On 2014-09-28 18:19, Stephen Cameron wrote:
Note: this patch is not really production quality. I was just messing
around with lex and yacc and wrote a little expression parser, and then
thought, hmm, I always wished I could say "runtime=(24*60*60)" in an fio
job file... how hard could it be to make that work?
Some known issues:
1) Have not integrated with autoconf (don't know how, esp. since it uses
lex and yacc).
2) overflow and underflow during arithmetic expression evaluation is not
handled, and detection of floating point divide by zero is probably a
bit iffy. Probably some other numeric subtleties lurking in there too.
To mitigate that, I required that expressions be enclosed in parens, so
existing jobs essentially use the existing code for conversion of
strings to numbers, the idea being to try to avoid accidentally breaking
existing job files.
3) It's been awhile since I looked at fio's source, so it's possible I
missed some avenues by which numbers are parsed. I *think* they all go
through str_to_float() and str_to_decimal() in parse.c. If there are
other avenues, I missed those.
4) I did do some testing, but I'm no lex / yacc expert by any stretch,
so there could be wild bugs in there.
Just a fun little project I did today so I thought I'd share it, but if
getting autoconf to deal with lex and yacc is too painful, or those
aren't available on windows, etc., or for whatever reason this patch is
deemed to be unusable, that won't hurt my feelings at all.
That's pretty awesome! I've wanted something like that as well, so I do
welcome an effort to make that work. That said, there seems to be some
hitches. I get this:
axboe@lenny:[.]git/fio/expression-parser $ make
yacc -d expression-parser.y
cc -Wall -Wextra -c -o y.tab.o y.tab.c
lex expression-parser.l
cc -Wall -Wextra -c -o lex.yy.o lex.yy.c
In file included from expression-parser.l:23:0:
y.tab.h:60:15: error: stray ‘#’ in program
typedef union #line 47 "expression-parser.y" /* yacc.c:1909 */
^
y.tab.h:60:21: error: expected identifier or ‘(’ before numeric constant
typedef union #line 47 "expression-parser.y" /* yacc.c:1909 */
^
y.tab.h:63:7: error: stray ‘#’ in program
union #line 47 "expression-parser.y" /* yacc.c:1909 */
^
y.tab.h:63:13: error: expected identifier or ‘(’ before numeric constant
union #line 47 "expression-parser.y" /* yacc.c:1909 */
^
In file included from expression-parser.l:23:0:
y.tab.h:83:1: error: unknown type name ‘YYSTYPE’
extern YYSTYPE yylval;
^
expression-parser.l: In function ‘yylex’:
expression-parser.l:53:11: error: request for member ‘v’ in something
not a structure or union
yylval.v.dval = dval;
^
expression-parser.l:54:11: error: request for member ‘v’ in something
not a structure or union
yylval.v.ival = (long long) dval;
^
expression-parser.l:55:11: error: request for member ‘v’ in something
not a structure or union
yylval.v.has_dval = 1;
^
expression-parser.l:56:11: error: request for member ‘v’ in something
not a structure or union
yylval.v.has_error = 0;
^
expression-parser.l:60:11: error: request for member ‘v’ in something
not a structure or union
yylval.v.has_error = 1;
^
expression-parser.l:68:10: error: request for member ‘v’ in something
not a structure or union
yylval.v.ival = intval;
^
expression-parser.l:69:10: error: request for member ‘v’ in something
not a structure or union
yylval.v.dval = (double) intval;
^
expression-parser.l:70:10: error: request for member ‘v’ in something
not a structure or union
yylval.v.has_dval = 0;
^
expression-parser.l:71:10: error: request for member ‘v’ in something
not a structure or union
yylval.v.has_error = 0;
^
expression-parser.l:75:10: error: request for member ‘v’ in something
not a structure or union
yylval.v.has_error = 1;
^
expression-parser.l:83:10: error: request for member ‘v’ in something
not a structure or union
yylval.v.ival = intval;
^
expression-parser.l:84:10: error: request for member ‘v’ in something
not a structure or union
yylval.v.dval = (double) intval;
^
expression-parser.l:85:10: error: request for member ‘v’ in something
not a structure or union
yylval.v.has_dval = 0;
^
expression-parser.l:86:10: error: request for member ‘v’ in something
not a structure or union
yylval.v.has_error = 0;
^
expression-parser.l:90:10: error: request for member ‘v’ in something
not a structure or union
yylval.v.has_error = 1;
^
expression-parser.l:97:9: error: request for member ‘v’ in something not
a structure or union
yylval.v.has_error = 1;
^
make: *** [lex.yy.o] Error 1
And there are a few issues around the Makefile and ensuring the lex/yacc
bits are built properly, but those can be easily fixed up.
Don't worry about the configure bits, Windows, etc. I can fix that stuff
up pretty easily. Would be nice to have it work for me, though :-)
p.s. I have a feeling the mailing list won't like that I'm sending this
from gmail.
Looked good from this end, but that may be the direct email, dunno.
--
Jens Axboe
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