From: Robert Haas <rhaas@postgresql.org>
Date: Tue, 21 Jan 2014 14:13:16 +0000 (-0500)
Subject: Hack.
X-Git-Url: http://waps.l3s.uni-hannover.de/gitweb/?a=commitdiff_plain;h=b69b27237f25dca93c0160ef7bc4679b2568c206;p=users%2Frhaas%2Fpostgres.git

Hack.
---

diff --git a/src/backend/utils/mmgr/mspan.c b/src/backend/utils/mmgr/mspan.c
index 372bd9f2e6..c0a81e5253 100644
--- a/src/backend/utils/mmgr/mspan.c
+++ b/src/backend/utils/mmgr/mspan.c
@@ -501,6 +501,33 @@ mspan_allocate_context_descriptor(char *base, mspan_manager *mgr)
 static char *
 mspan_allocate_from_superblock(char *base, mspan *superblock)
 {
+	char   *spanbase;
+	uint16	object_size;
+	uint16	total;
+
+	/* Quick exit if there are no free objects. */
+	object_size = mspan_size_classes[superblock->span_type];
+	total = MSPAN_SUPERBLOCK_SIZE / object_size;
+	if (superblock->nused >= total)
+		return NULL;
+
+	/* Try to reuse a previously-freed object. */
+	spanbase = base + superblock->first_page * MSPAN_PAGE_SIZE;
+	if (superblock->firstfree != MSPAN_FIRSTFREE_NONE)
+	{
+		uint16 *firstfree;
+
+		firstfree =
+			(uint16 *) (spanbase + (superblock->firstfree * object_size));
+		superblock->firstfree = *firstfree;
+		return (char *) firstfree;
+	}
+
+	/*
+	 * Carve out space from the uninitialized portion of the span.  This
+	 * should always work, since we already verified that nused < total.
+	 */
+
 	/*
 	 * XXX. Implementation needed.
 	 */