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authorc-blake <c-blake@users.noreply.github.com>2020-03-31 13:18:45 -0400
committerGitHub <noreply@github.com>2020-03-31 19:18:45 +0200
commitb1aa3b1eeada17453cee9af5c9227c85e0b73d54 (patch)
tree09868a6bbc7854ca18d71812c9941f9ed389dd0f /tests/arc
parent7abeba6aeb2de6ab55702524a2c35da1c7da2ee1 (diff)
downloadNim-b1aa3b1eeada17453cee9af5c9227c85e0b73d54.tar.gz
Unwind just the "pseudorandom probing" part of recent sets,tables changes (#13816)
* Unwind just the "pseudorandom probing" (whole hash-code-keyed variable
stride double hashing) part of recent sets & tables changes (which has
still been causing bugs over a month later (e.g., two days ago
https://github.com/nim-lang/Nim/issues/13794) as well as still having
several "figure this out" implementation question comments in them (see
just diffs of this PR).

This topic has been discussed in many places:
  https://github.com/nim-lang/Nim/issues/13393
  https://github.com/nim-lang/Nim/pull/13418
  https://github.com/nim-lang/Nim/pull/13440
  https://github.com/nim-lang/Nim/issues/13794

Alternative/non-mandatory stronger integer hashes (or vice-versa opt-in
identity hashes) are a better solution that is more general (no illusion
of one hard-coded sequence solving all problems) while retaining the
virtues of linear probing such as cache obliviousness and age-less tables
under delete-heavy workloads (still untested after a month of this change).

The only real solution for truly adversarial keys is a hash keyed off of
data unobservable to attackers.  That all fits better with a few families
of user-pluggable/define-switchable hashes which can be provided in a
separate PR more about `hashes.nim`.

This PR carefully preserves the better (but still hard coded!) probing
of the  `intsets` and other recent fixes like `move` annotations, hash
order invariant tests, `intsets.missingOrExcl` fixing, and the move of
`rightSize` into `hashcommon.nim`.

* Fix `data.len` -> `dataLen` problem.
Diffstat (limited to 'tests/arc')
-rw-r--r--tests/arc/trepr.nim2
1 files changed, 1 insertions, 1 deletions
diff --git a/tests/arc/trepr.nim b/tests/arc/trepr.nim
index 391622ff6..7a92112ed 100644
--- a/tests/arc/trepr.nim
+++ b/tests/arc/trepr.nim
@@ -1,7 +1,7 @@
 discard """
   cmd: "nim c --gc:arc $file"
   nimout: '''(a: true, n: doAssert)
-Table[system.string, trepr.MyType](data: @[], counter: 0, countDeleted: 0)
+Table[system.string, trepr.MyType](data: @[], counter: 0)
 nil
 '''
 """