Switch over to using our own qsort() all the time, as has been proposed

repeatedly.  Now that we don't have to worry about memory leaks from
glibc's qsort, we can safely put CHECK_FOR_INTERRUPTS into the tuplesort
comparators, as was requested a couple months ago.  Also, get rid of
non-reentrancy and an extra level of function call in tuplesort.c by
providing a variant qsort_arg() API that passes an extra void * argument
through to the comparison routine.  (We might want to use that in other
places too, I didn't look yet.)

1 files changed, 201 insertions, 0 deletions

diff --git a/src/port/qsort_arg.c b/src/port/qsort_arg.c
new file mode 100644
index 00000000000..ac7b149b5ff
--- /dev/null
+++ b/src/port/qsort_arg.c
@@ -0,0 +1,201 @@
+/*
+ *	qsort_arg.c: qsort with a passthrough "void *" argument
+ *
+ *	Modifications from vanilla NetBSD source:
+ *	  Add do ... while() macro fix
+ *	  Remove __inline, _DIAGASSERTs, __P
+ *	  Remove ill-considered "swap_cnt" switch to insertion sort,
+ *	  in favor of a simple check for presorted input.
+ *
+ *	CAUTION: if you change this file, see also qsort.c
+ *
+ *	$PostgreSQL: pgsql/src/port/qsort_arg.c,v 1.1 2006/10/03 22:18:23 tgl Exp $
+ */
+
+/*	$NetBSD: qsort.c,v 1.13 2003/08/07 16:43:42 agc Exp $	*/
+
+/*-
+ * Copyright (c) 1992, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *	  notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *	  notice, this list of conditions and the following disclaimer in the
+ *	  documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *	  may be used to endorse or promote products derived from this software
+ *	  without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.	IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include "c.h"
+
+
+static char *med3(char *a, char *b, char *c,
+				  qsort_arg_comparator cmp, void *arg);
+static void swapfunc(char *, char *, size_t, int);
+
+#define min(a, b)	((a) < (b) ? (a) : (b))
+
+/*
+ * Qsort routine based on J. L. Bentley and M. D. McIlroy,
+ * "Engineering a sort function",
+ * Software--Practice and Experience 23 (1993) 1249-1265.
+ * We have modified their original by adding a check for already-sorted input,
+ * which seems to be a win per discussions on pgsql-hackers around 2006-03-21.
+ */
+#define swapcode(TYPE, parmi, parmj, n) \
+do {		\
+	size_t i = (n) / sizeof (TYPE);			\
+	TYPE *pi = (TYPE *)(void *)(parmi);			\
+	TYPE *pj = (TYPE *)(void *)(parmj);			\
+	do {						\
+		TYPE	t = *pi;			\
+		*pi++ = *pj;				\
+		*pj++ = t;				\
+		} while (--i > 0);				\
+} while (0)
+
+#define SWAPINIT(a, es) swaptype = ((char *)(a) - (char *)0) % sizeof(long) || \
+	(es) % sizeof(long) ? 2 : (es) == sizeof(long)? 0 : 1;
+
+static void
+swapfunc(a, b, n, swaptype)
+char	   *a,
+		   *b;
+size_t		n;
+int			swaptype;
+{
+	if (swaptype <= 1)
+		swapcode(long, a, b, n);
+	else
+		swapcode(char, a, b, n);
+}
+
+#define swap(a, b)						\
+	if (swaptype == 0) {					\
+		long t = *(long *)(void *)(a);			\
+		*(long *)(void *)(a) = *(long *)(void *)(b);	\
+		*(long *)(void *)(b) = t;			\
+	} else							\
+		swapfunc(a, b, es, swaptype)
+
+#define vecswap(a, b, n) if ((n) > 0) swapfunc((a), (b), (size_t)(n), swaptype)
+
+static char *
+med3(char *a, char *b, char *c, qsort_arg_comparator cmp, void *arg)
+{
+	return cmp(a, b, arg) < 0 ?
+		(cmp(b, c, arg) < 0 ? b : (cmp(a, c, arg) < 0 ? c : a))
+		: (cmp(b, c, arg) > 0 ? b : (cmp(a, c, arg) < 0 ? a : c));
+}
+
+void
+qsort_arg(void *a, size_t n, size_t es, qsort_arg_comparator cmp, void *arg)
+{
+	char	   *pa,
+			   *pb,
+			   *pc,
+			   *pd,
+			   *pl,
+			   *pm,
+			   *pn;
+	int			d,
+				r,
+				swaptype,
+				presorted;
+
+loop:SWAPINIT(a, es);
+	if (n < 7)
+	{
+		for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
+			for (pl = pm; pl > (char *) a && cmp(pl - es, pl, arg) > 0;
+				 pl -= es)
+				swap(pl, pl - es);
+		return;
+	}
+	presorted = 1;
+	for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
+	{
+		if (cmp(pm - es, pm, arg) > 0)
+		{
+			presorted = 0;
+			break;
+		}
+	}
+	if (presorted)
+		return;
+	pm = (char *) a + (n / 2) * es;
+	if (n > 7)
+	{
+		pl = (char *) a;
+		pn = (char *) a + (n - 1) * es;
+		if (n > 40)
+		{
+			d = (n / 8) * es;
+			pl = med3(pl, pl + d, pl + 2 * d, cmp, arg);
+			pm = med3(pm - d, pm, pm + d, cmp, arg);
+			pn = med3(pn - 2 * d, pn - d, pn, cmp, arg);
+		}
+		pm = med3(pl, pm, pn, cmp, arg);
+	}
+	swap(a, pm);
+	pa = pb = (char *) a + es;
+	pc = pd = (char *) a + (n - 1) * es;
+	for (;;)
+	{
+		while (pb <= pc && (r = cmp(pb, a, arg)) <= 0)
+		{
+			if (r == 0)
+			{
+				swap(pa, pb);
+				pa += es;
+			}
+			pb += es;
+		}
+		while (pb <= pc && (r = cmp(pc, a, arg)) >= 0)
+		{
+			if (r == 0)
+			{
+				swap(pc, pd);
+				pd -= es;
+			}
+			pc -= es;
+		}
+		if (pb > pc)
+			break;
+		swap(pb, pc);
+		pb += es;
+		pc -= es;
+	}
+	pn = (char *) a + n * es;
+	r = min(pa - (char *) a, pb - pa);
+	vecswap(a, pb - r, r);
+	r = min(pd - pc, pn - pd - es);
+	vecswap(pb, pn - r, r);
+	if ((r = pb - pa) > es)
+		qsort_arg(a, r / es, es, cmp, arg);
+	if ((r = pd - pc) > es)
+	{
+		/* Iterate rather than recurse to save stack space */
+		a = pn - r;
+		n = r / es;
+		goto loop;
+	}
+/*		qsort_arg(pn - r, r / es, es, cmp, arg);*/
+}