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don't strdup tokens in the lexer

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every stringy token the lexer returns is turned into a Symbol and not
used further, so we don't have to strdup. using a string_view is
sufficient, but due to limitations of the current parser we have to use
a POD type that holds the same information.

gives ~2% on system build, 6% on search, 8% on parsing alone

 # before

Benchmark 1: nix search --offline nixpkgs hello
  Time (mean ± σ):     610.6 ms ±   2.4 ms    [User: 602.5 ms, System: 7.8 ms]
  Range (min … max):   606.6 ms … 617.3 ms    50 runs

Benchmark 2: nix eval -f hackage-packages.nix
  Time (mean ± σ):     430.1 ms ±   1.4 ms    [User: 393.1 ms, System: 36.7 ms]
  Range (min … max):   428.2 ms … 434.2 ms    50 runs

Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  Time (mean ± σ):      3.032 s ±  0.005 s    [User: 2.808 s, System: 0.223 s]
  Range (min … max):    3.023 s …  3.041 s    50 runs

 # after

Benchmark 1: nix search --offline nixpkgs hello
  Time (mean ± σ):     574.7 ms ±   2.8 ms    [User: 566.3 ms, System: 8.0 ms]
  Range (min … max):   569.2 ms … 580.7 ms    50 runs

Benchmark 2: nix eval -f hackage-packages.nix
  Time (mean ± σ):     394.4 ms ±   0.8 ms    [User: 361.8 ms, System: 32.3 ms]
  Range (min … max):   392.7 ms … 395.7 ms    50 runs

Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  Time (mean ± σ):      2.976 s ±  0.005 s    [User: 2.757 s, System: 0.218 s]
  Range (min … max):    2.966 s …  2.990 s    50 runs
This commit is contained in:
pennae 2021-12-21 09:17:31 +01:00
parent de273bbff2
commit 61a9d16d5c
2 changed files with 23 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

25
src/libexpr/parser.y
View file

@ -273,9 +273,16 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
nix::Formal * formal;
nix::NixInt n;
nix::NixFloat nf;
const char * id; // !!! -> Symbol
char * path;
char * uri;
// using C a struct allows us to avoid having to define the special
// members that using string_view here would implicitly delete.
struct StringToken {
const char * p;
size_t l;
operator std::string_view() const { return {p, l}; }
};
StringToken id; // !!! -> Symbol
StringToken path;
StringToken uri;
std::vector<nix::AttrName> * attrNames;
std::vector<std::pair<nix::Pos, nix::Expr *> > * string_parts;
}
@ -397,7 +404,7 @@ expr_select
expr_simple
: ID {
if (strcmp($1, "__curPos") == 0)
if (strncmp($1.p, "__curPos", $1.l) == 0)
$$ = new ExprPos(CUR_POS);
else
$$ = new ExprVar(CUR_POS, data->symbols.create($1));
@ -414,7 +421,7 @@ expr_simple
$$ = new ExprConcatStrings(CUR_POS, false, $2);
}
| SPATH {
string path($1 + 1, strlen($1) - 2);
string path($1.p + 1, $1.l - 2);
$$ = new ExprCall(CUR_POS,
new ExprVar(data->symbols.create("__findFile")),
{new ExprVar(data->symbols.create("__nixPath")),
@ -460,14 +467,14 @@ string_parts_interpolated
path_start
: PATH {
Path path(absPath($1, data->basePath));
Path path(absPath({$1.p, $1.l}, data->basePath));
/* add back in the trailing '/' to the first segment */
if ($1[strlen($1)-1] == '/' && strlen($1) > 1)
if ($1.p[$1.l-1] == '/' && $1.l > 1)
path += "/";
$$ = new ExprPath(path);
}
| HPATH {
Path path(getHome() + string($1 + 1));
Path path(getHome() + string($1.p + 1, $1.l - 1));
$$ = new ExprPath(path);
}
;
@ -543,7 +550,7 @@ attrpath
attr
: ID { $$ = $1; }
| OR_KW { $$ = "or"; }
| OR_KW { $$ = {"or", 2}; }
;
string_attr