Re: Debugging case refs

[Ben Pfaff]

John Darrington <address@hidden> writes:

> On Mon, Oct 25, 2010 at 09:57:47PM -0700, Ben Pfaff wrote:
>      
>      From: Ben Pfaff <address@hidden>
>      Date: Mon, 25 Oct 2010 21:56:48 -0700
>      Subject: [PATCH] case: Add support for debugging case reference count 
> leaks.
>       
>      -static inline struct ccase *case_ref (const struct ccase *);
>      +struct ccase *case_ref (const struct ccase *);
>
> I think it's important that the case_ref function has the WARN_UNUSED_RESULT 
> flag.
> When DEBUG_CASEREFS=1, simply calling case_ref (c) without assigning the 
> result
> will not copy the case.

Good point, thanks.

Here's the same patch with that one change:

--8<--------------------------cut here-------------------------->8--

From: Ben Pfaff <address@hidden>
Date: Tue, 26 Oct 2010 07:34:45 -0700
Subject: [PATCH] case: Add support for debugging case reference count leaks.

---
 src/data/case.c |   23 ++++++++++++++++++++++-
 src/data/case.h |   14 ++------------
 2 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/src/data/case.c b/src/data/case.c
index dc40292..ffb47fe 100644
--- a/src/data/case.c
+++ b/src/data/case.c
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 2004, 2007, 2009 Free Software Foundation, Inc.
+   Copyright (C) 2004, 2007, 2009, 2010 Free Software Foundation, Inc.
 
    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
@@ -30,6 +30,14 @@
 #include "minmax.h"
 #include "xalloc.h"
 
+/* Set this flag to 1 to copy cases instead of ref counting them.
+   This is sometimes helpful in debugging situations. */
+#define DEBUG_CASEREFS 0
+
+#if DEBUG_CASEREFS
+#warning "Caseref debug enabled.  CASES ARE NOT BEING SHARED!!"
+#endif
+
 static size_t case_size (const struct caseproto *);
 static bool variable_matches_case (const struct ccase *,
                                    const struct variable *);
@@ -80,6 +88,19 @@ case_clone (const struct ccase *c)
   return case_unshare (case_ref (c));
 }
 
+/* Increments case C's reference count and returns C.  Afterward,
+   case C is shared among its reference count holders. */
+struct ccase *
+case_ref (const struct ccase *c_)
+{
+  struct ccase *c = CONST_CAST (struct ccase *, c_);
+  c->ref_cnt++;
+#if DEBUG_CASEREFS
+  c = case_unshare__ (c);
+#endif
+  return c;
+}
+
 /* Returns an estimate of the number of bytes of memory that
    would be consumed in creating a case based on PROTO.  The
    estimate includes typical overhead from malloc() in addition
diff --git a/src/data/case.h b/src/data/case.h
index d00c2ad..c07b07d 100644
--- a/src/data/case.h
+++ b/src/data/case.h
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 2004, 2007, 2009 Free Software Foundation, Inc.
+   Copyright (C) 2004, 2007, 2009, 2010 Free Software Foundation, Inc.
 
    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
@@ -61,7 +61,7 @@ struct ccase *case_try_create (const struct caseproto *) 
MALLOC_LIKE;
 struct ccase *case_clone (const struct ccase *) MALLOC_LIKE;
 
 static inline struct ccase *case_unshare (struct ccase *) WARN_UNUSED_RESULT;
-static inline struct ccase *case_ref (const struct ccase *);
+struct ccase *case_ref (const struct ccase *) WARN_UNUSED_RESULT;
 static inline void case_unref (struct ccase *);
 static inline bool case_is_shared (const struct ccase *);
 
@@ -130,16 +130,6 @@ case_unshare (struct ccase *c)
   return c;
 }
 
-/* Increments case C's reference count and returns C.  Afterward,
-   case C is shared among its reference count holders. */
-static inline struct ccase *
-case_ref (const struct ccase *c_)
-{
-  struct ccase *c = CONST_CAST (struct ccase *, c_);
-  c->ref_cnt++;
-  return c;
-}
-
 /* Decrements case C's reference count.  Frees C if its
    reference count drops to 0.
 
-- 
Ben Pfaff 
http://benpfaff.org