a0b33f9408* 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. * This is an alternate resolution to https://github.com/nim-lang/Nim/issues/13393 (which arguably could be resolved outside the stdlib). Add version1 of Wang Yi's hash specialized to 8 byte integers. This gives simple help to users having trouble with overly colliding hash(key)s. I.e., A) `import hashes; proc hash(x: myInt): Hash = hashWangYi1(int(x))` in the instantiation context of a `HashSet` or `Table` or B) more globally, compile with `nim c -d:hashWangYi1`. No hash can be all things to all use cases, but this one is A) vetted to scramble well by the SMHasher test suite (a necessarily limited but far more thorough test than prior proposals here), B) only a few ALU ops on many common CPUs, and C) possesses an easy via "grade school multi-digit multiplication" fall back for weaker deployment contexts. Some people might want to stampede ahead unbridled, but my view is that a good plan is to A) include this in the stdlib for a release or three to let people try it on various key sets nim-core could realistically never access/test (maybe mentioning it in the changelog so people actually try it out), B) have them report problems (if any), C) if all seems good, make the stdlib more novice friendly by adding `hashIdentity(x)=x` and changing the default `hash() = hashWangYi1` with some `when defined` rearranging so users can `-d:hashIdentity` if they want the old behavior back. This plan is compatible with any number of competing integer hashes if people want to add them. I would strongly recommend they all *at least* pass the SMHasher suite since the idea here is to become more friendly to novices who do not generally understand hashing failure modes. * Re-organize to work around `when nimvm` limitations; Add some tests; Add a changelog.md entry. * Add less than 64-bit CPU when fork. * Fix decl instead of call typo. * First attempt at fixing range error on 32-bit platforms; Still do the arithmetic in doubled up 64-bit, but truncate the hash to the lower 32-bits, but then still return `uint64` to be the same. So, type correct but truncated hash value. Update `thashes.nim` as well. * A second try at making 32-bit mode CI work. * Use a more systematic identifier convention than Wang Yi's code. * Fix test that was wrong for as long as `toHashSet` used `rightSize` (a very long time, I think). `$a`/`$b` depend on iteration order which varies with table range reduced hash order which varies with range for some `hash()`. With 3 elements, 3!=6 is small and we've just gotten lucky with past experimental `hash()` changes. An alternate fix here would be to not stringify but use the HashSet operators, but it is not clear that doesn't alter the "spirit" of the test. * Fix another stringified test depending upon hash order. * Oops - revert the string-keyed test. * Fix another stringify test depending on hash order. * Add a better than always zero `defined(js)` branch. * It turns out to be easy to just work all in `BigInt` inside JS and thus guarantee the same low order bits of output hashes (for `isSafeInteger` input numbers). Since `hashWangYi1` output bits are equally random in all their bits, this means that tables will be safely scrambled for table sizes up to 2**32 or 4 gigaentries which is probably fine, as long as the integer keys are all < 2**53 (also likely fine). (I'm unsure why the infidelity with C/C++ back ends cut off is 32, not 53 bits.) Since HashSet & Table only use the low order bits, a quick corollary of this is that `$` on most int-keyed sets/tables will be the same in all the various back ends which seems a nice-to-have trait. * These string hash tests fail for me locally. Maybe this is what causes the CI hang for testament pcat collections? * Oops. That failure was from me manually patching string hash in hashes. Revert. * Import more test improvements from https://github.com/nim-lang/Nim/pull/13410 * Fix bug where I swapped order when reverting the test. Ack. * Oh, just accept either order like more and more hash tests. * Iterate in the same order. * `return` inside `emit` made us skip `popFrame` causing weird troubles. * Oops - do Windows branch also. * `nimV1hash` -> multiply-mnemonic, type-scoped `nimIntHash1` (mnemonic resolutions are "1 == identity", 1 for Nim Version 1, 1 for first/simplest/fastest in a series of possibilities. Should be very easy to remember.) * Re-organize `when nimvm` logic to be a strict `when`-`else`. * Merge other changes. * Lift constants to a common area. * Fall back to identity hash when `BigInt` is unavailable. * Increase timeout slightly (probably just real-time perturbation of CI system performance). |
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This directory contains the test cases.
Each test must have a filename of the form: t*.nim
Note: Tests are only compiled by default. In order to get the tester to
execute the compiled binary, you need to specify a spec with an action key
(see below for details).
Specs
Each test can contain a spec in a discard """ ... """ block.
Check out the parseSpec procedure in the specs module for a full and reliable reference
action
Specifies what action this test should take.
Default: compile
Options:
compile- compiles the module and fails the test if compilations fails.run- compiles and runs the module, fails the test if compilation or execution of test code fails.reject- compiles the module and fails the test if compilation succeeds.
There are certain spec keys that imply run, including output and
outputsub.
cmd
Specifies the Nim command to use for compiling the test.
There are a number of variables that are replaced in this spec option:
$target- the compilation target, e.g.c.$options- the options for the compiler.$file- the filename of the test.$filedir- the directory of the test file.
Example:
discard """
cmd: "nim $target --nimblePath:./nimbleDir/simplePkgs $options $file"
"""
Categories
Each folder under this directory represents a test category, which can be
tested by running koch tests cat <category>.
The folder rodfiles contains special tests that test incremental
compilation via symbol files.
The folder dll contains simple DLL tests.
The folder realtimeGC contains a test for validating that the realtime GC
can run properly without linking against the nimrtl.dll/so. It includes a C
client and platform specific build files for manual compilation.