From 26d92017d3b36cff940dcb7d1611c42232edb81a Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Mon, 29 Aug 2016 17:28:20 +0200 Subject: [PATCH] Add builtin function "partition" The implementation of "partition" in Nixpkgs is O(n^2) (because of the use of ++), and for some reason was causing stack overflows in multi-threaded evaluation (not sure why). This reduces "nix-env -qa --drv-path" runtime by 0.197s and memory usage by 298 MiB (in non-Boehm mode). --- src/libexpr/eval.cc | 2 ++ src/libexpr/eval.hh | 3 ++- src/libexpr/json-to-value.cc | 9 -------- src/libexpr/primops.cc | 35 ++++++++++++++++++++++++++++++ src/libexpr/value.hh | 9 ++++++++ tests/lang/eval-okay-partition.exp | 1 + tests/lang/eval-okay-partition.nix | 5 +++++ 7 files changed, 54 insertions(+), 10 deletions(-) create mode 100644 tests/lang/eval-okay-partition.exp create mode 100644 tests/lang/eval-okay-partition.nix diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc index ace0517fb..22396865f 100644 --- a/src/libexpr/eval.cc +++ b/src/libexpr/eval.cc @@ -293,6 +293,8 @@ EvalState::EvalState(const Strings & _searchPath, ref store) , sColumn(symbols.create("column")) , sFunctor(symbols.create("__functor")) , sToString(symbols.create("__toString")) + , sRight(symbols.create("right")) + , sWrong(symbols.create("wrong")) , store(store) , baseEnv(allocEnv(128)) , staticBaseEnv(false, 0) diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh index 47e4d99bf..6f1befa2a 100644 --- a/src/libexpr/eval.hh +++ b/src/libexpr/eval.hh @@ -71,7 +71,8 @@ public: const Symbol sWith, sOutPath, sDrvPath, sType, sMeta, sName, sValue, sSystem, sOverrides, sOutputs, sOutputName, sIgnoreNulls, - sFile, sLine, sColumn, sFunctor, sToString; + sFile, sLine, sColumn, sFunctor, sToString, + sRight, sWrong; Symbol sDerivationNix; /* If set, force copying files to the Nix store even if they diff --git a/src/libexpr/json-to-value.cc b/src/libexpr/json-to-value.cc index 1daf84600..f671802bc 100644 --- a/src/libexpr/json-to-value.cc +++ b/src/libexpr/json-to-value.cc @@ -12,15 +12,6 @@ static void skipWhitespace(const char * & s) } -#if HAVE_BOEHMGC -typedef std::vector > ValueVector; -typedef std::map, gc_allocator > ValueMap; -#else -typedef std::vector ValueVector; -typedef std::map ValueMap; -#endif - - static string parseJSONString(const char * & s) { string res; diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc index 51ee16353..5c0b77c15 100644 --- a/src/libexpr/primops.cc +++ b/src/libexpr/primops.cc @@ -1443,6 +1443,40 @@ static void prim_sort(EvalState & state, const Pos & pos, Value * * args, Value } +static void prim_partition(EvalState & state, const Pos & pos, Value * * args, Value & v) +{ + state.forceFunction(*args[0], pos); + state.forceList(*args[1], pos); + + auto len = args[1]->listSize(); + + ValueVector right, wrong; + + for (unsigned int n = 0; n < len; ++n) { + auto vElem = args[1]->listElems()[n]; + state.forceValue(*vElem); + Value res; + state.callFunction(*args[0], *vElem, res, pos); + if (state.forceBool(res)) + right.push_back(vElem); + else + wrong.push_back(vElem); + } + + state.mkAttrs(v, 2); + + Value * vRight = state.allocAttr(v, state.sRight); + state.mkList(*vRight, right.size()); + memcpy(vRight->listElems(), right.data(), sizeof(Value *) * right.size()); + + Value * vWrong = state.allocAttr(v, state.sWrong); + state.mkList(*vWrong, wrong.size()); + memcpy(vWrong->listElems(), wrong.data(), sizeof(Value *) * wrong.size()); + + v.attrs->sort(); +} + + /************************************************************* * Integer arithmetic *************************************************************/ @@ -1881,6 +1915,7 @@ void EvalState::createBaseEnv() addPrimOp("__all", 2, prim_all); addPrimOp("__genList", 2, prim_genList); addPrimOp("__sort", 2, prim_sort); + addPrimOp("__partition", 2, prim_partition); // Integer arithmetic addPrimOp("__add", 2, prim_add); diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh index f5e485748..048522016 100644 --- a/src/libexpr/value.hh +++ b/src/libexpr/value.hh @@ -250,4 +250,13 @@ void mkPath(Value & v, const char * s); size_t valueSize(Value & v); +#if HAVE_BOEHMGC +typedef std::vector > ValueVector; +typedef std::map, gc_allocator > ValueMap; +#else +typedef std::vector ValueVector; +typedef std::map ValueMap; +#endif + + } diff --git a/tests/lang/eval-okay-partition.exp b/tests/lang/eval-okay-partition.exp new file mode 100644 index 000000000..cd8b8b020 --- /dev/null +++ b/tests/lang/eval-okay-partition.exp @@ -0,0 +1 @@ +{ right = [ 0 2 4 6 8 10 100 102 104 106 108 110 ]; wrong = [ 1 3 5 7 9 101 103 105 107 109 ]; } diff --git a/tests/lang/eval-okay-partition.nix b/tests/lang/eval-okay-partition.nix new file mode 100644 index 000000000..846d2ce49 --- /dev/null +++ b/tests/lang/eval-okay-partition.nix @@ -0,0 +1,5 @@ +with import ./lib.nix; + +builtins.partition + (x: x / 2 * 2 == x) + (builtins.concatLists [ (range 0 10) (range 100 110) ])