Increase length of benchmark strings

This is needed to avoid the compiler eliding the call in
highly-optimised builds.

CMakeLists.txt

@@ -19,3 +19,4 @@ endfunction()
 add_subdirectory(lib)
 add_subdirectory(tests)
 add_subdirectory(demo)
+add_subdirectory(benchmarks)

README

@@ -7,8 +7,8 @@ so here we are.
 
                                Grammar
 
-This engine is not going to be strictly supporting any standard
+The engine does not support any specific standard's syntax, unless by
-syntax; the expression syntax I intend to support follows.
+coincidence.  The grammar I've implemented for expressions is:
 
 	regex ::= sequence ( '|' sequence )*
 	sequence ::= term+
@@ -23,7 +23,7 @@ syntax; the expression syntax I intend to support follows.
 
 The build uses CMake.  There are two scripts, build.sh and test.sh,
 which will (much to everybody's shock) build the project and run the
-tests.  I use Clang but the code is ISO C11, it should compile just
+tests.  I use Clang but the code is ISO C11 so it should compile just
 fine with GCC.  You might need to faff with CMakeLists.txt to get it
 to work with another compiler due to command-line flag nonsense.
 

benchmarks/CMakeLists.txt

@@ -0,0 +1,20 @@
+add_library(benchmarking benchmarking.c)
+set_default_target_options(benchmarking)
+target_include_directories(benchmarking PUBLIC include)
+
+function(add_benchmark_suite source)
+  string(REGEX REPLACE ".c$" "" name ${source})
+  add_executable(${name} ${source})
+  set_default_target_options(${name})
+  target_link_libraries(${name} PRIVATE lib benchmarking m)
+endfunction()
+
+function(add_benchmark_suites)
+  foreach(source ${ARGN})
+	add_benchmark_suite(${source})
+  endforeach()
+endfunction()
+
+add_benchmark_suites(
+  matching_benchmarks.c
+)

benchmarks/benchmarking.c

@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) Camden Dixie O'Brien
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+#include "benchmarking.h"
+
+#include <assert.h>
+#include <math.h>
+#include <stdio.h>
+
+#define SWAP(x, y) \
+	do { \
+		const double tmp = x; \
+		x = y; \
+		y = tmp; \
+	} while (0)
+
+clock_t benchmark_start, benchmark_end;
+
+static void sort(double *xs, int n)
+{
+	if (n <= 0)
+		return;
+
+	const double pivot = xs[(n - 1) / 2];
+	int lt = 0;
+	int eq = 0;
+	int gt = n - 1;
+	while (eq <= gt) {
+		if (xs[eq] < pivot) {
+			SWAP(xs[eq], xs[lt]);
+			++lt;
+			++eq;
+		} else if (xs[eq] > pivot) {
+			SWAP(xs[eq], xs[gt]);
+			--gt;
+		} else {
+			++eq;
+		}
+	}
+
+	sort(xs, lt);
+	sort(xs + gt + 1, n - (gt + 1));
+}
+
+void benchmark_summarise(double *res, int reps, benchmark_summary_t *out)
+{
+	assert(reps > 0);
+
+	sort(res, reps);
+	const double median = res[reps / 2];
+
+	double sum = 0;
+	for (int i = 0; i < reps; ++i)
+		sum += res[i];
+	const double mean = sum / reps;
+
+	double diff_sum = 0;
+	for (int i = 0; i < reps; ++i)
+		diff_sum += pow(res[i] - mean, 2);
+	const double variance = diff_sum / (reps - 1);
+
+	out->reps = reps;
+	out->total = sum;
+	out->median = median;
+	out->mean = mean;
+	out->min = res[0];
+	out->max = res[reps - 1];
+	out->stddev = sqrt(variance);
+}
+
+void benchmark_print_header(void)
+{
+	printf(
+	    "%-12s %13s %13s %13s %13s %12s\n", "benchmark", "median (µs)",
+	    "mean (µs)", "min (µs)", "max (µs)", "stddev");
+}
+
+void benchmark_print(const char *name, const benchmark_summary_t *s)
+{
+	printf(
+	    "%-12s %12.2f %12.2f %12.2f %12.2f %12.2f\n", name, s->median,
+	    s->mean, s->min, s->max, s->stddev);
+}

benchmarks/include/benchmarking.h

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) Camden Dixie O'Brien
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+#ifndef BENCHMARKING_H
+#define BENCHMARKING_H
+
+#include <time.h>
+
+typedef struct {
+	int reps;
+	double total, median, mean, min, max, stddev;
+} benchmark_summary_t;
+
+#define CLOCK_MICROS(c) (1000000 * (double)c / CLOCKS_PER_SEC)
+
+#define BENCHMARKING_BEGIN() benchmark_print_header()
+#define BENCHMARKING_END() 0
+
+#define START_CLOCK() \
+	do { \
+		benchmark_start = clock(); \
+	} while (0)
+
+#define STOP_CLOCK() \
+	do { \
+		benchmark_end = clock(); \
+	} while (0)
+
+#define RUN_BENCHMARK(reps, name, fn, ...) \
+	do { \
+		double res[reps]; \
+		for (int i = 0; i < reps; ++i) { \
+			fn(__VA_ARGS__); \
+			res[i] = CLOCK_MICROS(benchmark_end) \
+			    - CLOCK_MICROS(benchmark_start); \
+		} \
+		benchmark_summary_t summary; \
+		benchmark_summarise(res, reps, &summary); \
+		benchmark_print(name, &summary); \
+	} while (0)
+
+extern clock_t benchmark_start, benchmark_end;
+
+void benchmark_summarise(double *res, int reps, benchmark_summary_t *out);
+void benchmark_print_header(void);
+void benchmark_print(const char *name, const benchmark_summary_t *summary);
+
+#endif

benchmarks/matching_benchmarks.c

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) Camden Dixie O'Brien
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+#include "benchmarking.h"
+#include "compile.h"
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/time.h>
+
+#define LEN 1000
+#define RANGE_FIRST 'a'
+#define RANGE_LAST 'z'
+
+#define CLAMP_CHAR(x) (RANGE_FIRST + x % (RANGE_LAST - RANGE_FIRST + 1))
+
+#define RUN_MATCHING_BENCHMARK(reps, name, regex) \
+	do { \
+		fsa_t fsa; \
+		compile(regex, strlen(regex), &fsa); \
+		RUN_BENCHMARK(reps, name, matching_benchmark, &fsa); \
+		fsa_free(&fsa); \
+	} while (0)
+
+static void matching_benchmark(const fsa_t *fsa)
+{
+	char s[LEN];
+	for (int j = 0; j < LEN; ++j)
+		s[j] = CLAMP_CHAR(rand());
+
+	volatile bool match;
+	START_CLOCK();
+	match = fsa_accepts(fsa, s, LEN);
+	STOP_CLOCK();
+	(void)match;
+}
+
+int main(void)
+{
+	struct timeval tv;
+	gettimeofday(&tv, NULL);
+	srand(tv.tv_usec);
+
+	BENCHMARKING_BEGIN();
+
+	RUN_MATCHING_BENCHMARK(10000, "foo or bar", ".*(foo|bar).*");
+	RUN_MATCHING_BENCHMARK(10000, "regex #1", ".*(abc!?)*|dd+.*");
+	RUN_MATCHING_BENCHMARK(10000, "regex #2", ".*(l|wh)?[aeiou]+.*");
+
+	return BENCHMARKING_END();
+}

scripts/entr.sh

@@ -1,4 +1,4 @@
 #!/bin/sh
 cd "$(git rev-parse --show-toplevel)"
 find . -not \( -path './.git' -prune \) -not \( -path './build' -prune \) \
-	| entr -s 'clear && scripts/build.sh && scripts/test.sh'
+	| entr -cs 'scripts/build.sh && scripts/test.sh'