intobject.c: Save references to small integers, so that they can be

	shared.  The default is to save references to the integers in
	the range -1..99.  The lower limit can be set by defining
	NSMALLNEGINTS (absolute value of smallest integer to be saved)
	and NSMALLPOSINTS (1 more than the largest integer to be
	saved).
tupleobject.c: Save a reference to the empty tuple to be returned
	whenever a tuple of size 0 is requested.  Tuples of size 1
	upto, but not including, MAXSAVESIZE (default 20) are put in
	free lists when deallocated.  When MAXSAVESIZE equals 1, only
	share references to the empty tuple, when MAXSAVESIZE equals
	0, don't include the code at all and revert to the old
	behavior.
object.c: Print some more statistics when COUNT_ALLOCS is defined.

1 files changed, 50 insertions, 5 deletions

diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index fae9386968..bc6874445d 100644
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -26,6 +26,21 @@ OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
 #include "allobjects.h"
 
+#ifndef MAXSAVESIZE
+#define MAXSAVESIZE	20
+#endif
+
+#if MAXSAVESIZE > 0
+/* Entries 1 upto MAXSAVESIZE are free lists, entry 0 is the empty
+   tuple () of which at most one instance will be allocated.
+*/
+static tupleobject *free_list[MAXSAVESIZE];
+#endif
+#ifdef COUNT_ALLOCS
+int fast_tuple_allocs;
+int tuple_zero_allocs;
+#endif
+
 object *
 newtupleobject(size)
 	register int size;
@@ -36,15 +51,39 @@ newtupleobject(size)
 		err_badcall();
 		return NULL;
 	}
-	op = (tupleobject *)
-		malloc(sizeof(tupleobject) + size * sizeof(object *));
-	if (op == NULL)
-		return err_nomem();
+#if MAXSAVESIZE > 0
+	if (size == 0 && free_list[0]) {
+		op = free_list[0];
+		INCREF(op);
+#ifdef COUNT_ALLOCS
+		tuple_zero_allocs++;
+#endif
+		return (object *) op;
+	}
+	if (0 < size && size < MAXSAVESIZE && (op = free_list[size]) != NULL) {
+		free_list[size] = (tupleobject *) op->ob_item[0];
+#ifdef COUNT_ALLOCS
+		fast_tuple_allocs++;
+#endif
+	} else
+#endif
+	{
+		op = (tupleobject *)
+			malloc(sizeof(tupleobject) + size * sizeof(object *));
+		if (op == NULL)
+			return err_nomem();
+	}
 	op->ob_type = &Tupletype;
 	op->ob_size = size;
 	for (i = 0; i < size; i++)
 		op->ob_item[i] = NULL;
 	NEWREF(op);
+#if MAXSAVESIZE > 0
+	if (size == 0) {
+		free_list[0] = op;
+		INCREF(op);	/* extra INCREF so that this is never freed */
+	}
+#endif
 	return (object *) op;
 }
 
@@ -113,7 +152,13 @@ tupledealloc(op)
 		if (op->ob_item[i] != NULL)
 			DECREF(op->ob_item[i]);
 	}
-	free((ANY *)op);
+#if MAXSAVESIZE > 0
+	if (0 < op->ob_size && op->ob_size < MAXSAVESIZE) {
+		op->ob_item[0] = (object *) free_list[op->ob_size];
+		free_list[op->ob_size] = op;
+	} else
+#endif
+		free((ANY *)op);
 }
 
 static int