Move git_sort(), a stable sort, into into libgit.a
The `qsort()` function is not guaranteed to be stable, i.e. it does not promise to maintain the order of items it is told to consider equal. In contrast, the `git_sort()` function we carry in `compat/qsort.c` _is_ stable, by virtue of implementing a merge sort algorithm. In preparation for using a stable sort in Git's rename detection, move the stable sort into `libgit.a` so that it is compiled in unconditionally, and rename it to `git_stable_qsort()`. Note: this also makes the hack obsolete that was introduced in fe21c6b285d (mingw: reencode environment variables on the fly (UTF-16 <-> UTF-8), 2018-10-30), where we included `compat/qsort.c` directly in `compat/mingw.c` to use the stable sort. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Johannes Schindelin committed
Sep 30, 2019 at 10:21 UTC
97fff6101220b66bc293239ab2cf29fc3624072b
4 files changed
+13
-15
Makefile
+1
-1
@@ -983,6 +983,7 @@ LIB_OBJS += shallow.o
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LIB_OBJS += sideband.o
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LIB_OBJS += sigchain.o
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LIB_OBJS += split-index.o
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+LIB_OBJS += stable-qsort.o
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LIB_OBJS += strbuf.o
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LIB_OBJS += streaming.o
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LIB_OBJS += string-list.o
@@ -1714,7 +1715,6 @@ ifdef NO_GETPAGESIZE
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endif
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ifdef INTERNAL_QSORT
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COMPAT_CFLAGS += -DINTERNAL_QSORT
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- COMPAT_OBJS += compat/qsort.o
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endif
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ifdef HAVE_ISO_QSORT_S
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COMPAT_CFLAGS += -DHAVE_ISO_QSORT_S
compat/mingw.c
+3
-8
@@ -1229,11 +1229,6 @@ static int wenvcmp(const void *a, const void *b)
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return _wcsnicmp(p, q, p_len);
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}
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-/* We need a stable sort to convert the environment between UTF-16 <-> UTF-8 */
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-#ifndef INTERNAL_QSORT
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-#include "qsort.c"
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-#endif
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-
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/*
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* Build an environment block combining the inherited environment
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* merged with the given list of settings.
@@ -1272,8 +1267,8 @@ static wchar_t *make_environment_block(char **deltaenv)
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/*
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* If there is a deltaenv, let's accumulate all keys into `array`,
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- * sort them using the stable git_qsort() and then copy, skipping
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- * duplicate keys
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+ * sort them using the stable git_stable_qsort() and then copy,
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+ * skipping duplicate keys
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*/
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for (p = wenv; p && *p; ) {
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ALLOC_GROW(array, nr + 1, alloc);
@@ -1296,7 +1291,7 @@ static wchar_t *make_environment_block(char **deltaenv)
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p += wlen + 1;
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}
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- git_qsort(array, nr, sizeof(*array), wenvcmp);
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+ git_stable_qsort(array, nr, sizeof(*array), wenvcmp);
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ALLOC_ARRAY(result, size + delta_size);
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for (p = result, i = 0; i < nr; i++) {
git-compat-util.h
+6
-3
@@ -1094,10 +1094,10 @@ static inline int strtol_i(char const *s, int base, int *result)
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return 0;
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}
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+void git_stable_qsort(void *base, size_t nmemb, size_t size,
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+ int(*compar)(const void *, const void *));
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#ifdef INTERNAL_QSORT
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-void git_qsort(void *base, size_t nmemb, size_t size,
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- int(*compar)(const void *, const void *));
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-#define qsort git_qsort
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+#define qsort git_stable_qsort
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#endif
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#define QSORT(base, n, compar) sane_qsort((base), (n), sizeof(*(base)), compar)
@@ -1108,6 +1108,9 @@ static inline void sane_qsort(void *base, size_t nmemb, size_t size,
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qsort(base, nmemb, size, compar);
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}
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+#define STABLE_QSORT(base, n, compar) \
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+ git_stable_qsort((base), (n), sizeof(*(base)), compar)
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+
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#ifndef HAVE_ISO_QSORT_S
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int git_qsort_s(void *base, size_t nmemb, size_t size,
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int (*compar)(const void *, const void *, void *), void *ctx);
stable-qsort.c
renamed
+3
-3
@@ -1,4 +1,4 @@
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-#include "../git-compat-util.h"
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+#include "git-compat-util.h"
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/*
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* A merge sort implementation, simplified from the qsort implementation
@@ -44,8 +44,8 @@ static void msort_with_tmp(void *b, size_t n, size_t s,
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memcpy(b, t, (n - n2) * s);
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}
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-void git_qsort(void *b, size_t n, size_t s,
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- int (*cmp)(const void *, const void *))
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+void git_stable_qsort(void *b, size_t n, size_t s,
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+ int (*cmp)(const void *, const void *))
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{
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const size_t size = st_mult(n, s);
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char buf[1024];