-line statements · 056e133c
      Ondřej Surý authored
      The command used to reformat the files in this commit was:
      
      ./util/run-clang-tidy \
      	-clang-tidy-binary clang-tidy-11
      	-clang-apply-replacements-binary clang-apply-replacements-11 \
      	-checks=-*,readability-braces-around-statements \
      	-j 9 \
      	-fix \
      	-format \
      	-style=file \
      	-quiet
      clang-format -i --style=format $(git ls-files '*.c' '*.h')
      uncrustify -c .uncrustify.cfg --replace --no-backup $(git ls-files '*.c' '*.h')
      clang-format -i --style=format $(git ls-files '*.c' '*.h')
      056e133c
    • Ondřej Surý's avatar
      Use coccinelle to add braces to nested single line statement · 36c6105e
      Ondřej Surý authored
      Both clang-tidy and uncrustify chokes on statement like this:
      
      for (...)
      	if (...)
      		break;
      
      This commit uses a very simple semantic patch (below) to add braces around such
      statements.
      
      Semantic patch used:
      
      @@
      statement S;
      expression E;
      @@
      
      while (...)
      - if (E) S
      + { if (E) { S } }
      
      @@
      statement S;
      expression E;
      @@
      
      for (...;...;...)
      - if (E) S
      + { if (E) { S } }
      
      @@
      statement S;
      expression E;
      @@
      
      if (...)
      - if (E) S
      + { if (E) { S } }
      36c6105e
  5. 12 Feb, 2020 1 commit
  6. 10 Feb, 2020 1 commit
  7. 03 Feb, 2020 1 commit
  8. 14 Jan, 2020 1 commit
  9. 29 Nov, 2019 1 commit
  10. 01 Oct, 2019 3 commits
  11. 28 Aug, 2019 1 commit
  12. 31 Jul, 2019 1 commit
    • Ondřej Surý's avatar
      Replace usage of isc_mem_put+isc_mem_detach with isc_mem_putanddetach · a6dcdc53
      Ondřej Surý authored
      Using isc_mem_put(mctx, ...) + isc_mem_detach(mctx) required juggling with the
      local variables when mctx was part of the freed object. The isc_mem_putanddetach
      function can handle this case internally, but it wasn't used everywhere.  This
      commit apply the semantic patching plus bit of manual work to replace all such
      occurrences with proper usage of isc_mem_putanddetach().
      a6dcdc53
  13. 23 Jul, 2019 2 commits
  14. 09 Jul, 2019 1 commit
  15. 08 Mar, 2019 1 commit
  16. 22 Nov, 2018 2 commits
  17. 08 Nov, 2018 2 commits
  18. 23 Oct, 2018 1 commit
  19. 08 Aug, 2018 2 commits
  20. 20 Apr, 2018 1 commit
  21. 09 Apr, 2018 1 commit
    • Michał Kępień's avatar
      Use dns_fixedname_initname() where possible · 4df4a8e7
      Michał Kępień authored
      Replace dns_fixedname_init() calls followed by dns_fixedname_name()
      calls with calls to dns_fixedname_initname() where it is possible
      without affecting current behavior and/or performance.
      
      This patch was mostly prepared using Coccinelle and the following
      semantic patch:
      
          @@
          expression fixedname, name;
          @@
          -	dns_fixedname_init(&fixedname);
          	...
          -	name = dns_fixedname_name(&fixedname);
          +	name = dns_fixedname_initname(&fixedname);
      
      The resulting set of changes was then manually reviewed to exclude false
      positives and apply minor tweaks.
      
      It is likely that more occurrences of this pattern can be refactored in
      an identical way.  This commit only takes care of the low-hanging fruit.
      4df4a8e7
  22. 23 Feb, 2018 1 commit
  23. 15 Feb, 2018 1 commit
  24. 06 Oct, 2017 2 commits
  25. 05 Sep, 2017 1 commit
  26. 22 Apr, 2017 2 commits
  27. 30 Dec, 2016 1 commit
  28. 02 Nov, 2016 1 commit
  29. 12 Aug, 2016 1 commit
  30. 27 Jun, 2016 1 commit