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Make pgbench's expression lexer reentrant.
This is a necessary preliminary step for making it play with psqlscan.l given the way I set up the lexer input-buffer sharing mechanism in commit 0ea9efb. I've not tried to make it *actually* reentrant; there's still some static variables laying about. But flex thinks it's reentrant, and that's what counts. In support of that, fix exprparse.y to pass through the yyscan_t from the caller. Also do some minor code beautification, like not casting away const.
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4 files changed

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‎src/bin/pgbench/exprparse.y

Lines changed: 37 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -7,6 +7,8 @@
77
* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10+
* src/bin/pgbench/exprparse.y
11+
*
1012
*-------------------------------------------------------------------------
1113
*/
1214

@@ -19,16 +21,19 @@ PgBenchExpr *expr_parse_result;
1921
static PgBenchExprList *make_elist(PgBenchExpr *exp, PgBenchExprList *list);
2022
static PgBenchExpr *make_integer_constant(int64 ival);
2123
static PgBenchExpr *make_variable(char *varname);
22-
static PgBenchExpr *make_op(const char *operator, PgBenchExpr *lexpr,
23-
PgBenchExpr *rexpr);
24-
static int find_func(const char *fname);
25-
static PgBenchExpr *make_func(const int fnumber, PgBenchExprList *args);
24+
static PgBenchExpr *make_op(yyscan_t yyscanner, const char *operator,
25+
PgBenchExpr *lexpr, PgBenchExpr *rexpr);
26+
static int find_func(yyscan_t yyscanner, const char *fname);
27+
static PgBenchExpr *make_func(yyscan_t yyscanner, int fnumber, PgBenchExprList *args);
2628

2729
%}
2830

2931
%expect 0
3032
%name-prefix="expr_yy"
3133

34+
%parse-param {yyscan_t yyscanner}
35+
%lex-param {yyscan_t yyscanner}
36+
3237
%union
3338
{
3439
int64 ival;
@@ -43,7 +48,6 @@ static PgBenchExpr *make_func(const int fnumber, PgBenchExprList *args);
4348
%type <str> VARIABLE FUNCTION
4449

4550
%token INTEGER VARIABLE FUNCTION
46-
%token CHAR_ERROR /* never used, will raise a syntax error */
4751

4852
/* Precedence: lowest to highest */
4953
%left '+' '-'
@@ -61,18 +65,19 @@ elist: { $$ = NULL; }
6165

6266
expr: '(' expr ')' { $$ = $2; }
6367
| '+' expr %prec UMINUS { $$ = $2; }
64-
| '-' expr %prec UMINUS { $$ = make_op("-", make_integer_constant(0), $2); }
65-
| expr '+' expr { $$ = make_op("+", $1, $3); }
66-
| expr '-' expr { $$ = make_op("-", $1, $3); }
67-
| expr '*' expr { $$ = make_op("*", $1, $3); }
68-
| expr '/' expr { $$ = make_op("/", $1, $3); }
69-
| expr '%' expr { $$ = make_op("%", $1, $3); }
68+
| '-' expr %prec UMINUS { $$ = make_op(yyscanner, "-",
69+
make_integer_constant(0), $2); }
70+
| expr '+' expr { $$ = make_op(yyscanner, "+", $1, $3); }
71+
| expr '-' expr { $$ = make_op(yyscanner, "-", $1, $3); }
72+
| expr '*' expr { $$ = make_op(yyscanner, "*", $1, $3); }
73+
| expr '/' expr { $$ = make_op(yyscanner, "/", $1, $3); }
74+
| expr '%' expr { $$ = make_op(yyscanner, "%", $1, $3); }
7075
| INTEGER { $$ = make_integer_constant($1); }
7176
| VARIABLE { $$ = make_variable($1); }
72-
| function '(' elist ')'{ $$ = make_func($1, $3); }
77+
| function '(' elist ')' { $$ = make_func(yyscanner, $1, $3); }
7378
;
7479

75-
function: FUNCTION { $$ = find_func($1); pg_free($1); }
80+
function: FUNCTION { $$ = find_func(yyscanner, $1); pg_free($1); }
7681
;
7782

7883
%%
@@ -98,9 +103,10 @@ make_variable(char *varname)
98103
}
99104

100105
static PgBenchExpr *
101-
make_op(const char *operator, PgBenchExpr *lexpr, PgBenchExpr *rexpr)
106+
make_op(yyscan_t yyscanner, const char *operator,
107+
PgBenchExpr *lexpr, PgBenchExpr *rexpr)
102108
{
103-
return make_func(find_func(operator),
109+
return make_func(yyscanner, find_func(yyscanner, operator),
104110
make_elist(rexpr, make_elist(lexpr, NULL)));
105111
}
106112

@@ -139,7 +145,7 @@ static struct
139145
* or fail if the function is unknown.
140146
*/
141147
static int
142-
find_func(const char * fname)
148+
find_func(yyscan_t yyscanner, const char *fname)
143149
{
144150
int i = 0;
145151

@@ -150,7 +156,7 @@ find_func(const char * fname)
150156
i++;
151157
}
152158

153-
expr_yyerror_more("unexpected function name", fname);
159+
expr_yyerror_more(yyscanner, "unexpected function name", fname);
154160

155161
/* not reached */
156162
return -1;
@@ -198,21 +204,21 @@ elist_length(PgBenchExprList *list)
198204

199205
/* Build function call expression */
200206
static PgBenchExpr *
201-
make_func(const int fnumber, PgBenchExprList *args)
207+
make_func(yyscan_t yyscanner, int fnumber, PgBenchExprList *args)
202208
{
203209
PgBenchExpr *expr = pg_malloc(sizeof(PgBenchExpr));
204210

205211
Assert(fnumber >= 0);
206212

207213
if (PGBENCH_FUNCTIONS[fnumber].nargs >= 0 &&
208214
PGBENCH_FUNCTIONS[fnumber].nargs != elist_length(args))
209-
expr_yyerror_more("unexpected number of arguments",
215+
expr_yyerror_more(yyscanner, "unexpected number of arguments",
210216
PGBENCH_FUNCTIONS[fnumber].fname);
211217

212218
/* check at least one arg for min & max */
213219
if (PGBENCH_FUNCTIONS[fnumber].nargs == -1 &&
214220
elist_length(args) == 0)
215-
expr_yyerror_more("at least one argument expected",
221+
expr_yyerror_more(yyscanner, "at least one argument expected",
216222
PGBENCH_FUNCTIONS[fnumber].fname);
217223

218224
expr->etype = ENODE_FUNCTION;
@@ -226,4 +232,15 @@ make_func(const int fnumber, PgBenchExprList *args)
226232
return expr;
227233
}
228234

235+
/*
236+
* exprscan.l is compiled as part of exprparse.y. Currently, this is
237+
* unavoidable because exprparse does not create a .h file to export
238+
* its token symbols. If these files ever grow large enough to be
239+
* worth compiling separately, that could be fixed; but for now it
240+
* seems like useless complication.
241+
*/
242+
243+
/* First, get rid of "#define yyscan_t" from pgbench.h */
244+
#undef yyscan_t
245+
229246
#include "exprscan.c"

‎src/bin/pgbench/exprscan.l

Lines changed: 52 additions & 31 deletions
Original file line numberDiff line numberDiff line change
@@ -7,6 +7,8 @@
77
* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10+
* src/bin/pgbench/exprscan.l
11+
*
1012
*-------------------------------------------------------------------------
1113
*/
1214

@@ -16,16 +18,27 @@ static int yyline = 0, yycol = 0;
1618
/* Handles to the buffer that the lexer uses internally */
1719
static YY_BUFFER_STATE scanbufhandle;
1820
static char *scanbuf;
19-
static int scanbuflen;
2021

2122
/* context information for error reporting */
22-
static char *expr_source = NULL;
23+
static const char *expr_source = NULL;
2324
static int expr_lineno = 0;
24-
static char *expr_full_line = NULL;
25-
static char *expr_command = NULL;
25+
static const char *expr_full_line = NULL;
26+
static const char *expr_command = NULL;
2627
static int expr_col = 0;
28+
29+
/*
30+
* Work around a bug in flex 2.5.35: it emits a couple of functions that
31+
* it forgets to emit declarations for. Since we use -Wmissing-prototypes,
32+
* this would cause warnings. Providing our own declarations should be
33+
* harmless even when the bug gets fixed.
34+
*/
35+
extern int expr_yyget_column(yyscan_t yyscanner);
36+
extern void expr_yyset_column(int column_no, yyscan_t yyscanner);
37+
2738
%}
2839

40+
/* Except for the prefix, these options should match psqlscan.l */
41+
%option reentrant
2942
%option 8bit
3043
%option never-interactive
3144
%option nodefault
@@ -42,6 +55,15 @@ space [ \t\r\f]
4255

4356
%%
4457

58+
%{
59+
/*
60+
* Force flex into the appropriate start state ... which, for this
61+
* case, is always INITIAL. This ensures that we can transition
62+
* between different lexers sharing the same yyscan_t.
63+
*/
64+
BEGIN(INITIAL);
65+
%}
66+
4567
"+" { yycol += yyleng; return '+'; }
4668
"-" { yycol += yyleng; return '-'; }
4769
"*" { yycol += yyleng; return '*'; }
@@ -69,77 +91,76 @@ space [ \t\r\f]
6991

7092
[\n] { yycol = 0; yyline++; }
7193

72-
{space}+ { yycol += yyleng; /* ignore */ }
94+
{space}+ { yycol += yyleng; /* otherwise ignore */ }
7395

7496
. {
7597
yycol += yyleng;
7698
syntax_error(expr_source, expr_lineno, expr_full_line, expr_command,
7799
"unexpected character", yytext, expr_col + yycol);
78-
/* dead code, exit is called from syntax_error */
79-
return CHAR_ERROR;
100+
/* NOTREACHED, exit is called from syntax_error */
101+
return 0;
80102
}
81103
%%
82104

83105
void
84-
expr_yyerror_more(const char *message, const char *more)
106+
expr_yyerror_more(yyscan_t yyscanner, const char *message, const char *more)
85107
{
86108
syntax_error(expr_source, expr_lineno, expr_full_line, expr_command,
87109
message, more, expr_col + yycol);
88110
}
89111

90112
void
91-
yyerror(const char *message)
113+
yyerror(yyscan_t yyscanner, const char *message)
92114
{
93-
expr_yyerror_more(message, NULL);
115+
expr_yyerror_more(yyscanner, message, NULL);
94116
}
95117

96118
/*
97119
* Called before any actual parsing is done
98120
*/
99-
void
121+
yyscan_t
100122
expr_scanner_init(const char *str, const char *source,
101-
const int lineno, const char *line,
102-
const char *cmd, const int ecol)
123+
int lineno, const char *line,
124+
const char *cmd, int ecol)
103125
{
126+
yyscan_t yyscanner;
104127
Size slen = strlen(str);
105128

106-
/* save context informations for error messages */
107-
expr_source = (char *) source;
108-
expr_lineno = (int) lineno;
109-
expr_full_line = (char *) line;
110-
expr_command = (char *) cmd;
111-
expr_col = (int) ecol;
129+
/* Set up yyscan_t */
130+
yylex_init(&yyscanner);
131+
132+
/* save context information for error messages */
133+
expr_source = source;
134+
expr_lineno = lineno;
135+
expr_full_line = line;
136+
expr_command = cmd;
137+
expr_col = ecol;
112138

113139
/* reset error pointers for this scan */
114140
yycol = yyline = 0;
115141

116-
/*
117-
* Might be left over after error
118-
*/
119-
if (YY_CURRENT_BUFFER)
120-
yy_delete_buffer(YY_CURRENT_BUFFER);
121-
122142
/*
123143
* Make a scan buffer with special termination needed by flex.
124144
*/
125-
scanbuflen = slen;
126145
scanbuf = pg_malloc(slen + 2);
127146
memcpy(scanbuf, str, slen);
128147
scanbuf[slen] = scanbuf[slen + 1] = YY_END_OF_BUFFER_CHAR;
129-
scanbufhandle = yy_scan_buffer(scanbuf, slen + 2);
148+
scanbufhandle = yy_scan_buffer(scanbuf, slen + 2, yyscanner);
130149

131-
BEGIN(INITIAL);
150+
return yyscanner;
132151
}
133152

134153

135154
/*
136-
* Called after parsing is done to clean up after seg_scanner_init()
155+
* Called after parsing is done to clean up after expr_scanner_init()
137156
*/
138157
void
139-
expr_scanner_finish(void)
158+
expr_scanner_finish(yyscan_t yyscanner)
140159
{
141-
yy_delete_buffer(scanbufhandle);
160+
yy_delete_buffer(scanbufhandle, yyscanner);
142161
pg_free(scanbuf);
162+
yylex_destroy(yyscanner);
163+
143164
expr_source = NULL;
144165
expr_lineno = 0;
145166
expr_full_line = NULL;

‎src/bin/pgbench/pgbench.c

Lines changed: 10 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -2495,25 +2495,30 @@ process_commands(char *buf, const char *source, const int lineno)
24952495
}
24962496
else if (pg_strcasecmp(my_commands->argv[0], "set") == 0)
24972497
{
2498+
yyscan_t yyscanner;
2499+
24982500
if (my_commands->argc < 3)
24992501
{
25002502
syntax_error(source, lineno, my_commands->line, my_commands->argv[0],
25012503
"missing argument", NULL, -1);
25022504
}
25032505

2504-
expr_scanner_init(my_commands->argv[2], source, lineno,
2505-
my_commands->line, my_commands->argv[0],
2506-
my_commands->cols[2] - 1);
2506+
yyscanner = expr_scanner_init(my_commands->argv[2],
2507+
source,
2508+
lineno,
2509+
my_commands->line,
2510+
my_commands->argv[0],
2511+
my_commands->cols[2] - 1);
25072512

2508-
if (expr_yyparse() != 0)
2513+
if (expr_yyparse(yyscanner) != 0)
25092514
{
25102515
/* dead code: exit done from syntax_error called by yyerror */
25112516
exit(1);
25122517
}
25132518

25142519
my_commands->expr = expr_parse_result;
25152520

2516-
expr_scanner_finish();
2521+
expr_scanner_finish(yyscanner);
25172522
}
25182523
else if (pg_strcasecmp(my_commands->argv[0], "sleep") == 0)
25192524
{

‎src/bin/pgbench/pgbench.h

Lines changed: 18 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -11,6 +11,15 @@
1111
#ifndef PGBENCH_H
1212
#define PGBENCH_H
1313

14+
/*
15+
* This file is included outside exprscan.l, in places where we can't see
16+
* flex's definition of typedef yyscan_t. Fortunately, it's documented as
17+
* being "void *", so we can use a macro to keep the function declarations
18+
* here looking like the definitions in exprscan.l. exprparse.y also
19+
* uses this to be able to declare things as "yyscan_t".
20+
*/
21+
#define yyscan_t void *
22+
1423
/* Types of expression nodes */
1524
typedef enum PgBenchExprType
1625
{
@@ -73,17 +82,18 @@ struct PgBenchExprList
7382

7483
extern PgBenchExpr *expr_parse_result;
7584

76-
extern int expr_yyparse(void);
77-
extern int expr_yylex(void);
78-
extern void expr_yyerror(const char *str);
79-
extern void expr_yyerror_more(const char *str, const char *more);
80-
extern void expr_scanner_init(const char *str, const char *source,
81-
const int lineno, const char *line,
82-
const char *cmd, const int ecol);
85+
extern int expr_yyparse(yyscan_t yyscanner);
86+
extern int expr_yylex(yyscan_t yyscanner);
87+
extern void expr_yyerror(yyscan_t yyscanner, const char *str);
88+
extern void expr_yyerror_more(yyscan_t yyscanner, const char *str,
89+
const char *more);
90+
extern yyscan_t expr_scanner_init(const char *str, const char *source,
91+
int lineno, const char *line,
92+
const char *cmd, int ecol);
8393
extern void syntax_error(const char *source, const int lineno, const char *line,
8494
const char *cmd, const char *msg, const char *more,
8595
const int col);
86-
extern void expr_scanner_finish(void);
96+
extern void expr_scanner_finish(yyscan_t yyscanner);
8797

8898
extern int64 strtoint64(const char *str);
8999

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