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authorLibravatar Junio C Hamano <gitster@pobox.com>2017-01-31 13:15:00 -0800
committerLibravatar Junio C Hamano <gitster@pobox.com>2017-01-31 13:15:00 -0800
commit6ad8b8e98faa5a301a98a2997da162dea060672e (patch)
tree99ca685d15df287c1f686c033157756d439c119c
parentMerge branch 'ls/travis-p4-on-macos' (diff)
parentref-filter: use QSORT_S in ref_array_sort() (diff)
downloadtgif-6ad8b8e98faa5a301a98a2997da162dea060672e.tar.xz
Merge branch 'rs/qsort-s'
A few codepaths had to rely on a global variable when sorting elements of an array because sort(3) API does not allow extra data to be passed to the comparison function. Use qsort_s() when natively available, and a fallback implementation of it when not, to eliminate the need, which is a prerequisite for making the codepath reentrant. * rs/qsort-s: ref-filter: use QSORT_S in ref_array_sort() string-list: use QSORT_S in string_list_sort() perf: add basic sort performance test add QSORT_S compat: add qsort_s()
-rw-r--r--Makefile8
-rw-r--r--compat/qsort_s.c69
-rw-r--r--git-compat-util.h11
-rw-r--r--ref-filter.c6
-rw-r--r--string-list.c13
-rw-r--r--t/helper/test-string-list.c25
-rwxr-xr-xt/perf/p0071-sort.sh26
7 files changed, 146 insertions, 12 deletions
diff --git a/Makefile b/Makefile
index 27afd0f378..53ecc84e28 100644
--- a/Makefile
+++ b/Makefile
@@ -279,6 +279,9 @@ all::
# is a simplified version of the merge sort used in glibc. This is
# recommended if Git triggers O(n^2) behavior in your platform's qsort().
#
+# Define HAVE_ISO_QSORT_S if your platform provides a qsort_s() that's
+# compatible with the one described in C11 Annex K.
+#
# Define UNRELIABLE_FSTAT if your system's fstat does not return the same
# information on a not yet closed file that lstat would return for the same
# file after it was closed.
@@ -1418,6 +1421,11 @@ ifdef INTERNAL_QSORT
COMPAT_CFLAGS += -DINTERNAL_QSORT
COMPAT_OBJS += compat/qsort.o
endif
+ifdef HAVE_ISO_QSORT_S
+ COMPAT_CFLAGS += -DHAVE_ISO_QSORT_S
+else
+ COMPAT_OBJS += compat/qsort_s.o
+endif
ifdef RUNTIME_PREFIX
COMPAT_CFLAGS += -DRUNTIME_PREFIX
endif
diff --git a/compat/qsort_s.c b/compat/qsort_s.c
new file mode 100644
index 0000000000..52d1f0a73d
--- /dev/null
+++ b/compat/qsort_s.c
@@ -0,0 +1,69 @@
+#include "../git-compat-util.h"
+
+/*
+ * A merge sort implementation, simplified from the qsort implementation
+ * by Mike Haertel, which is a part of the GNU C Library.
+ * Added context pointer, safety checks and return value.
+ */
+
+static void msort_with_tmp(void *b, size_t n, size_t s,
+ int (*cmp)(const void *, const void *, void *),
+ char *t, void *ctx)
+{
+ char *tmp;
+ char *b1, *b2;
+ size_t n1, n2;
+
+ if (n <= 1)
+ return;
+
+ n1 = n / 2;
+ n2 = n - n1;
+ b1 = b;
+ b2 = (char *)b + (n1 * s);
+
+ msort_with_tmp(b1, n1, s, cmp, t, ctx);
+ msort_with_tmp(b2, n2, s, cmp, t, ctx);
+
+ tmp = t;
+
+ while (n1 > 0 && n2 > 0) {
+ if (cmp(b1, b2, ctx) <= 0) {
+ memcpy(tmp, b1, s);
+ tmp += s;
+ b1 += s;
+ --n1;
+ } else {
+ memcpy(tmp, b2, s);
+ tmp += s;
+ b2 += s;
+ --n2;
+ }
+ }
+ if (n1 > 0)
+ memcpy(tmp, b1, n1 * s);
+ memcpy(b, t, (n - n2) * s);
+}
+
+int git_qsort_s(void *b, size_t n, size_t s,
+ int (*cmp)(const void *, const void *, void *), void *ctx)
+{
+ const size_t size = st_mult(n, s);
+ char buf[1024];
+
+ if (!n)
+ return 0;
+ if (!b || !cmp)
+ return -1;
+
+ if (size < sizeof(buf)) {
+ /* The temporary array fits on the small on-stack buffer. */
+ msort_with_tmp(b, n, s, cmp, buf, ctx);
+ } else {
+ /* It's somewhat large, so malloc it. */
+ char *tmp = xmalloc(size);
+ msort_with_tmp(b, n, s, cmp, tmp, ctx);
+ free(tmp);
+ }
+ return 0;
+}
diff --git a/git-compat-util.h b/git-compat-util.h
index 87237b092b..f46d40e4a4 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -988,6 +988,17 @@ static inline void sane_qsort(void *base, size_t nmemb, size_t size,
qsort(base, nmemb, size, compar);
}
+#ifndef HAVE_ISO_QSORT_S
+int git_qsort_s(void *base, size_t nmemb, size_t size,
+ int (*compar)(const void *, const void *, void *), void *ctx);
+#define qsort_s git_qsort_s
+#endif
+
+#define QSORT_S(base, n, compar, ctx) do { \
+ if (qsort_s((base), (n), sizeof(*(base)), compar, ctx)) \
+ die("BUG: qsort_s() failed"); \
+} while (0)
+
#ifndef REG_STARTEND
#error "Git requires REG_STARTEND support. Compile with NO_REGEX=NeedsStartEnd"
#endif
diff --git a/ref-filter.c b/ref-filter.c
index 5f4b08792b..3820b21cc7 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -1594,8 +1594,7 @@ static int cmp_ref_sorting(struct ref_sorting *s, struct ref_array_item *a, stru
return (s->reverse) ? -cmp : cmp;
}
-static struct ref_sorting *ref_sorting;
-static int compare_refs(const void *a_, const void *b_)
+static int compare_refs(const void *a_, const void *b_, void *ref_sorting)
{
struct ref_array_item *a = *((struct ref_array_item **)a_);
struct ref_array_item *b = *((struct ref_array_item **)b_);
@@ -1611,8 +1610,7 @@ static int compare_refs(const void *a_, const void *b_)
void ref_array_sort(struct ref_sorting *sorting, struct ref_array *array)
{
- ref_sorting = sorting;
- QSORT(array->items, array->nr, compare_refs);
+ QSORT_S(array->items, array->nr, compare_refs, sorting);
}
static void append_literal(const char *cp, const char *ep, struct ref_formatting_state *state)
diff --git a/string-list.c b/string-list.c
index 8c83cac189..45016ad86d 100644
--- a/string-list.c
+++ b/string-list.c
@@ -211,21 +211,18 @@ struct string_list_item *string_list_append(struct string_list *list,
list->strdup_strings ? xstrdup(string) : (char *)string);
}
-/* Yuck */
-static compare_strings_fn compare_for_qsort;
-
-/* Only call this from inside string_list_sort! */
-static int cmp_items(const void *a, const void *b)
+static int cmp_items(const void *a, const void *b, void *ctx)
{
+ compare_strings_fn cmp = ctx;
const struct string_list_item *one = a;
const struct string_list_item *two = b;
- return compare_for_qsort(one->string, two->string);
+ return cmp(one->string, two->string);
}
void string_list_sort(struct string_list *list)
{
- compare_for_qsort = list->cmp ? list->cmp : strcmp;
- QSORT(list->items, list->nr, cmp_items);
+ QSORT_S(list->items, list->nr, cmp_items,
+ list->cmp ? list->cmp : strcmp);
}
struct string_list_item *unsorted_string_list_lookup(struct string_list *list,
diff --git a/t/helper/test-string-list.c b/t/helper/test-string-list.c
index 4a68967bd1..c502fa16d3 100644
--- a/t/helper/test-string-list.c
+++ b/t/helper/test-string-list.c
@@ -97,6 +97,31 @@ int cmd_main(int argc, const char **argv)
return 0;
}
+ if (argc == 2 && !strcmp(argv[1], "sort")) {
+ struct string_list list = STRING_LIST_INIT_NODUP;
+ struct strbuf sb = STRBUF_INIT;
+ struct string_list_item *item;
+
+ strbuf_read(&sb, 0, 0);
+
+ /*
+ * Split by newline, but don't create a string_list item
+ * for the empty string after the last separator.
+ */
+ if (sb.buf[sb.len - 1] == '\n')
+ strbuf_setlen(&sb, sb.len - 1);
+ string_list_split_in_place(&list, sb.buf, '\n', -1);
+
+ string_list_sort(&list);
+
+ for_each_string_list_item(item, &list)
+ puts(item->string);
+
+ string_list_clear(&list, 0);
+ strbuf_release(&sb);
+ return 0;
+ }
+
fprintf(stderr, "%s: unknown function name: %s\n", argv[0],
argv[1] ? argv[1] : "(there was none)");
return 1;
diff --git a/t/perf/p0071-sort.sh b/t/perf/p0071-sort.sh
new file mode 100755
index 0000000000..7c9a35a646
--- /dev/null
+++ b/t/perf/p0071-sort.sh
@@ -0,0 +1,26 @@
+#!/bin/sh
+
+test_description='Basic sort performance tests'
+. ./perf-lib.sh
+
+test_perf_default_repo
+
+test_expect_success 'setup' '
+ git ls-files --stage "*.[ch]" "*.sh" |
+ cut -f2 -d" " |
+ git cat-file --batch >unsorted
+'
+
+test_perf 'sort(1)' '
+ sort <unsorted >expect
+'
+
+test_perf 'string_list_sort()' '
+ test-string-list sort <unsorted >actual
+'
+
+test_expect_success 'string_list_sort() sorts like sort(1)' '
+ test_cmp_bin expect actual
+'
+
+test_done