From d40761d7258cd509d698c210fc6c478bd7788c6b Mon Sep 17 00:00:00 2001
From: Michael Brown
Date: Sun, 29 Apr 2007 23:53:39 +0000
Subject: Add (and use) generic reference counter, to improve signal:noise
 ratio in code defining reference-counted objects.

---
 src/core/interface.c | 43 +++----------------------------
 src/core/job.c       |  2 +-
 src/core/refcnt.c    | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/core/xfer.c      |  2 +-
 4 files changed, 78 insertions(+), 42 deletions(-)
 create mode 100644 src/core/refcnt.c

(limited to 'src/core')

diff --git a/src/core/interface.c b/src/core/interface.c
index 15df49d3c..8498425cd 100644
--- a/src/core/interface.c
+++ b/src/core/interface.c
@@ -16,7 +16,6 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
-#include <assert.h>
 #include <gpxe/interface.h>
 
 /** @file
@@ -25,30 +24,6 @@
  *
  */
 
-/**
- * Obtain reference to interface
- *
- * @v intf		Interface
- * @ret intf		Interface
- *
- * Increases the reference count on the interface.
- */
-static struct interface * intf_get ( struct interface *intf ) {
-	intf->refcnt ( intf, +1 );
-	return intf;
-}
-
-/**
- * Drop reference to interface
- *
- * @v intf		Interface
- *
- * Decreases the reference count on the interface.
- */
-static void intf_put ( struct interface *intf ) {
-	intf->refcnt ( intf, -1 );
-}
-
 /**
  * Plug an interface into a new destination interface
  *
@@ -63,19 +38,7 @@ static void intf_put ( struct interface *intf ) {
  * interface into a null interface.
  */
 void plug ( struct interface *intf, struct interface *dest ) {
-	intf_put ( intf->dest );
-	intf->dest = intf_get ( dest );
-}
-
-/**
- * Null update reference count
- *
- * @v intf		Interface
- * @v delta		Change to apply to reference count
- *
- * Use this as the refcnt() method for an interface that does not need
- * to support reference counting.
- */
-void null_refcnt ( struct interface *intf __unused, int delta __unused ) {
-	/* Do nothing */
+	ref_put ( intf->refcnt );
+	ref_get ( dest->refcnt );
+	intf->dest = dest;
 }
diff --git a/src/core/job.c b/src/core/job.c
index fc60f4ece..d6ec27bc0 100644
--- a/src/core/job.c
+++ b/src/core/job.c
@@ -71,7 +71,7 @@ struct job_interface_operations null_job_ops = {
 struct job_interface null_job = {
 	.intf = {
 		.dest = &null_job.intf,
-		.refcnt = null_refcnt,
+		.refcnt = NULL,
 	},
 	.op = &null_job_ops,
 };
diff --git a/src/core/refcnt.c b/src/core/refcnt.c
new file mode 100644
index 000000000..4efd9d715
--- /dev/null
+++ b/src/core/refcnt.c
@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <stdlib.h>
+#include <gpxe/refcnt.h>
+
+/** @file
+ *
+ * Reference counting
+ *
+ */
+
+/**
+ * Increment reference count
+ *
+ * @v refcnt		Reference counter, or NULL
+ *
+ * If @c refcnt is NULL, no action is taken.
+ */
+void ref_get ( struct refcnt *refcnt ) {
+
+	if ( ! refcnt )
+		return;
+
+	refcnt->refcnt++;
+
+	DBGC ( refcnt, "REFCNT %p incremented to %d\n",
+	       refcnt, refcnt->refcnt );
+}
+
+/**
+ * Decrement reference count
+ *
+ * @v refcnt		Reference counter, or NULL
+ *
+ * If the reference count decreases below zero, the object's free()
+ * method will be called.
+ *
+ * If @c refcnt is NULL, no action is taken.
+ */
+void ref_put ( struct refcnt *refcnt ) {
+
+	if ( ! refcnt )
+		return;
+
+	refcnt->refcnt--;
+	DBGC ( refcnt, "REFCNT %p decremented to %d\n",
+	       refcnt, refcnt->refcnt );
+
+	if ( refcnt->refcnt >= 0 )
+		return;
+
+	if ( refcnt->free ) {
+		refcnt->free ( refcnt );
+	} else {
+		free ( refcnt );
+	}
+}
diff --git a/src/core/xfer.c b/src/core/xfer.c
index d34808166..f927269ea 100644
--- a/src/core/xfer.c
+++ b/src/core/xfer.c
@@ -230,7 +230,7 @@ struct xfer_interface_operations null_xfer_ops = {
 struct xfer_interface null_xfer = {
 	.intf = {
 		.dest = &null_xfer.intf,
-		.refcnt = null_refcnt,
+		.refcnt = NULL,
 	},
 	.op = &null_xfer_ops,
 };
-- 
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