perf: make max and min dollar variables thread-local

check/user.frm

@@ -736,6 +736,52 @@ Print check;
 .end
 assert result("check") =~ expr("0")
 *--#] jodavies_prf_1 :
+*--#[ jodavies_dollar_locks :
+#-
+
+#: TermsInSmall 2M
+
+* A larger version of this test can be used to easily demonstrate the
+* performance improvement due to max/min dollar locking changes in TFORM,
+* see PR 807.
+
+Symbol x,i;
+CFunction sum;
+
+#define N "{32*8}"
+*#define BLOCK "200000"
+#define BLOCK "20"
+
+Local test =
+	#do i = 0,{`N'-1}
+		+ sum(i,`i'*`BLOCK',{`i'+1}*`BLOCK'-1,x^i)
+	#enddo
+	;
+.sort
+Identify sum(?a) = sum_(?a);
+.sort
+
+#$min = `N'*`BLOCK';
+#$max = -1;
+
+If (Count(x,1) > $max) $max = count_(x,1);
+If (Count(x,1) < $min) $min = count_(x,1);
+
+ModuleOption maximum $max;
+ModuleOption minimum $min;
+.sort
+
+#message max: `$max'
+#message min: `$min'
+.end
+assert succeeded?
+assert stdout =~ exact_pattern(<<'EOF')
+~~~max: 5119
+EOF
+assert stdout =~ exact_pattern(<<'EOF')
+~~~min: 0
+EOF
+*--#] jodavies_dollar_locks :
 *--#[ tueda_prf_1 :
 #-
 Off Statistics;

doc/manual/statements.tex

@@ -3164,30 +3164,36 @@ \section{moduleoption}
 \leftvitem{3.5cm}{local\index{moduleoption!local}}
 \rightvitem{13cm}{Should be followed by a list of \$-variables. Indicates 
 that the contents of the indicated \$-variables\index{\$-variable} are not 
-relevant once the module has been finished and neither is the term by term 
-order in which the \$-variables obtain their value. In practise each 
+relevant once the module has been finished, and neither is the term by term 
+order in which the \$-variables obtain their value. In practice each 
 processor\index{processor}/thread\index{thread} will work with its own copy 
 of this variable.}
 
 \leftvitem{3.5cm}{maximum\index{moduleoption!maximum}}
-\rightvitem{13cm}{Should be followed by a list of 
-\$-variables\index{\$-variable}. Indicates that of the contents of the 
-indicated \$-variables the maximum is the only thing that is relevant once 
-the module has been finished. The term by term order in which the 
-\$-variables obtain their value is not relevant.}
+\rightvitem{13cm}{Should be followed by a list of \$-variables\index{\$-variable}.
+Indicates that only the maximum value of the \$-variables is relevant once the
+module has finished. The term-by-term order in which the \$-variables obtain
+their value is not relevant. In practice each processor\index{processor}/thread
+\index{thread} will work with its own copy of the variable, and the
+maximal value is kept at the end of term processing. The variables should
+contain numbers only.}
 
 \leftvitem{3.5cm}{minimum\index{moduleoption!minimum}}
-\rightvitem{13cm}{Should be followed by a list of 
-\$-variables\index{\$-variable}. Indicates that of the contents of the 
-indicated \$-variables the minimum is the only thing that is relevant once 
-the module has been finished. The term by term order in which the 
-\$-variables obtain their value is not relevant.}
+\rightvitem{13cm}{Should be followed by a list of \$-variables\index{\$-variable}.
+Indicates that only the minimum value of the \$-variables is relevant once the
+module has finished. The term-by-term order in which the \$-variables obtain
+their value is not relevant. In practice each processor\index{processor}/thread
+\index{thread} will work with its own copy of the variable, and the
+minimal value is kept at the end of term processing. The variables should contain
+numbers only.}
 
 \leftvitem{3.5cm}{sum\index{moduleoption!sum}}
-\rightvitem{13cm}{Should be followed by a list of 
-\$-variables\index{\$-variable}. Indicates that the indicated \$-variables 
-are representing a sum. The term by term order in which the \$-variables 
-obtain their value is not relevant.}
+\rightvitem{13cm}{Should be followed by a list of \$-variables\index{\$-variable}.
+Indicates that the specified \$-variables represent a sum. The term-by-term
+order in which the \$-variables obtain their value is not relevant.
+In practice, this is a global dollar variable for which all parallel read and
+write accesses are protected by locks. The variables should contain numbers
+only.}
 
 \noindent The options `local', `maximum', `minimum' and `sum' are for 
 parallel versions of \FORM\@. The presence of \$-variables can be a problem 

sources/declare.h

@@ -1283,6 +1283,7 @@ extern WORD   *MakeDollarInteger(PHEAD WORD *,WORD **);
 extern WORD   *MakeDollarMod(PHEAD WORD *,WORD **);
 extern int    GetDolNum(PHEAD WORD *, WORD *);
 extern void   AddPotModdollar(WORD);
+extern int    DollarLocalCopy(WORD);
 
 extern int    Optimize(WORD, int);
 extern int    ClearOptimize(void);