Use kwset in pickaxe

Benchmarks in the hot cache case:

before:
$ perf stat --repeat=5 git log -Sqwerty

Performance counter stats for 'git log -Sqwerty' (5 runs):

       47,092,744 cache-misses             #      2.825 M/sec   ( +-   1.607% )
      123,368,389 cache-references         #      7.400 M/sec   ( +-   0.812% )
      330,040,998 branch-misses            #      3.134 %       ( +-   0.257% )
   10,530,896,750 branches                 #    631.663 M/sec   ( +-   0.121% )
   62,037,201,030 instructions             #      1.399 IPC     ( +-   0.142% )
   44,331,294,321 cycles                   #   2659.073 M/sec   ( +-   0.326% )
           96,794 page-faults              #      0.006 M/sec   ( +-  11.952% )
               25 CPU-migrations           #      0.000 M/sec   ( +-  25.266% )
            1,424 context-switches         #      0.000 M/sec   ( +-   0.540% )
     16671.708650 task-clock-msecs         #      0.997 CPUs    ( +-   0.343% )

      16.728692052  seconds time elapsed   ( +-   0.344% )

after:
$ perf stat --repeat=5 git log -Sqwerty

Performance counter stats for 'git log -Sqwerty' (5 runs):

       51,385,522 cache-misses             #      4.619 M/sec   ( +-   0.565% )
      129,177,880 cache-references         #     11.611 M/sec   ( +-   0.219% )
      319,222,775 branch-misses            #      6.946 %       ( +-   0.134% )
    4,595,913,233 branches                 #    413.086 M/sec   ( +-   0.112% )
   31,395,042,533 instructions             #      1.062 IPC     ( +-   0.129% )
   29,558,348,598 cycles                   #   2656.740 M/sec   ( +-   0.204% )
           93,224 page-faults              #      0.008 M/sec   ( +-   4.487% )
               19 CPU-migrations           #      0.000 M/sec   ( +-  10.425% )
              950 context-switches         #      0.000 M/sec   ( +-   0.360% )
     11125.796039 task-clock-msecs         #      0.997 CPUs    ( +-   0.239% )

      11.164216599  seconds time elapsed   ( +-   0.240% )

So the kwset code is about 33% faster.

Signed-off-by: Fredrik Kuivinen <frekui@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -533,6 +533,7 @@ LIB_H += graph.h
 LIB_H += grep.h
 LIB_H += hash.h
 LIB_H += help.h
+LIB_H += kwset.h
 LIB_H += levenshtein.h
 LIB_H += list-objects.h
 LIB_H += ll-merge.h
@@ -624,6 +625,7 @@ LIB_OBJS += hash.o
 LIB_OBJS += help.o
 LIB_OBJS += hex.o
 LIB_OBJS += ident.o
+LIB_OBJS += kwset.o
 LIB_OBJS += levenshtein.o
 LIB_OBJS += list-objects.o
 LIB_OBJS += ll-merge.o

diffcore-pickaxe.c

@@ -6,6 +6,7 @@
 #include "diff.h"
 #include "diffcore.h"
 #include "xdiff-interface.h"
+#include "kwset.h"
 
 struct diffgrep_cb {
 	regex_t *regexp;
@@ -146,7 +147,7 @@ static void diffcore_pickaxe_grep(struct diff_options *o)
 
 static unsigned int contains(struct diff_filespec *one,
 			     const char *needle, unsigned long len,
-			     regex_t *regexp)
+			     regex_t *regexp, kwset_t kws)
 {
 	unsigned int cnt;
 	unsigned long sz;
@@ -175,9 +176,12 @@ static unsigned int contains(struct diff_filespec *one,
 
 	} else { /* Classic exact string match */
 		while (sz) {
-			const char *found = memmem(data, sz, needle, len);
-			if (!found)
+			size_t offset = kwsexec(kws, data, sz, NULL);
+			const char *found;
+			if (offset == -1)
 				break;
+			else
+				found = data + offset;
 			sz -= found - data + len;
 			data = found + len;
 			cnt++;
@@ -195,6 +199,7 @@ static void diffcore_pickaxe_count(struct diff_options *o)
 	unsigned long len = strlen(needle);
 	int i, has_changes;
 	regex_t regex, *regexp = NULL;
+	kwset_t kws = NULL;
 	struct diff_queue_struct outq;
 	DIFF_QUEUE_CLEAR(&outq);
 
@@ -209,6 +214,10 @@ static void diffcore_pickaxe_count(struct diff_options *o)
 			die("invalid pickaxe regex: %s", errbuf);
 		}
 		regexp = &regex;
+	} else {
+		kws = kwsalloc(NULL);
+		kwsincr(kws, needle, len);
+		kwsprep(kws);
 	}
 
 	if (opts & DIFF_PICKAXE_ALL) {
@@ -219,16 +228,16 @@ static void diffcore_pickaxe_count(struct diff_options *o)
 				if (!DIFF_FILE_VALID(p->two))
 					continue; /* ignore unmerged */
 				/* created */
-				if (contains(p->two, needle, len, regexp))
+				if (contains(p->two, needle, len, regexp, kws))
 					has_changes++;
 			}
 			else if (!DIFF_FILE_VALID(p->two)) {
-				if (contains(p->one, needle, len, regexp))
+				if (contains(p->one, needle, len, regexp, kws))
 					has_changes++;
 			}
 			else if (!diff_unmodified_pair(p) &&
-				 contains(p->one, needle, len, regexp) !=
-				 contains(p->two, needle, len, regexp))
+				 contains(p->one, needle, len, regexp, kws) !=
+				 contains(p->two, needle, len, regexp, kws))
 				has_changes++;
 		}
 		if (has_changes)
@@ -251,16 +260,17 @@ static void diffcore_pickaxe_count(struct diff_options *o)
 				if (!DIFF_FILE_VALID(p->two))
 					; /* ignore unmerged */
 				/* created */
-				else if (contains(p->two, needle, len, regexp))
+				else if (contains(p->two, needle, len, regexp,
+						  kws))
 					has_changes = 1;
 			}
 			else if (!DIFF_FILE_VALID(p->two)) {
-				if (contains(p->one, needle, len, regexp))
+				if (contains(p->one, needle, len, regexp, kws))
 					has_changes = 1;
 			}
 			else if (!diff_unmodified_pair(p) &&
-				 contains(p->one, needle, len, regexp) !=
-				 contains(p->two, needle, len, regexp))
+				 contains(p->one, needle, len, regexp, kws) !=
+				 contains(p->two, needle, len, regexp, kws))
 				has_changes = 1;
 
 			if (has_changes)
@@ -271,6 +281,8 @@ static void diffcore_pickaxe_count(struct diff_options *o)
 
 	if (opts & DIFF_PICKAXE_REGEX)
 		regfree(&regex);
+	else
+		kwsfree(kws);
 
 	free(q->queue);
 	*q = outq;